SMOKE MANAGEMENT GUIDE FOR

PRESCRIBED AND WILDLAND FIRE

2001 Edition

EDITORS/COMPILERS: PRODUCED BY:

Colin C. Hardy National Wildfire Coordinating Group

Roger D. Ottmar Fire Use Working Team

Janice L. Peterson

John E. Core

Paula Seamon

Additional copies of this publication may be ordered by mail/fax from:

National Interagency Fire Center, ATTN: Great Basin Cache Supply Office

3833 S. Development Avenue

Boise, Idaho 83705. Fax: 208-387-5573.

Order NFES 1279

An electronic copy of this document is available at http://www.nwcg.gov.

________________________________________________________________________

The National Wildfire Coordinating Group (NWCG) has developed this information for the guidance of its member agencies and

is not responsible for the interpretation or use of this information by anyone except the member agencies. The use of trade, firm,

or corporation names in this publication is for the information and convenience of the reader and does not constitute an endorsement by NWCG of any product or service to the exclusion of others that may be suitable.

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2001 Smoke Management Guide Forward

Forward

The National Wildfire Coordinating Group’s (NWCG) Fire Use Working Team1 has assumed overall

responsibility for sponsoring the development and production of this revised Smoke Management

Guide for Prescribed and Wildland Fire (the “Guide”). The Mission Statement for the Fire Use Working Team includes the need to coordinate and advocate the use of fire to achieve management objectives, and to promote a greater understanding of the role of fire and its effects. The Fire Use Working

Team recognizes that the ignition of wildland fuels by land managers, or the use of wildland fires

ignited by natural causes to achieve specific management objectives is receiving continued emphasis

from fire management specialists, land managers, environmental groups, politicians and the general

public. Yet, at the same time that fire use programs are increasing, concerns are being expressed

regarding associated “costs” such as smoke management problems. This revised Guide is the Fire Use

Working Team’s contribution to a better national understanding and application of smoke management.

Bill Leenhouts—Chair

NWCG Fire Use Working Team

___________________________________

1 The NWCG website [http://www.nwcg.gov] contains documentation and descriptions for all NWCG working teams.
Preface 2001 Smoke Management Guide

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– iii –

2001 Smoke Management Guide Preface

Preface

The National Wildfire Coordinating Group’s Fire Use Working Team sponsored this 2001 edition of the

Smoke Management Guide for Prescribed and Wildland Fire. A six-member steering committee was

responsible for development of a general outline and for coordination of the Guide’s production. The

editors/compilers invited the individual contributions, edited submissions, authored many of the sections, obtained comprehensive reviews from the NWCG agencies and other partners, and compiled the

final material into a cohesive guidebook.

Steering Committee: Bill Leenhouts (chair, NWCG Fire Use Working Team), Colin C. Hardy, Roger

D. Ottmar, Janice L. Peterson, John E. Core, Paula Seamon.

Authors:

Gary Achtemeier, Research Meteorologist,

USDA Forest Service, Southern Research

Station. Athens, GA

James D. Brenner, Fire Management Administrator, State of Florida Dept. of Agriculture and

Consumer Service, Division of Forestry,

Tallahassee, FL

John E. Core, Consultant, Core Environmental

Consulting. Portland, OR

Sue A. Ferguson, Research Atmospheric Scientist, USDA Forest Service, Pacific Northwest

Research Station. Seattle, WA

Colin C. Hardy, Research Forester

USDA Forest Service, Rocky Mountain Research Station. Missoula, MT

Sharon M. Hermann, Research Ecologist,

Department of Biological Sciences, Auburn

University. Auburn, AL

Bill Jackson, Air Resource Specialist, USDA

Forest Service, Region 8, Asheville, NC

Peter Lahm, Air Resource Program Manager,

USDA Forest Service, Arizona National Forests.

Phoenix, AZ

Bill Leenhouts, Fire Ecologist, USDI Fish and

Wildlife Service, National Interagency Fire

Center. Boise, ID

Tom Leuschen, Owner—Fire Vision, USDA

Forest Service, Okanagon National Forest.

Okanagon, WA

Robert E. Mutch, Consultant Forester, Systems for Environmental Management. Missoula,

MT

Roger D. Ottmar, Research Forester, USDA

Forest Service, Pacific Northwest Research

Station. Seattle, WA

Janice L. Peterson, Air Resource Specialist,

USDA Forest Service, Mt. Baker-Snoqualmie

National Forest. Mountlake Terrace, WA

Timothy R. Reinhardt, Industrial Hygienist,

URS Corp. Bellevue, WA

Paula Seamon, Fire Management Coordinator,

The Nature Conservancy, Fire Management

Program. Tallahassee, FL

Dale Wade, Research Forester,

USDA Forest Service, Southern Research

Station. Athens, GA
Preface 2001 Smoke Management Guide

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– v –

2001 Smoke Management Guide Table of Contents

Table of Contents

Forward..................................................................................................... i

Bill Leenhouts—Chair, NWCG, Fire Use Working Team

Preface .................................................................................................... iii

1.0 Introduction .............................................................................................3

Colin C. Hardy

Bill Leenhouts

2.0 Overview

2.1 The Wildland Fire Imperative .............................................................11

Colin C. Hardy

Sharon M. Hermann

Robert E. Mutch

2.2 The Smoke Management Imperative...................................................21

Colin C. Hardy

Sharon M. Hermann

John E. Core

3.0 Smoke Impacts

3.1 Public Health and Exposure to Smoke......................................27

John E. Core

Janice L. Peterson

3.2 Visibility .........................................................................................35

John E. Core

3.3 Problem and Nuisance Smoke....................................................41

Gary L. Achtemeier

Bill Jackson

James D. Brenner

3.4 Smoke Exposure Among Fireline Personnel ............................51

Roger D. Ottmar

Timothy R. Reinhardt
Table of Contents 2001 Smoke Management Guide

– vi –

4.0 Regulations

4.1 Regulations For Smoke Management......................................... 61

Janice L. Peterson

4.2 State Smoke Management Programs.......................................... 75

John E. Core

4.3 Federal Land Management - Special Requirements ................. 81

Janice L. Peterson

5.0 Smoke Source Characteristics ............................................................ 89

Roger D. Ottmar

6.0 Fire Use Planning................................................................................ 109

Tom Leuschen

Dale Wade

Paula Seamon

7.0 Smoke Management Meteorology ..................................................... 121

Sue A. Ferguson

8.0 Smoke Management:

Techniques to Reduce or Redistribute Emissions ......................... 141

Roger D. Ottmar

Janice L. Peterson

Bill Leenhouts

John E. Core

9.0 Smoke Dispersion Prediction Systems ............................................ 163

Sue A. Ferguson

10.0 Air Quality Monitoring for Smoke ..................................................... 179

John E. Core

Janice L. Peterson

11.0 Emission Inventories .......................................................................... 189

Janice L. Peterson

12.0 Smoke Management Program Administration and Evaluation ..... 201

Peter Lahm

Appendix A – Glossary of Fire and Smoke Management Terminology .....209
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2001 Smoke Management Guide Introduction

INTRODUCTION

Chapter 1
Chapter 1 – Introduction 2001 Smoke Management Guide

– 2 –
– 3 –

2001 Smoke Management Guide Introduction

Introduction

Colin C. Hardy

Bill Leenhouts

Why Do We Need A National Smoke Management Guide?

As an ecological process, wildland fire is essential in creating and maintaining functional

ecosystems and achieving other land use objectives. As a decomposition process, wildland fire

produces combustion byproducts that are harmful to human health and welfare. Both the land

management benefits from using wildland fire

and the public health and welfare effects from

wildland fire smoke are well documented. The

challenge in using wildland fire is balancing the

public interest objectives of protecting human

health and welfare and sustaining ecological

integrity.

Minimizing the adverse effects of smoke on

human health and welfare while maximizing the

effectiveness of using wildland fire is an integrated and collaborative activity. Everyone

interested in natural resource management is

responsible and has a role. Land managers need

to assure that using wildland fire is the most

effective alternative of achieving the land

management objectives. State, regional, tribal

and national air resource managers must ensure

that air quality rules and regulations equitably

accommodate all legal emission sources.

The varied smoke management issues from

across the nation involve many diverse cultures

and interests, include a multitude of strategies

and tactics, and cover a heterogeneous landscape. No national answer or cookbook approach will adequately address them. But

people with a desire for responsible smoke

management working in partnership with the

latest science-based smoke management information can fashion effective regional smoke

management plans and programs to address

their individual and collective objectives. The

intent of the Guide is to provide the latest

science-based smoke management information

from across the nation to facilitate these collaborative efforts.

Awareness of smoke production, transport, and

effects on receptors from prescribed and wildland fires will enable us to refine existing smoke

management strategies and to develop better

smoke management plans and programs in the

future. This Guide addresses the basic control

strategies for minimizing the adverse effects of

smoke on human health and welfare—thus

maximizing the effectiveness of using wildland

fire. These control strategies are:

• Avoidance – using meteorological conditions when scheduling burning in order to

avoid incursions of wildland fire smoke

into smoke sensitive areas.

• Dilution – controlling the rate of emissions

or scheduling for dispersion to assure

tolerable concentrations of smoke in

designated areas.
Chapter 1 – Introduction 2001 Smoke Management Guide

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• Emissions-reduction – using techniques to

minimize the smoke output per unit area

treated and decrease the contribution to

regional haze as well as intrusions into

designated areas.

Guide Goals and

Considerations

The Smoke Management Guide steering committee and the NWCG Fire Use Working Team

developed this Guide with the following goals:

• Provide fire use practitioners with a

fundamental understanding of fire-emissions processes and impacts, regulatory

objectives, and tools for the management

of smoke from wildland fires.

• Provide local, state, tribal, and federal air

quality managers with background information related to the wildland fire and

emissions processes and air, land and

wildland fire management.

The following considerations provide the context within which these goals can be met:

• This document is about smoke management, not about the decision to use wildland fire or its alternatives. Its purpose is

not to advocate for or against the use of

fire to meet land management objectives.

• While the Guide contains relevant background material and resources generally

useful to development of smoke management programs, it is not a tutorial on how

to develop a state smoke management

program.

• Although the Guide is replete with information and examples for potential application at the local and regional level, the

Guide generally focuses on national smoke

management principles. For maximum

benefit to local or regional applications,

appropriate supplements should be developed for the scale or geographical location

of the respective application.

• The Guide is more appropriate for knowledgeable air, land, and wildland fire

managers, and is not intended for novice

readers.

Overview and

Organization of the Guide

The Smoke Management Guide for Prescribed

and Wildland Fire–2001 Edition follows a

textbook model so that it can be used as a

supplemental reference in smoke management

training sessions and courses such as the

NWCG Smoke Management course, RX-410

(formerly RX-450). Following an Introduction, a background chapter presents a primer on

wildland fire and a discussion of the imperatives

for smoke management. In the Wildland Fire

Imperative, the Guide addresses both the

ecological and societal aspects of wildland fire

(not agricultural, construction debris, or other

biomass burning), and provides the details

necessary for fire use practitioners and air

quality managers to understand the fundamentals of fire in wildlands. The Smoke Management Imperative discusses the needs for smoke

management as well as its benefits and costs.

The background sections are followed by chapters presenting details on Wildland Fire Smoke

Impacts—public health, visibility, problem and

nuisance smoke, and smoke exposure among

fireline personnel—and on Regulations for

Smoke Management. The chapter on Smoke

Source Characteristics follows a sequence

similar to the basic pathway that smoke produc-
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2001 Smoke Management Guide Introduction

___________________________________

1 For a comprehensive presentation of fire terminology, the reader should refer to the NWCG Glossary of Wildland

Fire Terminology (NWCG 1996—PMS #205, Boise, ID).

tion does—from the pre-fire fuel characteristics

and the fire phenomenon as an emissions

source, through the processes of combustion,

biomass consumption and emissions production.

The chapter on Fire Use Planning addresses

important considerations for developing a

comprehensive fire use plan (a “burn plan”).

The general planning process is reviewed, from

developing a general land use plan, through a

fire management plan and, ultimately, to a unitspecific burn plan.

The Smoke Management Meteorology chapter

presents a primer on the use of weather observations and forecasts, and then provides information regarding the transport and dispersion of

smoke from wildland fires.

Techniques to Reduce or Redistribute Emissions are presented in an exhaustive list and

synthesis of emissions reduction and impact

reduction practices and techniques. These

practices and techniques were initially compiled

as the outcomes of three regional workshops

held specifically for the purpose of synthesizing

current and potential smoke management tools.

Presented here in a nationally applicable format,

they are the fundamental tools available to fire

planners and fire use practitioners for the management and mitigation of smoke from wildland

fires.

The Smoke Dispersion Prediction Systems

chapter reviews current prediction tools within

the context of three “families” of model applications—screening, planning, or regulating.

Air Quality Monitoring for Smoke discusses

various objectives for monitoring, and emphasizes the need to carefully match the monitoring

objective with the appropriate equipment. In

addition, the chapter presents information on

some common monitoring equipment, methods,

and their associated costs.

Emission Inventories help managers and

regulators understand how to better include fire

in an emissions inventory. This chapter discusses the use of the three basic elements

needed to perform an emission inventory—area

burned, fuel consumed, and appropriate emission factor(s).

No smoke management effort can succeed

without continued assessment and feedback.

The chapter on Program Administration and

Assessment discusses the need to maintain a

balance between the level of effort in a program

and the level of prescribed or fire use activity as

well as their associated local or regional effects.

Each section in this Guide is now supported by

an extensive list of relevant references. Also,

authorship for a specific section is given in the

table of contents, where appropriate. In such

cases, the section can be cited with its respective

author(s) as an independent “chapter” in the

Guide.

A glossary of frequently used fire and smoke

management terms1 is provided as an appendix

to the Guide.

History of Smoke

Management Guidance

The first guidance document specifically addressing the management of smoke from prescribed fires was the Southern Smoke

Management Guidebook, produced in 1976 by

the Southern Forest Fire Laboratory staff
Chapter 1 – Introduction 2001 Smoke Management Guide

– 6 –

___________________________________

2 The Joint Fire Sciences Program is sponsoring extensive revisions to the Rainbow Series fire effects volumes,

including a new volume on fire effects on air.

(1976). It was a comprehensive treatment of the

various aspects fire behavior, emissions, transport and dispersion, and the management of

smoke in the southern United States.

In 1985, NWCG’s Prescribed Fire and Fire

Effects Working Team developed the widely

accepted Prescribed Fire Smoke Management

Guide that forms the basis for this 2001 revised

Guide (NWCG 1985). The 1985 edition focused on national smoke management principles

and, as a result, was far less comprehensive than

the Southern guidebook.

One of six state-of-knowledge reports prepared

for the 1978 National Fire Effects Workshop is a

review called Effects of Fire on Air (USDA

Forest Service 1978). The six volumes, called

the “Rainbow Series” on fire effects, were in

response to the changes in policies, laws, regulations, and initiatives. Objectives specific to the

volume on air were to: “...summarize the

current state-of-knowledge of the effects of

forest burning on the air resource, and to define

research questions of high priority for the

management of smoke from prescribed and wild

fires” (USDA Forest Service 1978, p.5).2

Conflicts between prescribed fire and air quality

began to be seriously addressed in the mid1980s. Prior to this, only a few states had

developed or implemented smoke management

programs, and national-level policies addressing

smoke from wildland burns were only beginning

to be drafted. Much has changed since then,

with numerous policies and initiatives raising

the potential for conflicting resource management objectives—principally air quality and

ecosystem integrity. The Clean Air Act amendments adopted in 1990 specifically addressed

regional haze. Smoke Management Plans have

been developed by many states as administrative

rules enforceable under state law. These rules

are often incorporated into State and Tribal

Implementation Plans (SIPs and TIPs) for

submission to the U.S. Environmental Protection Agency (EPA) and, once promulgated by

EPA, are then enforceable under federal law as

well. And now, the role of fire and the need for

its accelerated use has become widely recognized with respect to maintenance and restoration of fire-adapted ecosystems. These issues

all point to the imperative for better knowledge

and more informed collaboration between

managers of both the air and terrestrial resources.

The 2001 Edition of the Smoke

Management Guide

Recognizing the increasing likelihood of impacting the public, the proliferation of federal,

state, and local statutes, rules and ordinances

pertaining to smoke, as well as major improvements to our knowledge of smoke and its management, the NWCG Fire Use Working Team

(formerly named the Prescribed Fire and Fire

Effects Working Team) sponsored revision of

the Guide. Conceptually, the Fire Use Working

Team identified the need for a revised guidebook that targeted not just prescribed fire practitioners, but state and local air quality and public

health agency personnel as well. A consequence

of this expansion of the target audience was the

need to substantially augment the background

information with respect to fire in wildlands.

A suite of potential smoke management practices and techniques are not only suggested in
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2001 Smoke Management Guide Introduction

this Guide, but their relative effectiveness and

regionally-specific applicability are also provided. This information was acquired through

three regional workshops held in collaboration

with the U.S. Environmental Protection

Agency’s Office of Air Quality Planning and

Standards.

This revised Guide now emphasizes both emission and impact reduction methods that have

been found to be practical, useful, and beneficial. This new emphasis on reducing emissions

is in response to regional haze and fine particle

(PM2.5) control programs that will require

emission reductions from a wide variety of

pollution sources (including prescribed and

wildland fire). This is especially important in

view of the major increases in the use of fire

projected by federal land managers. Readers

will also find a greatly expanded discussion of

air quality regulatory requirements, reflecting

the growing complexities and demands on

today’s fire practitioners.

Literature Citations

NWCG. 1985. Prescribed fire smoke management

guide. NWCG publication PMS-420-2. Boise,

ID. National Wildfire Coordinating Group.

28 p.

Southern Forest Fire Laboratory Staff. 1976. Southern forestry smoke management guidebook.

USDA For. Serv. Gen. Tech. Rep. SE-10.

Asheville, N.C. USDA Forest Service, Southeast Forest Experiment Station. 140 p.

USDA Forest Service. 1978. Effects of fire on air.

USDA For. Serv. Gen. Tech. Rep. WO-9.

Washington, D.C. USDA Forest Service. 40 p.
Chapter 2 – Overview 2001 Smoke Management Guide

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– 9 –

2001 Smoke Management Guide 2.1 – The Wildland Fire Imperative

OVERVIEW

Chapter 2
Chapter 2 – Overview 2001 Smoke Management Guide

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2001 Smoke Management Guide 2.1 – The Wildland Fire Imperative

The Wildland Fire Imperative

Colin C. Hardy

Sharon M. Hermann

Robert E. Mutch

Perpetuating America’s Natural Heritage: Balancing

Wildland Management Needs and the Public Interest

Strategies for responsible and effective smoke

management cannot be developed without

careful consideration of the ecological and the

societal impacts of fire management in the

wildlands of modern America. The need to

consider both perspectives is acknowledged by

most land management agencies, as well as by

the U.S. Environmental Protection Agency

(EPA) —the primary Federal agency responsible

for protecting air quality. An awareness of this

challenge is reflected in NWCG’s education

message, Managing Wildland Fire: Balancing

America’s Natural Heritage and the Public

Interest (NWCG 1998). The preamble to this

document not only states that “fire is an important and inevitable part of America’s wildlands,”

but also recognizes that “wildland fires can

produce both benefits and damages—to the

environment and to people’s interests.”

The EPA’s Interim Air Quality Policy on Wildland and Prescribed Fires (U.S. EPA 1998)

employs similar language to describe related

public policy goals: (1) To allow fire to function,

as nearly as possible, in its natural role in

maintaining healthy wildland ecosystems; and,

(2) To protect public health and welfare by

mitigating the impacts of air pollutant emissions

on air quality and visibility. The document

comments on the responsibilities of wildland

owners/managers and State/tribal air quality

managers to coordinate fire activities, minimize

air pollutant emissions, manage smoke from

prescribed fires as well as wildland fires used

for resource benefits, and establish emergency

action programs to mitigate the unavoidable

impacts on the public. In addition, EPA asserts

that “this policy is not intended to limit opportunities by private wildland owners/managers to

use fire so that burning can be increased on

publicly owned wildlands.”

In this and the following section (2.2–The

Smoke Management Imperative), we outline

both ecological and societal aspects of wildland

and prescribed fire. We review the historical

role and extent of fire and the effects of settlement and land use changes. The influence of

fire exclusion policies on historical disturbance

processes is considered in light of modern

landscape conditions. This provides the basis

for discussion of significant, recent changes in

Federal wildland fire policy and new initiatives

for accelerating use of prescribed and wildland

fire to achieve resource management objectives.

Finally, we present examples of the impacts of
Chapter 2 – Overview 2001 Smoke Management Guide

– 12 –

wildland smoke on air quality, human health,

and safety.

Fire in Wildlands

Recurring fires are often an essential component

of the natural environment—as natural as rain,

snow, or wind. Evidence for the recurrence of

past fires is found in charcoal layers of lakes and

bogs, in fire-scars of trees, and in the morphological and life history adaptations of numerous

native plants and animals. Many ecosystems in

North America and throughout the world are

fire-dependent (Heinselman 1978) and periodic

burning is essential for healthy ecosystem

functioning in these wildlands. Fire acts at the

individual, population, and community levels

and can influence:

• Plant succession.

• Fuel accumulation and decay.

• Recruitment pattern and age distribution of individuals.

• Species composition of vegetation.

• Disease and insect pathogens.

• Nutrient cycles and energy flows.

• Biotic productivity, diversity, and

stability.

• Habitat structure for wildlife.

For millennia, lightning, volcanoes, and people

have ignited fires in wildland ecosystems. The

current emphasis on ecosystem management

calls for the maintenance of interactions between such disturbance processes and ecosystem functions. Therefore, it is incumbent on

both fire and natural resource managers to

understand the range of historical frequency,

severity, and aerial extent of past burns. This

knowledge provides a frame of reference for

applying appropriate management practices on a

landscape scale, including the use and exclusion

of fire.

Many studies have described the historical

occurrence of fires throughout the world. For

example, Swetnam (1993) used fire scars to

describe a 2000-year period of fire history in

giant sequoia groves in California. He found

that frequent small fires occurred during a warm

period from about A.D. 1000 to 1300, and less

frequent but more widespread fires occurred

during cooler periods from about A.D. 500-1000

and after 1300. Swain (1973) determined from

lake sediment analyses in the Boundary Waters

Canoe Area in Minnesota that tree species and

fire had interacted in complex ways over a

10,000-year period. Other studies ranging from

Maine (e.g. Copenheaver and others 2000) to

Florida (e.g. Watts and others 1992) have employed pollen and charcoal deposits to demonstrate shifts in fire frequency correlated with the

onset of European settlement.

There is an even larger body of science that

details the numerous effects of wildland fires on

components of ecosystems. Some of the most

compelling examples of fire dependency come

from studies on plant reproduction and establishment. For instance, there are at least ten

species of pines scattered over the United States

that have serotinous cones; that is to say the

cones are sealed by resin; the cone scales do not

open and seeds do not disperse until the resin is

exposed to high heat (reviewed in Whelan

1995). Examples of fire dependency in herbaceous plants include flowering of wiregrass in

Southeastern longleaf pine forests that is greatly

enhanced by growing season burns (Myers

1990) and seed germination of California

chaparral forbs that is triggered by exposure to

smoke (Keeley and Fotheringham 1997). Animals as diverse as rare Karner blue butterflies in

Indiana (Kwilosz and Knutson 1999) to whooping cranes in Texas (Chavez Ramirez and others

1996) benefit when fire is re-introduced into

their habitats. There are numerous other types

of fire dependency in North American ecosys-
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2001 Smoke Management Guide 2.1 – The Wildland Fire Imperative

tems and many studies on this topic are summarized in books and government publications

(e.g. Agee 1993, Bond and van Wilgen 1996,

Brown and Kapler Smith 2000, Johnson 1992,

Kapler Smith 2000, Wade and others 1980,

Whelan 1995). In addition, there is a small but

growing volume of literature that evaluates the

influence of fire on multiple trophic levels (e.g.

Hermann and others 1998).

Knowledge of fire history, fire regimes, and fire

effects allows land stewards to develop informed

management strategies. Application of fire may

be one of the tools used to meet resource management objectives. The role of fire as an

important disturbance process has been highlighted in a classification of continental fire

regimes (Kilgore and Heinselman 1990). These

authors describe a natural fire regime as the total

pattern of fires over time that is characteristic of

a region or ecosystem. Fire regimes are defined

in terms of fire type and severity, typical fire

sizes and patterns, and fire frequency, or length

of return intervals in years. Kilgore and

Heinselman (1990) placed natural fire regimes

of North America into seven classes, ranging

from Class 0, in which fires are rare or absent,

to Class 6, in which crown fires and severe

surface fires occur at return intervals longer than

300 years. Intermediate fire regimes, Classes 1-

5, are characterized by increasingly longer fire

return intervals and increasingly higher fire

intensities. Class 2, for example, describes the

situation for long-needled pines, like longleaf

pine, ponderosa pine, and Jeffrey pine; in this

class low severity, surface fires occur rather

frequently (return intervals of less than 25

years). Lodgepole pine, jackpine, and the boreal

forest of Canada and Alaska generally fall into

Class 4, a class in which high severity crown

fires occur every 25 to 100 years; or into Class

5, a class in which crown fires occur every 100

to 300 years. White bark pine forests at high

elevations typically fall into Class 6. For comparison, three general classes of fire are shown

in figure 2.1, including a low-intensity surface

fire, a mixed-severity fire, and a stand-replacing

crown fire.

Figure 2.1. The relative difference in general classes of fire are shown. This

series illustrates a low-intensity surface fire (a), a mixed-severity fire (b), and a

stand-replacing crown fire (c).

(b)

(a)

(c)
Chapter 2 – Overview 2001 Smoke Management Guide

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A noteworthy aspect of continental fire regimes

is that very few North American ecosystems fall

into Class 0. In other words, most ecosystems

in the United States have evolved under the

consistent influence of wildland fire, establishing fire as a process that affects numerous

ecosystem functions described earlier. Those

who apply prescribed burns or use wildland fire

often attempt to mimic the natural role of fire in

creating or maintaining ecosystems. Sustaining

the productivity of fire-adapted ecosystems

generally requires application of prescribed fire

on a sufficiently large scale to ensure that

various ecosystem processes remain intact.

Ecological Effects of

Altered Fire Regimes

As humans alter fire frequency and severity,

many plant and animal communities experience

a loss of species diversity, site degradation, and

increases in the sizes and severity of wildfires.

Ferry and others (1995) concluded that altered

fire regimes was the principal agent of change

affecting vegetative structure, composition, and

biological diversity of five major plant communities totaling over 350 million acres in the U.S.

As a way to evaluate the current amount of fire

in wildland habitat, Leenhouts (1998) compared

estimated land area burned 200-400 years ago

(“pre-industrial”) to data from the contemporary

conterminous United States. The result suggests

that ten times more acreage burned annually in

the pre-industrial era than does in modern times.

After accounting for loss of wildland area due to

land use changes such as urbanization and

agriculture, Leenhouts concluded that the

remaining wildland is burned approximately

fifty percent less compared to fire frequency

under historical fire regimes (figure 2.2).

Numerous ecosystem indicators serve as alarming examples of the effects of altered fire regimes. Land use changes, attempted fire

exclusion practices, prolonged drought, and

epidemic levels of insects and diseases have

coincided to produce extensive forest mortality,

or major changes in forest density and species

composition. Gray (1992) called attention to a

forest health emergency in parts of the western

Figure 2.2. Estimates of the range of annual area burned in the conterminous United States pre-European

settlement (Historic), applying presettlement fire frequencies to present land cover types (Expected), and

burning (wildland and agriculture) that has occurred during the recent past (Current). Source: Leenhouts

(1998).
– 15 –

2001 Smoke Management Guide 2.1 – The Wildland Fire Imperative

United States where trees have been killed

across millions of acres in eastern Oregon and

Washington. He indicated that similar problems

extend south into Utah, Nevada, and California,

and east into Idaho. Denser stands and heavy

fuel accumulations are also setting the stage for

high severity crown fires in Montana, Colorado,

Arizona, New Mexico, and Nebraska, where the

historical norm in long-needled pine forests was

for more frequent low severity surface fires (fire

regime Class 2; Kilgore and Heinselman 1990).

The paired photos in figure 2.3 illustrate 85

years of change resulting from fire exclusion on

a fire-dependent site in western Montana. In

North Carolina, Gilliam and Platt (1999) quantified the dramatic effects of over 80-years of fire

exclusion on tree species composition and stand

structure in a longleaf pine forest.

(a)

(b)

Figure 2.3. These two photos, taken of the same homestead near Sula, Montana, show 85 years of change on

a fire-dependent site where fire has been excluded. The top photo (a) was taken in 1895. By 1980 (b),

encroaching trees and shrubs occupy nearly all of the site. Stand-replacing crown fire visited this site in 2000.
Chapter 2 – Overview 2001 Smoke Management Guide

– 16 –

Since the 1960s, records show an alarming

trend towards more acres consumed by wild

fires, despite all of our advances in fire suppression technology (figure 2.4). The larger, more

severe wildfires have accelerated the rate of tree

mortality, threatening people, property, and

natural resources (Mutch 1994). These wildfires also have emitted large amounts of particulate matter into the atmosphere. One study

estimated that more than 53 million pounds of

respirable particulate matter were produced

over a 58-day period by the 1987 Silver Fire in

southwestern Oregon (Hardy and others 1992).

The ecological consequences of past policies of

fire exclusion have been foreseen for some

time. More than 50 years ago, Weaver (1943)

reported that the “complete prevention of forest

fires in the ponderosa pine region of California,

Oregon, Washington, northern Idaho, and

western Montana has certain undesirable ecological and silvicultural effects [and that]...

conditions are already deplorable and are becoming increasingly serious over large areas.”

Also, Cooper (1961) stated, “...fire has played a

major role in shaping the world’s grassland and

forests. Attempts to eliminate it have introduced

problems fully as serious as those created by

accidental conflagrations.” Only more recently

have concerns been expressed about potential

loss of biodiversity as a result of fire suppression. This issue may be especially pressing in

the Eastern United States. For example, in

southern longleaf pine ecosystems, at least 66

rare plant species are maintained by frequent

fire (Walker 1993). The ecological need for

high fire frequency in large areas of Southeastern native ecosystems coupled with the region’s

long growing season contribute to the rapid

buildup of fuel and subsequent change in habitat

structure.

Figure 2.4. The average annual burned area for the western States, shown here for the period

1916-2000, has generally been increasing since the mid-1960s
– 17 –

2001 Smoke Management Guide 2.1 – The Wildland Fire Imperative

Wildland and Prescribed Fire Terminology Update

The federal Implementation Procedures Reference Guide for Wildland and Prescribed Fire

Management Policy (USDI and USDA Forest

Service 1998) contains significant changes in

fire terminology. Several traditional terms have

either been omitted or have been made obsolete

by the new policy. These include: confine/

contain/control; escaped fire situation analysis;

management ignited prescribed fire; pre-suppression; and prescribed natural fire, or “PNF.”

Additionally, there was adoption of several new

terms and interpretations that supercedes earlier,

traditional terminology:

• Fire Use - the combination of wildland

fire use and prescribed fire application to

meet resource objectives.

• Prescribed Fire - Any fire ignited by

management actions to meet specific

objectives. A written, approved prescribed

fire plan must exist, and NEPA requirements must be met, prior to ignition. This

term replaces management ignited prescribed fire.

• Wildfire - An unwanted wildland fire.

This term was only included to give continuing credence to the historic fire prevention products. This is NOT a separate

type of fire under the new terminology.

• Wildland Fire - Any non-structure fire,

other than prescribed fire, that occurs in

the wildland. This term encompasses fires

previously called both wildfires and

prescribed natural fires.

• Wildland Fire Use - the management of

naturally-ignited wildland fires to accomplish specific pre-stated resource management objectives in predefined geographic

areas outlined in Fire Management Plans.

Wildland fire use is not to be confused

with “fire use,” which is a broader term

encompassing more than just wildland

fires.

Taking Action: The Federal Wildland and Prescribed Fire Policy

The decline in resiliency and ecological “health”

of ecosystems has reached alarming proportions

in recent decades, as evidenced by the trend

since the mid-1960’s towards more acres burned

in wildfires (figure 2.4). While national awareness of this trend has existed for some time, the

1994 fire season created a renewed awareness

and concern among Federal land management

agencies and their constituents regarding the

serious impacts of wildfires. The Federal

Wildland Fire Management Policy and Program

Review is chartered by the Secretaries of Agriculture and Interior to “ensure that uniform

federal policies and cohesive interagency and

intergovernmental fire management programs

exist” (USDI and USDA Forest Service 1995).

The review process is directed by an interagency

Steering Group whose members represented the

Departments of Agriculture and Interior, the

U.S. Fire Administration, the National Weather

Service, the Federal Emergency Management

Agency, and the Environmental Protection

Agency. In their cover letter accepting the Final

Report of the Review (December 18, 1995), the

Secretaries of Agriculture and Interior proclaimed:

“The philosophy, as well as the specific

policies and recommendations, of the

Report continues to move our approach to

wildland fire management beyond the

traditional realms of fire suppression by

further integrating fire into the management of our lands and resources in an

ongoing and systematic manner, consistent

with public health and environmental
Chapter 2 – Overview 2001 Smoke Management Guide

– 18 –

quality considerations. We strongly support the integration of wildland fire into

our land management planning and implementation activities. Managers must learn

to use fire as one of the basic tools for

accomplishing their resource management

objectives.”

USDI and USDA Forest

Service 1995—cover

memorandum

The Report asserts that “the planning, implementation, and monitoring of wildland fire

management actions will be done on an interagency basis with the involvement of all partners.” The term “partners” is all-encompassing,

including Federal land management and regulatory agencies; tribal governments; Department

of Defense; State, county, and local governments; the private sector; and the public. Partnerships are essential for establishing collective

priorities to facilitate use of fire at the landscape

level. Smoke does not respond to artificial

boundaries or delineations. Interaction among

partners is necessary to meet the dual challenge

of using fire for natural resource management

coupled with the need to minimize negative

effects related to smoke. Both concerns must be

met to fulfill the public need.

Literature Citations

Agee, J.K. 1993. Fire Ecology of Pacific Northwest

Forests. Island Press, Washington, DC.

Bond, W.J. and B.W. van Wilgen. 1996. Fire and

Plants. Chapman Hall, London.

Brown, J.K. and J. Kapler Smith (eds.). 2000.

Wildland Fire in Ecosystems: Effects of Fire on

Flora. Gen. Tech. Rep. RMRS-GTR-42-vol.2.

Ogden, UT.

Chavez Ramirez, F., H.E. Hunt, R.D. Slack and T.V.

Stehn. 1996. Ecological correlates of Whooping Crane use of fire-treated upland habitats.

Conservation Biology 10:217-223.

Cooper, C.F. 1961. The ecology of fire. Sci. Am.

204(4):150-160.

Copenheaver, C.A., A.S. White and W.A. Patterson.

2000. Vegetation development in a southern

Maine pitch pine-scrub oak barren. Journal

Torrey Botanical Soc.127:19-32.

Ferry, G.W. R.G. Clark, R.E. Montomery, R.W.

Mutch, W.P. Leenhouts, and G. T. Zimmerman.

1995. Altered fire regimes within fire-adapted

ecosystems. Pages 222-224. In: Our Living

Resources. W.T. LaRoe, G. S. Farris, C.E.

Puckett, P.D. Doran, and M.J. Mac eds. U.S.

Department of the Interior, National Biological

Service, Washington, D.C. 530p.

Gilliam, F.S. and W.J. Platt. 1999. Effects of longterm fire exclusion on tree species composition

and stand structure in an old-growth Pinus

palustris (Longleaf pine) forest. Plant Ecology

140:15-26.

Gray, G.L. 1992. Health emergency imperils western

forests. Resource Hotline. 8(9). Published by

American Forests.

Hardy, C. C., D. E. Ward, and W. Einfeld. 1992.

PM2.5 emissions from a major wildfire using a

GIS: rectification of airborne measurements. In:

Proceedings of the 29th Annual Meeting of the

Pacific Northwest International Section, Air and

Waste Management Association, November 11-

13, 1992, Bellevue, WA. Pittsburgh, PA: Air and

Waste Management Association.

Heinselman, M. L. 1978. Fire in wilderness ecosystems. In: Wilderness Management. J. C.

Hendee, G. H. Stankey, and R. C. Lucas, eds.

USDA Forest Service, Misc. Pub. 1365

Hermann, S.M., T. Van Hook, R.W. Flowers, L.A.

Brennan, J.S. Glitzenstein, D.R. Streng, J.L.

Walker and R.L. Myers. 1998. Fire and

biodiversity: studies of vegetation and

arthropods. Trans. North American Wildlife and

Natural Resources Conf. 63:384-401

Johnson, E.A. 1992. Fire and Vegetation Dynamics:

Studies from the North American Boreal Forest.

Cambridge University Press, Cambridge.

Keeley, J.E., and C.J. Fotheringham. 1997. Trace

gas emissions and smoke induced seed germination. Science 276:1248-1250.
– 19 –

2001 Smoke Management Guide 2.1 – The Wildland Fire Imperative

Kilgore, B. M., and M. L. Heinselman. 1990. Fire in

wilderness ecosystems. In: Wilderness Management, 2nd ed. J. C. Hendee, G. H. Stankey,

and R. C. Lucas, eds. North American Press,

Golden, CO. Pp. 297-335.

Kwilosz, J.R. and R.L. Knutson. 1999. Prescribed

fire management of Karner blue butterfly

habitat at Indiana Dunes National Lakeshore.

Natural Areas Journal 19:98-108

Leenhouts, Bill. 1998. Assessment of biomass

burning in the conterminous United States.

Conservation Ecology [online] 2(1): 1. Available from the Internet. URL:

Mutch, R. W. 1994. Fighting fire with prescribed

fire—a return to ecosystem health. J. For.

92(11):31-33.

Mutch, R. W. 1997. Need for more prescribed fire:

but a double standard slows progress. In Proceedings of the Environmental Regulation and

Prescribed Fire Conference, Tampa, Florida.

March 1995. Pp. 8-14.

Myers, R.L. 1990. Scrub and high pine. pages 150-

193 in (R.L. Myers and J.J. Ewel, eds.) Ecosystems of Florida. University of Central Florida

Press, Orlando.

National Wildfire Coordinating Group (NWCG).

1998. Managing Wildland Fire: Balancing

America’s Natural Heritage and the Public

Interest. National Wildfire Coordinating Group;

Fire Use Working Team [online]. Available

from the Internet. URL: http://www.fs.fed.us/

fire/fire_new/fireuse/wildland_fire_use/role/

role_pg8.html

Smith, J. Kapler (ed.). 2000. Wildland fire in

ecosystems: effects of fire on fauna. Gen. Tech.

Rep. RMRS-GTR-42-vol. 1. Ogden, UT.

Swain, A. 1973. A history of fire and vegetation in

northeastern Minnesota as recorded in lake

sediment. Quat. Res. 3: 383-396.

Swetnam, T. W. 1993. Fire history and climate

change in giant sequoia groves. Science.

262:885-889.

USDI and USDA Forest Service. 1995. Federal

wildland fire management policy and program

review. Final report. National Interagency Fire

Center, Boise, ID. 45 pp.

USDI and USDA Forest Service. 1998. Wildland

and prescribed fire management policy—

implementation procedures reference guide.

National Interagency Fire Center, Boise, ID. 81

pp. and appendices.

U.S. Environmental Protection Agency. 1998.

Interim air quality policy on wildland and

prescribed fires. Final report. U.S. Environmental Protection Agency.

Wade, D.D., J.J. Ewel, and R. Hofsetter. 1980. Fire

in South Florida Ecosystems. USDA Forest

Service General Technical Report SE-17.

Walker, J. 1993. Rare vascular plant taxa associated

with the longleaf pine ecosystems: patterns in

taxonomy and ecology. pages 105-125 in (S.M.

Hermann, ed.), The Longleaf Pine Ecosystem:

ecology, restoration, and management. Proceedings of the Tall Timbers Fire Ecology

Conference, No. 18.

Watts, W.A., B.C.S. Hansen and E.C. Grimm. 1992.

Camel Lake – A 4000-year record of vegetational and forest history from northwest Florida.

Ecology 73:1056-1066.

Weaver, H. 1943. Fire as an ecological and silvicultural factor in the ponderosa pine region of the

Pacific Slope. J. For. 41:7-14.

Whelan, R.J. 1995. The Ecology of Fire. Cambridge University Press, Cambridge.
Chapter 2 – Overview 2001 Smoke Management Guide

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– 21 –

2001 Smoke Management Guide 2.2 – Smoke Management Imperative

The Smoke Management Imperative

Colin C. Hardy

Sharon M. Hermann

John E. Core

Introduction

In the past, smoke from prescribed burning was

managed primarily to avoid nuisance conditions

objectionable to the public or to avoid traffic

hazards caused by smoke drift across roadways.

While these objectives are still valid, today’s

smoke management programs are also likely to

be driven, in part, by local, regional and federal

air quality regulations. These new demands on

smoke management programs have emerged as

a result of Federal Clean Air Act requirements

that include standards for regulation of regional

haze and the recent revisions to the National

Ambient Air Quality Standards (NAAQS) on

particulate matter.1

Development of the additional requirements

coincides with renewed efforts to increase use of

fire to restore forest ecosystem health. These

two requirements are interrelated:

• The purity of the air we breathe is essential to our health and quality of our lives

and smoke from wildland and prescribed

fire can have adverse effects on public

health.

• The national forests, national parks and

wilderness areas set aside by Congress are

among the nation’s greatest treasures.

They inspire us as individuals and as a

nation. Smoke from wildland burning can

obscure these natural wonders.

• Although smoke may be an inconvience

under the best conditions and a public

health and safety risk under the worst

conditions, without periodic fires, the

natural habitat that society holds in such

high esteem will decline and ultimately

dissapear. In addition, as ecosystem

health declines, fuel increases to levels

that also pose significant risks for wildfire

and consequently additional safety risks.

• Wildland and prescribed fire managers are

entrusted with balancing these and other,

often potentially conflicting responsibilities. Fire managers are charged with the

task of increasing the use of fire to accomplish important land stewardship

objectives and, at the same time, are

entrusted to protect public safety and

health.

Purpose of a Smoke

Management Program

The purpose of a smoke management

program is to:

1 See Chapter 4, Regulations for Smoke Management, for details on specific requirements.
Chapter 2 – Overview 2001 Smoke Management Guide

– 22 –

• minimize the amount of smoke entering

populated areas, preventing public health

and safety hazards (e.g. visual impairment

on roadways or runways) and problems at

sensitive sites (e.g. nursing homes or

hospitals),

• avoid significant deterioration of air

quality and NAAQS violations, and

• eliminate human-caused visibility impacts

in Class I areas.

Smoke management programs create a framework of procedures and requirements for managing smoke from prescribed fires and are

typically developed by States or tribes with

cooperation and participation from stakeholders.

Procedures and requirements developed through

partnerships are more effective at meeting

resource management goals, protecting public

health, and achieving air quality objectives than

programs that are created in isolation. Sophisticated programs for coordination of burning both

within a state and across state boundaries are

vital to obtain and maintain public support of

burning programs. Fire use professionals are

increasingly encouraged to burn at a landscape

level. In some cases, when objectives are based

in both ecology and fuel reduction, there is a

need to consider burning during challenging

times of the year (e.g. during the growing

season rather than the cooler dormant season).

Multiple objectectives for fire use are likely to

increase the challenges, consequently increasing

the value of partnerships for smoke management.

Smoke management is increasingly recognized

as a critical component of a state or tribal air

quality program for protecting public health and

welfare while still providing for necessary

wildland burning.

Usually, either a state or tribal natural resources

agency or air quality agency is responsible for

developing and administering the smoke management program. Occasionally a smoke

management program may be administered by a

local agency. California, for example, relies on

local area smoke management programs. Generally, on a daily basis the administering agency

approves or denies permits for individual burns

or burns meeting some criteria. Permits may be

required for all fires or only for those that

exceed an established de minimis level (which

could be based on projections of acres burned,

tons consumed, or emissions). Multi-day burns

may be subject to daily reassessment and reapproval to ensure compliance with smoke

management program goals.

Advanced smoke management programs evaluate individual and multiple burns; coordinate all

prescribed fire activities in an area; consider

cross-boundary (landscape) impacts; and weigh

decisions about fires against possible health,

visibility, and nuisance effects. With increasing

use of fire for forest health and ecosystem

management, interstate and interregional coordination of burning will be necessary to prevent

episodes of poor air quality. Development of,

and participation in, an effective smoke management program by state agents and land managers will go a long way towards building and

maintaining public acceptance of prescribed

burning.

The Need for Smoke

Management Programs

The call for increasingly effective smoke management programs has occurred because of

public and governmental concerns about the

possible risks to public health and safety, as well

as nuisance and regional haze impacts of smoke
– 23 –

2001 Smoke Management Guide 2.2 – Smoke Management Imperative

from wildland and prescribed fires. There are

also concerns about contributions to healthrelated National Ambient Air Quality Standards.

Each of these areas is summarized below.2

Public Health Protection: Fine Particle

National Ambient Air Quality Standards.–

EPA’s most recent review of the National Ambient Air Quality Standards for Particulate Matter

(PM10) concluded that significant changes were

needed to assure the protection of public health.

In July of 1997, following an extensive review

of the global literature, EPA adopted a fine

particle (PM2.5) standard.3

These small particles are largely responsible for

the health effects of greatest concern and for

visibility reduction in the form of regional haze.

More on EPA’s fine particle standard is found

elsewhere in this Guide.

The close link between regional haze and the

new fine particle National Ambient Air Quality

Standards means that smoke from prescribed

fire is again at the center of attention for air

regulators charged with adopting control strategies to attain the new standards.

Public Safety and Nuisance Issues.–Perhaps

the most immediate need for an effective smoke

management program is related to smoke

drifting across roadways and restricting motorist

visibility. Each year, people are killed on the

nation’s highways because of dust storms,

smoke and fog. Wildland and prescribed fire

managers must recognize the legal issues related

to their professional activities. Special care

must be taken in administering the smoke

management program to assure that smoke does

not obscure roadway or airport visibility. Liability issues vary by state. Some states such as

Florida have “right-to-burn” laws that provide

some protection for fire use professionals with

specific training and certification.

Probably the most common air quality issues

facing wildland and prescribed fire managers

are those related to public complaints about

nuisance smoke. Complaints may be about the

odor or soiling effects of smoke, poor visibility,

and impaired ability to breathe or other healthrelated effects. Sometimes complaints come

from the fact that some people don’t like or are

fearful of smoke intruding into their lives.

Whatever the reason, fire managers have a

responsibility to try to prevent or resolve the

issue through smoke management plans that

recognize the importance of proper selection of

management and burning techniquesand burn

scheduling based on meteorological conditions.

In additioncommunity public relations and

education coupled with pre-burn notification can

greatly improve public acceptance of fire management programs.

Visibility Protection.–Haze that obstructs the

scenic beauty of the Nation’s wildlands and

national parks does not respect political boundaries. Any program that is intended to reduce

visibility impairment in the nation’s parks and

wildlands must be based on multi-state cooperative efforts or on national legislation.

In 1999, the U.S. EPA issued regional haze

regulations to manage and mitigate visibility

impairment from the multitude of regional haze

sources.4

 Regional haze regulations call for

states to establish goals for improving visibility

in Class I national parks and wildernesses and to

develop long-term strategies for reducing emissions of air pollutants that cause visibility

impairment. Wildland and prescribed fire are

some of the sources of regional haze covered by

the new rules.

2 Details relating to Public Health effects, Problem and Nuisance Smoke, and Regional Haze are given in the sections

3.1, 3.3 and 4.1, respectively, of this Guide. 3 One thousand fine particles of this size could fit into the period at the end of this sentence.

4 [40 CFR Part 51]
Chapter 2 – Overview 2001 Smoke Management Guide

– 24 –

Past Success and Commitment

to Future Efforts

It is clearly noted in the preface to the 2001

Smoke Management Guide that conflicts among

natural resource needs, fire management, and air

quality issues are expected to increase. It is

equally important to acknowledge the benefits

to air quality resulting from the many successful

smoke management efforts in the past two

decades.

Since the 1980s, federal, state, tribal, and local

land managers have recognized the potential

impacts of smoke emissions from their activities. Additionally, they have sponsored and

pursued new efforts to learn the principles of

smoke management and to develop appropriate

smoke management applications. Many early

smoke management successes resulted from

proactive, voluntary inclusion of smoke management components in many burn plans as

early as the mid-1980s.

NWCG and its partners are committed to furthering their leadership role in the quest for new

information, technology, and innovative techniques. These 2001 revisions to the Guide are

evidence of that commitment.
– 25 –

2001 Smoke Management Guide 3.1 – Public Health Effects

SMOKE IMPACTS

Chapter 3
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 26 –
– 27 –

2001 Smoke Management Guide 3.1 – Public Health Effects

Public Health and Exposure to Smoke

John E. Core

Janice L. Peterson

Introduction

The purity of the air we breathe is an important

public health issue. Particles of dust, smoke,

and soot in the air from many sources, including

wildland fire, can cause acute health effects.

The effects of smoke range from irritation of the

eyes and respiratory tract to more serious disorders including asthma, bronchitis, reduced lung

function, and premature death. Airborne particles are respiratory irritants, and high concentrations can cause persistent cough, phlegm,

wheezing, and physical discomfort when breathing. Particulate matter can also alter the body’s

immune system and affect removal of foreign

materials from the lung like pollen and bacteria.

This section discusses the effects of air pollution, especially particulate matter, on human

health and morbidity. Wildland fire smoke is

discussed as one type of air pollution that can be

harmful to public health1

.

Human Health Effects of

Particulate Matter

Many epidemiological studies have shown

statistically significant associations of ambient

particulate matter levels with a variety of human

health effects, including increased mortality,

hospital admissions, respiratory symptoms and

illness measured in community surveys (Brauer

1999, Dockery and others 1993, EPA 1997).

Health effects from both short-term (usually

days) and long-term (usually years) particulate

matter exposures have been documented. The

consistency of the epidemiological data increases confidence that the results reported in

numerous studies justify the increased public

health concerns that have prompted EPA to

adopt increasingly stringent air quality standards (Federal Register 1997). There remains,

however, uncertainty regarding the exact

mechanisms that air pollutants trigger to cause

the observed health effects (EPA 1996).

Figure 3.1.1 illustrates respiratory pathways

that form the human body’s natural defenses

against polluted air. These pathways can be

divided into two systems - the upper airway

passage consisting of the nose, nasal passages,

mouth and pharynx, and the lower airway

passages consisting of the trachea, bronchial

tree, and alveoli. While coarse particles (larger

than about 5 microns in diameter) are deposited

in the upper respiratory system, fine particles

(less than 2.5 microns in diameter) can penetrate much deeper into the lungs. These fine

particles are deposited in the alveoli where the

body’s defense mechanisms are ineffective in

removing them (Morgan 1989).

___________________________________

1 Information on the effects of smoke on firefighters and prescribed burn crews can be found in Section 3.4.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 28 –

On a smoggy day in a major metropolitan area,

a single breath of air may contain millions of

fine particles. Some 74 million Americans —

28% of the population — are regularly exposed

to harmful levels of particulate air pollution

(EPA 1997). In recent studies, exposure to fine

particles – either alone or in combination with

other air pollutants – has been linked with many

health problems, including:

• An estimated 40,000 Americans die

prematurely each year from respiratory

illness and heart attacks that are linked

with particulate exposure, especially

elderly people (EPA 1997).

• Children and adults experience aggravated

asthma. Asthma in children increased

118% between 1980 and 1993, and it is

currently the leading cause of child hospital admissions (EPA 1997).

• Children become ill more frequently and

experience increased respiratory problems,

including difficult and painful breathing

(EPA 1997).

• Hospital admissions, emergency room

visits and premature deaths increase

among adults with heart disease, emphysema, chronic bronchitis, and other heart

and lung diseases (EPA 1997).

The susceptibility of individuals to particulate

air pollution (including smoke) is affected by

many factors. Asthmatics, the elderly, those

with cardiopulmonary disease, as well as those

with preexisting infectious respiratory disease

such as pneumonia may be especially sensitive

to smoke exposure. Children and adolescents

may also be susceptible to ambient particulate

matter effects due to their increased frequency

of breathing, resulting in greater respiratory

tract deposition. In children, epidemiological

studies reveal associations of particulate exposure with increased bronchitis symptoms and

small decreases in lung function.

Fine particles showed consistent and statistically

significant relationships to short-term mortality

in six U.S. cities while coarse particles showed

no significant relationship to excess mortality in

five of the six cities that were studied (Dockery

and others 1993).

Figure 3.1.1: Particle deposition in the respiratory system.

From: Canadian Center for Occupational Health & Safety, available at

http://www.ccohs.ca/oshanswers/ chemicals/how_do.html
– 29 –

2001 Smoke Management Guide 3.1 – Public Health Effects

Impacts of Wildland Fire

Smoke on Public Health

There is not much data which specifically

examines the effects of wildland fire smoke on

public health, although some studies are

planned or underway. We can, however, infer

health responses from the documented effects of

particulate air pollutants. Eighty to ninety

percent of wildfire smoke (by mass) is within

the fine particle size class (PM2.5), making

public exposure to smoke a significant concern.

The Environmental Protection Agency has

developed some general public health warnings

for specific air pollutants including PM2.5

(table 3.1.1) (EPA 1999). The concentrations in

table 3.1.1 are 24-hour averages, which can be

problematic when dealing with smoke impacts

that may be severe for a short period of time and

then virtually non-existent soon after. Another

guidance document was developed recently to

relate short-term, 1-hour averages to the potential human health effects given in table 3.1.1

(Therriault 2001).

Figure 3.1.2 contains these short-term averages

plus approximate corresponding visual range in

miles. Members of the public can use the

methods described to estimate visual range and

determine when air quality may be hazardous to

their health even if they are located in an area

that is not served by an official state air quality

monitor.

Figure 3.1.3 is an information sheet developed

during a prolonged wildfire smoke episode in

Montana during the summer of 2000. The

questions and answers address many common

concerns voiced by the public during smoke

episodes.

Other Pollutants of Concern

in Smoke

Although the principal air pollutant of concern

is particulate matter, there are literally hundreds

of compounds emitted by wildland fires that are

found in very low concentrations. Some of

these compounds that also deserve mention

include:

• Carbon monoxide has well known, serious

health effects including dizziness, nausea

and impaired mental functions but is

usually only of concern when people are in

close proximity to a fire (including firefighters). Blood levels of carboxyhemoglobin tend to decline rapidly to normal

levels after a brief period free from exposure (Sharkey 1997).

• Benzo(a)pyrene, anthracene, benzene and

numerous other components found in

smoke from wildland fires can cause headaches, dizziness, nausea, and breathing

difficulties. In addition, they are of concern because of long term cancer risks

associated with repeated exposure to

smoke.

• Acrolein and formaldehyde are eye and

upper respriatory irritants to which some

segments of the public are especially

sensitive.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 30 –

Ta

ble 3.1.1. EPA’s pollutant standard index for PM2.5 can be used for general assessment of health risks from existing air quality.
– 31 –

2001 Smoke Management Guide 3.1 – Public Health Effects

Figure 3.1.2. Visibility range can be used by the public to assess air quality in areas with no state air

pollution monitors.

Conclusions

The health effects of wildland smoke are of real

concern to wildland fire managers, public health

officials, air quality regulators and all segments

of the public. Fire practitioners have an important responsibility to understand the potential

health impacts of fine particulate matter and

minimize the public’s exposure to smoke.

Wildland fire managers should be aware of

sensitive populations and sites that may be

affected by prescribed fires, such as medical

facilities, schools or nursing homes, and plan

burns to minimize the smoke impacts. This is

especially true when exposure may be prolonged. Days or weeks of smoke exposure are

problematic because the lung’s ability to sweep

these particles out of the respiratory passages

may be suppressed over time. Prolonged exposure may occur as the result of topographic or

meteorological conditions that trap smoke in an

area. Familiarity with the location and seasonal

weather patterns can be invaluable in anticipating and avoiding potential problems while still

in the planning phase.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 32 –

What’s in smoke from a wildfire?

Smoke is made up of small particles, gases and water vapor.

Water vapor makes up the majority of smoke. The remainder

includes carbon monoxide, carbon dioxide, nitrogen oxide, irritant

volatile organic compounds, air toxics and very small particles.

Is smoke bad for me?

Yes. It’s a good idea to avoid breathing smoke if you can help it. If

you are healthy, you usually are not at a major risk from smoke.

But there are people who are at risk, including people with heart or

lung diseases, such as congestive heart disease, chronic

obstructive pulmonary disease, emphysema or asthma. Children

and the elderly also are more susceptible.

What can I do to protect myself?

• Many areas report EPA’s Air Quality Index for particulate

matter, or PM. PM (tiny particles) is one of the biggest

dangers from smoke. As smoke gets worse, that index

changes — and so do guidelines for protecting yourself. So

listen to your local air quality reports.

• Use common sense. If it looks smoky outside, that’s probably

not a good time to go for a run. And it’s probably a good time

for your children to remain indoors.

• If you’re advised to stay indoors, keep your windows and

doors closed. Run your air conditioner, if you have one. Keep

the fresh air intake closed and the filter clean.

• Help keep particle levels inside lower by avoiding using

anything that burns, such as wood stoves and gas stoves –

even candles. And don’t smoke. That puts even more pollution

in your lungs – and those of the people around you.

• If you have asthma, be vigilant about taking your medicines,

as prescribed by your doctor. If you’re supposed to measure

your peak flows, make sure you do so. Call your doctor if your

symptoms worsen.

How can I tell when smoke levels are dangerous? I don’t live

near a monitor.

Generally, the worse the visibility, the worse the smoke. In

Montana, the Department of Environmental Quality uses visibility

to help you gauge wildfire smoke levels.

How do I know if I’m being affected?

You may have a scratchy throat, cough, irritated sinuses, headaches, runny nose and stinging eyes. Children and people with

lung diseases may find it difficult to breathe as deeply or vigorously

as usual, and they may cough or feel short of breath. People with

diseases such as asthma or chronic bronchitis may find their

symptoms worsening.

Should I leave my home because of smoke?

The tiny particles in smoke do get inside your home. If smoke

levels are high for a prolonged period of time, these particles can

build up indoors. If you have symptoms indoors (coughing, burning

eyes, runny nose, etc.), talk with your doctor or call your county

health department. This is particularly important for people with

heart or respiratory diseases, the elderly and children.

Are the effects of smoke permanent?

Healthy adults generally find that their symptoms (runny noses,

coughing, etc.) disappear after the smoke is gone.

Do air filters help?

They do. Indoor air filtration devices with HEPA filters can reduce

the levels of particles indoors. Make sure to change your HEPA

filter regularly. Don’t use an air cleaner that works by generating

ozone. That puts more pollution in your home.

Do dust masks help?

Paper “comfort” or “nuisance” masks are designed to trap large

dust particles — not the tiny particles found in smoke.

These masks generally will not protect your lungs from wildfire

smoke.

How long is the smoke going to last?

That depends on a number of factors, including the number of

fires in the area, fire behavior, weather and topography. Smoke

also can travel long distances, so fires in other areas can affect

smoke levels in your area.

I’m concerned about what the smoke is doing to my animals.

What can I do?

The same particles that cause problems for people may cause

some problems for animals. Don’t force your animals to run or

work in smoky conditions. Contact your veterinarian or county

extension office for more information.

How does smoke harm my health?

One of the biggest dangers of smoke comes from particulate

matter — solid particles and liquid droplets found in air. In smoke,

these particles often are very tiny, smaller than 2.5 micrometers in

diameter. How small is that? Think of this: the diameter of the

average human hair is about 30 times bigger.

These particles can build up in your respiratory system, causing a

number of health problems, including burning eyes, runny noses

and illnesses such as bronchitis. The particles also can aggravate

heart and lung diseases, such as congestive heart failure, chronic

obstructive pulmonary disease, emphysema and asthma.

What about firefighters?

Firefighters do experience short-term effects of smoke, such as

stinging, watery eyes, coughing and runny noses. Firefighters

must be in good physical condition, which helps to offset adverse

effects of smoke. In addition to being affected by particles,

firefighters can be affected by carbon monoxide from smoke. A

recent Forest Service study showed a very small percentage of

firefighters working on wildfires were exposed to levels higher

than occupational safety limits for carbon monoxide and irritants.

Why can’t the firefighters do something about the smoke?

Firefighters first priorities in fighting a fire are, by necessity,

protecting lives, protecting homes and containing the wildfire.

Sometimes the conditions that are good for keeping the air clear

of smoke can be bad for containing fires. A windy day helps

smoke disperse, but it can help a fire spread.

Firefighters do try to manage smoke when possible. As they

develop their strategies for fighting a fire, firefighters consider fire

behavior and weather forecasts, topography and proximity to

communities – all factors than can affect smoke.

Why doesn’t it seem to be as smoky when firefighters are

working on prescribed fires.

Land managers are able to plan for prescribed fires. They get to

choose the areas they want to burn, the size of those areas and

the weather and wind conditions that must exist before they begin

burning. This allows them to control the fire more easily and limit

its size. Those choices don’t exist with wildfires. In addition,

wildfires that start in areas that haven’t been managed with

prescribed fire often have more fuel, because vegetation in the

forest understory has built up, and dead vegetation has not been

removed.

This document was prepared by the Air Program, U.S. Forest Service – Northern Region, with assistance from the Office of Air

Quality Planning & Standards in the US Environmental Protection Agency. For more information, call 406-329-3493. August 2000.

Figure 3.1.3. Public health information developed during the Montana wildfires of 2000.
– 33 –

2001 Smoke Management Guide 3.1 – Public Health Effects

Literature Citations

Brauer, Michael. 1999. Health impacts of biomass

air pollution. In: Health guidelines for vegetation fire events: background papers. Edited by

Kee-Tai Goh, Dietrich Schwela, Johann G.

Goldammer, and Orman Simpson. World

Health Organization. Available at http://

www.who.int/peh/air/vegetationfirbackgr.htm.

69p.

Dockery DW, Pope CA III, Xu X, Spengler JD,

Ware JH, Fay ME, Ferris BG Jr, and Speizer

FE. 1993. An association between air pollution

and mortality in six U.S. cities. New England

Journal of Medicine. 329:1753-1759.

Environmental Protection Agency-Region 8. 1997.

Public health effects of ozone and fine particle

pollution. Environmental Fact Sheet. Available

at http://www.epa.gov/region08/news/

news9697/ofpo.html

Environmental Protection Agency. 1996. Air quality

criteria for particulate matter - Volume 1. US

Environmental Protection Agency, Research

Triangle Park, NC. EPA/600/P-95/001aF.

Environmental Protection Agency. 1999. Guideline

for reporting of daily air quality – air quality

index (AQI). EPA-454/R-99-010. U.S. EPA

Office of Air Quality Planning and Standards,

Research Triangle Park, NC 27711. 25p.

Federal Register. 1997. Memorandum from the

President re: Implementation of Revised Air

Quality Standards for Ozone and Particulate

Matter. Federal Register Vol. 62, No. 138. July

18, 1997.

Morgan, Michael S. 1989. Health risks from slash

fire smoke. In: The Burning Decision – Regional Perspectives on Slash. University of

Washington College of Forest Resources.

Seattle, WA. pp. 226-236.

Sharkey, Brian, ed. 1997. Health hazards of smoke:

recommendations of the April 1997 Consensus

Conference. Tech. Rep. 9751-2836-MTDC.

Missoula, MT: U.S. Department of Agriculture,

Forest Service, Missoula Technology and

Development Center. 84 p.

Therriault, Shannon. 2001. Wildfire smoke: a guide

for public health officials. Missoula CityCounty Health Department. Missoula, MT. 13p.

Available at: http://depts.washington.edu/

wildfire/resources/pubhealthguide.pdf
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 34 –
– 35 –

2001 Smoke Management Guide 3.2 – Visibility

Visibility

John E. Core

Introduction

Every year there are over 280 million visitors to

our nation’s wilderness areas and national parks.

Congress has set these special places aside for

the enjoyment of all that seek spectacular and

inspiring vistas. Unfortunately, many visitors

are not able to see the beautiful scenery they

expect. During much of the year, a veil of haze

often blurs their view. The haze is caused by

many sources of both natural and manmade air

pollution sources, including wildland fire.

This section describes measures of scenic

visibility, the properties of the atmosphere and

how these properties are affected by smoke from

wildland fires, natural and current visibility

conditions, as well as sources that contribute to

visibility degradation. This is an important

issue to wildland fire practitioners because

smoke is of increasing interest to air regulators

responsible for solving regional haze problems.

Measures of Visibility Impairment

Visibility is most often thought of in terms of

visual range or the furthest distance a person can

see a landscape feature. However, visibility is

more than how far one can see; it also encompasses how well scenic landscape features can

be seen and appreciated. Changes in visual

range are not proportional to human perception.

For example, a five-mile change in visual range

can result in a scene change that is either imperceptible or very obvious depending on the

baseline visibility conditions. Therefore, a more

meaningful visibility index has been adopted.

The scale of this index, expressed in deciviews

(dv) is linear with respect to perceived visual

changes over its entire range, analogous to the

decibel scale for sound. A one-deciview change

represents a change in scenic quality that would

be noticeable to most people regardless of the

initial visibility conditions. A deciview of zero

is equivalent to clear air while deciviews greater

than zero depict proportionally increased visibility impairment (IMPROVE 1994). The more

deciviews measured, the greater the impairment,

which limits the distance you can see. Finally,

extinction in inverse megameters (Mm-1) is

proportional to the amount of light lost as it

travels through a million meters of atmosphere

and is most useful for relating visibility directly

to particulate concentrations. Table 3.2.1 compares each of these three forms of measurement

(Malm 1999).

Properties of the Atmosphere &

Wildland Fire Smoke

An observer sees an image of a distant object

because light is reflected from the object along

the sight path to the observer’s eye. Any of this

image-forming light that is removed from the

sight path by scattering or light absorption
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 36 –

reduces the image-forming information and

thereby diminishes the clarity of the landscape

feature. Ambient light is also scattered into the

sight path, competing with the image-forming

light to reduce the clarity of the object of

interest. This “competition” between imageforming light and scattered light is commonly

experienced while driving in a snowstorm at

night with the car headlights on.

In addition, relative humidity also indirectly

affects visibility. Although relative humidity

does not by itself cause visibility to be degraded, some particles, especially sulfates,

accumulate water from the atmosphere and

grow to a size where they are particularly

efficient at scattering light. Poor visibility in

the eastern states during the summer months is

a result of the combination of high sulfate

concentrations and high relative humidity.

The sum of scattering and absorption is referred

to as atmospheric light extinction. Particles that

are responsible for scattering are categorized as

primary and secondary where primary sources

include smoke from wildland fires and windblown dust. Other sources of secondary parTable 3.2.1. Comparison of the four expressions of visibility measurement.

ticles include sulfate and nitrate particles

formed in the atmosphere. The closer the

particle size is to the wavelength of light, the

more effective the particle is in scattering light.

As a result, relatively large particles of windblown dust are far less efficient in scattering

light per unit mass than are the fine particles

found in smoke from wildland fires. Finally, an

important component of smoke from wildland

fires is elemental carbon (also known as soot),

which is highly effective in absorbing light

within the sight path. This combination of light

absorption by elemental carbon and light

scattering caused by the very small particles

that make up wildland fire smoke explains why

emissions from wildland fire play such an

important role in visibility impairment.

The effect of regional haze on a Glacier National Park vista is shown in the four panels of

figure 3.2.1. The view is of the Garden Wall

from across Lake McDonald. Particulate

concentrations associated with these photographs correspond to 7.6, 12.0, 21.7 and

65.3 μg/m3, respectively (Malm 1999). Note

the loss of color and detail in the mountains as

the particulate concentrations increase and

visibility decreases.
– 37 –

2001 Smoke Management Guide 3.2 – Visibility

Figure 3.2.1. The effect of regional haze on a Glacier National Park vista.

Photo courtesy of the National Park Service, Air Resources Division.

7.6 μg/m3 12.0 μg/m3

21.7 μg/m3 65.3 μg/m3

Natural Visibility Conditions

Some light extinction occurs naturally due to

scattering caused by the molecules that make up

the atmosphere. This is called Rayleigh scattering and is the reason why the sky appears blue.

But even without the influence of human-caused

air pollution, visibility would not always reach

the approximately 240-mile limit defined by

Rayleigh scattering. Naturally occurring particles, such as windblown dust, smoke from

natural fires, volcanic activity, and biogenic

emissions (e.g. pollen and gaseous hydrocarbon)

also contribute to visibility impairment although

the concentrations and sources of some of these

particles remain a point of investigation.

Average natural visibility in the eastern U.S. is

estimated to be about 60-80 miles (8-11 dv),

whereas in the western US it is about 110-115

miles (4.5-5 dv) (Malm 1999). Lower natural

visibility in the eastern U.S. is due to higher

average humidity. Humidity causes fine particles to stick together, grow in size, and become

more efficient at scattering light. Under natural

conditions, carbon-based particles are responsible for most of the non-Rayleigh particle-
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 38 –

Figure 3.2.2. Average annual visual range, in miles, for the years 1996-1998 measured at IMPROVE network

monitors.

associated visibility reduction, with all other

particle species contributing significantly less.

Scattering from naturally occurring sulfate

particles from volcanic sulfur dioxide emissions and oceanic sources of primary sulfate

particles are estimated to account for 9-12% of

the impairment in the East and 5% in the West

(NPS 1997). It is expected that coastlines and

highly vegetated areas may be lower than these

averages, while some elevated areas (mountains) could exceed these background estimates.

Current Visibility Conditions

Currently, average visual range in the eastern

U.S. is about 15-30 miles, or about one-third

of the estimated natural background for the

East. In the West, visual range currently averages about 60-90 miles, or about one-half of the

estimated natural background for the West.

Current annual visual range conditions expressed in miles are shown in figure 3.2.2.

Notice how much more impaired visibility is in

the East versus the West.

In the East, 60-70% of the visibility impairment

is attributed to sulfates. Sulfate particles form

from sulfur dioxide gas, most of which is released from coal-burning power plants and other

industrial sources such as smelters, industrial

boilers, and oil refineries. Carbon-based particles contribute about 20% of the impairment in

the East. Sources of organic carbon particles

include vehicle exhaust, vehicle refueling,

solvent evaporation, food cooking, and fires.
– 39 –

2001 Smoke Management Guide 3.2 – Visibility

Literature Citations

IMPROVE. 1994. Visibility protection. Interagency

Monitoring of Protected Visual Environments

Brochure. Ft. Collins, Colorado. August 1994.

Available at: www2.nature.nps.gov/ard/impr/

index.htm

National Park Service. 1997. Visibility protection.

National Park Service Air Resources Division

Web Page. Available at www2.nature.nps.gov/

ard/vis/visprot.html

Malm, William C. 1999. Introduction to visibility.

Cooperative Institute for Research in the

Atmosphere. NPS Visibility Program, Colorado

State University, Fort Collins, CO: 79 p.

Elemental carbon particles (or light absorbing

carbon) are emitted by virtually all combustion

activities, but are especially prevalent in diesel

exhaust and smoke from wood burning.

In the West, sulfates contribute less than 30%

(Oregon, Idaho and Nevada) to 40-50% (Arizona, New Mexico and Southwest Texas) of

light extinction. Carbon particles in the West

are a greater percentage of the extinction budget

ranging from 50% or greater in the Northwest to

30-40% in the other western regions. The

higher percentages of the extinction budget

associated with carbon particles in the West

appear to be from smoke emitted by wildland

and agricultural fires (NPS 1994).

In summary, the physics of light extinction in

the atmosphere coupled with the chemical

composition and physical size distribution of

particles in wildland fire smoke combine to

make fire (especially in the West) an important

contributor to visibility impairment. Wildland

fire managers responsible for the protection of

the scenic vistas of this nation’s wilderness

areas and national parks have a difficult challenge in balancing the need to protect visibility

with the need to use fire for other resource

management goals.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 40 –
– 41 –

2001 Smoke Management Guide 3.3 – Nuisance Smoke

Problem and Nuisance Smoke

Gary L. Achtemeier

Bill Jackson

James D. Brenner

Introduction

The particulate matter (or particles) produced

from wildland fires can be a nuisance or safety

hazard to people who come in contact with the

smoke – whether the contact is directly through

personal exposure, or indirectly through visibility impairment. Nuisance smoke is defined by

the US Environmental Protection Agency as the

amount of smoke in the ambient air that interferes with a right or privilege common to

members of the public, including the use or

enjoyment of public or private resources (US

EPA 1990).

Although the vast majority of prescribed burns

occur without negative smoke impact, wildland

fire smoke can be a problem anywhere in the

country. Complaints about loss of visibility,

odors, and soiling from ash fallout are not

unique to any region. Reduced visibility from

smoke has caused fatal collisions on highways

in several states, from Florida to Oregon. Acrolein (and possibly formaldehyde) in smoke is

likely to cause eye and nose irritation for distances up to a mile from the fire, exacerbating

public nuisance conditions (Sandberg and Dost

1990). The abatement of nuisance or problem

smoke is one of the most important objectives of

any wildland fire smoke management plan

(Shelby and Speaker 1990).

This section provides information on the issue

of visibility reduction from wildland fire smoke,

and focuses particularly on smoke as a major

concern in the Southern states. Meteorology,

climate and topography combine with population density and fire frequency to make nuisance

smoke a chronic issue in the South. Lessons

from this regional example can be extrapolated

and applied to other parts of the country. This

section also briefly summarizes tools currently

used or under development to aid the land

manager in reducing the problematic effects of

smoke.

Wildland fire smoke may also be a nuisance to

the public by producing a regional haze, which

is discussed in Section 3.2.

Nuisance Smoke and

Visibility Reduction

A prescribed fire is a combustion process that

has no pollution control devices to remove the

pollutants. Instead, prescribed fire practitioners

often rely on favorable atmospheric conditions

to successfully disperse the smoke away from

smoke-sensitive areas, such as communities,
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 42 –

areas of heavy vehicle traffic, and scenic vistas.

At times, however, unexpected changes in

weather (especially wind), or planning which

does not adequately factor in such elements as

topography, diurnal weather patterns, or residual

combustion, may result in an intrusion of smoke

that causes negative impacts on the public.

Smoke intrusions and nuisance- or safetyrelated episodes may happen at any time during

the course of a wildland fire, but they frequently

occur in valley bottoms and drainages during the

night. Within approximately one half hour of

sunset, air cools rapidly near the ground, and

wind speeds decline as the cooled stable airmass

“disconnects” from faster-moving air just above

it. High concentrations of smoke accumulate

near the ground, particularly smoke from smoldering fuels that don’t generate much heat.

Smoke then tends to be carried through drainages with little dispersion or dilution. If the

drainages are wet, smoke can act as a nucleating

agent and can actually assist the formation of

local fog, a particular problem in the Southeast.

Typically, the greatest fog occurs where smoke

accumulates in a low drainage. This can cause

hazardous conditions where a drainage crosses a

road or bridge, reducing visibility for traffic.

Visibility reduction may also result from the

direct impact of the smoke plume. Fine particles (less than 2.5 microns in diameter) of

smoke are usually transported to the upper

reaches of the atmospheric mixing height, where

they are dispersed. They may, however, disperse

gradually back to ground level in an unstable

atmosphere (figure 3.3.1). When this occurs,

such intrusions of smoke can cause numerous

nuisance impacts as well as specific safety

hazards.

Visibility reduction is used as a metric of smoke

intrusions in several State smoke management

programs. The State of Oregon program operational guidance defines a “moderately” intense

intrusion as a reduction of visibility from 4.6 to

11.4 miles from a background visibility of more

than 50 miles (Oregon Dept. Forestry 1992).

The State of Washington smoke intrusion

reporting system uses “slightly visible, noticeable impact on visibility, or excessive impact on

visibility” to define light, medium and heavy

intrusions (Washington Dept. Natural Resources

1993). The New Mexico program requires that

visibility impacts of smoke be considered in

development of the unit’s burn prescription

(New Mexico Environmental Improvement

Board 1995).

Smoke plume-related visibility degradation in

urban and rural communities is not subject to

regulation under the Clean Air Act. Nuisance

smoke is usually regulated under state and local

laws and is frequently based on either public

complaint or compromise of highway safety

(Eshee 1995). Public outcry regarding nuisance

smoke often occurs before smoke exposures

reach levels that violate National Ambient Air

Quality Standards. The Courts have ruled that

the taking of private property by interfering with

its use and enjoyment caused by smoke without

just compensation is in violation of federal

constitutional provisions under the Fifth

Amendment. The trespass of smoke may

diminish the value of the property, resulting in

losses to the owner (Supreme Court of Iowa

1998).

Smoke as a Southern Problem

The Forest Atlas of the United States (figure

3.3.2) shows that the thirteen Southern states

contain approximately 40% of U.S. forests –

about 200 million acres. While not all of this

forested land is regularly burned, the extensive

forest type generally known as “southern pines”

burns with a high fire frequency, about every 2-5

years. When shrublands and grasslands are

added to the total, from four to six million acres

of southern wildlands are subjected to pre-
– 43 –

2001 Smoke Management Guide 3.3 – Nuisance Smoke

Figure 3.3.1. Graphic from the dispersion model VSmoke-GIS, showing the rise and

descent of a smoke plume during a daytime prescribed fire, assuming 25% of the

smoke disperses at ground level.

Figure 3.3.2. National Atlas of Forest Cover Types. Southern forests (outlined in blue extend

from Virginia to Texas and from the Ohio River southward and account for approximately 40% of

U.S. forest land.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 44 –

scribed fire each year. This is by far the largest

acreage of wildlland subjected to prescribed fire

in any region of the country.

Figure 3.3.3 shows the 1998 Population Density

Classes for the United States. Of particular

importance regarding problem smoke is the

class “Wildland/Urban Interface,” designated in

red. A comparison with figure 3.3.2 shows that

the wildland/urban interface falls within much

of the range of Southern forests. Southern

forests, with highest treatment intervals of

prescribed fire and with the largest acreages

subjected to prescribed fire, are connected with

human habitation and activity through an enormous wildland/urban interface. The potential

exists for significant smoke problems in this

region.

Smoke and Southern Climate

Several factors regarding climate add to the

smoke problem in the South. The long growing

season allows time for more annual biomass

production relative to other areas of the country

with shorter growing seasons. Most of the

Southern forests are located farther south than

forests elsewhere in the country. Consequently,

the sun angle is higher in the South and is

capable of supplying warmth well into the late

fall and early winter. Further, most southern

wildlands are located at low elevations where

the air is warmer. These factors contribute to

the long growing season, which runs from

March/April through October/November.

Abundant rainfall also encourages growth of a

large number of grasses, shrubs, and trees.

Most of the South receives 40-60 inches (100-

150 cm) of precipitation annually. This copious

rainfall, in combination with the long growing

season, creates conditions for rapid buildup of

both dead and live fuels. If burns are not conducted frequently, the increase in emissions

from the accumulated fuels may enhance the

likelihood of negative smoke impacts when fires

do occur.

Figure 3.3.3. Population density classes showing wildland/urban interface in red.

Southern forests outlined in blue. [http://www.fs.fed.us/fire/fuelman]
– 45 –

2001 Smoke Management Guide 3.3 – Nuisance Smoke

The coincidence of dormant-season burning

with the winter rain season is a third factor

contributing to nuisance smoke. Although

burning is conducted year round throughout the

South, a significant amount of burning is done

during January through March. In a typical

year, anywhere from 10-20 inches (25-50 cm) of

rain will fall over Southern forests during this

three-month period. In some areas of the country, the question might be, “Is it wet enough to

burn?” In the South, the question is commonly,

“Is it dry enough to burn?” Fires burning into

moist fuel burn less efficiently and smolder

longer than fires burning dry fuels. Both factors

increase smoke production. In addition, less

heat is produced during inefficient combustion

and smoldering. Therefore, more smoke stays

near the ground and increases the risk of problem smoke.

Smoke and

Southern Meteorology

All thirteen Southern states have implemented

burning regulations designed to limit open

burning to those days when burning is considered “safe” and the risks of fire escapes are

minimal. Many have implemented smoke

management regulations. The need to conduct

burning in a manner to reduce impacts on air

quality over sensitive targets has encouraged

“best practice” approaches to open burning.

Efforts to avoid smoke incursions over sensitive

targets are often complicated by the highly

variable meteorology of Southern weather

systems during the extensive burn season. Four

weather features that cause frequent wind shifts

and may be accompanied by rapid changes in air

mass stability and mixing height are described

below.

1. Synoptic scale high- and low-pressure

systems and accompanying fronts frequent

the South during the winter burn season.

In a typical sequence of events, the winds

shift to blow from the southeast through

southwest in advance of a storm, then shift

rapidly to the northwest with cold front

passage. Winds blow from the northwest

for a day or so but gradually diminish with

the approach of a high pressure system,

becoming light and variable as the system

passes. Then winds shift back to southerly

in advance of the next storm. Low clouds,

low mixing heights, and high stability often

accompany low-pressure systems. Depending upon moisture availability, cold

fronts may be accompanied by bands of

low clouds and precipitation. Mixing

heights are more favorable during highpressure episodes. Although the movement

of synoptic scale weather systems into the

South can be predicted with lead times of

several days, the timing of arrival of frontal

wind shifts over specific burn sites is less

certain.

2. Much of the Piedmont and Coastal Plain

are flat and it would be expected that winds

there are steady and predictable. However,

the region is frequented by transient eddies

that can cause unexpected wind shifts and

carry smoke into sensitive areas. The

vertical circulation of air that can force

smoke plumes to the ground or carry

smoke safely upward are well-understood,

but the location, timing and strength of the

vertical eddies cannot be predicted. Horizontal eddies have not been well documented, and the timing, location and

intensity cannot be predicted.

3. The South has the longest coastline of any

fire-prone area in the country. Thus it is

axiomatic that large areas of the South are
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 46 –

subject to wind shifts brought on by sea

breezes during the day and by land breezes

during the night. However, the onset,

duration, and intensity of these land/waterinduced circulations are not consistent

from one day to the next. The region is

subject at different times to warm, humid

airmasses drawn northward from the Gulf

of Mexico, or cold, dry airmasses drawn

southward from Canada. Both systems

have an impact on land surface temperatures, which results in a significant effect

on the duration and extent of land and sea

breezes and whether they form at all. The

unpredictability of these wind systems adds

to the difficulties faced by Southern land

managers planning whether smoke from a

prescribed burn might impact downwind

sensitive targets.

4. The “flying wedge,” a wind system caused

by cold air channeled southwestward along

the eastern slopes of the Appalachian

Mountains, can cause sudden wind shifts

with large changes in wind direction and

lowering of mixing heights. Although

Virginia, the Carolinas and Georgia are

most frequently impacted, flying wedges

have been observed as far south as central

Florida and as far west as the Mississippi

River. “Flying wedges” occur throughout

the year but are most intense, and hence

bring with them strong shifting winds and

lowering of mixing heights, during winter

and early spring, the period of maximum

wildland burning in the South.

Smoke and Southern Highways

As previously noted, several million acres of

Southern wildlands are burned each year, the

vast majority without incident. However, smoke

and smoke-induced fog obstructions of visibility

on highways sometimes cause accidents with

loss of life and personal injuries. Several

attempts to compile records of smoke-implicated highway accidents have been made. For

the 10-year period from 1979-1988, Mobley

(1989) reported 28 fatalities, over 60 serious

injuries, numerous minor injuries and millions

of dollars in lawsuits. During 2000, smoke from

wildfires drifting across Interstate 10 caused at

least 10 fatalities, five in Florida and five in

Mississippi. In their study of the relationship

between fog and highway accidents in Florida,

Lavdas and Achtemeier (1995) compared three

years of accident reports that mentioned fog

with fog reports at nearby National Weather

Service stations. Highway accidents were more

likely to be associated with local ground radiation fogs than with widespread advection fogs.

Accidents tended to happen when fog created

conditions of sudden and unexpected changes in

visibility.

There are several reasons why smoke on the

highways is a serious problem in the South,

some of them interrelated.

Road density: The density of the road network

in the South is far greater than in other wildland

areas in the country where prescribed fire is in

widespread use. The difference in road density

between generally forested areas in the west and

in the south exists primarily because of land use

history. While Western forested lands have

always been in forest, in the Southern area,

roads and communities remain essentially

unchanged from the old agricultural South.

Population in wildland areas: The population

dwelling near or within Southern wildlands is

greater than that in other areas of the country

where prescribed fire is in widespread use

(figure 3.3.3). Many people live in close proximity to Southern forests; many more live in
– 47 –

2001 Smoke Management Guide 3.3 – Nuisance Smoke

areas interfacing fire-prone grasslands and

shrublands. Southern States are becoming more

urban, and the numbers of tourists driving to

resort areas along the Gulf coast, the Atlantic

coast, and the Florida peninsula are increasing.

Therefore, the number of accidents related to

smoke and fog can only be expected to increase.

Climate and meteorology: Factors of Southern

climate and meteorology combine to produce

airmasses that entrap smoke close to the ground

at night. Smoke is most often trapped by either

a surface inversion or inversion aloft. This is a

condition in which temperature increases with

height through a layer of the atmosphere. Vertical motion is restricted in this very stable air

mass. Although most inversions dissipate with

daytime heating, inversions aloft caused by

large-scale subsidence may persist for several

days, resulting in a prolonged smoke management problem

Most smoke-related highway accidents occur

just before sunrise when temperatures are

coldest and smoke entrapment has maximized

under a surface-level inversion. The high sun

angle during the burn season contributes to

warm daytime temperatures. Near sunset, under

clear skies and near calm winds, temperatures in

shallow stream basins can drop up to 20 degrees

F. in one hour (Achtemeier 1993). Smoke from

smoldering heavy fuels can be entrapped near

the ground and carried by local drainage winds

into these shallow basins where temperatures

are colder and relative humidities are higher.

Hygroscopic particles within smoke can assist in

development of local dense fog. Weak drainage

winds of approximately 1 mile per hour (0.5

m/sec) can carry smoke over 10 miles during the

night—far enough in many areas to carry the

smoke or fog over a roadway.

Problem Smoke: What is being

done to Minimize the Problem

As population growth in the South continues,

there is an increasing likelihood that more

people will be adversely impacted by smoke.

Unless methods are found to mitigate the impacts of smoke, increasingly restrictive regulations may curtail the use of prescribed fire, or

fire as a management tool may be prohibited.

Several approaches are underway to reduce the

uncertainty in predicting smoke movement.

• Several states have devised smoke management guidelines to regulate the amount

of smoke put into the atmosphere from

prescribed burning. The South Carolina

Forestry Commission (1998) has established guidelines to define smoke sensitive

areas, amounts of vegetative debris that

may be burned, and atmospheric conditions suitable for burning this debris.

• The Forestry Weather Interpretation

System (FWIS) was developed by the U.S.

Forest Service in the late 1970’s and early

1980’s in cooperation with the southern

forestry community (Paul 1981; Paul and

Clayton 1978). The system has been

enhanced and automated by the Georgia

Forestry Commission (Paul et al. 2000) to

serve forestry sources in Georgia and

clients in other southern states. The GFC

provides weather information and forecasts specified for forest districts, and

indices used for interpretations for smoke

management, prescribed fire, fire danger,

and fire behavior. Indices include the

Keetch-Byram Drought Index, National

Fire Danger Rating System, Ignition

component, Burning Index, and Manning

Class Day.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 48 –

• High resolution weather prediction models

promise to provide increased accuracy in

predictions of wind speeds and directions

and mixing heights at time and spatial

scales useful for land managers. The

Florida Division of Forestry (FDOF) is a

leader in the use of high resolution modeling for forestry applications in the South

(Brackett et al. 1997). Accurate predictions of sea/land breezes and associated

changes in temperature, wind direction,

atmospheric stability and mixing height

are critical to the success of the FDOF

system as much of Florida is located

within 20 miles of a coastline. High

resolution modeling consortia are also

being established by the U.S. Forest

Service to serve clients with interests as

diverse as fire weather, air quality, oceanography, ecology, and meteorology.

• Several smoke models are in operation or

are being developed to predict smoke

movement over Southern landscapes.

VSMOKE (Lavdas 1996), a Gaussian

plume model that assumes level terrain

and unchanging winds, predicts smoke

movement and concentration during the

day. VSMOKE is now part of the FDOF

fire and smoke prediction system. It is a

screening model that aids land managers

in assessing where smoke might impact

sensitive targets as part of planning for

prescribed burns. PB-Piedmont

(Achtemeier 2001) is a wind and smoke

model designed to simulate smoke movement near the ground under entrapment

conditions at night. The smoke plume is

simulated as an ensemble of particles that

are transported by local winds over complex terrain characteristic of the shallow

(30-50 m) interlocking ridge/valley systems typical of the Piedmont of the South.

PB-Piedmont does not predict smoke

concentrations as emissions from smoldering combustion are usually not known.

Two sister models are planned, one that

will simulate near ground smoke movement near coastal areas influenced by sea/

land circulations and the other for the

Appalachian mountains.

In summary, the enormous wildland/urban

interface and dense road network located in a

region where up to six million acres of wildlands per year are subject to prescribed fire

combine to make problem smoke the foremost

land management-related air quality problem in

the South. During the daytime, smoke becomes

a problem when it drifts into areas of human

habitation. At night, smoke can become entrapped near the ground and, in combination

with fog, create visibility reductions that cause

roadway accidents. Public outcry regarding

problem smoke usually occurs before smoke

exposures increase to levels that violate air

quality standards. With careful planning and

knowledge of local conditions, the fire manager

can usually avoid problematic smoke intrusions

on the public.

Literature Citations

Achtemeier, G.L. 2001. Simulating nocturnal smoke

movement. Fire Management Today, 61: 28-33

Achtemeier, G. L. 1993. Measurements of drainage

winds along a small ridge. In: Proceedings of

the 86th Annual Meeting and Exhibition, Air &

Waste Management Association, 93-FA-155.06,

15 pp.

Brackett, D.P., L. G. Arvanitus, J. Brenner, and M.

Long, 1997. A high-tech approach to openburning authorization and wildfire response. J.

Forestry, 95: 10-15.
– 49 –

2001 Smoke Management Guide 3.3 – Nuisance Smoke

Eshee, W.D. 1995. Legal implications of using

prescribed fire. In: Proceedings: Environmental

regulation & prescribed fire conference. D.C.

Bryan, ed. Division of Forestry, Florida Department of Agriculture and Consumer Services,

Tallahassee, Florida. pp. 126-130.

Lavdas, L. G. 1996. Program VSMOKE–users

manual. USDA Forest Service General Technical Report SRS-6. 147 pp.

Lavdas, L., and G. L. Achtemeier. 1995. A fog and

smoke risk index for estimating roadway

visibility hazard. National Weather Digest, 20:

26-33.

Mobley, H. E. 1989. Summary of smoke-related

accidents in the South from prescribed fire

(1979-1988). American Pulpwood Association

Technical Release 90-R-11.

New Mexico Environmental Improvement Board

Rules. 1995. Open Burning 20-NMAC2.60.

Santa Fe, New Mexico.

Paul, J. T., 1981: A real-time weather system for

forestry (FWIS). Bulletin of the American

Meteorological Society, 62: 1466-1472.

Paul, J. T., and J. Clayton, 1978. User manual:

Forestry Weather Interpretation System

(FWIS). Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern

Forest Experiment Station and Atlanta, GA:

Southeastern Area State and Private Forestry, in

cooperation with the U.S. National Weather

Service, NOAA, Silver Spring, MD, 83pp.

Paul, J. T., D. Chan, and A. Dozier, 2000. Fire

Weather and Smoke Management System.

Georgia Forestry Commission, 74 pp.

Sandberg, D.V., and F. N. Dost. 1990. Effects of

prescribed fire on air quality and human health.

In: Natural and Prescribed Fire in Pacific

Northwest Forests. J.D. Walstad; S.R.

Radosevich; D.V. Sandberg, eds. Oregon State

University Press, Corvallis, OR. pp. 91-298.

Shelby, B., and R. W. Speaker. 1990. Public attitudes and perceptions about prescribed burning.

In: J.D. Walstad; S.R. Radosevich; D.V.

Sandberg, eds. Natural and Prescribed Fire in

Pacific Northwest Forests. Oregon State

University Press. Corvallis, OR. pp. 253-260.

South Carolina Forestry Commission, 1998. Smoke

Management Guidelines for Vegetative Debris

Burning Operations in the State of South

Carolina. SCFC 4th Printing, 21 p.

State of Oregon Department of Forestry. 1992.

Smoke Management Program Directives,

Appendix 2. Salem, Oregon.

State of Washington Department of Natural Resources. 1993. Smoke Management Program

Appendix 5. Olympia, Washington.

Supreme Court of Iowa, No. 192/96-2276.

Bormann, et al vs. Board of Supervisors in and

for Kossuth County Iowa. September 23, 1998.

{http://www.webcom.com/bi /iowa.htm}

US Environmental Protection Agency. 1990. Air

Quality Criteria for Particulate Matter Volume

II of III. Office of Research and Development.

EPA/600/P-95/00ibF. pp. 8-82 – 8-89.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 50 –
– 51 –

2001 Smoke Management Guide 3.4 – Smoke Exposure

Smoke Exposure Among

Fireline Personnel

Roger D. Ottmar

Timothy R. Reinhardt

Wildland firefighting presents many hazards to

fireline workers, including inhalation exposure

to smoke (Sharkey 1998; Reinhardt and Ottmar

1997; Sharkey 1997). Many experienced

fireline personnel consider this to be only an

inconvenience, occasionally causing acute cases

of eye and respiratory irritation, nausea and

headache. Others express concern about longterm health impacts, especially when largescale fires occur in terrain and atmospheric

conditions that force fireline workers to work

for many days in smoky conditions. At the

present time, no one can say whether there are

long-term adverse health effects from occupational smoke exposure. This is because there

have been no epidemiological studies to track

the health of fireline personnel and compare it

with other workers to see if fireline personnel

have more or fewer health problems during and

after their careers. Until such long-term data

are examined to tell us if a problem exists, we

can only assess the occurrence of relatively

short-term adverse health effects. We can

measure fireline worker’s exposure to particles

and individual chemicals found in smoke and

compare these exposures to standards established to protect worker health (Reinhardt and

Ottmar 2000; Reinhardt and others 2000;

Reinhardt and others 1999). We can evaluate

the relative risk of disease among fireline

workers based on the exposure data and the

potency of the health hazards (Booze and

Reinhardt 1996).

Health Hazards in Smoke

Smoke from wildland fires is composed of

hundreds of chemicals in gaseous, liquid, and

solid forms (Sandberg and Dost 1990; Reinhardt

and Ottmar 2000; Reinhardt and others 2000;

Sharkey 1998; Sharkey 1997). The chief inhalation hazards for fireline personnel and to the

general public when they are exposed to smoke

appear to be carbon monoxide and respirable

irritants which include particulate matter, acrolein, and formaldehyde.

Carbon Monoxide — Carbon monoxide (CO)

has long been known to interfere with the body’s

ability to transport oxygen. It does this by

bonding with hemoglobin, the molecule in the

bloodstream which shuttles oxygen from the

lungs throughout the body, to form carboxyhemoglobin (COHb). When people are exposed to

CO, the time until a toxic level of COHb results

can be predicted as a function of CO concentration, breathing rate, altitude, and other factors

(Coburn, Forster and Kane 1965). The harder

the work and the higher the altitude, the more
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 52 –

rapidly COHb forms at a given level of atmospheric CO. At the highest CO levels found in

heavy smoke, symptoms of excessive COHb can

result in 15 minutes during hard physical labor.

Carbon monoxide causes acute effects ranging

from diminished work capacity to nausea,

headache, and loss of mental acuity. It has a

well-established mechanism of action, causing

displacement of oxygen from hemoglobin in the

blood and affecting tissues that do not stand the

loss of oxygen very well, such as the brain,

heart, and unborn children. Fortunately, most of

these effects are reversible and CO is rapidly

removed from the body, with a half-life on the

order of 4 hours. Some studies have linked CO

exposure to longer-term heart disease, but the

evidence is not clearcut.

Respirable Irritants — Experienced fireline

workers can attest to eye, nose and throat irritation at both wildfires and prescribed burns.

Burning eyes, runny nose, and scratchy throat

are common symptoms in smoky areas at

wildland fires, caused by the irritation of mucous membranes. These adverse health effects

are symptoms of exposure to aldehydes, including formaldehyde, acrolein, as well as respirable

particulate matter (PM2.5)—very fine particles

less than a few micrometers (μm) in diameter—

composed mostly of condensed organic and

inorganic carbon (Dost 1991). Other rapid

adverse health effects of aldehydes include

temporary paralysis of the respiratory tract cilia

(microscopic hairs which help to remove dust

and bacteria from the respiratory tract) and

depression of breathing rates (Kane and Alarie

1977), while over the long term, formaldehyde

is considered a potential cause of nasal cancer

(U.S. Department of Labor, Occupational Safety

and Health Administration 1987).

Adverse health effects of smoke exposure begin

with acute, instantaneous eye and respiratory

irritation and shortness of breath but can develop into headaches, dizziness and nausea

lasting up to several hours. The aldehydes, such

as acrolein and formaldehyde, and PM2.5 cause

rapid minor to severe eye and upper respiratory

tract irritation. Total supsended particulate

(TSP) also irritates the eyes, upper respiratory

tract and mucous membranes, but the larger

particulates in TSP do not penetrate as deeply

into the lungs as the finer PM2.5 particles.

Longer-term health effects lasting days to

perhaps months have recently been identified

among fireline workers, including modest losses

of pulmonary function. These include a slightly

diminished capacity to breathe, constriction of

the repsiratory tract, and hypersensitivity of the

small airways (Letts and others 1991; Reh and

others 1994).

A discussion of particulate inhalation hazards

faced by fireline personnel is incomplete without mentioning crystalline silica, which can be

an additional hazard in the presence of smoke.

If crystalline silica is a component of the soil at

a site, dust stirred up by walking, digging, mopup, or vehicles may be a significant irritation

hazard, and the threat of silicosis (fibrous

scarring of the lungs decreasing oxygenation

capability) is a possibility.

Evaluation Criteria

On what basis do we decide whether smoke

exposure is safe or unsafe? Workplace exposures to health hazards must be evaluated with

care for several reasons. First, people vary in

their sensitivity to pollutants. Second, personal

habits and physical condition are important

factors. For example, smokers already commonly experience 5% COHb because of the CO
– 53 –

2001 Smoke Management Guide 3.4 – Smoke Exposure

from their cigarettes, thus they may be at greater

risk of adverse health effects from additional

CO exposure at fires. Assumptions are made by

regulatory agencies when establishing exposure

limits. These assumptions may not be valid for

the wildland fire workplace. For example, the

current CO standard was set to protect a sedentary worker in an 8-hour per day job over a

working lifetime, not a hard-working fireline

worker on a 12-hour/day job for a few summers.

Given these issues, how should we judge the

safety of smoke exposure? At a minimum, a

fireline worker’s inhalation exposures must

comply with the occupational exposure limits,

called “Permissible Exposure Limits” (PEL’s),

by the Occupational Safety and Health Administration (OSHA) (U.S. Department of Labor,

Occupational Safety and Health Administration

1994). These limits are set at levels considered

feasible to attain, and necessary to protect most

workers from adverse health effects over their

working lifetime. The more stringent exposure limits recommended by the American

Conference of Governmental Industrial Hygienists (ACGIH) are the “Threshold Limit Values”

(TLVs) (American Conference of Governmental

Industrial Hygienists 2000). These are also

established to prevent adverse health effects in

most workers, but without adjustment for

economic feasibility. The ACGIH limits are

periodically updated to incorporate the latest

scientific knowledge where as many of the

PEL’s have not been revised since the 1960’s.

All exposure limits are expressed in terms of a

time-weighted average (TWA) exposure, which

is an average exposure over the workshift. For

health hazards which quickly cause adverse

effects from acute exposures, the limits are

supplemented by short-term exposure limits

(STELs) for 15-minute periods in a workshift

and ceiling exposure limits (C), which are not to

be exceeded at any time. These various exposure limits are listed in table 3.4.1, along with a

third set of “Recommended Exposure Limits”

established by the National Institute for Occupational Safety and Health; these also incorporate

recent scientific evidence. Depending on the

pollutant, the units of measure are either milligrams per cubic meter of air (mg/m3

) or parts

per million by volume (ppm). Without a more

detailed analysis of a given work/rest regime,

adhering to the ACGIH TLV limits should

provide reasonable protection for workers.

 

Table 3.4.1. Occupational exposure limitsa
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 54 –

Smoke Exposure at Prescribed

Burns and Wildfires

Several studies (Reinhardt and Ottmar 1997)

have evaluated smoke exposure during prescribed burns by obtaining personal exposure

samples, which are collected within a foot of a

worker’s face (the breathing zone) while they

are on the job (figure 3.4.1). One study in

particular measured smoke exposure among

fireline workers at 39 prescribed burns in the

Pacific Northwest. The study found that about

10% of firefighter exposures to respiratory

irritants and CO exceeded recommended occupational exposure limits (Reinhardt and others

2000) and could pose a hazard. The actual

incidence of illness and mortality among wildland fireline workers has not been systematically studied, but short-term adverse health

impacts have been observed among fireline

personnel at prescribed fires. A study in 1992-

93 found small losses in lung function among 76

fireline personnel working at prescribed burns

(Betchley and others 1995).

Between 1992 and 1995 a study of smoke

exposure and health effects at wildfires in the

western United States found results similar to

those at prescribed fires. Exposure to carbon

monoxide and respiratory irritants exceeded

recommended occupational exposure limits for

5 percent of workers (Reinhardt and Ottmar

2000).

At wildfires where fireline workers encounter

concentrated smoke, or moderate smoke over

longer times, there is a likelihood that many will

develop symptoms similar to those seen at

prescribed fires. In 1988, engine-based

firefighters of the California Department of

Forestry and Fire Protection underwent lung

function testing before and after the fire season.

Small (0.3 to 2%) losses in lung function were

observed among the firefighters. These losses

Figure 3.4.1. Bitterroot Hotshot crew member wearing backpack that obtains smoke

exposure samples collected within several inches of a worker’s face.
– 55 –

2001 Smoke Management Guide 3.4 – Smoke Exposure

were associated with the amount of recent

firefighting activity in the study period. The

firefighters also reported increased eye and nose

irritation and wheezing during the fire season.

Monitoring Smoke Exposure of

Fireline workers

During prescribed fire and wildfire exposure

studies, it was found that exposure to respiratory

irritants could be predicted from measurements

of carbon monoxide (Reinhardt and Ottmar

2000). Fire managers and safety officers concerned with smoke exposure among fire crews

can use electronic carbon monoxide (CO)

monitors to track and prevent overexposure to

smoke (figure 3.4.2). Commonly referred to as

dosimeters, these lightweight instruments

measure the concentration of CO in the air

thatfireline personnel breath. Protocols have

been developed for sampling smoke exposure

among fireline workers with CO dosimeters.

These protocols and a basic template have been

outlined by Reinhardt and others (1999) for

managers and safety officers interested in

establishing their own smoke-exposure monitoring program.

Respirator Protection

The Missoula Technology and Development

Center (MTDC) has the lead role in studying

respiratory protection for fireline workers

(Thompson and Sharkey 1966, Sharkey 1997).

Figure 3.4.2. Carbon monoxide exposure data from a electronic CO data recorder for a fireline worker

during a work-shift on a prescribed fire (Reinhardt and others 2000)
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

– 56 –

Although respirators reduce work capacity, they

may have merit under certain circumstances to

minimize hazardous exposures. Field evaluations by MTDC found that disposable respirators were acceptable for short-term use but they

deteriorated in the heat during several hours of

use (Sharkey 1997). Maintenance free halfmask devices were satisfactory, except for the

heat stress found with all facemasks. Full-face

masks were preferred for the long-term use on

prescribed fires because of the eye protection

they provided, but workers often complained of

headaches, a sign of excess CO exposure since

respirators do not eliminate the intake of CO

(Sharkey 1997). Full-face respirators protect the

eyes, removing eye irritation as an important

early warning of exposure to smoke. Any respiratory protection program for fireline workers

would require employees to be instructed and

trained in the proper use and limitations of the

respirators issued to them.

Management Implications

Evidence to date suggests that fireline workers

exceed recommended exposure limits during

prescribed burns and wildfires less than 10

percent of the time (Reinhardt and others 2000;

Reinhardt and Ottmar 2000). The concept that

few fireline personnel spend a working lifetime

in the fire profession and should be exempt from

occupational exposure standards which are set

to protect workers over their careers is little

comfort to those who do, and irrelevant for

irritants and fast-acting hazards such as CO.

Most of the exposure limits that are exceeded

are established to prevent acute health effects,

such as eye and respiratory irritation, headache,

nausea and angina. An exposure standard

specifically for fireline workers, and appropriate

respiratory protection, needs to be developed.

In addition, a long-term program to manage

smoke exposure at wildland fires is needed

(Sharkey 1997). The program could include:

1) hazard awareness training; 2) implementation

of practices to reduce smoke exposure; 3)

routine CO monitoring with electronic dosimeters (Reinhardt and others 1999); 4) improved

record keeping on accident reports to include

separation of smoke related illness among

fireline workers and fire camp personnel; and 4)

implementing and training for an OSHAcompliant respirator program to protect fireline

personnel from respiratory irritants and CO

when they must work in smoky conditions.

Literature Citations

American Conference of Governmental Industrial

Hygienists. 2000. 2000 TLVs® and BEIs®

:

Threshold Limit Values for chemical substances

and physical agents and biological exposure

indices. Cincinnati, OH 192 p.

Betchley, C.; Koenig, J.Q.; van Belle G.;

Checkoway, H. and Reinhardt, T. 1995. Pulmonary function and respiratory symptoms in

forest firefighters, Unpublished report, University of Washington, Departments of Environmental Health and Epidemiology, Seattle, WA

Booze, Tom F.; Reinhardt, Timothy E. 1996.

Assessment of the health risks of chronic smoke

exposure for wildland firefighters. Unpublished

report, Pacific Northwest Research Station,

Seattle forestry Science Laboratory, 4043

Roosevelt Way N.E., Seattle, WA. 29 p.

Coburn, R.F.; Forster, R.E.; Kane, P.B. 1965. Considerations of the physiological variables that

determine the blood carboxyhemoglobin

concentration in man. Journal of Clinical

Investigation 44: 1899-1910.
– 57 –

2001 Smoke Management Guide 3.4 – Smoke Exposure

Dost, F.N. 1991. Acute toxicology of components of

vegetation smoke. In: Reviews of Environmental Contamination and Toxicology, Vol 119,

Springer-Verlag New York, Inc., New York, NY,

1991 pp 2-46.

Kane, L.E.; Alarie, Y. 1977. Sensory irritation to

formaldehyde and acrolein during single and

repeated exposures in mice. American Industrial

Hygiene Association Journal 38(10): 509-522.

Letts, D.; Fidler, A.T.; Deitchman, S.; Reh, C.M.

1991. Health hazard evaluation report 91-152-

2140. U.S. Department of the Interior, National

Park Service, Southern California, U.S. Department of Health and Human Services, Public

Health Service, Centers for Disease Control,

National Institute for Occupational Safety and

Health, Cincinnati, OH.

Reh, C.M.; Letts, D.; Deitchman, S.D. 1994. Health

hazard evaluation report 90-0365-2415. U.S.

Department of the Interior, National Park

Service, Yosemite National Park, California,

U.S. Department of Health and Human Services, Public Health Service, Centers for

Disease Control, National Institute for Occupational Safety and Health, Cincinnati, OH.

Reinhardt, Timothy E.; Ottmar, Roger D. 1997.

Smoke exposure among wildland firefighters: a

review and discussion of current literature. Gen.

Tech. Rep. GTR-373. Portland, OR: U.S.

Department of Agriculture, Forest service,

Pacific Northwest research Station. 61 p.

Reinhardt, Timothy E.; Ottmar, Roger D. 2000.

Smoke exposure at western wildfires. Res. Pap.

PNW-RP-525. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Research Station. 72 p.

Reinhardt, Timothy E.; Ottmar, Roger D.;

Hanneman, Andrew J.S. 2000. Smoke exposure

among firefighters at prescribed burns in the

Pacific Northwest. Res. Pap. PNW-RP-526.

Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research

Station. 45 p.

Reinhardt, Tim E.; Ottmar, Roger D.; Hallett,

Michael R. 1999. Guide to monitoring smoke

exposure of wildland firefighters. Gen. Tech.

Rep. PNW-GTR-448. Portland, OR: U.S.

Department of Agriculture, Forest service,

Pacific Northwest Research Station. 17 p.

Sandberg, David V.; Dost, Frank N. 1990. Effects of

prescribed fire on air quality and human health.

In: Walstad, John D.; Radosevich, Steven R.;

Sandberg, David V., eds. Natural and prescribed

fire in the Pacific Northwest forests. Corvallis,

OR: Oregon State University Press: 191-298.

Sharkey, Brian, ed. 1997. Health hazards of smoke:

recommendations of the April 1997 Consensus

Conference. Tech. Rep. 9751-2836-MTDC.

Missoula, MT: U.S. Department of Agriculture,

Forest Service, Missoula Technology and

Development Center. 84 p.

Sharkey, Brian, ed. 1998. Health hazards of smoke.

Closed caption video. Missoula, MT: U.S.

Department of Agriculture, Forest Service,

Missoula Technology and Development Center.

19 minutes.

Thompson, S.; Sharkey, B. 1966. Physiological cost

and air flow resistance of respiratory protective

devices. Ergonomics 9:495.

U.S. Department of Labor, Occupational Safety and

Health Admnistration. 1987. Occupational

exposure to formaldehyde, final rule. Federal

Register 52(233): 46312, Washington D.C.

1987.

U.S. Department of Labor, Occupational Safety and

Health Administration. 1994. Code of Federal

Regulations, Title 29, Part 1910.1048(d)(2)(i),

Washington, DC, 1994.
Chapter 3 – Smoke Impacts 2001 Smoke Management Guide

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– 59 –

2001 Smoke Management Guide 4.1 – Smoke Management

REGULATIONS

Chapter 4
Chapter 4 – Regulations 2001 Smoke Management Guide

– 60 –
– 61 –

2001 Smoke Management Guide 4.1 – Smoke Management

Regulations For Smoke Management

Janice L. Peterson

Some of the components of smoke from prescribed fire are regulated air pollutants. And, as

with any other rule or regulation, fire managers

must understand and follow federal, state, and

local regulations designed to protect the public

against possible negative effects of air pollution.

Air pollution is defined as the presence in the

atmosphere of a substance or substances added

directly or indirectly by a human act, in such

amounts as to adversely affect humans, animals,

vegetation, or materials (Williamson 1973). Air

pollutants are classified into two major categories: primary and secondary. Primary pollutants are those directly emitted into the air.

Under certain conditions, primary pollutants can

undergo chemical reactions within the atmosphere and produce new substances known as

secondary pollutants.

Emissions from prescribed fire are managed and

regulated through an often-complex web of

interrelated laws and regulations. The overarching law that is the foundation of air quality

regulation across the nation is the Federal Clean

Air Act (Public Law 95-95).

Federal Clean Air Act

In 1955, Congress passed the first Federal Clean

Air Act with later amendments in 1967, 1970,

1977, and 1990. The Clean Air Act is a legal

mandate designed to protect public health and

welfare from air pollution. States develop

specific programs for implementing the goals of

the Clean Air Act through their State Implementation Plans (SIP’s). States may develop programs that are more restrictive than the Clean

Air Act requires but never less. Burners must

know the specifics of state air programs and

how fire emissions are regulated to responsibly

conduct a prescribed fire program.

Roles and Responsibilities

Although the Clean Air Act is a federal law and

therefore applies to the entire country, the states

do much of the work of implementation. The

Act recognizes that states should have the lead

in carrying out provisions of the Clean Air Act,

since appropriate and effective design of pollution control programs requires an understanding

of local industries, geography, transportation,

meteorology, urban and industrial development

patterns, and priorities.

The Clean Air Act gives the Environmental

Protection Agency (EPA) the task of setting

limits on how much of various pollutants can be

in the air where the public has access1

 (ambient

air). These air pollution limits are the National

Ambient Air Quality Standards or NAAQS and

___________________________________

1 Note that the Occupational Safety and Health Administration (OSHA), rather than EPA, sets air quality standards

for worker protection.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 62 –

are intended to be established regardless of

possible costs associated with achieving them,

though EPA is allowed to consider the costs of

controlling air pollution during the implementation phase of the NAAQS in question. In addition, EPA develops policy and technical

guidance describing how various Clean Air Act

programs should function and what they should

accomplish. States develop State Implementation Plans (SIPs) that define and describe customized programs that the state will implement

to meet requirements of the Clean Air Act.

Tribal lands are legally equivalent to state lands

and tribes prepare Tribal Implementation Plans

(TIPs) to describe how they will implement the

Clean Air Act. The individual states and tribes

can require more stringent pollution standards,

but cannot weaken pollution goals set by EPA.

The Environmental Protection Agency must

approve each SIP/TIP, and if a proposed or active

SIP/TIP is deemed inadequate or unacceptable,

EPA can take over enforcing all or parts of the

Clean Air Act requirements for that state or tribe

through implementation of a Federal Implementation Plan or FIP (figure 4.1.1).

National Ambient Air

Quality Standards

The primary purpose of the Clean Air Act is to

protect humans against negative health or

welfare effects from air pollution. National

Ambient Air Quality Standards (NAAQS) are

defined in the Clean Air Act as amounts of

pollutant above which detrimental effects to

public health or welfare may result. NAAQS

are set at a conservative level with the intent of

protecting even the most sensitive members of

the public including children, asthmatics, and

persons with cardiovascular disease. NAAQS

Figure 4.1.1. Role of EPA and the states and tribes in Clean Air Act implementation.

 
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2001 Smoke Management Guide 4.1 – Smoke Management

have been established for the following criteria

pollutants: particulate matter2 (PM10 and

PM2.5), sulfur dioxide (SO2), nitrogen dioxide

(NO2), ozone, carbon monoxide and lead (table

4.1.1). Primary NAAQS are set at levels to

protect public health; secondary NAAQS are to

protect public welfare. The standards are

established for different averaging times, for

example, annual, 24-hour, and 3-hour.

 

 

 

 

 

 

 

Table 4.1.1. National Ambient Air Quality Standards.

The major pollutant of concern in smoke from

wildland fire is fine particulate matter, both

PM10 and PM2.5. Studies indicate that 90

percent of smoke particles emitted during

wildland burning are PM10 and about 90

percent of PM10 is PM2.5 (Ward and Hardy

1991). The most recent human health studies

on the effects of particulate matter indicate that

it is fine particles, especially PM2.5, that are

largely responsible for health effects including

___________________________________

2 Particulate matter NAAQS are established for two aerodynamic diameter classes: PM10 is particulate matter 10

micrometers or less in diameter, and PM2.5 is particulate matter that is 2.5 micrometers or less in diameter.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 64 –

mortality, exacerbation of chronic disease, and

increased hospital admissions (Dockery and

others 1993, EPA 1996).

An area that is found to be in violation of a

primary NAAQS is labeled a non-attainment

area (figure 4.1.2). An area once in non-attainment but recently meeting NAAQS, and with

appropriate planning documents approved by

EPA, is a maintenance area. All other areas are

attainment or unclassified (due to lack of monitoring). State air quality agencies can provide

up-to-date locations of local non-attainment

areas

3

. States are required through their SIP’s to

define programs for implementation, maintenance, and enforcement of the NAAQS within

their boundaries. A non-attainment designation

is a black mark on the states air agency’s ability

to protect citizens from the negative effects of

air pollution so states generally develop aggressive programs for bringing non-attainment areas

into compliance with clean air goals. Wildland

fire in and near non-attainment areas will be

scrutinized to a greater degree than in attainFigure 4.1.2. PM10 nonattainment areas as of August 2001. See the EPA AIRData web page for

current nonattainment status for PM10 and al other criteria pollutants

(http://www.epa.gov/air/data/mapview.html).

___________________________________

3 PM2.5 is a newly regulated pollutant so attainment/non-attainment status has not yet been determined. Monitoring

must take place for at least 3 years before a designation can be made.
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2001 Smoke Management Guide 4.1 – Smoke Management

ment areas (and may be subject to General

Conformity rules, see section 4.3: Federal Land

Management-Special Requirements). Extra preplanning, documentation, and careful scheduling

of wildland fires will likely be required to

minimize smoke effects in the non-attainment

area to the greatest extent possible. In some

cases, the use of fire may not be possible if

significant impacts to a non-attainment area are

likely.

Natural Events Policy

PM10 NAAQS exceedences caused by natural

events are not counted toward non-attainment

designation if a state can document that the

exceedance was truly caused by a natural event

and if the state then prepares a Natural Events

Action Plan (NEAP) to address human health

concerns during future events4

. Natural events

are defined by this policy as wildfire, volcanic

and seismic events, and high wind events.

Prescribed fires used to mimic the natural role

of fire in the ecosystem are not considered

natural events under this policy. In response to

this potential conflict of terms, the Interim Air

Quality Policy on Wildland and Prescribed Fires

(EPA 1998) states that EPA will exercise its

discretion not to redisignate an area as nonattainment if the evidence is convincing that

fires managed for resource benefits caused or

significantly contributed to violations of the

daily or annual PM2.5 or PM10 standards and

the state has a formal smoke management

program (see Section 4.2: State Smoke Management Programs for more information).

A NEAP is developed by the state air pollution

control agency in conjunction with the stakeholders affected by the plan. States should

include input from Federal, state, and private

land managers in areas vulnerable to fire when

developing a wildland fire NEAP. Also, agencies responsible for suppressing fires, local

health departments, and citizens in the affected

area should be involved in developing the plan.

The NEAP should include documented agreements among stakeholders as to planned actions

and the parties responsible for carrying out

those actions.

A wildfire NEAP should include commitments

by the state and stakeholders to:

1. Establish public notification and education

programs.

2. Minimize public exposure to high concentrations of PM10 due to future natural

events such as by:

- identifying the people most at risk,

- notifying the at-risk public that an event

is active or imminent,

- recommending actions to be taken by the

public to minimize their pollutant exposure,

- suggesting precautions to take if exposure cannot be avoided.

3. Abate or minimize controllable sources of

PM10 including the following:

- prohibition of other burning during

pollution episodes caused by wildfire,

- proactive efforts to minimize fuel loadings in areas vulnerable to fire,

- planning for prevention of NAAQS

exceedances in fire management plans.

___________________________________

4 Nichols, Mary D. 1996. Memorandum dated May 30 to EPA Regional Air Directors. Subject: Areas Affected by

PM10 Natural Events. Available from the EPA Technology Transfer Network, Office of Air and Radiation Policy and

Guidance at http://www.epa.gov/ttn/oarpg.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 66 –

4. Identify, study, and implement practical

mitigating measures as necessary.

5. Periodic reevaluation of the NEAP.

Preparation of a NEAP provides the opportunity

for land managers to formally document, in

cooperation with state air agencies, that it is

appropriate to consider prescribed fire a prevention, control, and mitigation measure for wildfire (see item 4 above). Prescribed fire can be

used to minimize fuel loadings in areas vulnerable to fire so that future wildfires can be contained in a smaller area and will produce less

emissions. This can lead to a greater understanding by state air agencies of the potential air

quality benefits from some types of prescribed

fire in certain ecosystems. A recent NEAP

prepared for the Chelan county area of Washington State accomplished this goal5

. The Chelan

County NEAP recognizes planned efforts by the

Wenatchee National Forest to reduce fuel

loadings through thinning, pruning of lower

branches, and careful use of prescribed fire as

ways to minimize public exposure to particulate

matter during wildfire season.

Hazardous Air Pollutants

Hazardous air pollutants or (HAPs) are identified in Title III of the Clean Air Act Amendments of 1990 (Public Law 101-549) as 188

different pollutants “which present, or may

present, through inhalation or other routes of

exposure, a threat of adverse human health or

environmental effects whether through ambient

concentrations, bioaccumulation, deposition, or

other routes.” The listed HAPs are substances

which are known or suspected to be carcinogenic, mutagenic, teratogenic, neurotoxic, or

which cause reproductive dysfunction. Criteria

pollutants (the six pollutants that are regulated

through established National Ambient Air

Quality Standards) are excluded from the list of

HAPs.

De minimis Emission Levels

Air quality regulations allow omission of certain

pollution sources in air quality impact analyses

if they are considered very minor and are certain

to have no detrimental effects. These sources

are considered to emit pollutant amounts below

de minimis levels. For example, burning a slash

pile with less than 100 tons of material is not

subject to permit or regulation in some areas.

Emissions below de minimis levels are often

excluded from air quality regulations so this is

an important concept to define in reference to

wildland fire. De minimis levels have been

defined for many industrial sources but little

guidance is available for many wildland activities including prescribed fire. Some states have

locally defined de minimis levels for example in

Utah, fires less than 20 acres per day in size and

emitting less than 0.5 ton of total particulate per

day are considered de minimis and can be

ignited without permit if burners register the

project and comply with clearing index procedures. Definition of de minimis levels is a topic

that needs further discussion between wildland

fire managers and regulatory agencies so guidance can be developed at the local and/or national level.

___________________________________

5 Washington Department of Ecology. June 1997. Natural event action plan for wildfire particulate matter in Chelan

County, Washington. 21p. Available from the Washington Department of Ecology, PO Box 47600, Olympia, WA 98504-

7600.
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2001 Smoke Management Guide 4.1 – Smoke Management

Prevention of Significant

Deterioration

Another provision of the Clean Air Act that

sometimes comes up when discussing wildland

burning activities is the Prevention of Significant Deterioration provisions or PSD. The goal

of PSD is to prevent areas that are currently

cleaner than is allowed by the NAAQS from

being polluted up to the maximum ceiling

established by the NAAQS. States and tribes

use the permitting requirements of the PSD

program to manage and limit air pollution

increases over a baseline concentration. A PSD

baseline is the pollutant concentration at a point

in time when the first PSD permit was issued for

the airshed. New or modified major air pollution sources must apply for a PSD permit prior

to construction and test their proposed emissions

against allowable PSD increments.

Three air quality classes were established by the

Clean Air Act, PSD provisions, including Class

I, Class II, and Class III. Class I areas are

subject to the tightest restrictions on how much

additional pollution, or increment, can be added

to the air. Class I areas include Forest Service

wildernesses and national memorial parks over

5000 acres, National parks exceeding 6000

acres, and international parks, all of which must

have been in existence as of August 7, 1977,

plus later expansions to these areas (figure

4.1.3). These original Class I areas are declared

“mandatory” and can never be redesignated to

another air quality classification. In addition, a

few Indian tribes have redesignated their lands

to Class I. Redesignated Class I areas are not

mandatory Class I areas so are not automatically

protected by all the same rules as defined by the

Clean Air Act unless a state or tribe chooses,

through a SIP or TIP, to do so. Since no areas

have ever been designated Class III, all other

lands are Class II, including everything from

non-Class I wildlands to urban areas.

Historically, EPA has regarded smoke from

wildland fires as temporary and therefore not

subject to issuance of a PSD permit, but whether

or not wildland fire smoke should be considered

when calculating PSD increment consumption

or PSD baseline was not defined. EPA recently

reaffirmed that states could exclude managed

fire emissions from increment analyses, provided the exclusion does not result in permanent

or long-term air quality deterioration (EPA

1998). States are also expected to consider the

extent to which a particular type of burning

activity is truly temporary, as opposed to an

activity that can be expected to occur in a

particular area with some regularity over a

period of time. Oregon is the only state that has

thus far chosen to include prescribed fire emissions in PSD increment and baseline calculations.

Visibility

The 1977 amendments to the Clean Air Act

established a national goal of “the prevention of

any future, and the remedying of any existing,

impairment of visibility in mandatory class I

Federal areas which impairment results from

manmade air pollution” (Public Law 95-95).

States are required to develop implementation

plans that make “reasonable progress” toward

the national visibility goal.

Atmospheric visibility is influenced by scattering and absorption of light by particles and

gases. Particles and gases in the air can obscure

the clarity, color, texture, and form of what we

see. The fine particles most responsible for

visibility impairment are sulfates, nitrates,

organic compounds, elemental carbon (or soot),

and soil dust. Sulfates, nitrates, organic carbon,

and soil tend to scatter light, whereas elemental

carbon tends to absorb light. Wildland fire
Chapter 4 – Regulations 2001 Smoke Management Guide

– 68 –

Figure 4.1.3. Mandatory Cass I areas.
– 69 –

2001 Smoke Management Guide 4.1 – Smoke Management

smoke is primarily made up of elemental carbon, organic carbon, and particulate matter.

Fine particles (PM2.5) are more efficient per

unit mass than coarse particles (PM10 and

larger) at causing visibility impairment. Naturally occurring visual range in the East is estimated to be between 60 and 80 miles, while

natural visual range in the West is between 110-

115 miles (Trijonis and others 1991). Currently,

visual range in the Eastern US is about 15 to 30

miles and about 60 to 90 miles in the Western

US (40 CFR Part 51). The theoretical maximum

visual range with nothing in the air except air

molecules is about 240 miles.

Federal Land Managers (FLMs) have somewhat

conflicting roles when it comes to protecting

visibility in the Class I areas they manage. On

the one hand, FLMs are given the responsibility

by the Clean Air Act for reviewing PSD permits

of major new and modified stationary pollution

sources and commenting to the state on whether

there is concern for visibility impacts (or other

resource values) in Class I areas downwind of

the proposed pollution source. In this case

FLMs play a proactive role in air pollution

prevention. On the other hand, however, FLMs

also use wildland fire, which emits visibilityimpairing pollutants. In this case the FLM is the

polluter and is often in the difficult position of

trying to explain why wildland burning smoke

may be acceptable in wilderness whereas other

types of air pollution are not. The answer to this

dilemma is that wildernesses are managed to

preserve and protect natural conditions and

processes. So in this context, smoke and visibility impairment from wildland fire that closely

mimics what would occur naturally is generally

viewed as acceptable under wilderness management objectives, whereas visibility impairment

from “unnatural” pollutants and “unnatural”

pollution sources is not.

The key to successfully promoting this distinction is an honest and scientific definition of how

much, and what types, of fire are “natural” that

FLMs, air quality regulators, and the public can

agree upon. This is a critical area of future

cooperation in smoke management and air

quality regulation.

Regional Haze

Regional haze is visibility impairment produced

by a multitude of sources and activities that emit

fine particles and their precursors, and are

located across a broad geographic area. This

contrasts with visibility impairment that can be

traced largely to a single, very large pollution

source. Until recently, the only regulations for

visibility protection addressed impairment that

is reasonably attributable to a permanent, large

emission source or small group of large sources.

Recently, EPA issued regional haze regulations

to manage and mitigate visibility impairment

from the multitude of diverse regional haze

sources (40 CFR Part 51). The regional haze

regulations call for states to establish goals for

improving visibility in Class I national parks

and wildernesses and to develop long-term

strategies for reducing emissions of air pollutants that cause visibility impairment. Wildland

fire is one of the sources of regional haze covered by the new rules.

Current data from a national visibility monitoring network (Sisler and others 1996) do not

show fire to be the predominant source of

visibility impairment in any Class I area (40

CFR Part 51). Emissions from fire are an

important episodic contributor to atmospheric

loading of visibility-impairing aerosols, including organic carbon, elemental carbon, and

particulate matter. Certainly the contribution to

visibility impairment from fires can be substan-
Chapter 4 – Regulations 2001 Smoke Management Guide

– 70 –

tial over short periods of time, but fires in

general, occur relatively infrequently and thus

have a lesser contribution to long-term averages.

Fire events contribute less to persistent visibility

impairment than sources with emissions that are

more continuous.

Reasonable Progress

The visibility regulations require states to make

“reasonable progress” toward the Clean Air Act

goal of “prevention of any future, and the

remedying of any existing, impairment of

visibility...”. The regional haze regulations did

not define visibility targets, but instead gave the

states flexibility in determining reasonable

progress goals for Class I areas. States are

required to conduct analyses to ensure that they

consider the possibility of setting an ambitious

reasonable progress goal, one that is aimed at

reaching natural background conditions in 60

years. The rule requires states to establish goals

for each affected Class I area to 1) improve

visibility on the haziest 20 percent of days and

2) ensure no degradation occurs on the clearest

20 percent of days over the period of each

implementation plan.

The states are to analyze and determine the rate

of progress needed for the implementation

period extending to 2018 such that, if maintained, this rate would attain natural visibility

conditions by the year 2064. To calculate this

rate of progress, the state must compare

baseline visibility conditions to estimate natural

visibility conditions in Class I areas and determine the uniform rate of visibility improvement

that would need to be maintained during each

implementation period in order to attain natural

visibility conditions by 2064. Baseline visibility conditions will be determined from data

collected from a national network of visibility

monitors representing all Class I areas in the

country for the years 2000 to 2004. The state

must determine whether this rate and associated

emission reduction strategies are reasonable

based on several statutory factors. If the state

finds that this rate is not reasonable, it must

provide a demonstration supporting an alternative rate.

Regional Visibility

Protection Planning

Regional haze is, by definition, from widespread, diverse sources. The regional haze rule

encourages states to work together to improve

visibility. The Environmental Protection

Agency (EPA) has encouraged the 48 contiguous states to engage in regional planning to

coordinate development of strategies for controlling pollutant emissions across a multi-state

region. This means that groups of states will be

addressing groups of “Class I” areas through

established organizations. In the West, the

Western Regional Air Partnership, sponsored

through the Western Governors’ Association and

the National Tribal Environmental Council is

coordinating regional planning and needed

technical assessments. In the Eastern U.S., four

formal groups address regional planning issues:

CENRAP (Central States Response Air Partnership), OTC (Ozone Transport Commission), and

VISTAS (Visibility Improvement State and

Tribal Association of the Southeast) and the

Midwest Regional Planning Organization

(figure 4.1.4).

Natural Visibility

Air quality regulations often distinguish between human-caused and natural sources of air

pollution. Natural sources of air pollution

generally are not responsive to control efforts,
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2001 Smoke Management Guide 4.1 – Smoke Management

Figure 4.1.4. Regional air quality planning groups.

and state air regulatory agencies manage and

monitor them in a manner different from human-caused air pollution. The definition of

natural sources of air pollution includes volcanoes, dust, and wildfires. The regional haze

regulations propose to measure progress towards achieving natural visibility conditions,

but how do we define natural visibility impairment when considering wildland fires as a

source?

In most parts of the country, much less fire

occurs today than historically. Should natural

visibility consider the contribution to haze from

these historic, natural fires? And if so, how will

we reconcile a definition of natural visibility

that includes historic levels of smoke with the

need to improve air quality and meet the national visibility goal? Previously, wildfires have

been considered natural sources while prescribed fires have generally been classified as

human-caused for the purpose of air regulation.

That classification is proving to be unsatisfactory because aggressive wildfire suppression

and land use changes have made the current

pattern of wildfires anything but natural. Are

some prescribed fires destined to be categorized

as natural emission sources along with the

resulting visibility impairment, and how much

prescribed burning should be considered

natural?
Chapter 4 – Regulations 2001 Smoke Management Guide

– 72 –

How Much Smoke is Natural?

Few wildlands in the United States are without

significant modification by humans, whether by

resource utilization, fire suppression, or invasion

of exotic species. So in defining natural emissions some possible definitions of natural fire

may include: 1) historic fire frequency in

vegetation types present on wildlands today, 2)

historic fire frequency only on wildlands where

the current overriding management goal is to

maintain natural ecosystem processes, 3) human-defined fire needed on wildlands to maintain natural ecosystem processes, 4) humandefined fire needed to maximize wildfire controllability, and 5) prescribed fire needed to

minimize the sum of prescribed fire and wildfire

emissions.6

Most any approach to estimating natural emissions from fire will look to historic fire frequencies for preliminary guidance. Historic fire

frequency can be defined in numerous ways and

called by various terms (fire frequency, fire

return interval, natural fire rotation, ecological

fire rotation). Fire frequency can vary greatly

by vegetative cover type, site-specific meteorology, stand age, aspect, and elevation. Fire

frequency is often defined as a range that reflects site variation. For example, a given area

of ponderosa pine ecosystem may have a defined fire rotation of 7 to 15 years. The drier

southwestern slopes will have an average fire

rotation of approximately 7 years, whereas the

northern slopes will have an average fire rotation of approximately 15 years. Even within the

average site fire rotation interval there can be

significant temporal variation depending on

weather and ignition potential.

Any change in fire frequency will eventually be

expressed by change in the ecosystem. The

natural fire regime for an ecosystem may not be

the same as the historic fire regime, because

neither the current fuel condition nor the climate

is the same as in the past. Nor will they be the

same in the future.

Wildland fire is highly variable in place and

time. Historic fire regimes are well known and

described for most major ecosystem types.

These historic frequencies can be used as a

starting point for definition of natural emissions

although, in many parts of the country,historic

fire frequency would likely result in much more

emissions than would be acceptable in today’s

society (figure 4.1.5). Prescribed burning in the

southeastern US is, in some cases, near the

natural rotation and the public has been largely

tolerant of the smoke. Burning to maintain

natural ecosystem conditions may not need to

occur any more frequently than the middle to

upper end of the historical average fire frequency. Some areas may be maintained adequately even if the infrequent end of the

natural fire frequency range is increased although potential long-term effects of this sort of

ecological manipulation are uncertain. On the

other hand, the environment is not static. Climate change, for example, may change the

frequency of fire necessary to maintain any

given ecosystem in the future or make retention

of the present ecosystem impossible.

Conclusions

Because smoke from fire can cause negative

effects to public health and welfare, air quality

protection regulations must be understood and

followed by responsible fire managers. Likewise, air quality regulators need an understanding of how and when fire use decisions are

___________________________________

6 Peterson, Janice; Sandberg, David, Leenhouts, Bill. 1998. Estimating natural emissions from wildland and

prescribed fire. An unpublished technical support document to the EPA Interim Air Quality Policy on Wildland and Prescribed Fires. April 23, 1998. (Available from the author).
– 73 –

2001 Smoke Management Guide 4.1 – Smoke Management

Figure 4.1.5. Estimates of the range of annual area burned in the conterminous United States preEuropean settlement (Historic), applying presettlement fire frequencies to present land cover types

(Expected), and burning (wildland and agriculture) that has occurred during the recent past (Current).

Source: Leenhouts (1998).

 

 

 

Table 4.1.2. Recommended cooperation between wildland fire managers and air quality regulators depending

on air quality protection instrument.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 74 –

made and should become involved in fire and

smoke management planning processes, including the assessment of when and how

alternatives to fire will be used. Many fire and

air quality issues need further work including,

definition of de minimis emission levels from

fire, prescribed fire as BACM for wildfire,

clarification of the difference between visibility

impairment from fire vs. industrial sources,

amounts of smoke from natural ecosystem

burning that is acceptable to the public, and

definition of natural visibility. Cooperation

and collaboration between wildland fire managers and air quality regulators on these and

other issues is of great importance. Table 4.1.2

contains recommendations for various types of

cooperation by these two groups depending on

the applicable air quality protection instrument.

Literature Citations

40 CFR Part 51. Vol. 64 No. 126. Regional Haze

Regulations – Final Rule. July 1, 1999.

Dockery DW, Pope CA III, Xu X, Spengler JD,

Ware JH, Fay ME, Ferris BG Jr, and Speizer

FE. 1993. An association between air pollution

and mortality in six U.S. cities. New England

Journal of Medicine. 329:1753-1759.

Environmental Protection Agency. 1996. Review

of the national ambient air quality standards

for particulate matter: policy assessment of

scientific and technical information.

EPA-452 \ R-96-013. Office of Air Quality

Planning and Standards, U.S. Environmental

Protection Agency. Research Triangle Park,

NC.

Environmental Protection Agency. 1998. Interim air

quality policy on wildland and prescribed fires.

Office of Air Quality Planning and Standards,

Research Triangle Park, NC 27711. 39p.

Leenhouts, Bill. 1998. Assessment of biomass

burning in the conterminous United States.

Conservation Ecology [online] 2(1). Available

from the Internet. URL: http://

ns2.resalliance.org/pub/www/journal/vol2/iss1/

art1.

Sisler, James F., William C. Malm, Kristi A.

Gebhart. 1996. Spatial and seasonal patterns

and long term variability of the composition of

the haze in the United States: An analysis of

data from the IMPROVE network. Cooperative

Institute for Research in the Atmosphere,

Colorado State University. ISSN: 0737-5352-

32.

Trijonis, J., R. Charlson, R. Husar, W. C. Malm, M.

Pitchford, W. White. 1991. Visibility: existing

and historical conditions - causes and effects.

In: Acid Deposition: State of Science and

Technology. Report 24. National Acid Precipitation Assessment Program.

Ward, Darold E.; Hardy, Colin C. 1991. Smoke

emissions from wildland fires. Environmental

International, Vol 17:117-134.

Williamson, Samuel J. 1973. Fundamentals of air

pollution. Reading, Massachusetts: AddisonWesley Publishing Co. 472 p.

U.S. Laws, Statutes, etc.; Public Law 95-95. Clean

Air Act as Amended August 1977. 42 U.S.C.

1857 et seq.

U.S. Laws, Statutes, etc.; Public Law 101-549. Clean

Air Act as Amended Nov. 1990. 104 Stat. 2399.
– 75 –

2001 Smoke Management Guide 4.2 – State Programs

State Smoke Management Programs

John E. Core

Introduction

Smoke management programs establish a basic

framework of procedures and requirements for

managing smoke from prescribed fires. The

purposes of a smoke management program are

to minimize smoke entering populated areas,

prevent public safety hazards (such as smoke

impairment on roadways or runways), avoid

significant deterioration of air quality and

National Ambient Air Quality Standards

(NAAQS) violations, and to avoid visibility

impacts in Class I areas. Smoke management is

increasingly recognized as a critical component

of a state’s air quality program for protecting

public health and welfare, while still providing

for necessary wildland burning. Sophisticated

programs for coordination of burning both

within a state and across state boundaries are

vital to obtain and continue public support of

burning programs. States typically develop

these programs, with cooperation and participation from stakeholders. Smoke management

programs developed through partnerships are

much more effective at meeting resource management goals, protecting public health, and

meeting air quality objectives.

Usually, either the state or tribal natural resources agency or air quality agency is responsible for developing and administering the

smoke management program. Occasionally, a

program may be administered by a local agency

and apply to a subset of a state. Generally the

administering agency will give daily approval or

disapproval of individual bums. All burning

may be subject to permit, or only burning

exceeding an established de minimis level that

could be based on projections of acres burned,

tons consumed, or emissions. Multi-day burns

may be subject to daily reassessment and

reapproval to ensure smoke does not violate

program goals.

An advanced smoke management program will

evaluate individual and multiple bums; coordinate all prescribed fire activities in an area;

consider cross-boundary impacts; and weigh

burning decisions against possible health,

visibility, and nuisance effects.

With increasing use of fire for forest health and

ecosystem management, interstate and interregional coordination of burning will be necessary

to prevent poor air quality episodes. Every state

has unique needs and issues driving development of smoke management programs so a

specific program cannot be defined that is

applicable to all. State and land manager development of, and participation in, an effective,

locally specific smoke management program

will go a long way to build and maintain public

acceptance of prescribed burning.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 76 –

EPA Interim Fire Policy -

Recommendations on

Smoke Management Programs

In the Interim Air Quality Policy on Wildland

and Prescribed Fires (EPA 1998), EPA urges

State and tribal air quality managers to collaborate with wildland owners and managers to

mitigate the air quality impacts that could be

caused by the increase of fires managed to

achieve resource benefits. The EPA especially

urges development and implementation of at

least basic smoke management programs when

conditions indicate that fires will adversely

impact the public. In exchange for states and

tribes proactively implementing smoke management programs, EPA intends to exercise its

discretion not to redesignate an area as

nonattainment if the evidence is convincing that

fires managed for resource benefits caused or

significantly contributed to violations of the

daily or annual PM2.5 or PM10 standards.

Rather, EPA will call on the state or tribe to

review the adequacy of the smoke management

program in collaboration with wildland owners

and managers and make appropriate improvements to mitigate future air quality impacts. The

state or tribe must certify in a letter to the EPA

Administrator that at least a basic program has

been adopted and implemented in order to

receive special consideration for NAAQS violations under this policy.

To be certifiable by EPA, a smoke management

program should include the following basic

components, some of which are the responsibility of the administering agency and some of

which are provided by the land manager:

1. Process for assessing and authorizing burns.

Reporting of burn plan information to administering agency (not mandatory for states to

be compliant with EPA recommendations for

a certified smoke management program, but

is highly recommended especially for fires

greater than a predefined de minimis size),

including the following information:

• location and description of the area to be

burned,

• personnel responsible for managing the

fire,

• type of vegetation to be burned,

• area (acres) to be burned,

• amount of fuel to be consumed (tons/

acre),

• fire prescription including smoke management components,

• criteria the fire manager will use for

making burn/no burn decisions, and

• safety and contingency plans addressing

smoke intrusions.

2. Plan for long-term minimization of emissions and impacts, including promotion of

alternatives to burning and use of emission

reduction techniques.

3. Smoke management goals and procedures to

be described in burn plans (when burn plan

reporting is required):

• actions to minimize fire emissions,

• smoke dispersion evaluation,

• public notification and exposure reduction

procedures to be implemented during air

pollution episodes or smoke emergencies,

and

• air quality monitoring.

4. Public education and awareness.

5. Surveillance and enforcement of smoke

management program compliance.

6. Program evaluation and plan for periodic

review.
– 77 –

2001 Smoke Management Guide 4.2 – State Programs

7. Optional programs (for example, special

protection zones or buffers or performance

standards).

Smoke Management Programs

Prescribed burning programs across the nation

use both emission reduction methods and smoke

management techniques (avoidance and dilution) to minimize the impacts of smoke on air

quality as well as concerns about public exposure to smoke. The complexity of these programs varies greatly from state to state, ranging

from the comprehensive and well-funded programs found in Oregon and Washington to the

far simpler program found in Alaska. While the

comprehensive programs gather detailed information on all burning activity needed for burn

coordination, emission inventory calculation

purposes, and to assure compliance with air

quality regulations, many prescribed fire practitioners work independently with mainly selfimposed constraints. In most cases, smoke

management programs focus primarily on

achieving land management objectives. Other

issues in priority order are: minimizing public

exposure to smoke, achieving and/or maintaining healthful air quality, and achieving emission

reductions. Often, emission reductions are only

an important side benefit of a burning technique

selected for another management purpose. Few

existing smoke management programs quantify

emission reductions achieved either intentionally or unintentionally. Table 4.2.1 summarizes

a few of the features of the smoke management

programs. Significantly, only Oregon and

Washington have active, on-going programs to

calculate pollutant emissions and pollutant

emission reductions on a daily basis for each

burn. The Utah program has been certified

under the EPA Interim Air Quality Policy on

Wildland and Prescribed Fire; Nevada and

Florida have incorporated the Policy into the

design of their programs. Oregon and Washington have adopted special provisions for

prescribed burning for forest health restoration

purposes. The Oregon program includes an

emissions cap and offset program for Eastern

Oregon burning. Although most state air agencies estimate annual emissions from land manager records, only those states that calculate

emissions on a daily basis, burn-by-burn, are

listed as having an emissions calculation program. The adequacy of each program to the

specific state situation is not addressed in table

4.2.1. That issue is best addressed by the

stakeholders of each program and the citizens of

the state.

A summary of smoke management program

reporting attributes related to emissions tracking

is shown in table 4.2.2.

As an example, in the Colorado program, field

personnel collect pre-burn acreage, predominate

fuel type and fuel loading information annually

before the burning season begins. A generalized

emissions estimate is reported on the SASEM

output they submit with their permit application

(see Chapter 9 for information on SASEM and

other models). Post-burn information including

acreage actually burned, fuel types, fuel loading,

and fuel consumption is collected in the field at

the end of the season. If the project is classified

as “High Risk for Smoke Impacts,” the central

office Program Coordinator compiles the endof-year acreage actually burned and fuel actually consumed from all cooperating agencies.

The program office then uses this information to

calculate annual emissions. The program office

has no responsibilities related to fuel type data.

The Colorado smoke management program is

fairly basic compared to some more complex

programs, but is appropriate to the specifics of

the state burning programs and their potential

impacts to air quality.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 78 –

Table 4.2.1. Smoke Management Program features. Smoke Management programs are periodically reviewed

and revised; the features listed here reflect program status in 2001.
– 79 –

2001 Smoke Management Guide 4.2 – State Programs Ta

ble 4.2.2. Selected Smoke Management Program Emission Inventory Reporting Attributes.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 80 –

Literature Citations

Environmental Protection Agency. 1998. Interim air

quality policy on wildland and prescribed fires.

Office of Air Quality Planning and Standards,

Research Triangle Park, NC 27711. 39p.
– 81 –

2001 Smoke Management Guide 4.3 – Federal Requirements

Federal Land Management–

Special Requirements

Janice L. Peterson

Federal agencies are subject to certain laws and

requirements that are not necessarily applicable

to states or private entities in the same manner

or at all. Federal agencies are required to do

long-range planning for management of the

lands they manage through numerous agencyspecific planning mandates. The National

Environmental Policy Act (NEPA) requires

Federal agencies to examine and disclose

potential impacts of their actions on the environment. The General Conformity regulations

require federal agencies to examine the effect of

their actions on the ability of a state to reach air

quality goals and modify their actions if air

quality targets would be delayed. Federal

agencies also manage wilderness areas and the

Wilderness Act contains language with implications for air quality protection.

Land Management Planning

Each Federal land management agency has

some sort of overarching planning mandate.

These broad scale, long-term plans define how

Federal lands will be managed for many years

into the future. For the USDA Forest Service,

the National Forest Management Act (NFMA)

(Public Law 94-588) requires National Forests

to prepare plans for land management that

address a long-term planning perspective and

provide the opportunity for other agencies and

the public to comment on decisions on how

these public lands are managed. Forest Plans

are to address protection, management, improvement, and use of renewable resources on

the National Forests and should “recognize the

fundamental need to protect and, where appropriate, improve the quality of soil, water, and air

resources.” Forest Plans must be updated and

revised at least every 15 years and many National Forests are in the process of, or have

recently completed this task. Other federal

agencies have similar land management planning mandates. For the U.S. Department of the

Interior, the Bureau of Land Management has

the Integrated Resource Management Plan; the

National Park Service has the Resource Management Plan; and the Fish and Wildlife Service

has the Comprehensive Conservation Plan.

In some parts of the country, resource management agencies have fairly recently recognized

the importance of fire as an ecological process

in the maintenance of sustainable ecosystems.

Therefore, existing federal land management

plans do not always adequately address this

topic. Planning revisions provide the opportunity to define and resolve issues that involve

wildland fire, its relationship to forest health,

and its environmental costs and benefits. Revisions should address the fact that smoke knows

no boundaries and alternative management

scenarios must be analyzed in this same context.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 82 –

A Forest Service Example

Forest Plans provide the long-term, big picture

view of goals for management of a National

Forest. Specific projects are planned at a later

date to fit the goals and framework of the Forest

Plan and to meet more short term planning

horizons. For example, the philosophy of how

fire will be used to manage various ecosystems

on a National Forest and the general effects of

this fire on air quality will be described in the

Forest Plan whereas specific prescribed fire

projects and specific air quality effects will be

defined at a later date. The environmental

consequences of specific projects are analyzed

through the National Environmental Policy Act

(NEPA) planning process.

Recent Forest Service internal guidance1

 advises

that air quality status within 100km of the Forest

boundary be assessed for attainment/nonattainment status, Class I or Class II, availability

of monitoring data, and identification of special

smoke sensitive areas (such as airports, hospitals, etc.). The complexity of the subsequent

Forest Plan air quality analysis will be determined by what is found in this initial assessment

and can range from preparation of a simple

emissions inventory and development of standards and guidelines for smoke management if

the complexity is low; up to a detailed emissions

inventory, standards and guidelines for smoke

management including visibility protection,

modeling to estimate mitigation benefits and/or

consequences, worst case emissions analysis,

and identification of possible emissions offsets

if complexity is high.

National Environmental Policy Act

The National Environmental Policy Act (NEPA)

(Public Law 91-190) directs all federal agencies

to consider every significant aspect of the

environmental impacts of a proposed action. It

also ensures that an agency will inform the

public that it has considered environmental

concerns in its decision-making process. NEPA

does not require agencies to elevate environmental concerns over other appropriate considerations; only that agencies fully analyze,

understand, and disclose environmental consequences before deciding to take an action.

NEPA is a procedural mandate to federal agencies to ensure a fully informed decision where

short- and long-term environmental consequences are not forgotten.

An analysis of possible air quality impacts may

be needed in a NEPA analysis if the project:

• raised air quality as a significant issue in

scoping2

,

• includes burning,

• includes significant road construction,

road use, or other soil disturbing procedures where fugitive dust may be a concern,

• includes significant machinery operation

in close proximity to publicly accessible

areas,

• may have any impact on air quality in a

Class I area,

• may have any impact on sensitive vistas or

visibility in a Class I area,

___________________________________

1 USDA Forest Service. 1999. Draft desk guide for integrating air quality and fire management into land management planning. USDA Forest Service guidance document. Available at: http://www.fs.fed.us/clean/air/

2 Scoping is the process of determining the issues to be included in NEPA analysis and for identifying any significant issues that will need to be addressed in depth. Scoping requires the lead agency to invite participation of affected

Federal, State, and local agencies, any affected Indian tribe, the proponent of the action, and other interested persons

(including those who might not be in accord with the action on environmental grounds).
– 83 –

2001 Smoke Management Guide 4.3 – Federal Requirements

• is in close proximity to a non-attainment

area,

• will make a significant amount of firewood

available to the public.

The appropriate level of analysis for each

project will vary with the size of the project.

For example, a small project will likely have a

brief analysis and a large project will require a

detailed analysis. The complexity and potential

effects of the project will determine whether an

environmental impact statement (EIS), an

environmental assessment (EA), a biological

evaluation (BE), or a categorical exclusion (CE)

is the appropriate NEPA tool. If an air quality

analysis is deemed unnecessary, the NEPA

document should state that potential air quality

impacts were considered but were determined to

be inconsequential. In this case, a justification

for this determination must be included.

A project NEPA analysis is where specific

environmental effects from specific projects are

analyzed and assessed. This process provides a

good opportunity for fire managers and air

quality regulators to come to a common understanding of how smoke from prescribed fire

projects will be managed and reduced. Section

309 of the 1977 Clean Air Act Amendments

(Public Law 95-95) gives EPA a role in reviewing NEPA documents and making those reviews

public. How actively EPA pursues this role

tends to vary between EPA regions and with the

complexity and potential environmental risk

from the project.

A complete disclosure of air quality impacts in a

NEPA document should include the following

information:

1. Description of the air quality environment

of the project area

2. Description of alternative fuel treatments

considered and reasons why they were not

selected over prescribed fire.

3. Quantification of the fuels to be burned

(areas, tons, types).

4. Description of the types of burning

planned (broadcast, piles, understory, etc.).

5. Description of measures taken to reduce

emissions and emission impacts.

6. Estimation of the amount and timing of

emissions to be released.

7. Description of the regulatory and permit

requirements for burning (for example,

smoke management permits).

8. Modeled estimates of where smoke could

go under certain common and worst case

meteorological scenarios and focusing on

new or increased impacts on down wind

communities, visibility impacts in Class I

wildernesses, etc. In some areas and for

some fuel types, an appropriate dispersion

model is not available. In this situation,

qualitative analysis will need to suffice.

Qualitative analysis can also be used for

simple projects with little risk of air

quality impact.

Conformity

“No department, agency, or instrumentality of the Federal Government shall

engage in, support in any way or provide

financial assistance for, license or

permit, or approve, any activity which

does not conform to a State Implementation Plan.”

Clean Air Act Amendments of 1990
Chapter 4 – Regulations 2001 Smoke Management Guide

– 84 –

The 1990 Clean Air Act Amendments (Public

Law 101-549) require planned federal actions to

conform to state or tribal implementation plans

(SIPs/TIPs). EPA’s General Conformity rule

established specific criteria and procedures for

determining the conformity of planned federal

projects and activities. In so doing, EPA chose

to apply general conformity directly to nonattainment and maintenance areas only. EPA

continues to consider application of general

conformity rules to attainment areas but at

present has not done so, although an activity in

an attainment area that causes indirect emission

increases within a non-attainment area may have

to be analyzed for conformity. Federal agencies

have the responsibility for making conformity

determinations for their own actions.

General conformity rules prohibit federal agencies from taking any action within a non-attainment or maintenance area that causes or

contributes to a new violation of air quality

standards, increases the frequency or severity of

an existing violation, or delays the timely

attainment of a standard as defined in the applicable SIP or area plan. If a proposed federal

project (non-temporary) were projected to

contribute pollution to a non-attainment area the

project would likely be canceled or severely

modified. Temporary proposed federal projects

that could impact a non-attainment area must

also pass a conformity determination.

Federal activities must not:

1. Cause or contribute to new violations of

any standard.

2. Increase the frequency or severity of any

existing violations.

3. Interfere with timely attainment or maintenance of any standard.

4. Delay emission reduction milestones.

5. Contradict SIP requirements.

A conformity determination is required for each

pollutant where the total of direct and indirect

emissions caused by an agency’s actions would

equal or exceed conformity de minimis levels

(table 4.3.1), or are regionally significant.

Regionally significant is defined as emissions

representing 10 percent or more of the total

emissions for the area.

Table 4.3.1. Particle and carbon monoxide de minimis levels for general conformity.
– 85 –

2001 Smoke Management Guide 4.3 – Federal Requirements

The general conformity rule covers direct and

indirect emissions of criteria pollutants or their

precursors that are caused by a Federal action,

reasonably foreseeable, and can practicably be

controlled by the Federal agency through its

continuing program responsibility. In general, a

conformity analysis is not required for wildland

fire emissions at the Forest Plan level because

specifics of prescribed fire timing and locations

are not known, so at this planning level the

reasonably foreseeable trigger is not met. A

conformity determination will likely be required

at a later date when planning specific projects

under NEPA.

Wilderness Act

The Wilderness Act (Public Law 88-157) (and

subsequent Acts designating individual Wilderness Areas) was enacted to preserve and protect

wilderness resources in their natural condition.

Wildernesses are to be administered for “the use

and enjoyment of the American people in such

manner as will leave them unimpaired for future

use and enjoyment as wilderness, and so as to

provide for the protection of these areas, the

preservation of their wilderness character, and

for the gathering and dissemination of information regarding their use and enjoyment as

wilderness...” Although air quality is not

directly mentioned in the Wilderness Act, the

Act requires wilderness managers to minimize

the effects of human use or influence on natural

ecological processes and preserve “untrammeled” the earth and its community of life.

Federal agencies have interpreted the goals of

the Wilderness Act to mean that wilderness

character and ecosystem health should not be

impacted by unnatural, human-caused air

pollution. Most Class I areas are entirely wilderness although some Class I National Parks

contain areas that are not wilderness.

Literature Citations

U.S. Laws, Statutes, etc.; Public Law 88-157.

Wilderness Act of Sept. 3, 1964. 78 Stat. 890;

16 U.S.C. 1131-1136.

U.S. Laws, Statutes, etc.; Public Law 91-190. [S.

1075], National Environmental Policy Act of

1969. Act of Jan. 1, 1970. In its: United States

statutes at large, 1969. 42 U.S.C. sec. 4231, et

seq. (1970). Washington, DC: U.S. Government

Printing Office: 852-856. Vol. 83.

U.S. Laws, Statutes, etc.; Public Law 94-588.

National Forest Management Act of 1976. Act

of Oct. 22, 1976. 16 U.S.C. 1600 (1976).

U.S. Laws, Statutes, etc.; Public Law 95-95. Clean

Air Act as Amended August 1977. 42 U.S.C.

1857 et seq.

U.S. Laws, Statutes, etc.; Public Law 101-549. Clean

Air Act as Amended Nov. 1990. 104 Stat. 2399.
Chapter 4 – Regulations 2001 Smoke Management Guide

– 86 –
– 87 –

2001 Smoke Management Guide 5.0 – Source Characteristics

SMOKE SOURCE CHARACTERISTICS

Chapter 5
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 88 –
– 89 –

2001 Smoke Management Guide 5.0 – Source Characteristics

Smoke Source Characteristics

Roger D. Ottmar

Whether you are concerned with particulate

matter, carbon monoxide, carbon dioxide, or

hydrocarbons, all smoke components from

wildland fires are generated from the incomplete

combustion of fuel. The amount of smoke

produced can be derived from knowledge of

area burned, fuel loading (tons/acre), fuel

consumption (tons/acre), and pollutant-specific

emission factors. Multiplying a pollutantspecific emission factor (lbs/ton) by the fuel

consumed, and adding the time variable to the

emission production and fuel consumption

equations results in emission and heat release

rates that allow the use of smoke dispersion

models (figure 5.1). This section discusses the

characteristics of emissions from wildland fire

and the necessary inputs to obtain source

strength and heat release rate for assessing

smoke impacts.

Prefire Fuel Characteristics

Fuel consumption and smoke production are

influenced by preburn fuel loading categories

such as grasses, shrubs, woody fuels, litter,

moss, duff, and live vegetation; condition of the

fuel (live, dead, sound, rotten); fuel moisture;

arrangement; and continuity. These characteristics can vary widely across fuelbed types (figure

5.2) and within the same fuelbed type (figure

Figure 5.1. Combustion and emission processes.
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 90 –

Figure 5.2. The preburn fuel loading (downed, dead woody, grasses, shrubs, litter, moss, and duff) can

vary widely between fuel types as shown in (A) midwest grassland, 2.5 tons/acre; (B) longleaf pine, 4

tons/acre; (C) southwest sage shrubland, 6 tons/acre; (D) California chaparral, 40 tons/acre; (E) western

mixed conifer with mortality, 67 tons/acre; and (F) Alaska black spruce, 135 tons/acre.
– 91 –

2001 Smoke Management Guide 5.0 – Source Characteristics

5.3). For instance, fuel loadings range considerably: less than 3 tons/acre for perennial grasses

in the Midwest with no rotten material or

duff (Ottmar and Vihnanek 1999); 4 tons per

acre of mostly grass and a shallow litter and duff

layers for a southern pine stand treated regularly

with fire (Ottmar and Vihnanek 2000b); 6 tons/

acre in a Great Basin sage shrubland (Ottmar

and others 2000a); 40 tons per acre in a mature

California chaparral shrubland (Ottmar and

others 2000a); 67 tons per acre of 80 percent of

which is rotten woody fuels, stump, snags, and

deep duff in a multi-story, ponderosa pine and

Douglas-fir forest with high mortality from

disease and insects (Ottmar and others 1998); to

167 tons/acre in a black spruce forest in Alaska

with a deep moss and duff layer (Ottmar and

Vihnanek 1998). The heaviest fuel loadings

encountered are normally associated with

material left following logging, unhealthy

forests, mature brush and tall grasses, or deep

layers of duff, moss or organic (muck) soils.

The large variation in potential fuel loading can

contribute up to 80 percent of the error associated with estimating emissions (Peterson 1987,

Peterson and Sandberg 1988).

Higher fuel loading generally equates to more

fuel consumption and emissions if the combustion parameters remain constant. For example, a

frequently burned southern or western pine

stand may have a fuel loading of 12 tons per

acre while a recently harvested pine stand with

logging slash left on the ground may have a fuel

loading of 50 tons per acre. Prescribed burning

under a moderately dry fuel moisture situation

Figure 5.3. Variability of fuel loading across several fuelbed types. Sources are referenced in the text.
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 92 –

would achieve 50 percent biomass consumption

equating to 3 tons per acre consumed in the

unlogged pine stand and 25 tons/acre consumed

in the logged stand.

There are several techniques available for

determining fuel loading (U.S. Department of

Interior 1992). Collecting and weighing the fuel

is the most accurate method but is impractical

for many fuel types except grasses and small

shrubs. Measuring some biomass parameter and

estimating the biomass using a pre-derived

equation is less accurate but also less time

consuming (Brown 1974). Ongoing development of several techniques including the natural

fuels photo series (Ottmar and others 1998,

Ottmar and Vihnanek 2000a) and the Fuel

Characteristic Class system (FCC) (Sandberg

and others 2001) will provide managers new

tools to better estimate fuel loadings and reduce

the uncertainty that currently exist with assigning fuel characteristics across a landscape. The

photo series is a sequence of single and stereo

photographs with accompanying fuel characteristics. Over 26 volumes are available for logging and thinning slash and natural fuels in

forested, shrubland, and grassland fuelbed types

throughout the United States. The Fuel Characteristic Class System is a national system being

designed for classifying wildland fuelbeds

according to a set of inherent properties to

provide the best possible fuels estimates and

probable fire parameters based on available sitespecific information.

Fuel moisture content is one of the most influential factors in the combustion and consumption

processes. Live fuel moisture content can vary

by temperature, relative humidity, rainfall, soil

moisture, seasonality and species. Dead fuel

moisture content varies by temperature, relative

humidity, rainfall, species, material size, and

decay class. Fuel moisture content affects the

flame temperature that in turn influences the

ease of ignition, the amount and rate of consumption, and the combustion efficiency (the

ratio of energy produced compared to energy

supplied). In other words, higher fuel moisture

content requires more energy to drive off the

water, enabling fuel to reach a point where

pyrolysis can begin. Generally, fuels with low

fuel moisture content burn more efficiently and

produce fewer emissions per unit of fuel consumed. On the other hand, even though emissions per unit of fuel burned will be greater at

higher fuel moistures because of a less efficient

combustion environment, total emissions may

be less if some fraction of the fuels do not

totally burn—typically the large wood fuels and

forest floor.

Since combustion generally takes place at the

fuel/atmosphere interface, the time necessary to

ignite and consume an individual fuel particle

with a given fuel moisture content depends upon

the smallest dimension of the particle. The

surface area to volume ratio of a particle is often

used to depict a particle’s size—the greater the

ratio, the smaller the particle. Small twigs and

branches have a much larger surface to volume

ratio than large logs and thus a much greater

fuel surface exposed to the atmosphere. Consequently, fine fuels will have a greater probability

of igniting and consuming for a given fuel

moisture.

The arrangement of the particles is also important. The structuring of fuel particles and air

spaces within a fuel bed can either enhance or

retard fuel consumption and affect combustion

efficiency. The packing ratio (the fraction of the

fuel bed volume, occupied by fuel) is the measure of the fuel bed porosity. A loosely packed

fuel bed (low packing ratio) will allow plenty of

oxygen to be available for combustion, but may

result in inefficient heat transfer between burning and adjacent unburned fuel particles. Many

particles cannot be preheated to ignition tem-
– 93 –

2001 Smoke Management Guide 5.0 – Source Characteristics

perature and are left unconsumed. On the other

hand, a tightly packed fuel bed (high packing

ratio) allows efficient heat transfer between the

particles, but may restrict oxygen availability

and reduce consumption and combustion efficiency. An efficiently burning fuel bed will

have particles close enough for adequate heat

transfer while at the same time large enough

spaces between particles for oxygen availability.

Fuel discontinuity—both horizontal and vertical—isolates portions of the fuel bed from preignition heating and subsequent ignition.

Sustained ignition, and combustion will not

occur when the spacing between the fuel particles is too large.

Biochemical differences between species also

play a role in combustion. Certain species such

as hoaryleaf ceanothus (Ceanothus crassifolius),

palmetto (Serenoa repens) and gallberry (Ilex

glabra) contain volatile compounds that make

them more flammable than species such as

Carolina azalea (Rhododendron carolinianum)

under similar live moisture contents.

Fire Behavior

Fire behavior is the manner in which fire reacts

to the fuels available for burning (DeBano and

others 1998) and is dependent upon the type,

condition, and arrangement of smaller woody

fuels, local weather conditions, topography and

in the case of prescribed fire, lighting pattern

and rate. Two aspects of fire behavior include

fire line intensity (the amount of heat released

per unit length of fire line) and rate of spread

(activity of the fire in extending its horizontal

dimensions). These aspects influence combustion efficiency of consuming biomass and the

resultant pollutants produced from wildland

fires. During fires with rapid rates of spread and

high intensity but relatively short duration, a

majority of the biomass consumed will be

smaller woody fuels and will occur during the

more efficient flaming period resulting in less

smoke. Burning dry grass and shrublands,

forestlands with high large woody and duff fuel

moisture contents, clean, dry piles, and rapidly

igniting an area with circular or strip-head fires

will produce these characteristics. In simple,

uniform fuelbeds such as pine and leaf litter

with only shallow organic material beneath, a

backing fire with lower rates of spreads and

intensities may consume fuels very efficiently

producing less smoke. In more complex

fuelbeds, the backing flame may become more

turbulent and this combustion efficiency may

lessen. During wildland fires with a range of

fire intensities and spread rates but long burning

durations, a large portion of the biomass consumed will occur during the less efficient

smoldering phase, producing more smoke

relative to the fuel consumed. Smoldering fires

often occur during drought periods in areas with

high loadings of large woody material or deep

duff, moss, or organic soils. The Emissions

Production Model (EPM) (Sandberg and

Peterson 1984, Sandberg 2000) and FARSITE

(Finney 2000) take into account fire behavior

and lighting pattern to estimate emission production rates.

Fuel Consumption

Fuel consumption is the amount of biomass

consumed during a fire and is another critical

component required to estimate emissions

production from wildland fire. Fuels are consumed in a complex combustion process that

adds to a variety of combustion products including particulate matter, carbon dioxide, carbon

monoxide, water vapor and a variety of various

hydrocarbons. Biomass consumption varies

widely among fires and is dependent on the fuel

type (e.g. grass versus woody fuels), arrange-
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 94 –

ment of the fuel (e.g. piled versus non-piled

woody debris), condition of the fuel (e.g. high

fuel moisture versus low fuel moisture) and the

way the fire is applied in the case of a prescribed fire (e.g. a helicopter or fixed wing

aircraft ignited high intensity, short duration

mass fire versus a slow, low intensity hand

ignition). As with fuel characteristics, extreme

variations associated with fuel consumption can

contribute errors of 30 percent or more when

emissions are estimated for wildland fires

(Peterson 1987; Peterson and Sandberg 1988).

In the simplest terms, combustion of vegetative

matter (cellulose) is a thermal/chemical reaction

where by plant material is rapidly oxidized

producing carbon dioxide, water, and heat

(figure 5.4). This is the reverse of plant photosynthesis where energy from the sun combines

with carbon dioxide and water, producing

cellulose (figure 5.4).

In the real world, the burning process is much

more complicated than this. Burning fuels is a

two-stage process of pyrolysis and combustion.

Although both stages occur simultaneously,

pyrolysis occurs first and is the heat-absorbing

reaction that converts fuel elements such as

cellulose into char, carbon dioxide, carbon

monoxide, water vapor, and highly combustible

hydrocarbon vapors and gases, and particulate

matter. Combustion follows as the escaping

hydrocarbon vapors released from the surface of

the fuels burn. Because combustion efficiency

is rarely 100 percent during wildland fires,

hundreds of chemical compounds are emitted

into the atmosphere, in addition to carbon

dioxide and water. Pyrolsis and combustion

proceed at many different rates since wildland

fuels are often very complex and non-homogeneous (DeBano and others 1998).

It has been recognized that there are four major

phases of combustion when fuel particles are

consumed (figure 5.5) (Mobley 1976, Prescribed

Fire Working Team 1985). These phases are:

(1) pre-ignition; (2) flaming; (3) smoldering;

and (4) glowing (figure 5.4). During the preignition phase, fuels ahead of the fire front are

heated by radiation and convection and water

vapor is driven to the surface of the fuels and

expelled into the atmosphere. As the fuel’s

internal temperature rises, cellulose and lignin

begin to decompose, releasing combustible

organic gases and vapors (Ryan and McMahon

1976). Since these gases and vapors are extremely hot, they rise and mix with oxygen in

the air and ignite at temperatures between 6170 F

and 6620 F leading to the flaming phase

(DeBano and others 1998).

In the flaming phase, the fuel temperature rises

rapidly. Pyrolysis accelerates and is accompanied by flaming of the combustible gases and

CELLULOSE + O2 CO2 + H20 + ENERGY

Heat/chemical energy

CELLULOSE + O2 CO2 + H20 + ENERGY

Sun/thermal energy

Figure 5.4. The energy flow for combustion is reverse to that for photosynthesis.
– 95 –

2001 Smoke Management Guide 5.0 – Source Characteristics

vapors. The combustion efficiency during the

flaming stage is usually relatively high as long

as volatile emissions remain in the vicinity of

the flames. The predominant products of

flaming combustion are carbon dioxide (CO2)

and water vapor (H2O). The water vapor is a

product of the combustion process and also

derives from moisture being driven from the

fuel. Temperatures during the flaming stage

range between 9320 F to 25520 F (Ryan and

McMahon 1976). During the flaming period,

the average exterior diameter reduction of round

wood material occurs at a rate of 1 inch per 8

minutes (Anderson 1969). For example, a dry

limb 3 inches in diameter would take approximately 24 minutes to completely consume if

flaming combustion was sustained during the

entire time period.

During the smoldering phase, emissions of

combustible gases and vapors above the fuel is

too low to support a flaming combustion resulting in a fire spread decrease and significant

temperature drop. Peak smoldering temperatures range from 572o

F to 1112oF (Agee 1993).

The gases and vapors condense, appearing as

visible smoke as they escape into the atmosphere. The smoke consists mostly of droplets

less than a micrometer in size. The amount of

particulate emissions generated per mass of fuel

consumed during the smoldering phase is more

than double that of the flaming phase.

Smoldering combustion is more prevalent in

certain fuel types (e.g. duff, organic soils, and

rotten logs) due to the lack of oxygen necessary

to support flaming combustion. Smoldering

combustion is often less prevalent in fuels with

high surface area to volume ratios (e.g. grasses,

shrubs, and small diameter woody fuels)

(Sandberg and Dost 1990). Since the heat

generated from a smoldering combustion is

seldom sufficient to sustain a convection column, the smoke stays near the ground and often

concentrates in nearby valley bottoms, compounding the impact of the fire on air quality.

Figure 5.5. The four phases of combustion.

Pre-ignition

Flaming

Smoldering

Glowing
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 96 –

Near the end of the smoldering phase, the

pyrolysis process nearly ceases, leaving the fuel

that did not completely consume with a layer of

black char, high in carbon content.

In the glowing phase, most volatile gases have

been driven off. Oxygen in the air can now

reach the exposed surface of char left from the

flaming and smoldering phase and the remaining fuels begin to glow with the characteristic

orange color. Peak temperatures of the burning

fuel during the glowing phase are similar to

those found in the smoldering phase and range

from 572o

F to 1117oF (DeBano and others

1998). There is little visible smoke. Carbon

dioxide, carbon monoxide, and methane are the

principal products of glowing combustion. This

phase continues until the temperature of the fuel

drops or until only noncombustible, mineral

gray ash remains.

The combustion phases occur both sequentially

and simultaneously as a fire front moves across

the landscape. The efficiency of combustion

that takes place in each combustion phase is not

the same, resulting in a different set of chemical

compounds being released at different rates into

the atmosphere. Understanding the combustion

process of each phase will assist managers in

employing various emission reduction techniques. Fuel type, fuel moisture content,

arrangement, and the way the fuels are ignited

in the case of prescribed fires, can affect the

amount of biomass consumed during various

combustion stages. Between 20 and 90 percent

of the biomass consumed during a wildland fire

occurs during the flaming stage, with the remainder occurring during the smoldering and

glowing stages (Ottmar and others [in preparation]. The flaming stage has a high combustion efficiency; that is it tends to emit the least

emissions relative to the mass of fuel consumed.

The smoldering stage has a low combustion

efficiency and produces more smoke relative to

the mass of fuel consumed.

Biomass consumption of the woody fuels, piled

slash, and duff in forested areas has become

better understood in recent years (Sandberg and

Dost 1990, Sandberg 1980, Brown and others

1991, Albini and Reinhardt 1997, Reinhardt and

others 1997, Ottmar and others 1993, Ottmar

and others [in preparation]). Large woody fuel

consumption generally depends on moisture

content of the woody fuel and duff. Approximately 50 percent of the consumption occurs

during the flaming period. Duff consumption

depends on fire duration of woody fuels and

duff moisture content. Consumption occurs

primarily during the smoldering stage when duff

moisture is low. Consumption of tree crowns in

forests and shrub crowns in shrublands are

poorly understood components of biomass

consumption and research is currently underway

(Ottmar and Sandberg 2000) to develop or

modify existing consumption equations for

these fuel components.

Since consumption during the flaming phase is

more efficient than during the smoldering phase,

separate calculations of flaming consumption

and smoldering consumption are required for

improved assessment of total emissions. Equations for predicting biomass consumption by

combustion phase are widely available in two

major software packages including Consume 2.1

(Ottmar and others [in preparation]) and First

Order Fire Effects Model (FOFEM 5.0)

(Reinhardt and Keane 2000).

Consume 2.1 is a revision of Consume 1.0

(Ottmar and others 1993) and uses a set of

theoretical models based on empirical data to

predict the amount of fuel consumption from the

burning of logging slash, piled woody debris, or

natural forest, shrub, grass fuels. Input variables

include the amount of fuel, woody fuel and duff

moisture content, and meteorological data. The

software product incorporates the original Fuel

Characteristic System (Ottmar and others [in

preparation]) for assigning default fuel loadings.
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2001 Smoke Management Guide 5.0 – Source Characteristics

It also incorporates features that allow users to

receive credit for applying fuel consumption

reduction techniques. FOFEM 5.0 (Reinhardt

and Keane 2000) is a revision of FOFEM 4.0

(Reinhardt and others 1997) and relies on

BURNUP. a new model of fuel consumption

(Albini and Reinhardt 1997). The software

computes duff and woody fuel consumption for

many forest and rangeland systems of the

United States. Both Consume 2.1 and FOFEM

5.0 packages are updated on a regular basis as

new consumption models are being developed.

Smoke Emissions

The chemistry of the fuel as well as the efficiency of combustion governs the physical and

chemical properties of the resulting smoke from

fire. Although smoke from different sources

may look similar to the eye, it is often quite

different in terms of its chemical and physical

properties. Generally, the emissions we cannot

see are gas emissions and the emissions we can

see are particulate emissions.

Carbon dioxide and water—Two products of

complete combustion during fires are carbon

dioxide (CO2) and water (H2O) and generally

make up over 90 percent of the total emissions

from wildland fire. Under ideal conditions

complete combustion of one ton of forest fuels

requires 3.5 tons of air and yields 1.84 tons of

CO2 and 0.54 tons of water (Prescribed Fire

Effects Working Team 1985). Under wildland

conditions, however, inefficient combustion

produces different yields. Neither carbon

dioxide nor water vapor are considered air

pollutants in the usual sense, even though

carbon dioxide is considered a greenhouse gas

and the water vapor will sometimes condense

into liquid droplets and form a visible white

smoke near the fire. This fog/smoke mixture

can dramatically reduce visibility and create

hazardous driving conditions.

As combustion efficiency decreases, less carbon

is converted to CO2 and more carbon is available to form other combustion products such as

carbon monoxide (CO), hydrocarbons (HC),

nitrogen oxides(NOx), and sulfur oxides (SOx),

all of which are considered pollutants.

Carbon Monoxide—Carbon monoxide (CO) is

the most abundant emission product from

wildland fires. Its negative effect on human

health depends on the duration of exposure, CO

concentration, and level of physical activity

during the exposure. Generally, dilution occurs

rapidly enough from the source of the fire that

carbon monoxide will not be a problem for local

citizens unless a large fire occurs and inversion

conditions trap the carbon monoxide near rural

communities. Carbon monoxide is always a

concern for wildland firefighters however, both

on the fire line at prescribed fires and wildfires,

and at fire camps (Reinhardt and Ottmar 2000,

Reinhardt and others 2000).

Hydrocarbons—Hydrocarbons (HC) are an

extremely diverse class of compounds containing hydrogen, carbon and sometimes oxygen.

Usually, the classes of hydrocarbon compounds

are identified according to the number of carbon

atoms per molecule. Emission inventories often

lump all gaseous hydrocarbons together. Although a majority of the HC pollutants may

have no harmful effects, there are a few that are

toxic. More research is needed to characterize

hydrocarbon production from fires.

Nitrogen Oxides—In wildland fires, small

amounts of nitrogen oxides (NOx) are produced,

primarily from oxidation of the nitrogen contained in the fuel. Thus the highest emissions of

Nox occur from fuels burning with a high

nitrogen content. Most fuels contain less than 1

percent nitrogen. Of that about 20 percent is

converted to NOx when burned.
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 98 –

Hydrocarbons and possibly nitrogen oxides

from large wildland fires contribute to increased

ozone formation under certain conditions.

Particulate Matter—Particulate matter produced from wildland fires limits visibility,

absorbs harmful gases, and aggravates respiratory conditions in susceptible individuals (figure

5.6). Over 90 percent of the mass of particulate

matter produced by wildland is less than 10

microns in diameter and over 80-90 percent is

less than 2.5 microns in diameter (figure 5.7).

These small particles are inhalable and respirable. Respirable suspended particulate matter

is that proportion of the total particulate matter

that, because of its small size has an especially

long residence time in the atmosphere and

penetrates deeply into the lungs. Small smoke

particles also scatter visible light and thus

reduce visibility.

Figure 5.6. Relative sizes of beach sand, flour, and a PM2.5 particle in smoke.
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2001 Smoke Management Guide 5.0 – Source Characteristics

Emission Factors

An emission factor for a particular pollutant of

interest is defined as the mass of pollutant

produced per mass of fuel consumed (i.e., lbs/

ton in the English system or g/kg as the metric

equivalent). Multiplying an emission factor in

grams/kg by a factor of two will convert the

emission factor to English units (pounds/ton).

Emission factors vary depending on type of

pollutant, type and arrangement of fuel and

combustion efficiency. The average fire emission factors have a relatively small range and

contributes approximately 16 percent of the total

error associated with predicting emissions

production (Peterson 1987; Peterson and

Sandberg 1988). In general, fuels consumed by

flaming combustion produce less smoke than

fuels consumed by smoldering combustion.

Emission factors for several smoke compounds

are presented in table 5.1 for the flaming,

smoldering, and fire average for generalized fuel

types and arrangements. Emission factors can

be used by air quality agencies to calculate local

and regional emissions inventories or by managers to develop strategies to mitigate downwind

smoke impacts. Additional emission factors

have been determined for other fuel types and

will be available in the future.

Total Emissions, Source

Strength, and Heat Release Rate

Total emissions from a fire or class of fires (that

is, a set of fires similar enough to be characterized by a single emission factor) can be estimated by multiplying that emission factor by the

biomass consumed and an accurate assessment

of the total acreage burned. For instance,

assume that 10 tons/acre of fuels will be conFigure 5.7. Particulate matter size-class distribution from typical wildland fire smoke.
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 100 –

Table 5.1. Forest and rangeland emission factors 1Ward and others 1989; 2Hardy and others 1996; 3

Hardy and Einfield 1992).

 
– 101 –

2001 Smoke Management Guide 5.0 – Source Characteristics

sumed during a 200 acre landscape prescribed

burn in a ponderosa pine stand. Following the

fire, ground surveys and aerial reconnaissance

indicate a mosaic fire pattern and only 100 acres

of the 200 acres within the fire perimeter actually burned. Since the emission factor for

particulate matter 2.5 microns in diameter or

less (PM2.5) for pine fuels is approximately 22

lbs/ton, then total emission production would

be:

Managers can make better estimates of emissions produced from a wildland fire if the

amount of fuel consumption in the flaming and

smoldering combustion period is known. The

same general approach is used although it is

slightly more complicated. The fuel consumed

during the flaming period and smoldering period

are multiplied by the appropriate flaming and

smoldering emission factor for a particular fuel

type, then summed. Computer software such as

Consume 2.1 (Ottmar and others [in preparation]) and FOFEM 5.0 (Reinhardt and Keane

2000) use this approach to improve estimates of

total emissions produced from wildland fire as

compared with the fire average approach. An

emission inventory is the aggregate of total

emissions from all fires in a given period for a

specific geographic area and requires total

emissions.

Modeling emissions from wildland fires requires

not only total emissions, but also source

strength. Source strength is the rate of air

pollutant emissions in mass per unit of time or

in mass per unit of time per unit of area and is

the product of the rate of biomass consumption

and an emission factor for the pollutant(s) of

interest. Source strength can be calculated by

the equation:

Emission rates vary by fuel loading, fuel consumption, and emission factors. Figure 5.8

graphically depicts general trend differences in

emission production rate and total emissions

production (area under each curve) for various

prescribed fire scenarios. Mechanically treating

fuels before burning, mosaic burning, burning

under high fuel moisture contents, and burning

piles are specific ways emission rates can be

reduced to meet smoke management requirements.

The consumption of biomass produces thermal

energy and this energy creates buoyancy to lift

smoke particles and other pollutants above the

fire. Heat release rate is the amount of thermal

energy generated per unit of time or per unit of

time per unit of area. Heat release rate can be

calculated by the equation:

Both source strength and heat release rate are

required by all sophisticated smoke dispersion

models (Breyfogle and Ferguson 1996). Dispersion models are used to assess the impact of

smoke on the health and welfare of the public in

cities and rural communities and on visibility in

sensitive areas such as National Parks, Wilderness areas, highways, and airports. The Emissions Production Model (EPM) (Sandberg and

Peterson 1984; Sandberg 2000) is the only

model that predicts source strength and heat

release rate for wildland fires. The EPM software package imports fuel consumption predictions from Consume 2.1 or FOFEM 5.0 and uses

ignition pattern, ignition periods, and burn area

components to calculate source strength, heat

release rate, and plume buoyancy.
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

– 102 –

Figure 5.8a. Emission production rate over time for

PM2.5 during an underburn with and without fuels

mechanically removed.

Figure 5.8b. Emission production rate over time for

PM2.5 during a mosaic burn and a burn where fire

covers the entire area within the perimeter.

Figure 5.8c. Emission production rate over time for

PM2.5 during an underburn with low and high fuel

moisture content.

Figure 5.8d. Emission production rate over time for

PM2.5 during an underburn and a pile burn.
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2001 Smoke Management Guide 5.0 – Source Characteristics

Literature Citations

Agee, James K. 1993. Fire ecology of Pacific

Northwest forests. Island Press, Washington

D.C. 493 p.

Albini, Frank A.; Reinhardt, Elizabeth D. 1997.

Improved calibration of a large fuel burnout

model. International Journal of Wildland Fire.

7(1): 21-28.

Anderson, Hal E. 1969. Heat transfer and fire

spread. USDA For. Serv. Res. Pap. INT-69,

Intermt. For. And Range Exp. Stn., Ogden, UT,

20 p.

Breyfogle, Steve; Ferguson, Sue A. 1996. User

assessment of smoke-disperion models for

wildland biomass burning. Gen. Tech. Rep.

PNW-GTR-379. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 30 p.

Brown, James K. 1974. Handbook for inventorying

downed woody material. Gen Tech, Rep. INT16. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station. 24 p.

Brown, Jame K.; Reinhardt, Elizabeth D.; Fischer,

Wiliam C. 1991. Predicting duff and woody

fuel consumption in northern Idaho prescribed

fires. Forest Science, Vol. 37, (6): 1550-1566.

Debano, Leonard F.; Neary, Daniel G.; Ffolliott,

Peter F. 1998. Fire’s effects on ecosystems.

New York: John Wiley and Sons, Inc. 333 p.

Finney, Mark. 2000. Personal communication.

USDA Forest Service Rocky Mountain Research Station, Fire Laboratory, Missoula, MT.

Hardy, C.C.; Ward, D.E.; Einfield, W. 1992. PM2.5

emissions from a major wildfire using a GIS;

rectification of airborne measurements. In:

Proceedings of the 29th annual meeting of the

Pacific Northwest International Section, Air and

Waste Management Association; 1992 November 11-13; Bellevue, WA. Pittsburgh, PA: Air

and Waste Management Association.

Hardy, C.C.; Conard, S.G.; Regelbrugge, J.C.;

Teesdale, D.T. 1996. Smoke emissions from

prescribed burning of southern California

chaparral. Res. Pap. PNW-RP-486. Portland,

OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station.

37p.

Mobley, Hugh E. 1976. Smoke management—What

is it? In southern smoke management guide

book. Gen. Tech. Rep. SE-10. U.S. Department

of Agriculture, Forest Service, Southeast Range

and Experiment Station. pp. 1-8.

Ottmar, Roger D.; Burns, Mary F.; Hall, Janet N.;

Hanson, Aaron D. 1993. CONSUME users

guide. Gen. Tech. Rep. PNW-GTR-304. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research

Station. 117 p.

Ottmar, Roger D.; Vihnanek, Robert E.; Wright,

Clinton S. 1998. Stereo photo series for quantifying natural fuels: Volume I: Mixed-conifer

with mortality, western juniper, sagebrush and

grassland types in the interior Pacific Northwest. PMS 830. Boise, ID: National Wildfire

Coordinating Group, National Interagency Fire

Center. 73 p.

Ottmar, Roger D.; Vihnanek, Robert E. 1998. Stereo

photo series for quantifying natural fuels:

Volume II: Black spruce and white spruce types

in Alaska . PMS 831. Boise, ID: National

Wildfire Coordinating Group, National Interagency Fire Center. 65 p.

Ottmar, Roger D.; Vihnanek, Robert E. 1999. Stereo

photo series for quantifying natural fuels:

Volume V: Midwest red and white pine, northern tallgrass prairie, and mixed oak types in the

central and lake states. PMS 834. Boise, ID:

National Wildfire Coordinating Group, National

Interagency Fire Center. 99 p.

Ottmar, Roger D.; Sandberg, David V. 2000. Modification and validation of fuel consumption

models for shrub and forested lands in the

Southwest, Pacific Northwest, Rockies, Midwest, Southwest, and Alaska. Abstract. Presented at the Joint Fire Science Program

Principle Investigators Meeting, October 3-5,

2000, Reno, Nevada. http://www.nifc.gov/

joint_fire_sci/jointfiresci.html

Ottmar, Roger D.; Vihnanek, Robert E. 2000a. Photo

series for major natural fuel types of the United
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States—phase II. Abstract. Presented at the

Joint Fire Science Program Principle Investigators Meeting; 2000 October 3-5; Reno, Nevada.

http://www.nifc.gov/joint_fire_sci/

jointfiresci.html.

Ottmar, Roger D.; Vihnanek, Robert E. 2000b.

Stereo photo series for quantifying natural

fuels: Volume VI: Longleaf pine, pocosin, and

marshgrass types in the southeast United States.

PMS 831. Boise, ID: National Wildfire Coordinating Group, National Interagency Fire Center.

56 p.

Ottmar, Roger D.; Vihnanek, Robert E.;

Regelbrugge, Jon C. 2000a. Stereo photo series

for quantifying natural fuels: Volume IV:

Pinyon-juniper, sagebrush, and chaparral types

in the Southwestern United States. PMS 833.

Boise, ID: National Wildfire Coordinating

Group, National Interagency Fire Center. 97 p.

Ottmar, Roger D.; Reinhardt, Timothy E.; Anderson,

Gary, DeHerrera, Paul J. [In preparation].

Consume 2.1 user’s guide. Portland, OR: U.S.

Department of Agriculture, Forest Service,

Pacific Northwest Research Station.

Peterson, Janice L.; Sandberg, David V. 1988. A

national PM10 emissions inventory approach

for wildfires and prescribed fires. In: Mathai,

C.V.; Stonefield, David H., eds. Transactions

PM-10 implementation of standards: an APCA/

EPA International Specialty Conference; 1988

February 23-24; San Francisco, CA. Pittsburg,

PA: Air Pollution Control Association: 353-371.

Peterson, Janice L. 1987. Analysis and reduction of

the errors of predicting prescribed burn emissions. Thesis. Seattle: University of Washington. 70 p.

Prescribed Fire and Fire Effects Working Team.

1985. Smoke management guide. PMS 420-2,

NFES 1279. Boise ID: National Wildfire

Coordinating Group, National Interagency Fire

Center. 28 p.

Reinhardt, Elizabeth D.; Keane, Robert E.; Brown,

James K. 1997. First Order Fire Effects Model:

FOFEM 4.0, users guide. Gen. Tech. Rep. INTGTR-344. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain

Research Station. 65 p.

Reinhardt, Elizabeth D; Keane, Robert E. 2000. A

national fire effects prediction model—revision

of FOFEM. Abstract. Joint Fire Science

Program Principle Investigators Meeting; 2000

October 3-5, 2000; Reno, Nevada. http://

www.nifc.gov/joint_fire_sci/jointfiresci.html

Reinhardt, Timothy E.; Ottmar, Roger D. 2000.

Smoke exposure at western wildfires. Res. Pap.

PNW-RP-525. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Research Station. 72 p.

Reinhardt, Timothy E.; Ottmar, Roger D.;

Hanneman, Andrew J.S. 2000. Smoke exposure

among firefighters at prescribed burns in the

Pacific Northwest. Res. Pap. PNW-RP-526.

Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research

Station. 45 p.

Ryan, P.W.; McMahon, C.K. 1976. 1976. Some

chemical characteristics of emissions from

forest fires. In: Proceedings of the 69th Annual

Meeting of the Air Pollution Control Association, Portland, OR, Air Pollution Control

Association, Pittsburgh, PA. Paper No. 76-2.3.

Sandberg, David V. 1980. Duff reduction by prescribed unferburning in Douglas-fir. USDA For.

Serv. Res. Pap. PNW-272. 18 p.

Sandberg, David V. 2000. Implementation of an

improved Emission Production Model. Abstract. Joint Fire Science Program Principle

Investigators Meeting; 2000 October 3-5; Reno,

NV. http://www.nifc.gov/joint_fire_sci/

jointfiresci.html.

Sandberg, David V.; Dost, Frank N. 1990. Effects of

prescribed fire on air quality and human health.

In: Natural and Prescribed Fire in the Pacific

Northwest edited by John D. Walstad, Steven R

Radosevich, David V. Sandberg. Orgon State

University Press, Corvallis, Oregon. 191-218.

Sandberg, David V.; Ottmar, Roger D. 2001 Characterizing fuels in the 21st century. International

Journal of Wildland Fire, 10: 381-387.

Sandberg, D.V.; Peterson, J.L. 1984. A source

strength model for prescribed fires in coniferous

logging slash. Presented to the 1984 Annual

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Pacific Northwest Section. Reprint #84.20.

Portland, Oregon: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 10 p.

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handbook. San Francisco: U.S. Department of

Interior, National Park service, Western Region.

[Pages unknown].

Ward, D.E.; Hardy, C.C.; Sandberg, D.V.; Reinhardt,

T.E. 1989. Part III-emissions characterization.

In; Sandberg, D.V.; Ward, D.E.; Ottmar, R.D.,

comp. eds. Mitigation of prescribed fire atmospheric pollution through increased utilization

of hardwoods, piled residues, and long-needled

conifers. Final report. U.S. DOE, EPA. Available from: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research

Station, Seattle WA.
Chapter 5 – Smoke Source Characteristics 2001 Smoke Management Guide

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– 107 –

2001 Smoke Management Guide 6.0 – Fire Use Planning

FIRE USE PLANNING

Chapter 6
Chapter 6 – Fire Use Planning 2001 Smoke Management Guide

– 108 –
– 109 –

2001 Smoke Management Guide 6.0 – Fire Use Planning

Fire Use Planning

Tom Leuschen

Dale Wade

Paula Seamon

The success of a fire use program is in large part

dependent on a solid foundation set in clear and

concise planning. The planning process results

in specific goals and measurable objectives for

fire application, provides a means of setting

priorities, and establishes a mechanism for

evaluating and refining the process to meet the

desired future condition. It is an ongoing

process, beginning months or even years in

advance of actual fire use, with plans becoming

increasingly specific as the day of the burn

approaches. Although details differ between fire

practitioners, the general planning process is

essentially the same.

Land and Resource

Management Planning

Fire use planning should begin as a component

of the overall land and resource management

planning for a site. Consideration of the intentional use of fire to achieve stated resource

management goals should be an integral part of

this process. In deciding whether or not fire use

is the best option to accomplish a given objective, an analysis of potential alternative treatments should be completed. This analysis

should describe the risks associated with use of

a given treatment and include expected negative

as well as beneficial outcomes. Care should be

exercised to separate statements that are supported by data (preferably local and ecosystemspecific), from those only purported to be true.

Many private landowners do not have written

resource management plans, but most have a

vision of what natural resource attributes they

want to favor and what they want their lands to

look like. We recommend they put this vision

on paper to provide guidance to themselves and

their heirs.

The plans should identify any barriers to implementing a treatment judged best from a resource management standpoint, such as

regulations, cost, or insufficient resources. If

such a treatment is not recommended because

of these barriers, the probable ecological ramifications of this decision should be documented.

On sites where fire is selected as the best

alternative to accomplish the desired resource

management objectives, the next step in fire use

planning is to develop a fire management plan.

The Fire Management Plan

The fire management plan addresses fire use at

the level of the administrative unit, such as a

forest, nature preserve, park, ranch or plantation. It ensures that background information
Chapter 6 – Fire Use Planning 2001 Smoke Management Guide

– 110 –

about the area has been researched, legal constraints reviewed, and a burn program found to

be both justified and technically feasible. It

proposes how fire will be applied to the landscape, both spatially and temporally. When

managing for multiple resources (e.g., range,

wildlife, and timber) on a tract, guidance should

be provided regarding the allocation of benefits;

i.e., should benefits to the same resource always

be maximized on given burn units, or should the

focus be rotated among benefits on some, or all

burn units over time?

Items commonly addressed in the fire management plan are:

• Background information on the area, such

as topography, soils, climate and fuels

• Applicable fire laws and regulations,

including any legal constraints

• Landowner policy governing fire use on

this tract of land

• Fire history of the area, including the

natural fire regime, and recent fire occurrence or use

• Justification for fire management

• Fire management goals for the area,

including a description of the desired

future condition. (Objectives for specific

burns are set in the burn unit plan, see

below.)

• Fire management scheduling, qualitatively

describing how fire will be applied to the

site over time to achieve stated resource

objectives. (Quantitative descriptions of

fireline intensity, fire severity, and season

of burn are set in the burn unit plan, see

below.)

• Species of special concern, wildlife habitat

issues, invasive species issues

• Definition and descriptions of treatment

units or burning blocks

• Air quality and smoke management

considerations

• Neighbor and community factors

• Maps illustrating fuels distribution, treatment units, smoke sensitive areas, etc.

When complete, this document should enable

the resource manager to gain the support (both

internal and external) and identify the resources

needed to effectively and efficiently use fire as a

management tool.

Community involvement in the fire planning

process is crucial to public acceptance of fire

use. At what stage to involve the public in the

process will depend on regional issues, regulations, and organizational policy. In general, the

earlier the public is involved, the easier it is to

reach agreement on any concerns. Whenever it

is done, it is important to remember that public

support is key to the long-term success of a fire

management program. Unexpected results,

including under-achievement and over-achievement of objectives, are bound to occur. A full,

honest discussion of the potential for such

results, and their ramifications, can defuse

negative reaction to the occasional bad outcome,

especially if the public was involved early in the

planning process.

Further guidance for developing a fire management plan is available from a number of federal

sources, including Wildland and Prescribed

Fire Management Policy: Implementation

Procedures Reference Guide (USDI and USDA

Forest Service 1998), and from The Nature
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2001 Smoke Management Guide 6.0 – Fire Use Planning

Conservancy’s Fire Management Manual

(www.tncfire.org/manual).

The Burn Plan

Once the fire management plan is completed

and approved, the next step is implementation—

not an easy task. Resource managers are usually faced with numerous constraints, such as

budget and staff limitations, equipment availability, timing of good burning conditions, and a

lack of information on potential effects. A

successful prescribed fire program requires the

complete dedication of the fire management

staff, full cooperation of all personnel and

functional areas involved, and unwavering

support and commitment throughout the chain

of command.

Although the overall resource management

goals for an individual burn unit often remain

unchanged for long periods, the specific burn

objectives for a given unit will likely vary over

time, necessitating modifications to the unit plan

for each burn. For example, the use of a heading fire during the growing season to promote

biodiversity and flowering of ground layer

plants may be the current burn objective, while a

backing fire during the dormant season may

have been used to reduce hazardous fuels loads

the last time the unit was burned.

A written burn plan serves several important

purposes:

• It makes the planner think about what he/

she wants to achieve, and how it will be

accomplished.

• It allows the fire manager to prioritize

between burn units based on constraints

and objectives.

• It functions as the operational plan that

details how a burn will be safely and

effectively conducted.

• It serves as the standard by which to

evaluate the burn.

• It provides a record for use when planning

future burns (which makes it essential to

document any changes when the burn is

conducted, directly on the plan).

• It becomes a legal record of the intended

purpose and execution of the burn project.

There is no standard format for a burn unit plan;

numerous examples are available which can be

consulted for guidance. Sources include state

and federal land management agencies, The

Nature Conservancy’s internet site

(www.tncfire.org), or publications such as A

Guide to Prescribed Fire in Southern Forests

(Wade and Lunsford, 1989), which is available

online from the Alabama Private Forest Management Team website (www.pfmt.org/

standman/prescrib.htm), and from the Florida

Division of Forestry (flame.fl-dof.com/Env/Rx/

guide/).

Although formats differ, certain components

should be included in all burn plans. They

should address at least the following 12 topics:

1. Assessment and Description of the Burn

Unit. The first step in developing a burn

plan is to evaluate and document existing

conditions. Factors to include depend on the

site itself, as well as the complexity of the

planned burn. The information recorded here

will serve as the baseline from which success

of the burn will be determined, so parameters

used in the burn objectives should be assessed and described. Include details on the

unit size (broken into single-day burn units);

date of the last burn; overstory and under-
Chapter 6 – Fire Use Planning 2001 Smoke Management Guide

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story vegetation, density and size; fuel type,

density and size; soil type and topography;

threatened and endangered species present;

invasive species present; and current wildlife

use.

2. Maps. Good maps of the treatment area are a

key component of the burn plan. The map

scale should be adequate to show pertinent

information in meaningful detail. Be careful

not to include too much information on a

single map, making it difficult to read. The

burn plan should include a series of maps

showing the following: unit boundaries;

adjacent land ownerships, including contact

person and phone numbers; topography and

manmade obstacles such as canals, ditches,

and erosion gullies that would impede equipment or people; natural and constructed fire

control lines; areas to be protected or excluded such as sawdust piles, utility poles

and sensitive vegetation areas; firing plan;

initial placement of equipment and holding

personnel, and; escape routes and safety

zones. Every crew member should receive a

map with the information essential to personnel safety and burn operations.

3. Measurable Burning Objectives. Unitspecific treatment objectives identify the

desired changes in affected resources from

the present to the future condition. Treatment objectives are prepared within the

context and intent of all resource management objectives. They are the measures

against which the success of a burn is determined. Burn objectives make clear to everyone involved what is expected - including the

burners, cooperators, managers, and the

public. The objectives should be detailed

statements that describe what the treatment is

intended to accomplish, and as such, must be

specific and quantifiable.

4. Weather and Fuel Prescription. The

prescription defines the range of conditions

under which a fire is ignited and allowed to

burn to obtain given objectives. Fuel moisture (by size class) and weather conditions

(temperature, humidity, wind, drought,

dispersion index) are key factors in achieving

objectives because they in large part determine fire behavior (intensity and severity),

which in turn, governs ease of fire control

and effects. These same parameters also

affect smoke production and transport.

Considerable care should therefore be taken

in defining the window of conditions under

which the projected burn may take place.

Although there may be an ideal set of conditions that will maximize a single objective,

the likelihood of this set of conditions occurring at the right time is typically extremely

low. Therefore, a range of fuel and weather

conditions are usually specified in the burn

prescription that allow the skilled burner to

compensate between various parameters to

safely and efficiently conduct a successful

burn—a burn which meets both the resource

and smoke management objectives.

5. Season and Time of Day. The season of

burn influences many burn parameters.

Typically, acceptable burning conditions are

more predictable during certain seasons,

making it easier to plan and prepare for burns

days in advance, but not all burn objectives

may be achievable under those weather and

fuel conditions. Regional effects are important in decision-making for this factor. For

example, in the southeast, dormant season

burns are generally more uniform in effects

while growing season burns are more likely

to be patchy. Backing fires are much easier

to conduct during the dormant season when

ground layer herbaceous plants are dead and

burn readily, rather than green and succulent
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2001 Smoke Management Guide 6.0 – Fire Use Planning

thereby retarding fire spread. In the Pacific

Northwest, season of burn can be used to

reduce emissions. Broadcast burning of

slash in the wet spring has been shown to

produce 50% fewer emissions when compared to burning periods in the dry fall

(Sandberg and Dost 1990). Selecting the

correct season to execute a burn will help

maximize the probability of achieving the

burn objectives.

The timing of ignition determines whether

the burn can be completed and mopped up as

scheduled during the burning period. Timing

is also important when considering factors

such as: when solar radiation will break a

nighttime inversion or dissipate any dew

which formed during the night, when atmospheric conditions will support adequate

transport and dissipation of smoke, when

surface winds may develop or change speed

or direction, or when a sea breeze front may

reach the unit. Experienced burners become

familiar with the area, and learn how to

factor these time-sensitive influences into

their burn plans.

6. Smoke Management. Planning a fire use

project that has the potential to impact areas

sensitive to smoke requires assessment of

airshed and meteorological conditions that

influence both the movement and concentration of smoke. The expected effects of wind

speed and direction, air stability, and nighttime inversions should be specifically outlined. Specific regional issues should be

addressed, such as mountainous terrain, fog,

or sea breeze effects. This information

normally will be developed by fire managers

using their personal experience and knowledge of fire behavior, smoke transport and

dispersion in the area, along with more

formal emissions prediction and dispersion

modeling.

Sensitive areas downwind of the burn unit

should be identified and plotted on a map.

Information such as distance and direction

from the burn unit, the nature of the sensitivity, and when the area is considered sensitive

should be included. Examples of smoke

sensitive areas include Class I areas (generally, international parks, and large national

parks and national wilderness areas), nonattainment areas, communities or individual

residences, airports, highways, and medical

facilities. Several procedures for predicting

the potential impact of smoke on sensitive

areas are discussed in chapter 9.

Smoke dispersion in areas prone to inversions, such as deep, mountainous valleys, is

especially problematic in fire use planning.

If the smoke remains trapped by the inversion, all of the emissions produced will

remain trapped within the airshed.

The following smoke-related questions

should be addressed in every plan:

• What quantity of emissions will it take to

saturate this airshed?

• Where will the smoke concentrate if it

settles under an inversion?

• Do special arrangements need to be made

to protect populations impacted by these

emissions?

• How many burning projects will it take

cumulatively to exceed acceptable levels

within this airshed?

• How long will the airshed remain stable

and harbor the emissions?
Chapter 6 – Fire Use Planning 2001 Smoke Management Guide

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In instances where a burn may affect an area

especially sensitive to smoke, the use of air

quality monitors may be advisable to ensure

that an agreed-upon emission level or limit is

not exceeded. Factors to consider in using

monitors include placement of the device,

personnel to operate the instrument, quality

checks, data analysis, and provisions for realtime feedback if data is to be used in making

a decision to terminate a burn in progress.

Monitors are not commonly accessible and

are costly to use, so this option is chiefly

available to federal and state agencies. Air

quality monitoring for evaluating a fire

management program is discussed in Chapter

10.

Smoke impacts to fireline personnel should

also be considered in a smoke management

plan. The burn planner should consider

projected exposure when determining the

size of the burn crew and the duration of the

work shift. More information on smoke

exposure to fireline personnel can be found

in Chapter 3.4.

Once an analysis of significant factors is

complete, the planner should set specific,

measurable smoke management objectives

for the burn. These may include, for example, minimum visibility standards for

roads or viewsheds, and an emissions limit if

air quality monitors are to be used. Objectives provide a common understanding for all

individuals involved in or affected by the

burn, of what constitutes acceptable smoke

impacts. They also provide a tool for the

burn boss when deciding whether to terminate a fire because of problematic smoke

behavior. If the decision is made to terminate a burn because of smoke problems, it

should be remembered that direct suppression often temporarily exacerbates smoke

problems. If ignition has been completed,

the best strategy may be too let the fire burn

out.

The amount of air quality analysis required at

all levels of fire planning will be influenced

by air quality laws and smoke management

regulations. Formal state smoke management programs are becoming increasingly

common, but are not yet universal. Some

states include only regulatory language

regarding “nuisance smoke.” Complying

with all applicable laws and regulations is a

basic tenet of conscientious land stewardship,

but responsible fire use and air quality

planning include looking beyond the requirements of the law. Communities likely to be

impacted by a fire-use program should be

involved in determining what their threshold

of acceptance is for smoke from wildland

fire. Thorough attention to smoke management planning can prevent future problems.

7. Notification of Local Authorities and the

Public. Early development of a notification

plan will assist in the necessary communication with local authorities and the public. A

wide variety of methods have proven successful, including distribution of pamphlets

or flyers, public meetings, newspaper and

radio announcements, and Internet postings.

The public should be notified well in advance of the proposed burn day, and again

within a few days of executing the burn.

Generally, there is a list of individuals to be

notified on the actual burn day. This list is

often unit-specific, and should be included

along with telephone numbers in the burn

plan.

8. Environmental and Legal Constraints. If

constraints to the burn plan have not already

been addressed in a fire management plan for

the entire site, they should be addressed here

because they can limit or determine how a

burn is implemented. These may include

environmental, economic, operational,

administrative, and legal constraints.
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2001 Smoke Management Guide 6.0 – Fire Use Planning

9. Operations. The burn plan must describe in

detail how fire will be used. This section of

the plan may take any number of formats, but

the topics to be addressed include:

• Safety. What provisions will be made to

ensure the safety of the crew?

• Communications. How will the crew

communicate with each other, and with

dispatch or emergency support?

• Equipment and Personnel. What resources are needed to effectively accomplish the burn and how will they be

deployed?

• Fire Lines. What is the width and condition of existing fire lines? How many

chains of fireline need to be prepared or

cleared? How will this be accomplished?

• Ignition Pattern and Sequence. How will

the burn be ignited? Ignition duration and

firing patterns play an important role in

production and lofting of emissions.

Rapid ignition may reduce consumption,

therefore emissions, and be successful in

lofting a smoke column high into the

atmosphere. Backing fires produce fewer

emissions than heading fires. More

information on using ignition to manage

emissions production can be found in

Chapter 8, Techniques to Reduce Emissions and Impacts.

• Holding. How will the fire be kept within

its predetermined boundaries? How will

snags be dealt with?

• Mop-up. How will the burn be extinguished? What standard will be used to

consider the burn unit safe to leave?

10. Contingency Planning. Contingency plans

outline procedures for dealing with a burn

gone awry. They are a normal part of a burn

plan and should include provisions to deal

not only with escaped fire, but also with

unexpected smoke intrusions during an

otherwise controlled burn. Some of the

issues to be addressed include safety of the

general public and the fire crew, sources of

assistance for fire control and smoke-related

problems, deployment of resources, actions

to be taken to rectify the problem, notification of authorities and the public, and measures to mitigate smoke on roadways. It

should be recognized that in some cases

where smoke problems dictate shutting

down a burn after ignition has been completed, the most prudent action may be to

allow the unit to burn out rather than to

immediately extinguish it, which can temporarily exacerbate smoke production.

11. Preburn Checklist. Every burn plan

should include a checklist to be reviewed

immediately prior to ignition. The checklist

should include the factors essential to safe

execution of the burn project, and a list of

points to review with the crew during the

preburn briefing. The use of the checklist

ensures that some detail does not slip by the

burn manager’s attention in the busy moments preceding a fire.

12. Monitoring and Evaluation. Monitoring

and evaluation of the burn are key to learning from the process and making refinements for subsequent burns. Where

appropriate and practical, monitoring and

post-fire evaluation protocols describing the

effects on soil, water, air, vegetation, and

wildlife should be included in the burn unit

plan. Alternatively, the information can be

included in a post-burn evaluation report or

form, which is attached to the burn plan after

completion.
Chapter 6 – Fire Use Planning 2001 Smoke Management Guide

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• Documenting air quality conditions before,

during, and after a fire is useful in identifying nuisance smoke thresholds and

assuring that air quality standards have not

been exceeded. Additionally, monitoring

and documenting smoke transport, dilution, or concentrations in each airshed can

help develop local knowledge that is the

basis of predicting smoke impacts. In

addition to environmental effects, the

following topics should be addressed:

adequacy of preburn treatments, fire

behavior, degree to which objectives were

achieved, discrepancies between planned

fuel and weather components and on site

measurements, observations, accidents or

near-accidents, slopovers, and recommend

changes for future burns. A series of

photographs over time at permanent photo

points is an excellent inexpensive method

to document vegetation changes.

Fire Use Planning for Federal

Land Managers

The Wildland and Prescribed Fire Management

Policy: Implementation Procedures Reference

Guide (USDI and USDA Forest Service 1998)

represents an effort by Federal wildland fire

management agencies to establish standardized

procedures to guide implementation of the

policy described in the 1995 Federal Wildland

Fire Management Policy and Program Review.

It uses new terminology and definitions to

provide consistency and interpretation to

facilitate policy implementation, and describes

relationships between planning tiers to fire

management objectives, products, and

applications.

The federal process generally follows the planning process described above. The flow of

information begins with the land and resource

management plan, variously called the Forest

Management Plan (FS), Integrated Resource

Management Plan (BIA), Resource Management Plan (NPS), Comprehensive Conservation

Plan (FWS) and the Forest Management Plan

(FS). This plan determines the availability of

land for resource management, predicts levels of

resource use and outputs, and provides for a

variety of resource management practices.

The next step is preparation of the Fire Management Plan (FMP). The FMP is the primary tool

for translating programmatic direction developed in the land management plan into on-theground action. The FMP must satisfy NEPA

requirements, or follow direction provided by a

Forest Plan that has been developed through the

NEPA process. Comparisons between fire use

activities and no fire use should be described in

the NEPA process. This includes implications

of wildland fire and prescribed fire use over

extended periods of time.

The most detailed step in the process involves

the tactical implementation of strategic objectives for the wildland and prescribed fire management programs. It is at this level where

specific plans are prepared to guide implementation of fire-related direction on the ground. This

step includes Prescribed Fire Plans, Wildland

Fire Implementation Plans, and the Wildland

Fire Situation Analysis.

More information on the smoke management

requirements and federal planning process is

contained in Chapter 4.
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2001 Smoke Management Guide 6.0 – Fire Use Planning

Literature Citations

Sandberg, D.V.; Dost, F.N. 1990. Effects of prescribed fire on air quality and human health. In:

Walstad, John D.; Radosevich, S.R.; Sandberg,

D.V., eds. Natural and prescribed fire in Pacific

Northwest forests. Corvallis, OR: Oregon State

University Press; 191-298.

The Nature Conservancy. 2000. Fire Management

Manual. <http://www.tncfire.org/ manual/>.

USDI and USDA Forest Service. 1998. Wildland

and prescribed fire management policy—

implementation procedures reference guide.

National Interagency Fire Center, Boise, ID.

81 p.

Wade, Dale D. and James D. Lunsford. 1989. A

guide for prescribed fire in southern forests.

Tech. Pub. R8-TP11. Atlanta, GA. USDA

Forest Service, Southern Region. 56 p.
Chapter 6 – Fire Use Planning 2001 Smoke Management Guide

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2001 Smoke Management Guide 7.0 – Meteorology

SMOKE MANAGEMENT METEOROLOGY

Chapter 7
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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2001 Smoke Management Guide 7.0 – Meteorology

Smoke Management Meteorology

Sue A. Ferguson

Once smoke enters the atmosphere, its concentration at any one place or time depends on

mechanisms of transport and dispersion. By

transport, we mean whatever carries a plume

vertically or horizontally in the atmosphere.

Dispersion simply is the scattering of smoke.

Vertical transport is controlled by the buoyancy

of the smoke plume and stability of the atmosphere. Horizontal transport is controlled by

wind. The larger the volume of space that

smoke is allowed to enter and the farther it can

be transported, the more disperse and less

concentrated it will become. To begin understanding stability and wind that control transport

and dispersion, we begin with a few elemental

concepts.

Air Pressure

It is helpful to understand air pressure because

storms and stagnant air conditions are described

in terms of low pressure and high pressure,

respectively. Lines of constant pressure are used

to illustrate the state of the atmosphere on

weather maps, and pressure influences the

expansion and contraction of smoke parcels as

they travel through the atmosphere. Air pressure

is the force per unit area exerted by the weight

of the atmosphere above a point on or above the

earth’s surface. More simply it can be thought

of as the weight of an overlying column of air.

Air pressure is greatest near the ground, where

the overlying column of air extends the full

height of the atmosphere. Pressure decreases

with increasing altitude as the distance to the top

of the atmosphere shortens.

In a standard atmosphere, which represents the

horizontal and time-averaged structure of the

atmosphere as a function of height only, pressure decreases approximately exponentially with

height. With 1,013 millibars (mb) being the

standard atmospheric pressure at sea level, the

average height of the 850 mb pressure level

typically occurs at about 5,000 feet (~1,500 m),

the 700 mb pressure level typically occurs at

about 10,000 feet (~3,000 m), and the 500 mb

height averages around 20,000 feet (~6,000 m).

In the lowest part of the atmosphere (less than

about 8,000 feet) pressure decreases by approximately 30 mb per 1000 feet. These are useful

values to remember when analyzing meteorological data and maps for smoke management.

Actual pressure is nearly always within about

30% of standard pressure.

Lapse Rates

Lapse rate is the decrease of temperature with

height. Lapse rates help determine whether

smoke will rise from a fire or sink back to the

surface and are used to estimate atmospheric

stability. When air is heated it expands, becomes less dense and more buoyant. This

causes it to rise. A parcel of air that is heated at

the ground surface by fire or solar radiation

becomes warmer than its surroundings, causing
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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it to lift off the surface. As it rises, it encounters lower pressure that causes further expansion. The more air expands, the cooler it

becomes. If a parcel of air becomes cooler than

its surroundings, it will sink.

Cooling by expansion without an exchange of

heat at the parcel boundaries is called adiabatic

cooling. In dry air, rising air parcels typically

cool at a rate of about 5.5 °F per 1,000 feet (~

10 °C/km). This is called the dry adiabatic lapse

rate (DALR). For example, on a clear day if a

heated parcel of air begins at sea level with a

temperature of 70 °F (~21 °C), it will cool dryadiabatically as it rises, reaching a temperature

of 53.5 °F (~12 °C) at 3,000 feet (~915 m).

Rising moist air (relative humidity greater than

about 70%) is said to undergo a saturationadiabatic process. The saturated adiabatic lapse

rate (SALR) or moist adiabatic lapse rate is a

function of temperature and water content. This

is because as moist air cools its water vapor

condenses, giving off latent heat in the condensation process and causing a saturated parcel to

cool more slowly than a dry parcel. Near the

ground in mid-latitudes the SALR can be approximated at a rate of about 3 °F per 1,000 feet

(~ 5.5 °C/km). For example, on a humid or

rainy day, a heated parcel with a 70 °F (~21 °C)

initial temperature at sea level, will reach a

temperature of 61 °F (~16 °C) at 3,000 feet

(~915 m).

Lapse rates are determined by comparing

temperatures between different elevations. The

temperature from a ridge-top weather station

can be subtracted from the temperature at a

nearby valley-located weather station to calculate lapse rate. More commonly, radiosonde

observations (raobs) are used to determine lapse

rates. These balloon-mounted instruments

measure temperature, wind, pressure, and

humidity at several elevations from the ground

surface to thousands of feet. Raobs are available from weather services or at several sites on

the Internet twice each day: at 0000 Universal

Time Coordinated (UTC)1

 and 1200 UTC.

There are several ways of plotting raob data.

Typically a pseudo-adiabatic chart is used. This

chart shows measured values of temperature vs.

pressure over lines of DALR and SALR. Figure

7.1 illustrates how the above examples would

appear on a standard pseudo-adiabatic chart.

More recently, skew-T/log-P diagrams (skew-T

for short) have become popular. Instead of

plotting temperature and pressure on linear,

orthogonal axes, skew-T diagrams plot the log

of pressure and skew the temperature axis by

45°. The skew-T/log-P view of raob data

allows features of the atmosphere to be more

obvious than when plotted on a standard

pseudo-adiabatic chart. Figure 7.2 illustrates the

above examples on a skew-T diagram. On both

standard pseudo-adiabatic charts and skew-T

diagrams, elevation in meters or feet (corresponding to the pressure of a standard atmosphere) may be shown and wind direction and

speed with height is represented parallel to or

along the right-hand vertical axis. Many other

features also may be included.

Atmospheric Stability

Atmospheric stability is the resistance of the

atmosphere to vertical motion and provides an

indication of the behavior of a smoke plume.

Full characterization of a smoke plume requires

a complete estimation of the atmosphere’s

turbulent structure that depends on the vertical

patterns of wind, humidity, and temperature,

1 Universal Time Coordinated (UTC) is Standard Time in Greenwich, England. UTC is 9 hours ahead of Alaska

Standard Time (AST), where 0000 UTC = 1500 AST and 1200 UTC = 0300 AST. UTC is 5 hours ahead of Eastern

Standard Time (EST), where 0000 UTC = 1900 EST and 1200 UTC = 0700 EST.
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2001 Smoke Management Guide 7.0 – Meteorology

Figure 7.1. Standard pseudo-adiabatic chart. Short-dashed lines show the saturated adiabatic lapse rate

(SALR) and long-dashed lines show the dry adiabatic lapse rate (DALR). Point A marks a parcel of air at the

surface with a temperature of 21 °C (70 °F). If the atmosphere is dry, the parcel will follow a DALR as it rises

and reach point B with a temperature of 12 °C (53.5 °F) at 915m (3000 ft). If the atmosphere is saturated, the

parcel will follow a SALR as it rises and reach point C with a temperature of 16°C (61 °F) at 915m (3000 ft).

Figure 7.2. Skew-T pseudo-adiabatic chart. Short-dashed lines show the saturated adiabatic lapse rate

(SALR) and long-dashed lines show the dry adiabatic lapse rate (DALR). Point A marks a parcel of air at the

surface with a temperature of 21 °C (70 °F). If the atmosphere is dry, the parcel will follow a DALR as it rises

and reach point B with a temperature of 12 °C (53.5 °F) at 915m (3000 ft). If the atmosphere is saturated, the

parcel will follow a SALR as it rises and reach point C with a temperature of 16°C (61 °F) at 915m (3000 ft).
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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which are highly variable in space and time.

Because this can be a complex calculation, it

often is approximated by estimates of static

stability. The static stability of the atmosphere

is determined by comparing the adiabatic lapse

rate with ambient, environmental lapse rates (as

would be measured from instruments on a rising

balloon). By this approximation, an unstable

air mass is one in which the temperature of a

rising parcel of air remains warmer than its

surroundings. In a stable air mass, a rising

parcel’s temperature is cooler than ambient and

a neutral air mass is one in which the ambient

temperature is equal to the adiabatic lapse rate.

The most common way of estimating static

stability is to note the slope of vertically measured temperature in relation to the slope of the

dry (or moist) adiabatic line from a pseudoadiabatic chart. Figure 7.3 shows raob-measured dry-bulb and dew-point temperatures and

the theoretical trajectory of a parcel being lifted

from the surface. The parcel trajectory begins at

the current surface temperature then follows a

DALR until it becomes saturated. The point of

saturation is called the lifting condensation level

(LCL). Its height in meters can be approximated as 120 x (T0

 – Td), where T0 is the temperature at the surface and Td

 is the mean

dew-point temperature in the surface layers,

both in degrees Celsius. From the LCL, the

parcel trajectory follows a SALR.

Throughout the depth of the diagram in figure

7.3, the slope of the measured temperature is

nearly always steeper than the slope of the

adiabatic temperature, suggesting that a lifted

parcel always will remain cooler than the ambient temperature, which is a sign of stability. The

large distance between the measured temperature and the temperature of the theoretical parcel

trajectory also gives an indication of strong

Figure 7.3. Skew-T plot of a stable atmosphere. The thick black line on the right is the measured environmental dry-bulb

temperature. The thick black line on the left is the measured environmental dew-point temperature. The red line is a

theoretical parcel trajectory. Short-dashed lines are the SALR and long-dashed lines are the DALR.
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2001 Smoke Management Guide 7.0 – Meteorology

stability. In a stable atmosphere, smoke emanating from relatively cool fires will stay near

the ground. Hot fires may allow plumes to loft

somewhat through a relatively stable atmosphere but fumigation of smoke near the ground

remains common. Figure 7.4 shows smoke

from a vigorous wildfire under a stable atmosphere. Smoke plumes are trying to develop but

a strongly stable layer is trapping most smoke

just above the ridge tops.

Parcel trajectories in an unstable atmosphere

remain warmer than the measured environmental temperatures (figure 7.5). During unstable

conditions, smoke can be carried up and away

from ground level. Downwind of the source the

instability causes smoke plumes to develop a

looping appearance (figure 7.6). Obviously

there are many variations between stable and

unstable atmospheres that cause various patterns

of lofting, fanning, coning, looping, and fumigation. Each situation shows characteristic

signatures on a pseudo-adiabatic chart but some

experience may be required to distinguish the

subtle differences.

Because upper-air observations and observations

from significantly different elevations are not

always available, Pasquill (1961 and 1974)

developed a scheme to estimate stability from

ground-based observations. Not only is this

classification system used to estimate plume

characteristics; it also is used in many smoke

dispersion models as a proxy for atmospheric

turbulence. Table 7.1 shows the Pasquill classification criteria as modified by Gifford (1962)

and Turner (1961, 1964, 1970). In this example, surface wind is measured at 10 meters

above open terrain. With clear skies, the class

of incoming solar radiation is considered strong,

moderate, or slight if the solar altitude angle is

greater than 60°, between 35° and 60°, or less

than 35°, respectively. If more than 50 per cent

opaque cloud cover is present and the cloud

Figure 7.4. A smoke plume from a vigorous wildfire during stable atmospheric

conditions. Photo by Roger Ottmar.
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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Figure 7.5. Skew-T plot of an unstable atmosphere. The thick black line on the right is the measured

environmental dry-bulb temperature. The thick black line on the left is the measured environmental dew-point

temperature. The red line is a theoretical parcel trajectory. Short-dashed lines are the SALR and long-dashed

lines are the DALR.

Table 7.1. Pasquill stability classification criteria, where A = extremely unstable, B = moderately unstable,

C = slightly unstable, D = neutral, E = slightly stable, and F= moderately stable. See text for an

explanation of the incoming solar radiation classes.
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2001 Smoke Management Guide 7.0 – Meteorology

ceiling height is less than 7,000 feet (~2,100m),

the solar class is slight. If ceiling height is

between 7,000 feet and 16,000 feet (~4,800m),

then the solar class is one step below what it

would be in clear sky conditions. At night,

classification is based on the amount of sky that

is obscured by clouds. An objective way of

determining stability classification is shown in

Lavdas (1986) and Lavdas (1997).

Mixing Height

Mixing height (also called mixing depth) is the

height above ground level through which relatively vigorous vertical mixing occurs. Low

mixing heights mean that the air is generally

stagnant with very little vertical motion; pollutants usually are trapped near the ground surface.

High mixing heights allow vertical mixing

within a deep layer of the atmosphere and good

dispersion of pollutants. As such, mixing

heights sometimes are used to estimate how far

smoke will rise. The actual rise of a smoke

plume, however, considers complex interactions

between atmospheric stability, wind shear, heat

release rate of the fire, initial plume size, density

differences between the plume and ambient air,

and radiant heat loss. Therefore, an estimate of

mixing height provides only an initial estimate

of plume height.

Mixing heights usually are lowest late at night

or early morning and highest during mid to late

afternoon. This daily pattern often causes

smoke to be concentrated in basins and valleys

during the morning and dispersed aloft in the

afternoon. Average morning mixing heights

range from 300 m (~980 ft) to over 900 m

(~2,900 ft) above ground level (Holzworth

1972). The highest morning mixing heights

occur in coastal areas that are influenced by

moist marine air and cloudiness that inhibit

radiation cooling at night. Average afternoon

mixing heights are typically higher than morning heights and vary from less than 600 m

(~2,000 ft) to over 1400 m (~4,600 ft) above

ground level. The lowest afternoon mixing

heights occur during winter and along the

coasts. Mixing heights vary considerably

between locations and from day to day.

Figure 7.6. A smoke plume during unstable atmospheric conditions.

Photo by Roger Ottmar.
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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Ferguson and others (2001) generated detailed

maps and statistics of mixing heights in the

United States.

Smoke plumes during the flaming stage of fires

often can penetrate through weak stable layers

or the top of mixed layers. Once the plume

dynamics are lost, however, the atmosphere

retains control of how much mixing occurs.

Low-level smoke impacts increase once a

convective column collapses.

The depth of the mixed layer depends on complex interactions between the ground surface

and the atmosphere in a region called the planetary boundary layer (PBL). As such, it is

difficult to measure exactly and there are many

ways in which it is calculated. At times, it is

possible to estimate the mixing height by noting

the tops of cumulus clouds or the presence of an

upper-level inversion, which may appear as a

deck of strata-form clouds.

Typically, National Weather Service (NWS)

smoke management forecast products will

estimate the mixing height by the so-called

parcel method. This method considers turbulence related only to buoyancy. When a parcel

is lifted adiabatically from the surface, the point

at which it intersects the ambient temperature

profile, or where it becomes cooler than its

surroundings, is the mixing height. Usually the

maximum daily temperature is used as the

parcel’s starting temperature and its adiabatic

lapse rate is compared with the afternoon (0000

UTC) sounding profile. Conversely, the minimum daily temperature is used to compare with

the morning (1200 UTC) raob for calculating

morning mixing heights. If an elevated inversion (see next section) occurs before this height

is reached, the height of the inversion base

would determine the mixing height. If a surface

inversion exists, then its top marks the mixing

height. For example, the mixing height in figure

7.3 is at the top of the surface-based inversion at

about 750 mb (approximately 2,400 meters or

7,800 feet above ground level).

Instead of approximating a mixing depth,

physical calculations of the PBL are possible

through numerical meteorological models.

These calculations are more precise than the

parcel method because they consider turbulence

generated by wind shear as well as buoyancy.

Each prognostic model, however, may calculate

the PBL slightly differently as some functions

are approximated while others are explicitly

derived to enhance computational efficiency and

the vertical resolution, which varies between

models, affect PBL calculations.

Temperature Inversions

When the ambient temperature increases with

height, an inversion is said to be present. It

usually marks a layer of strong stability. When

a heated air parcel from the surface encounters

an inversion, it will stop rising because the

ambient air is warming faster than the expanding parcel is cooling. The parcel being cooler

than its surroundings will sink. Although the

heat from some fires is enough to break through

a weak inversion, inversions often are referred to

as lids because of their effectiveness in stopping

rising air and trapping pollutants beneath it.

Smoke trapped under an inversion can substantially increase concentrations of particles and

gases, aggravating respiratory problems and

reducing visibility at airports and along roadways.

There are three ways that surface-based inversions typically form: (1) valley inversions are

very common in basins and valleys during clear

nights when radiation heat losses cause air near

the ground to rapidly cool: the cold surface air

flows from the surrounding slopes and collects
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2001 Smoke Management Guide 7.0 – Meteorology

in hollows and pockets, allowing warmer air to

remain aloft; (2) advective inversions are caused

by cold air moving into a region from a nearby

lake or ocean, usually during the afternoon when

onshore lake and sea breezes tend to form; and

(3) subsidence inversions can occur at any time

of day or night as cold air from high altitudes

subsides or sinks under a region of relatively

stagnant high pressure. Valley inversions cause

tremendous problems when managing longduration fires that continue into the night. Advective inversions can surprise smoke managers

who are unfamiliar with local lake- and seabreeze effects, creating poor dispersal conditions

in an afternoon when typically good dispersion is

expected. Subsidence inversions are difficult to

predict even for a well-trained meteorologist.

Figure 7.7 shows smoke caught under a valley

inversion that is being transported by downvalley winds in the early morning.

Surface inversions also occur in the gaps (passes

and gorges) of mountain ranges. Approaching

storms usually have an associated center of low

pressure that causes a pressure gradient across

the range. If cold air is on the opposite side of

the range, the gradient in pressure causes the

cold air to be drawn through the gap, creating an

inversion in the gap. Gap inversions are most

common in winter but also are frequent during

spring and autumn.

In addition to surface-based inversions, temperature inversions also occur in layers of the atmosphere that are above the ground surface, which

sometimes are called thermal belts. Upper-level

inversions usually are associated with incoming

warm fronts that bring moisture and warmth to

high altitudes well ahead of a storm. The

inversion lowers to the ground as the front

approaches. Upper-level inversions also may be

associated with subsidence or surface-based

inversions that have been lifted, usually by

daytime heating.

Wind

Not only does smoke mix and disperse vertically, the horizontal component of wind readily

transports and disperses pollutants. The stronFigure 7.7. A plume of smoke flowing out of a mountain valley with down-slope

winds during the early morning. Photo by Roger Ottmar.
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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ger the wind, the more scattered particles become and the less concentrated they will be.

Strong winds at the surface, however, can

increase fire behavior and associated emission

rates. Also, significant surface winds may “laydown” a plume, keeping smoke close to the

ground for long distances.

Friction with the ground causes winds to slow

down. Therefore, wind speed usually increases

with height, causing a smoke column to gradually bend with height as it encounters increasingly strong winds. This pattern is complicated

in regions of complex terrain, however, and it is

common to find stronger surface winds in

mountain passes, saddles, and gorges as air is

squeezed and funneled through the gap. Forest

clearings also allow surface winds to accelerate

because surface friction is lower in a clearing

than over a forest canopy.

Because smoke from different stages of a fire

rises to different levels of the atmosphere, it is

important to know wind speed and direction at

several different heights. For example, smoldering smoke at night responds to surface winds

while daytime smoldering and smoke from the

ignition and flaming phase of a fire will respond

to upper-level winds. Depending on the buoyancy of the smoke and stability of the atmosphere, winds that influence the upper-level

smoke trajectories may be from just above a

forest canopy to 10,000 feet (about 3,000

meters) or more. Because flaming heat can

create convective columns with strong vertical

motion, most smoke during the flaming portion

of a fire will be carried to at least the top of the

mixing height or an upper-level inversion height

before dispersing. In this way, a fire hot enough

to pull itself into a single convection column can

reduce concentrations near the ground and

knowledge of winds at the top of the mixing

height or inversion level will determine smoke

trajectory and dispersion. Smoldering smoke,

on the other hand, has very little forced convection so it often fumigates away from a fire as it

rises with daytime buoyancy. Knowledge of

wind all the way from the surface to top of the

mixing height may be needed to determine

smoldering trajectories.

Storm Winds – Storms change the structure of

winds entirely. Because storms often bring high

instability and good dispersion, it is common to

plan fires slightly ahead of an approaching

storm. Knowing storm wind patterns can help

anticipate associated smoke impacts. Figure 7.8

shows surface wind directions2 typically associated with a passing cyclonic storm. Because air

flows from high pressure to low pressure (like

the rush of air from a punctured tire) and storms

usually have a center of low pressure at the

surface, surface winds ahead of a storm in the

northern hemisphere will be from the east or

southeast. As the low center approaches, surface winds will become southerly to southwesterly. After the storm passes, surface winds may

become more westerly or northwesterly. This

pattern can cause smoke to move toward the

west to northwest then north to northeast ahead

of a cyclonic storm, moving toward the east and

southeast following storm passage.

Each cyclonic storm usually contains at least

one front (a boundary between two different air

masses). A typical storm has a warm front

aligned northwest to southeast ahead of the low

center, a cold front trailing northeast to southwest near and closely behind the low, and an

occluded front (formed when a cold front

overtakes a warm front) to the north of the low.

Winds change direction most rapidly and become gusty when fronts pass by. Warm fronts

can bring increasing stability and cause upper2 Wind direction is the direction from which the wind is blowing. For example, a west wind is coming from the west

and blowing toward the east. If you face east, a west wind will hit your back.
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2001 Smoke Management Guide 7.0 – Meteorology

Figure 7.8. Schematic of surface winds associated with a typical cyclonic storm in the Northern Hemisphere.

The letter, L, marks position of the surface low pressure center. Thin lines represent isobars (constant pressure

contours that are labeled in millibars) at sea level. The thick line marked with barbs represents a surface cold

front, marked with half-circles is a warm front, and marked with both is an occluded front. East to southeast

surface winds are common ahead of a warm front, south to southwest winds are common ahead of a cold front,

and west to northwest winds are common following a cold front.

level inversions, while cold fronts usually are

associated with strong instability. The stronger

the front, the more dramatic the wind shift and

the stronger the gusts. Cold frontal passage

typically improves dispersion of smoke with

stronger winds and an unstable air mass that can

scour away existing inversions. Smoke trajectories should be expected to change direction with

the passage of a storm front and storms can

cause significant changes in fire behavior and

resulting emission rates. Storm fronts are not

always typical, however, and the number,

strength, and orientation of fronts are quite

variable.

Strong winds above the influence of the earth’s

surface experience forces associated with the

earth’s rotation in addition to pressure gradient

and other forces. This causes winds in the upper

atmosphere to follow lines of constant pressure

instead of moving across lines of constant

pressure as surface or lower-speed winds do

when air flows from high pressure to low pressure. In the upper atmosphere the pressure

pattern of a typical storm is shaped like a trough

(figure 7.9). As air follows the pressure contours around the trough, southwesterly upperlevel winds occur ahead of the storm, becoming

westerly as the storm trough passes, and northwesterly following the trough. The upper-level

trough usually trails the surface low center in

most moving fronts, causing smoke trajectories

aloft to change directions sometime after trajectories at the surface have changed following a

storm passage.

Thunderstorms, which are the result of strong

convection, create much different wind patterns
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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than cyclonic storms. Gusty, shifty winds are

common at times of strong convection. Strong

down bursts of wind in a direction away from

the thunder cell may occur several minutes

ahead the storm, while winds around the cell

may be oriented towards it. Although mixing

heights usually are quite high during thunderstorms, allowing for well-lofted plumes, the

shifting wind directions and strong gusts can

cause variable and unpredictable smoke trajectories and fire behavior in close proximity to

thunderstorms.

Diurnal Winds – In the absence of storms,

diurnal wind patterns dominate trajectories of

smoke near the ground. Diurnal patterns are

caused by differences between radiational

cooling at night and solar heating during the

day, and by different thermal properties of land

and sea surfaces that cause them to heat and

cool at different rates. The differential heating

causes changes in surface pressure patterns that

control air movement. Slope winds and sea and

lake breezes, all of which are common in wildland smoke management situations, typify

diurnal patterns.

Slope winds are caused by the same mechanisms that cause valley and basin inversions.

When cold air from radiation cooling at night

drains into a valley or basin, it causes a

downslope wind. The cold air, being denser

Figure 7.9. Schematic of upper-level (700 mb) winds associated with a typical stormy trough pattern in the

Northern Hemisphere. Thin lines represent pressure height contours that are labeled in tens of meters. South

to southwest upper-level winds are common ahead of a 700 mb trough, westerly winds are common as the

trough passes, and northwesterly winds are common following an upper-level trough.
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2001 Smoke Management Guide 7.0 – Meteorology

than its surroundings, usually hugs the terrain in

such a way that smoke following a drainage

wind will follow contours of the terrain. During

the day, heated air from the surface rises, causing upslope winds. Because daytime heating

causes more turbulence than nighttime cooling,

the daytime winds do not follow terrain as

readily as nighttime winds, causing thermallyinduced upslope winds to be less noticeable than

downslope winds.

Downslope winds at night are notorious for

carrying smoke into towns and across roadways

(e.g., Achtemeier et al. 1988), especially where

roads and bridges cross stream channels or

when towns are located in valleys, basins, or

near outwash plains. Downslope winds are

most likely to occur when skies are clear and

ambient winds are nearly calm. The speed and

duration of a downslope wind is related to the

strength of its associated valley inversion.

Downslope winds usually begin around sunset

and persist until shortly before sunrise.

Sea and lake breezes usually occur during the

afternoon when land surfaces have had a chance

to heat sufficiently. The heated air rises, as if

lifting the overlying column of air. This causes

a region of low pressure at the surface. Because

land heats more rapidly than water, the differential heating causes a pressure gradient to form.

Relatively cool air remaining over a lake or

ocean will flow into the low pressure formed

over heated land surfaces. The sea or lake

breeze not only can change smoke trajectories

but the incoming cool air can cause surface

based inversions that will trap smoke at low

levels near the ground. Also, strong sea breezes

can knock plumes down, causing increasing

smoke concentrations near the ground.

Terrain-Influenced Wind – Surface winds are

strongly influenced by small undulations in

terrain that channel, block, or accelerate air as it

tries to move around or over features. For

example, if upper-level winds are oriented

perpendicular to a terrain barrier, surface winds

on the lee side of the barrier often are light and

variable. Upper-level winds oriented in the

same direction as a valley will enhance upvalley

or downvalley winds. Cross-valley winds will

be 90° different than those in the valley itself.

The combination of wind and atmospheric

stability determine whether smoke will collect

on the windward side of a terrain barrier, move

up, over and away, or traverse the barrier only to

accumulate on the leeward side. Weak winds

and a stable atmosphere will enhance blocking

and windward accumulations of smoke. Stronger winds in a stable atmosphere may allow

accumulations of smoke in leeward valleys and

basins. An unstable atmosphere allows smoke

to be lifted over and above the terrain. The

height, steepness, and orientation of the terrain

to the wind direction determine how strong the

wind or unstable the atmosphere must be to

influence smoke trajectories.

Often very small-scale undulations in topography can affect smoke trajectories, especially at

night when atmospheric stability keeps smoke

close to the ground. Gentle saddles in ridges

may offer outflow of smoke from a valley.

Small streambeds can collect and transport

significant amounts of smoke even with only

shallow or weak downslope winds. A simple

band of trees or brush may provide enough

barrier to block or deflect smoke. As the urbanwildland interface becomes increasingly complex, the role of subtle topographic influences

becomes increasingly important.

Higher in the atmosphere, away from the earth’s

surface, topography plays a decreasing role in

controlling wind speed and direction. Upperlevel winds above the influence of underlying

terrain are referred to as “free-air” winds and

tend to change slowly from one place to another,

except around fronts and thunderstorms.
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The Role of Inversions on Wind – Temperature inversions significantly influence wind

direction and speed. Under many inversions

there is little or no transport wind and smoke

tends to smear out in all directions. Some

inversions, such as advected inversions that are

associated with sea breezes and valley inversions, may have significant surface wind but it

usually is in a different direction to winds aloft.

In these cases, surface smoke may be transported rapidly under the inversion in one direction while lofted smoke may be transported in

an opposite direction.

Wind Observations – Because surface winds

are strongly influenced by small undulations in

terrain, vegetation cover, and proximity to

obstacles and water bodies, it is important to

know where a surface wind observation is taken

in relation to the burn site. For example, observations from a bare slope near the ridgeline will

give a poor indication of winds affecting surface

smoke trajectories if most of the burn area is on

a forested slope or in a valley, even if the two

sites are very close. Also, if a burn site is in an

east-west oriented valley and the nearest observation is in a north-south oriented valley, observed winds can be 90° different from those

influencing the fire and its related smoke.

Sometimes, a nearby Remote Automated

Weather Station (RAWS) will be less representative of burn-site conditions than one that is

farther away if the distant station is in a location

that better matches terrain effects expected at

the burn site.

There are four principle sources of surface wind

data: (1) on-site measurements with a portable

RAWS or hand-held anemometer, (2) observations that estimate winds using the Beaufort

wind scale3

 or wind sock,4 (3) local measurements with a standard RAWS, and (4) measurements from NWS observing stations. Because

stations vary in their surroundings, from small

clearings on forested slopes to open fields, and

different types of anemometers are used that are

mounted at different heights, wind data is very

difficult to compare between one site and

another. Therefore, it is useful to become

familiar with measurements and observations

from reliable sites and understand local effects

that make data from that site unique. Also,

smoke near the ground can be transported by

winds that are too light to spin the cups or

propeller of an anemometer or turn its tail.

Frequently light and variable wind measurements actually are responding to very light

winds that have a preferred direction, often

influenced by surrounding topography or land

use.

Because free-air winds are above the influence

of topography, often it is possible to use an

upper-level observation from some point well

away from the burn site to estimate upper-level

smoke trajectories. Also, surface RAWS that

are mounted on the tops of ridges or mountains

may compare well with free-air winds at a

similar elevation. If clouds are in the area,

upper-level winds can be estimated by their

movement relative to the ground. High clouds

look fibrous or bright white. Because the base

of high clouds ranges between 5 km and 13 km

(about 16,000 to 45,000 feet) their movement

can indicate wind at those high levels. Midlevel clouds may have shades of gray or bulbous

edges with bases ranging from 2 km to 7 km

(about 6,6000 to 24,000 feet). Mid-level clouds

often have a strata-form or layered appearance,

which may indicate the presence of an inversion.

3 The Beaufort wind scale estimates wind speed using observations of wind-effects in the landscape. For example,

wind speeds of 1.6 to 3.3 m/s (4 to 7 mph) will cause leaves to rustle slightly. If leaves move around vigorously then the

wind speed is approximately 3.4 to 5.4 m/s (8 to 12 mph). 4 Wind socks continue to be used at airports and are useful if trying to monitor winds on a nearby ridge that is

visible.
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2001 Smoke Management Guide 7.0 – Meteorology

Therefore, movement of these types of clouds

may closely approximate steering winds for a

rising smoke plume.

In addition to observations, it is becoming

increasingly common to have available the

output from wind models. These data do not

provide the detail of a point observation the way

an individual site measurement does, but they do

provide a broad view of wind patterns over the

landscape. Standard analyses from the NWS

use models to interpolate between observations.

These products help illustrate upper-level wind

patterns and typically are available for 850 mb,

700 mb, and 500 mb heights, either from a state,

federal, or private meteorological service, or a

variety of Internet sites. For surface winds,

standard NWS analyses are helpful in regions of

flat or gently rolling terrain but mesoscale

meteorological models typically are needed to

resolve surface wind fields in regions of complex topography. Several regions throughout the

country are beginning to employ mesoscale

models (e.g., MM5, RAMS, and MASS)

producing wind maps with less than 15 km

horizontal spacing. Local universities, research

labs, state offices, and consortia of local, state,

and federal agencies have undertaken mesoscale

modeling efforts. Output usually can be found

on a local Internet site through the NWS forecast office, a fire weather office, university, state

regulator, EPA office, or regional smoke manager. Also, many smoke dispersion models

have built-in wind models to generate surface

winds at very fine spatial resolutions (less than 5

km grid spacings) from inputs of surface and

upper-air observations or data from coarser

meteorological models. Smoke dispersion

models and their related wind models may be

available through a regional smoke manager or

EPA office (see Chapter 9—Smoke Dispersion

Prediction Systems).

Atmospheric Moisture

Because water vapor in the atmosphere reduces

visibility, if smoke is added to an already humid

environment, visibility can be severely degraded. Also, if the air is saturated with water

vapor, particles from smoke may act as condensation nuclei causing water droplets to form.

This promotes the formation of clouds or fog,

which further degrades visibility. Often a

deadly combination occurs during the darkness

of night as smoldering smoke drains downvalley to encounter high humidities from condensing cold air under a valley inversion. The

effect can be fatal, especially along transportation corridors (Achtemeier and others 1998).

Favorable conditions for fog occur when the

dew point temperature is within a few degrees of

the dry bulb temperature, wind is less than a few

meters per second, and there is a high content of

moisture in the soil. Fog is most common at

night when temperatures often drop to near the

dew point value and winds are most likely to be

weak. Common places for fog to form are over

lakes and streams and in the vicinity of bogs and

marshes.

There are times when atmospheric moisture can

improve visibility, however. Smoke particles

can adhere to rain droplets, causing them to be

carried with the rain as it falls. This “scavenging” effect removes smoke particles out of the

atmosphere, reducing smoke concentrations and

improving visibility.

Weather Forecasts

Weather forecasts typically are produced twice

each day and become available within 3 to 6

hours after 0000 UTC and 1200 UTC observations are complete. This is because prognostic
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

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models require input data from the 0000 UTC

and 1200 UTC upper-air observations and a few

hours of run-time on a super computer. Prognostic models (progs) form the basis of most

forecast products. For example, the first forecast of the day should be available by 7 am to 10

am local daylight time from Anchorage and by

10 am to 1 pm local standard time from Miami.

Earlier forecasts or forecasts updated throughout

the day are possible if the most recently available upper-air observations and prognostic

model outputs are combined with updated

surface observations. While public forecasts

issued by the NWS and the media are useful,

they typically lack the detail needed for smoke

management. For this reason, spot-weather

forecasts may be requested from state, federal,

or private weather services that provide predictions of critical variables that influence smoke at

specified times and locations.

Even though there are increasing numbers of

numerical guidance tools, weather forecasting

still is an art, especially in places with few

observations or where there are complex local

interactions with terrain, water bodies, and

vegetation cover. The primary source of smoke

weather forecasts remains the National Weather

Service. Their rigorous training, fire weather

program, and state-of-the art equipment and

analysis tools help maintain a unique expertise.

Most NWS fire weather forecast offices now

issue special dispersion and transport forecasts.

In addition to NWS forecasters, many states

maintain a smoke management program with

highly skilled meteorologists. Also, the number

of inter-agency fire weather offices and private

meteorological services is growing and can

provide reliable forecast products specifically

designed for smoke management. Whatever the

source of a forecast, it is helpful to combine the

forecast with your own general understanding of

weather conditions by reviewing the many

satellite pictures, current observation summaries, and prognostic model output products now

available on the World Wide Web. In this way,

apparent trends and local influences can be

determined and the need for last minute changes

can be recognized more quickly. For example,

increasing afternoon cloudiness in the forecast

may have indicated an approaching storm that

was predicted for the following morning. If

clouds do not increase when predicted, however,

it could be suspected that the storm has been

delayed or it was diverted elsewhere. A check

with the forecaster or updated satellite picture

may confirm the suspicion and the management

plan may be altered.

Because the atmosphere behaves chaotically, the

accuracy of a weather forecast improves as time

to an event shortens. For example, it is possible

to provide an indication of storminess within 30

to 90 days. A storm passage, however, may not

be predicted until about 14 days in advance with

about 2 days accuracy. Within 5 days, 1-day

accuracy on storm passage may be possible.

Increasing accuracy should be expected within

48 hours and the timing of storm passage within

1/2 hour may be possible with 12 hours advance

notice. Spot weather forecasts usually are

available 24 to 48 hours in advance of a scheduled burn. This allows a smoke manager to

anticipate a potential burning window well in

advance. Specific timing, however, should not

be made before 2 days in advance if the situation is highly dependent on an accurate weather

forecast.

Our increasing knowledge of air-sea interactions

is making it possible to predict some aspects of

weather up to a year in advance as certain

regions of the country respond to the El Niño

Southern Oscillation (ENSO). Precipitation and

temperature during winter and spring are most

strongly related to ENSO. Relating key factors

for smoke management such as wind and mixing height or stability is more difficult, espe-
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2001 Smoke Management Guide 7.0 – Meteorology

cially during summer. Nevertheless, an ENSObased seasonal prediction gives prescribed

burners an idea of general weather conditions to

be expected, thereby helping prioritize scheduled burns and decide if marginal days or

weekends early in the burning season should be

used or whether a more optimum season will

ensue.

Climate

Climate simply describes the prevailing weather

of an area. Understanding climate patterns can

help develop long-range smoke management

plans or adapt short-range plans. For example,

afternoon mixing heights in most coastal regions

of the United States are typically lower than the

interior because moist, marine air is relatively

stable. This means that there may be fewer days

with optimum dispersion along the coast than

interior. It usually is windier along the coast,

however, and burns might be scheduled in the

early morning if offshore breezes are desired to

reduce smoke impacts on cities and towns.

It is possible to infer climate just by local

proximity to oceans, lakes, rivers, and mountains. Also, vegetation cover can give an indication of climate. Desert landscapes, with a lot of

bare soil or sand, heat and cool rapidly, causing

them typically to have high daytime mixing

heights and very low nighttime mixing heights.

Natural landscapes of lush green forests tend to

absorb sunlight while transpiring moisture, both

of which help to modify heating and cooling of

the ground surface. This can reduce daytime

mixing heights and keep nighttime heights

relatively high, with respect to deserts. Also, the

structural deformation of trees often indicates

high winds, where the direction of branches or

flagging point away from prevailing wind

directions.

Quantitative summaries of climate can be

obtained from the state climatologist or Regional Climate Center (RCC), many of whom

also maintain informative Internet sites and can

be reached through the National Climatic Data

Center (NCDC) <www.ncdc.noaa.gov>. It is

most common to find temperature and precipitation in climate summaries. Monthly or annual

averages or extremes are readily available while

climate summaries of daily data are just beginning to emerge. For example, a recently generated climate database by Ferguson and others

(2001) provides information on twice-daily

variations in surface wind, mixing height, and

ventilation index over a 30-year period.

We know that there are year-to-year variations

in climate (e.g., ENSO) so at least 10 years of

weather data are needed to obtain a preliminary

view of climate in a particular area. There also

are natural, “decadal” patterns in climate that

last from 7 to 20 years. Therefore, it is appropriate to acquire 30 to 50 years of weather

observation data for any reliable climate summary.

Summary

Managing smoke in ways that prevent serious

impact to sensitive areas from single burns or

multiple burns occurring simultaneously requires knowledge of the weather conditions that

will affect smoke emissions, trajectories, and

dispersion. Not only is it necessary to anticipate

the weather ahead of time through the use of

climatology and forecasts, but it also is useful to

monitor conditions prior to and during the burn

with regional, local, and on-site observations.

On-site observations are helpful because air

movement, and therefore smoke movement, is

influenced by small variations in terrain and

vegetation cover, and proximity to lakes and
Chapter 7 – Smoke Management Meteorology 2001 Smoke Management Guide

– 138 –

oceans, which off-site observations usually

cannot capture. Also, forecasts are not always

accurate and last-minute changes in a burn or

smoke management plan may be needed. To

gain more insight into the physical process of

weather in wildland areas and its effect on

biomass fires, refer to the Fire Weather handbook (Schroeder and Buck 1970).

In using weather observations, forecasts, and

climate summaries effectively for smoke management there are 3 general guidelines; (1)

become familiar with local terrain features that

influence weather patterns, (2) develop a dialogue with a reliable local weather forecaster,

and (3) ask for and use climate summaries of

wind and mixing height. By combining your

knowledge of local weather effects, trust and

communication with an experienced forecaster,

and understanding of climate patterns, it is

possible to fine-tune or update forecasts to meet

your specific smoke management needs.

Literature Citations

Achtemeier, G.L., W. Jackson, B. Hawkins, D.D.

Wade, and C. McMahon. 1998. The smoke

dilemma: a head-on collision! Transactions of

the 63rd North American Wildlife and Natural

Resource Conference. 20-24 March 1998.

Orlando FL. 415-421.

Ferguson, S.A.; S. McKay; D. Nagel; T. Piepho;

M.L. Rorig; and C. Anderson. 2001. The

potential for smoke to ventilate from wildland

fires in the United States. In Proceedings of the

4th Symposium on Fire and Forest Meteorology, 13-15 November 2001, Reno, Nevada. p.

115.

Gifford, F. A. 1962. Use of routine meteorological

observations for estimating atmospheric dispersion. Nuclear Safety. 2(4):47-51.

Holzworth, George C. 1972. Mixing heights, wind

speeds and potential for urban air pollution

throughout the contiguous united states. Environmental Protection Agency, Office of Air

Programs Publication NO. AP-101. Research

Triangle Park, NC 27711. 118 p.

Lavdas, L.G. 1986. An Atmospheric Dispersion

Index for Prescribed Burning. U.S. Department

of Agriculture, Forest Service, Southeastern

Forest Experiment Station. Research Paper

SE-256. 35 pp.

Lavdas, L.G. 1997. Estimating Stability Class in

the Field. U.S. Department of Agriculture,

Forest Service, Southeastern Forest Experiment

Station. Research Note SRS-4.

Pasquill, F. 1961. The estimation of the dispersion

of windborne material. Meteorological Magazine. 90:33-49.

Pasquill, F. 1974. Atmospheric Diffusion: The

Dispersion of Windborne Material from Industrial and Other Sources. 2nd Edition. John

Wiley and Sons, New York. 429 pp.

Schroeder, M.J. and C.C. Buck. 1970. Fire

Weather: A guide for application of meteorological information to forest fire control operations. U.S. Department of Agriculture, Forest

Service, Agriculture Handbook 360. 229 pp.

Turner, D.B. 1961. Relationship between 24-hr.

Mean air quality measurement and meteorological factors in Nashville, TN. Journal of Air

Pollution Control Association. 11:483-489.

Turner, D.B. 1964. A diffusion model for an urban

area. Journal of Applied Meteorology. 3:83-

91.

Turner, D.B. 1970. Workbook of Atmospheric

Dispersion Estimates. Office of Air Programs

Pub. No. AP-26, U.S. Environmental Protection

Agency, Research Triangle Park, NC.
– 139 –

2001 Smoke Management Guide 8.0 – Smoke Management Techniques

SMOKE MANAGEMENT TECHNIQUES

Chapter 8
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

– 140 –
– 141 –

2001 Smoke Management Guide 8.0 – Smoke Management Techniques

Smoke Management: Techniques

to Reduce or Redistribute Emissions

Roger D. Ottmar

Janice L. Peterson

Bill Leenhouts

John E. Core

Introduction

A land manager’s decision to use a specific

burning technique is influenced by many considerations, only one of which is a goal to

reduce smoke emissions. Other important

considerations include ensuring public and

firefighter safety, maintaining control of the fire

and keeping it within a given perimeter, complying with numerous environmental regulations,

minimizing nuisance and hazard smoke, minimizing operational costs, and maximizing the

likelihood of achieving the land management

objective of the burn. Often these other considerations preclude the use of techniques that

reduce emissions. In some cases, however,

smoke emission reductions are of great importance and are achieved by compromising other

goals. Emission reduction techniques vary

widely in their applicability and effectiveness by

vegetation type, burning objective, region of the

country, and whether fuels are natural or activity-generated.

Emission reduction techniques (or best available

control measures–BACM) are not without

potential negatives and must be prescribed and

used with careful professional judgment and full

awareness of possible tradeoffs. Fire behavior is

directly related to both fire effects and fire

emissions. Emission reduction techniques alter

fire behavior and fire effects and can impair or

prevent accomplishment of land management

objectives. In addition, emission reduction

techniques do not necessarily reduce smoke

impacts and some may, under certain circumstances, actually increase the likelihood that

smoke will impact the public. Emission reduction techniques can cause negative effects on

other valuable resources such as through soil

compaction, loss of nutrients, impaired water

quality, and increased tree mortality; or they

may be dangerous or expensive to implement.

Land managers are concerned about the repeated

application of any resource treatment technique

that does not replicate the ecological role that

fire plays in the environment. Such applications

may result in unintended resource damage,

which may only be known far in the future.

Some examples of resource damage that could

occur from the use of emission reduction techniques include the loss of nutrients to the soil if

too much woody debris is removed from the
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

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site, or the effects of soil compaction associated

with mechanical processing (chipping, shredding, or yarding) of fuels. The application of

herbicides and other chemicals and/or the

effects on soils of the intense heat achieved

during mass ignition are also of concern. These

issues are difficult to quantify but are of universal importance to land managers, who must

weigh the impact of their decisions on long-term

ecosystem productivity.

Multiple resource values must be weighted

along with air quality benefits before emission

reduction techniques are prescribed. Flexibility

is key to appropriate application of emission

reduction techniques and use of particular

techniques should be decided on a case-by-case

basis. Emission reduction goals may be targeted

but the appropriate mix of emission reduction

techniques to achieve those goals will require a

careful analysis of the short and long term

ecological and social costs and benefits. Air

quality managers and land managers should

work together to better understand the effectiveness, options, difficulties, applicability, and

tradeoffs of emission reduction techniques.

There are two general approaches to managing

the effects of wildland fire smoke on air quality:

1. Use techniques that reduce the emissions

produced for a given area treated.

2. Redistribute the emissions through meteorological scheduling and by sharing the

airshed.

Although each method can be discussed independently, fire practitioners often choose lighting and fuels manipulation techniques that

complement, or are consistent with, meteorological scheduling for maximum smoke dispersion and favorable plume transport.

Meteorological scheduling is often the most

effective way to prevent direct smoke impacts to

the public and some emission reduction techniques may actually increase the likelihood of

smoke impacts by decreasing the energy in the

plume resulting in more smoke close to the

ground. A few of the potential negative consequences of specific emission reduction techniques are mentioned in this chapter although

this topic is not addressed comprehensively.

Use of Smoke

Management Techniques

Much of the information presented in this

chapter was gathered from fire practitioners at

three national workshops held during the fall of

1999. Practitioners were asked to describe how

(or if) they apply emission reduction techniques

in the field, how frequently these methods are

used, how effective they are, and what constraints limit their wider use. The information

gained at each of the workshops was then

synthesized into a draft report that was distributed to the participants for further review and

comment. Twenty-nine emission reduction and

emission redistribution methods within seven

major classifications were identified as currently

in use to reduce emissions and impacts from

prescribed burning.

The emission reduction methods described in

this document may be used independently or in

combination with other methods on any given

burn. In addition, a number of different firing

methods potentially can be applied to any given

parcel of land depending on the objectives and

judgments made by the fire manager. As a

result, no two burns are the same in terms of

pollutant emissions, smoke impacts, fuel consumption, or other parameters.
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

Significant changes in public land management

have occurred since EPA’s release of the first

document describing best available control

measures (BACM) for prescribed burning (EPA

1992). Some of these changes have dramatically impacted when and how emission reduction methods for prescribed fire can be applied.

On federally managed lands, the following

constraints apply to many of the emission

reduction techniques: National Environmental

Policy Act (NEPA), Threatened and Endangered

Species (T&E) considerations, water quality and

impacts on riparian areas, administrative constraints imposed by Congress (eg, roadless and

wilderness area designations), impacts on

archaeological resources, smoke management

program requirements, and other state environmental or forestry regulations.

The following emission reduction and emission

redistribution techniques are a comprehensive

compilation of the current state of the knowledge. Any one of these may or may not be

applicable in a given situation depending upon

specifics of the fire use objectives, project

locations, time and cost constraints, weather and

fuel conditions, and public and firefighter safety

considerations.

Reducing the Amount

of Emissions

Emissions from wildland fire are complex and

contain many pollutants and toxic compounds.

Emission factors for over 25 compounds have

been identified and described in the literature

(Ward and Hardy 1991; Ward and others 1993).

A simplifying finding from this research is that

all pollutants except nitrous oxide (NOx) are

negatively correlated with combustion efficiency, so actions that reduce one pollutant

results in the reduction of all (expect NOx).

Nitrous oxide and CO2

 (not considered a pollutant) can increase if the emission reduction

technique increases combustion efficiency.

Emission reduction techniques may reduce

emissions from a given prescribed burn area by

as much as about 60 percent to as little as

virtually zero1. Considering all burning nationally, if emission reduction techniques were

optimally used, emissions could probably be

reduced by approximately 20-25 percent assuming all other factors (vegetation types, acres,

etc.) were held constant and land management

goals were still met1

. Individual states or regions may be able to achieve greater emission

reductions than this or much less depending on

the state’s or region’s biological decomposition

capability or ability to utilize available biomass.

In the context of air quality regulatory programs, current or future emissions are typically

measured against those that occurred during a

baseline period (annual, 24-hour, and seasonal)

to determine if reductions have or will occur in

the future. Within this framework, land managers need to know their baseline emissions to

determine the degree of emission reduction that

a method described here will provide in order to

conform to a State Implementation Plan, State

Smoke Management Program, or local nuisance

standards.

Because of all these variables, wildland fire

emission models such as the First Order Fire

Effects Model (FOFEM) (Reinhardt and others

1997), Consume 2.1 (Ottmar and others [in

___________________________________

1 Peterson, J. and B. Leenhouts. 1997. What wildland fire conditions minimize emissions and hazardous air pollutants and can land management goals still be met? An unpublished technical support document to the EPA Interim Air

Quality Policy on Wildland and Prescribed Fires. August 15, 1997. (Available from the authors or online at http://

www.epa.gov/ttncaaa1/faca/pbdirs/emissi.pdf
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

– 144 –

preparation]), and Emissions Production Model

(EPM) (Sandberg and Peterson 1984) can be

used to estimate particulate, gaseous and hazardous pollutant emissions based on the specifics of each burn. There are seven general

categories that encompass all of the techniques

described in this document. Each is described

below.

1. Reduce the Area Burned

Perhaps the most obvious method to reduce

wildland fire emissions is to reduce the area

burned. Area burned can be reduced by not

burning at all or by burning a subset of the area

within a designated perimeter. Caution must be

applied though, and programs to reduce the area

burned must not ultimately result in just a delay

in the release of emissions either through prescribed burning at a later date or as the result of

a wildland fire. Reducing the area burned

should be accomplished by methods that truly

result in reduced emissions over time rather than

a deferral of emissions to some future date.

This technique can have detrimental effects on

ecosystem function in fire-adapted vegetation

community types and is least applicable when

fire is needed for ecosystem or habitat management, or forest health enhancement. In some

areas and some vegetation types, when fire is

used to eliminate an undesirable species or

dispose of biomass waste, alternative methods

can be used to accomplish effects similar to

what burning would accomplish. Examples of

specific techniques include:

• Burn Concentrations. Sometimes concentrations of fuels can be burned rather

than using fire on 100 percent of an area

requiring treatment. The fuel loading of

the areas burned using this technique tend

to be high. The total area burned under

these circumstances can be very difficult

to quantify.

• Isolate fuels. Large logs, snags, deep

pockets of duff, sawdust piles, squirrel

middens, or other fuel concentrations that

have the potential to smolder for long

periods of time can be isolated from

burning. This can be accomplished by

several techniques including: 1) constructing a fireline around the fuels of concern;

2) not lighting individual or concentrated

fuels; 3) using natural barriers or snow; 4)

scattering the fuels; and 5) spraying with

foam or other fire retardant material.

Eliminating these fuels from burning is

often faster, safer, and less costly than

mop-up, and allows targeted fuels to

remain following the prescribed burn.

• Mosaic burning. Landscapes often

contain a variety of fuel types that are noncontinuous and vary in fuel moisture

content. Prescribed fire prescriptions and

lighting patterns can be assigned to use

this fuel and fuel moisture non-homogeneity to mimic a natural wildfire and create

patches of burned and non-burned areas or

burn only selected fuels. Areas or fuels

that do not burn do not contribute to

emissions. For example, an area may be

continuously ignited during a prescribed

fire but because the fuels are not continuous, patches within the unit perimeter may

not ignite and burn (figure 8.1). Depressional wetlands, swamps, and hardwood

stringers can be excluded by burning when

soil moisture is abundant. Furthermore, if

the burn prescription calls for low humidity and high live fuel moisture, continuous

burning in the dead fuels may occur while

the live fuels exceed the moisture of

extinction. In both cases, the unburned

live fuels may be available for future

burning in a prescribed or wildland fire

during droughts or dormant seasons.
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

2. Reduce Fuel Load.

Some or all of the fuel can be permanently

removed from the site, biologically decomposed, and/or prevented from being produced.

Overall emissions can be reduced when fuel is

permanently excluded from burning.

• Mechanical removal. Mechanically

removing fuels from a site reduces emissions proportionally to the amount of fuel

removed. This is a broad category and can

include such techniques as mechanical

removal of logging debris from clearcuts,

onsite chipping of woody material and/or

brush for offsite utilization, and mechanical removal of fuels which may or may not

be followed by offsite burning in a more

controlled environment. Sometimes

mechanical treatments (such as whole-tree

harvesting or yarding of unmerchantable

material [YUM]) may result in sufficient

treatment so that burning is not needed.

Mechanical treatments are applicable on

lands where this activity is allowable (i.e.,

non-wilderness, etc.), supported by an

access road network, and where there is an

economic market for disposal of the

removed fuel. This technique is most

effective in forest fuel types and has some

limited applicability in shrub and grass

fuel types. A portion of the emission

reduction gains from this technique may

be offset by increased fossil fuel and

particulate emissions from equipment used

for harvest, transportation, and disposal

operations. Mechanical treatments may

cause undue soil disturbance or compaction, stimulate alien plant invasion, remove

natural nutrient sources, or impair water

quality.

• Mechanical processing. Mechanical

processing of dead and live vegetation into

wood chips or shredded biomass is effective in reducing emissions if the material is

removed from the site or biologically

decomposed (figure 8.2). If the biomass is

spread across the ground as additional

litter fuels, emission reductions are not

achieved if the litter is consumed either in

a prescribed or wildland fire. Use of this

technique may eliminate the need to burn.

• Firewood sales. Firewood sales may

result in sufficient removal of woody

debris making onsite burning unnecessary.

This technique is particularly effective for

piled material where the public has easy

access. This technique is generally applicable in forest types with large diameter,

woody biomass. The emissions from

wildland fuels when burned for residential

heating are not assessed as wildland fire

emissions but as residential heating emissions. The impact of these emissions on

the human environment is not attributed to

wildland fire in the national or state

emissions inventories.

• Biomass for electrical generation.

Woody biomass can also be removed and

used to provide electricity in regions with

cogeneration facilities. Combustion

efficiency in electricity production is

greater than open burning and emissions

from biomass fuel used offset fossil fuel

emissions. Although this method of

reducing fuel loading is cost-effective

where there is a market for wood chips,

there are significant administrative, logistical, and legal barriers that limit its use.

• Biomass utilization. Woody material can

be used for many miscellaneous purposes

including pulp for paper, methanol production, wood pellets, garden bedding, and

specialty forest products. Demand for

these products varies widely from place to
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

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Figure 8.1. Mosaic burning creates patches of burned and unburned areas

resulting in reduced emissions.

Figure 8.2. Mechanical processing of biomass.
– 147 –

2001 Smoke Management Guide 8.0 – Smoke Management Techniques

place and year to year. Biomass utilization

is most applicable in forest and shrub

types that include large diameter woody

biomass and where fuel density and

accessibility makes biomass utilization

economically viable.

• Ungulates. Grazing and browsing live

grassy or brushy fuels by sheep, cattle, or

goats can reduce fuels prior to burning or

reduce the burn frequency. Goats will

sometimes consume even small, dead

woody biomass. However, ungulates are

selective, favoring some plants over others.

The cumulative effect of this selectivity

can significantly change plant species

composition and long-term ecological

processes on an area, eventually converting grass dominated areas to brush. On

moderate to steep slopes, high populations

of ungulates contribute to increased soil

erosion.

3. Reduce Fuel Production.

Management techniques can be used to shift

species composition to vegetation types that

produce less biomass per acre per year, or

produce biomass that is less likely to burn or

burns more efficiently with less smoke.

• Chemical treatments. Broad spectrum

and selective herbicides can be used to

reduce or remove live vegetation, or alter

species diversity respectively. This often

reduces or eliminates the need to use fire.

Chemical production and application have

their own emissions, environmental, and

public relations problems. A NEPA

(National Environmental Policy Act)

analysis is generally required prior to any

chemical use on public lands and states

often require similar analyses prior to

chemical use on state or private lands.

• Site conversion. Natural site productivity

can be decreased by changing the vegetation composition. For example, frequent

ground fires in southern pine forests will

convert an understory of flammable shrubs

(such as palmetto and gallberry) to open

woodlands with less total fuel but also

with more grass and herbs. Grass and

herbs tend to burn cleaner than shrubs.

Total fuel loading can also be reduced

through conversion to species that are less

productive.

• Land use change. Changing wildlands to

another land use category may result in

elimination of the need to burn. Conversion of a wildland site to agriculture or an

urbanized use significantly alters the

ecological structure and function and

presents numerous legal and philisophical

issues. This alternative is probably not an

option on Federally managed lands.

4. Reduce Fuel Consumed.

Emission reductions can be achieved when

significant amounts of fuel are at or above the

moisture of extinction, and therefore unavailable

for combustion. Burning when fuels are wet

may leave significant amounts of fuel in the

treated area only to be burned in the future.

This may not result in a real reduction in emissions then, but rather a delay of emissions to a

later date. Real emission reductions are

achieved only if the fuels left behind will biologically decompose or be otherwise sequestered at a time of subsequent burning. Even

though wet fuels burn less efficiently

and produce greater emissions relative to the

amount of fuel consumed, emissions from a

given event are significantly reduced because so

much less fuel is consumed.
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

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In the appropriate fuel types, the ability to target

and burn only the fuels necessary to meet

management objectives is one of the most

effective methods of reducing emissions. When

the objective of burning is to reduce wildfire

hazard, removal of fine and intermediate diameter fuels may be sufficient. The opportunity to

limit large fuel and organic layer consumption

can significantly reduce emissions.

• High moisture in large woody fuels.

Burning when large-diameter woody fuels

(3+ inches in diameter or greater) are wet

can result in lower fuel consumption and

less smoldering. When large fuels are wet

they will not sustain combustion on their

own and are extinguished by their own

internal moisture once the small twigs and

branch-wood in the area finish burning

(figure 8.3). The large logs therefore

consume less in total, they do not smolder

as much, and they do not cause as much of

the organic layer on the forest floor to

burn. This can be a very effective technique for reducing total emissions from a

prescribed burn area and can have secondary benefits by leaving more large-woody

debris in place for nutrient cycling. This

technique can be effective in natural and

activity fuels in forest types. When large

fuel consumption is needed, burning under

high moisture conditions is not a viable

alternative.

• Moist litter and/or duff. The organic

layer that forms from decayed and partially decayed material on the forest floor

often burns during the inefficient smoldering phase. Consequently, reducing the

consumption of this material can be very

effective at reducing emissions. Consumption of this litter and/or duff layer can

be greatly reduced if the material is quite

moist. The surface fuels can be burned

and the organic layer left virtually intact.

The appropriate conditions for use of this

technique generally occurs within a few

days of a soaking rain or shortly after

snowmelt. This technique is most effective in non-fire adapted forest and brush

types. This technique may not be appropriate in areas where removal of the

organic layer is desired. Burning litter

and/or duff to expose mineral soil is often

necessary in fire adapted ecosystems for

plant regeneration.

• Burn before precipitation. Scheduling a

prescribed fire before a precipitation event

will often limit the consumption of large

woody material, snags, stumps, and organic ground matter, thus reducing the

potential for a long smoldering period and

reducing the fire average emission factor.

Sucessful application of this procedure

depends on accurate meteorological

forecasts for the area.

Figure 8.3. Burning when large fuel moisture is high

can result in less total fuel consumption.
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

• Burn before large fuels cure. Living

trees contain very high internal fuel moistures, which take a number of months to

dry after harvest. If an area can be burned

within 3-4 drying months of timber harvest, many of the large fuels will still

contain a significant amount of live fuel

moisture. This technique is generally

restricted to activity-generated fuels in

forest-types.

5. Schedule Burning Before New Fuels

Appear.

Burning can sometimes be scheduled for times

of the year before new fuels appear. This may

interfere with land management goals if burning

is forced into seasons and moisture conditions

where increased mortality of desirable species

can result.

• Burn before litter fall. When decidous

trees and shrubs drop their leaves this

ground litter contributes extra volume to

the fuel bed. If burning takes place prior

to litter fall there is less available fuel and

therefore less fuel consumed and fewer

emissions.

• Burn before green-up. Burning in cover

types with a grass and/or herbaceous

fuelbed component can produce fewer

emissions if burning takes place before

these fuels green-up for the year. Less fuel

is available therefore fewer emissions are

produced.

6. Increase Combustion Efficiency.

Increasing combustion efficiency, or shifting the

majority of consumption away from the smoldering phase and into the more efficient flaming

phase, reduces emissions.

• Burn piles or windrows. Fuels concentrated into clean and dry piles or windrows

generate greater heat and burn more

efficiently (figure 8.4). A greater amount

of the consumption occurs in the flaming

phase and the emission factor is lower.

This technique is primarily effective in

forest fuel types but may have some

applicability in brush types also. Concentrating fuels into piles or windrows generally requires the use of heavy equipment,

which can negatively impact soils and

water quality. Piles and windrows also

cause temperature extremes in the soils

directly underneath and can result in areas

of soil sterilization. If fuels in piles or

windrows are wet or mixed with dirt,

extended smoldering of the debris can

result in residual smoke problems.

• Backing fires. Flaming combustion is

cleaner than smoldering combustion. A

backing fire takes advantage of this relationship by causing more fuel consumption to take place in the flaming phase than

Figure 8.4. Fuels burned in dry, clean piles burn

more efficiently and generate less emissions
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

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would occur if a heading fire were used

(figure 8.5). In applicable vegetation types

where fuels are continuous and dry, the

flaming front backs more slowly through

the fuelbed and by the time it passes, most

available fuel is consumed so the fire

quickly dies out with very little smoldering. In a heading fire, the flaming front

passes quickly and the ignited fuels continue to smolder until consumed. The

opportunity to use backing fires is not

always an option and often increase

operational costs.

• Dry conditions. Burning under dry

conditions increases combustion efficiency

and less emissions may be produced.

However, dryer conditions makes fuel that

was not available to burn (at or above the

moisture of extinction) available to burn.

The emissions from additional fuel burned

generally more than offsets emission

reduction advantages gained by greater

combustion efficiency. This technique is

effective only if all fuels will consume

under either wet or dry conditions.

• Rapid mop-up. Rapidly extinguishing a

fire can reduce fuel consumption and

smoldering emissions somewhat although

this technique is not particularly effective

at reducing total emissions and can be very

costly (figure 8.6). Rapid mop-up primarily effects smoldering consumption of

large-woody fuels, stumps, snags, and

duff. Rapid mop-up is more effective as

an avoidance technique by reducing

residual emissions that tend to get caught

in drainage flows and end up in smoke

sensitive areas.

• Aerial ignition / mass ignition. “Mass”

ignition can occur through a combination

of dry fine-fuels and very rapid ignition,

which can be achieved through a technique

such as a helitorch (figure 8.7). Mass

ignition can shorten the duration of the

smoldering phase of a fire and reduce the

total amount of fuel consumed. When

properly applied, mass ignition causes

rapid consumption of dry, surface fuels

and creates a very strong plume or convecFigure 8.5. Backing fires in uniform,

noncomplex fuelbeds consume fuels more

efficiently than during a head fire resulting in

fewer emissions.

Figure 8.6. Quickly extinguishing a smoldering

fire is a costly but effective technique for

reducing smoldering emissions and impacts.
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

tion column which draws much of the heat

away from the fuelbed and prevents drying

and preheating of larger, moister fuels.

This strong plume may result in improved

smoke dispersal. The fire dies out shortly

after the fine fuels fully consume and there

is little smoldering or consumption of the

larger fuels and duff. The conditions

necessary to create a true mass ignition

situation include rapid ignition of a large,

open area with continuous, dry fuels (Hall

1991).

• Air Curtain Incinerators. Burning fuels

in a large metal container or pit with the

aid of a powerful fan-like device to force

additional oxygen into the combustion

process results in a very hot and efficient

fire that produces little smoke (figure 8.8).

These devices are commonly used to burn

land clearing, highway right-of-ways, or

demolition debris in areas sensitive to

smoke and may be required by air quality

agency regulations in some areas.

Figure 8.7. Mass ignition can shorten the

duration of the smoldering phase and reduce

total consumption resulting in fewer emissions

Redistributing the

Emissions

Emissions can be spatially and temporally

redistributed by burning during periods of good

atmospheric dispersion (dilution) and when

prevailing winds will transport smoke away

from sensitive areas (avoidance) so that air

quality standards are not violated. Redistribution of emissions does not necessarily reduce

overall emissions.

1. Burn when dispersion is good.

Smoke concentrations can be reduced by diluting the smoke through a greater volume of air,

either by burning during good dispersion conditions when the atmosphere is unstable or burning at slower rates. If burning progresses too

slowly, smoke accumulation due to evening

atmospheric stability can occur.

2. Share the airshed.

Establishing a smoke management program that

links both local and interstate jurisdictions will

create opportunities to share the airshed and

reduce the likelihood of smoke impacts.

Figure 8.8. Air curtain incinerators result in very

hot and efficient fires that produce little smoke.
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

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3. Avoid sensitive areas.

The most obvious way to avoid smoke impacts

is to burn when the wind is blowing away from

all smoke-sensitive areas such as highways,

airports, populated areas, and scenic vistas.

Wind direction must be considered during all

phases of burning. For example, the prevailing

winds during the day time may move the smoke

away from a major highway; however, at night,

drainage winds can carry the smoke toward the

highway.

4. Burn smaller units.

Short term emissions and impacts can be reduced by burning subsets of a large unit over

multiple days. Total emissions are not reduced

if the entire area is eventually burned.

5. Burn more frequently.

Burning more frequently does not allow fuels to

accumulate, thus there are less emissions with

each burn. Frequent, low intensity fires can

prevent unwanted vegetation from becoming

established. If longer fire rotations are used, the

vegetation has time to grow resulting in the

production of extra biomass and extra fuel

loading at the time of burning. This technique

generally has positive effects on land management goals since it results in fire regimes that

more closely mimic the frequency of natural fire

in many ecosystems.

The Use and Effectiveness of

Emission Reduction and

Redistribution Techniques

The overall potential for emission reductions

from prescribed fire depends on the frequency

of use of emission reduction techniques and the

amount of emission reduction that each method

offers. This section provides information on the

overall potential for emission reduction and

redistribution from prescribed fire based on (a)

the frequency of use of each emission reduction

and emission redistribution technique by region

of the country, (b) the relative effectiveness of

each smoke management technique, and (c)

constraints on application of the technique

(administrative, legal, physical, etc.).

Much of the information in this section was

provided by participants in regional workshops

(as described previously). The information

provided can, and should, be improved upon by

local managers who will have better information

about specific, local burning situations.

The use of each smoke management technique

is organized by U.S. region as shown in figure

8.9. They are the Pacific Northwest including

Alaska (PNW), Interior West (INT), Southwest

(SW), Northeast (NE), Midwest (MW), and

Southeast including Hawaii (SE) regions. Each

region has its own vegetation cover types,

climatology, and terrain characteristics, all of

which influence the land manager’s decision to

burn and the appropriateness of various emission reduction techniques.

Manager use of emission reduction techniques is

influenced by numerous factors including land

management objectives, the type and amount of

vegetation being burned, safety considerations,

costs, laws and regulations, geography, etc. The

effect of some of these many influencing factors

can be assessed through general knowledge of

the frequency of use of a particular technique in

a specific region. Table 8.1 provides general

information about frequency of use of each

smoke management technique by region of the

country, grouped as shown in figure 8.9.
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

Figure 8.9. Prescribed burning regions including Pacific Northwest including Alaska (PNW), Intermountain

(INT), Midwest (MW), Southwest (SW), Southeast including Hawaii (SE), and Northeast (NE).

Information in table 8.1 summarizes regional

applicability of each of the twenty-nine smoke

management methods. Interviews with fire

practitioners demonstrate that, on a national

scale, several smoke management techniques

are rarely used. These include biomass for

electrical generation, biomass utilization, site

conversion, land use change, burning before

litter fall, burning under dry conditions, air

curtain incineration, and burning smaller units.

In most of the regions, firewood sales and

chemical treatments are also seldom used. The

methods most commonly applied include aerial

ignition/mass ignition, burning when dispersion

is good, sharing the airshed, and avoiding

sensitive areas.

The general effectiveness of the emission

reduction and redistribution techniques is

described in table 8.2 based on input from

managers at the workshops. Local managers

will have better information about specific

situations and can improve upon the information in the tables. Each technique was assigned

a general rank of “High” for those techniques

most effective at reducing emissions or “Low”

for those techniques that are less effective.

Some emission reduction techniques also have

secondary benefits of delaying or eliminating

the need to use prescribed fire. Some smoke

management techniques, are also effective for

reducing local smoke impacts if they promote

plume rise or decrease the amount of residual
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

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Table 8.1. Frequency of smoke management method use by region. Alaska is included in the Pacific

Northwest (PNW) region, and Hawaii is included in the southeast region (SE)
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

Table 8.2. Relative effectiveness of various smoke management techniques.
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

– 156 –

smoldering combustion where smoke is more

likely to get caught in drainage winds and

carried into populated areas. These factors are

also addressed in table 8.2.

Table 8.3 summarizes significant constraints

identified by fire managers that limit the wider

application of techniques to reduce and redistribute emissions. This table excludes consideration of the objective of the burn, which is

generally the overriding constraint. Some of the

techniques would probably be used more frequently if specific constraints could be overcome.

Smoke management techniques that, in the

opinion of workshop participants, show particular promise for wider use in the future are listed

below:

1. Mosaic Burning: Since this method

reduces the area burned and replicates the

natural role of fire, it is being increasingly

used for forest health restoration burning

on a landscape scale.

2. Mechanical Removal: In areas where

slope and access are not a problem and

fuels have economic value, the wider use

of whole tree yarding, YUM yarding, cutto-length logging practices and other

methods that remove fuel from the unit

prior to burning (if the unit is burned at

all) may have potential for wider application if economic markets for the removed

fuels can be found.

3. High Moisture in Large Woody Fuels,

and/or Moist Litter and Duff: In situations where the objective is not to maximize the consumption of large woody

debris, litter, and/or duff, this option is

favored by fire practitioners as an effective

means of reducing emissions, smoldering

combustion, and smoke impacts.

4. Pile and Windrow Burning: Pile burning, although already widely used in all

regions, is gaining popularity among land

managers because of the flexibility offered

in scheduling burning and the resultant

lower impacts on smoke sensitive locations. Lower impacts may not result if

piles or windrows are wet or mixed with

dirt.

5. Aerial/Mass Ignition: Little clear information currently exists as to the extent to

which aerial ignition achieves true mass

ignition and associated emission reduction

benefits. More effort to achieve true mass

ignition using aerial techniques may yield

significant emission reduction benefits.

6. Burn More Frequently: Fire managers

generally favor more frequent burning

practices to reduce fuel loading on second

and subsequent entry, thereby reducing

emissions over long time periods. This

will increase daily or seasonal emissions.

Estimated Emission Reductions

While the qualitative assessment of emission

reduction technique effectiveness shown in table

8.2 is a useful way to gauge how relatively

successful a particular technique may be in

reducing emissions, it is also useful to model

potential quantitative emission reduction. Table

8.4 summarizes potential emission reductions

that may be achieved by employing various

techniques as estimated by the fuel consumption

and emissions model Consume 2.1 (Ottmar and

others [in preparation]). For example, use of

mosaic burning techniques in natural, mixed

conifer fuels in which one-half of a 200-acre

project is burned is projected to reduce PM2.5

emissions from 14.8 to 7.4 tons for a 50%

reduction in emissions. A 33% reduction in
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

Table 8.3. Constraints to the use of emission reduction and redistribution techniques as reported by regional

workshop participants.
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

– 158 –

Ta

ble 8.4. Approximate emission reduction effectiveness for various emission reduction techniques in certain vegetation types. (Values generated

with Consume 2.1 [Ottmar and others, in preparation]).
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2001 Smoke Management Guide 8.0 – Smoke Management Techniques

PM2.5 emissions can be achieved by pile burning mixed conifer fuels under the conditions

noted in the table. Specific simplifying assumptions were made in each case to produce the

estimates of emission reduction potential seen in

table 8.4. Other models using the same field

assumptions would yield similar trends.

Wildfire Emission Reduction

Little thought has been given to reducing emissions from wildfire, but many fire management

actions do affect emission production from

wildfires because they intentionally reduce

wildfire occurrence, extent, or severity. For

example, fire prevention efforts, aggressive

suppression actions, and fuel treatments (mechanical or prescribed fire) all reduce emissions

from wildfires. Although fire suppression

efforts may only delay the emissions rather then

eliminate them altogether. Allowing fires to

burn without suppression early in the fire season

to prevent more severe fires in drier periods

would reduce fuel consumption and reduce

emissions. All fire management plans that allow

limited suppression consider air quality impacts

from potential wildfires as a decision criterion.

So, although only specific emission reduction

techniques for prescribed fires are discussed in

this chapter, we should remember that there is

an inextricable link between fuels management,

prescribed fire, wildfire severity, and emission

production.

Literature Citations

Environmental Protection Agency. Sept. 1992.

Prescribed burning background document and

technical information document for prescribed

burning best available control methods. U.S.

EPA, Office of Air Quality Planning and

Standards. Research Triangle Park, NC. EPA450/2-92-003.

Hall, Janet. 1991. Comparison of fuel consumption

between high and moderate intensity fires in

logging slash. Northwest Science. 64(4): 158-

165.

Ottmar, Roger D.; Reinhardt, Timothy E.; Anderson,

Gary, DeHerrera, Paul J. [In preparation].

Consume 2.1 User’s guide. Gen. Tech. Rep.

PNW-GTRxxx. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Research Station.

Reinhardt, Elizabeth D.; Keane, Robert E.; Brown,

James K. 1997. First Order Fire Effects Model:

FOFEM 4.0, users guide. Gen. Tech. Rep. INTGTR-344. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain

Research Station. 65 p.

Sandberg, D.V.; Peterson, J. 1984. A source strength

model for prescribed fires in coniferous logging

slash. Presented at the 1984 Annual Meeting,

Air Pollution Control Association, Pacific

Northwest Section, 1984 November 12.

Ward, Darold E.; Hardy, Colin C. 1991. Smoke

emissions from wildland fires. Environmental

International, Vol 17:117-134.

Ward, Darold E.; Peterson, Janice; Hao, Wei Min.

1993. An Inventory of Particulate Matter and

Air Toxic Emissions from Prescribed Fires in

the USA for 1989. In: Proceedings of the 86th

Annual Meeting of the Air and Waste Management Association; 1993 June 13-18; Denver,

CO. 19p.
Chapter 8 – Smoke Management Techniques 2001 Smoke Management Guide

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2001 Smoke Management Guide 9.0 – Dispersion Prediction

DISPERSION PREDICTION SYSTEMS

Chapter 9
Chapter 9 – Dispersion Prediction Systems 2001 Smoke Management Guide

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2001 Smoke Management Guide 9.0 – Dispersion Prediction

Smoke Dispersion Prediction Systems

Sue A. Ferguson

Smoke dispersion prediction systems are becoming increasingly valuable tools in smoke

management. There are a variety of potential

applications that can help current management

issues. These include screening, where methods and models are used to develop “worstcase” scenarios that help determine if

alternative burn plans are warranted or if more

in-depth modeling is required. Such tools also

help in planning, where dispersion predictions

aid in visualizing what fuel and weather conditions are best suited for burning or when supporting data are needed to report potential

environmental impacts. Also, prediction systems can be used as communication aids to help

describe potential impacts to clients and managers. For regulating, some states use dispersion

prediction systems to help determine approval

of burn permits, especially if ignition patterns

or fuel complexes are unusual. Other states

require dispersion model output in each burn

permit application as supporting proof that a

burn activity will not violate clean air thresholds.

There are a variety of tools that can be applied

to screening and some planning applications.

The easiest of these are simple approximations

of dispersion potential, emission production,

and proximity to sensitive receptors. The

approximations are based on common experience with threshold criteria that consider worstcase conditions or regulatory requirements.

More detailed planning and many regulatory

situations require numerical modeling techniques. While numerical models output a

calculated physical approximation of dispersion

features, they can be adjusted to predict worstcase scenarios by altering such things as emission production or trajectory winds. Often the

easily applied numerical models are used for

screening. Typically, more rigorous applications

require the use of complex models by trained

personnel.

Methods of Approximation

A first level of approximation can simply determine whether the atmosphere has the capacity to

effectively disperse smoke by using indexes of

ventilation or dispersion. These indexes are

becoming widely used and may be a regular

feature of fire weather or air quality forecasts in

your area. Usually the ventilation index is a

product of the mixing height times the average

wind within the mixed layer. For example, a

mixing height of 600 meters (~2,000 feet) above

the ground surface with average winds of 4 m/s

(~7.8 knots or ~8.9 mph) produces a ventilation

index of 2,400 m2

/sec (~15,600 knots-feet).

With similar wind speeds, the ventilation index

would increase to 12,000 m2/sec (~78,000

knots-feet) if the mixing height rose to 3,000

meters (~10,000 feet). Ventilation indexes

calculated from model output may use the

product of the planetary boundary layer (PBL)

and lowest level winds (e.g., 10 to 40 meters

above ground level). Others calculate the index
Chapter 9 – Dispersion Prediction Systems 2001 Smoke Management Guide

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___________________________________

1 Transport winds are those considered most likely to carry smoke away from a fire, usually near mid-level of the

horizontal portion of a spreading plume.

Table 9.1. Common values of the ventilation index (VI) and associated smoke conditions.

The Index is calculated by multiplying mixing height (MH) or planetary boundary layer (PBL)

times trajectory winds (Traj.), average winds through the depth of the mixed layer (Avg.), or

winds at 40 meters above ground level (40m).

by multiplying the mixing height by a determined transport wind speed,1

 which might be

near the top of the mixed layer. Because of

different methods of calculating ventilation

index, the scales used for burning recommendations may vary.

It helps to gain experience with a ventilation

index before making management decisions

based on its value. Defining a uniform method

for calculating the index and comparing it

frequently with observed smoke dispersal

conditions can do this. Ferguson et al. (2001)

developed a national historical database of

ventilation index based on model generated 10-

meter winds and interpolated mixing height

observations. It is useful in illustrating the

spatial and temporal variability of potential

ventilation all across the country. In South

Carolina the index is divided into 5 categories

that correspond to specific prescribed burning

recommendations, where no burning is recommended if the index is less than 4,500 m2

/sec

(28,999 knots-feet) and restrictions apply if it is

between 4,500 and 7,000 m2/sec (29,000-

49,999 knots-feet) (South Carolina Forestry

Commission, 1996). In Utah the ventilation

index is referred to as a “clearing index” and is

defined as the mixing depth in feet times the

average wind in knots divided by 100. In this

way, a clearing index of less than 200 would

indicate poor dispersion and likely pollution; an

index between 200 and 500 indicates fair dispersion, while indexes greater than 500 represent

good to excellent dispersion. Commonly, the

clearing index must be greater than 400 before

burning is recommended. In the northwestern

U.S., where a mesoscale weather model is used

to predict ventilation index, the South Carolina

scale has been slightly adjusted to match local

burning habits and to accommodate for the

slightly different way of computing the index.

Table 9.1 gives common values of the ventilation index (VI) and associated smoke conditions.

Ventilation indexes have no value when there is

no mixing height, which is common at night.

Also, if the atmosphere is very stable within the

mixed layer, the ventilation index may be too

optimistic about the ultimate potential of dispersing a smoke plume. Therefore, to help
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2001 Smoke Management Guide 9.0 – Dispersion Prediction

Table 9.2. Atmospheric Dispersion Index (ADI) with its current interpretation

(Lavdas 1986).

determine the atmosphere’s capacity to disperse

smoke during all atmospheric conditions,

Lavdas (1986) developed an Atmospheric

Dispersion Index (ADI) that combines Pasquill’s

stability classes (see table 7.1) and ventilation

indexes with a simple dispersion model. National Weather Service (NWS) fire weather

offices are beginning to include the ADI as a

regular part of their smoke management forecast. See table 9.2 for an explanation of the ADI

categories. Commonly the ADI must be greater

than 30 before burning is recommended.

Another way to approximate smoke impacts is

through a geometric screening process that is

outlined in “A Guide for Prescribed Fire in

Southern Forests” (Wade 1989) and “Southern

Forestry Smoke Management Guidebook”

(USDA-Forest Service, Southern Forest Experiment Station 1976). The recommended steps

include: 1) plotting the direction of the smoke

plume, 2) identifying common areas of smoke

sensitivity (receptors) such as airports, highways, hospitals, wildernesses, schools, and

residential areas, 3) identifying critical areas

that already have an air pollution or visibility

problem (non-attainment areas), 4) estimating

smoke production, and 5) minimizing risk.

It is suggested that the direction of the smoke

plume during the day be estimated by considering the size of the fire and assuming a dispersion

of 30° on either side of the centerline trajectory

if wind direction is planned or measured and

45° if forecasted winds are used. At night, the

guide suggests that smoke follows down-valley

winds and spreads out to cover valley bottoms.

Fuel type, condition, and loading are used to

help estimate the amount of smoke that will be

produced. In minimizing risk, it is suggested to

consider mixing height, transport wind speed,

background visibility, dispersion index, and

various methods of altering ignition and mop-up

patterns.

Because the guidebooks for southern forestry

estimate emissions based on fuel types specific

to the southeastern U.S., other methods of
Chapter 9 – Dispersion Prediction Systems 2001 Smoke Management Guide

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estimating emissions are needed to employ

geometric screening applications elsewhere.

Existing models such as FOFEM (Reinhardt and

others 1997) and CONSUME (Ottmar and

others 1993) are designed for this purpose.

Schaaf and others (1999) describe a similar

screening process for deciding the level of

analysis for each project. The screening steps

include: 1) determining fire size, 2) estimating

fuel load, 3) identifying distance to sensitive

areas, and 4) calculating emission production.

Unlike the southern forestry screening method,

which estimates downwind impacts from simple

geometry, Schaaf and others (1999) recommend

running a numerical dispersion model to help

calculate smoke concentrations if initial screening thresholds are met. Further analysis or

efforts to reduce potential impacts are then

recommended only if predicted concentrations

exceed specified standards.

Before relying on simple screening methods to

determine if additional modeling may be required or if alternatives are necessary, it is

helpful to define appropriate threshold criteria

by consulting regulations, surrounding community opinions, and management concerns. For

example, the criteria of sensitive receptor proximity may range from fractions of a mile to

several miles. On the other hand, some places

may base criteria on total tonnage of emissions,

no matter how close or far from a sensitive area.

Most often criteria are combinations of proximity to receptors and fire size, which vary from

place to place.

Numerical Models

Most of the available dispersion prediction

systems are in the form of deterministic numerical models and there are three types designed to

estimate the timing and location of pollutant

concentrations; dispersion, box, and threedimensional grid models. Dispersion models

are used to estimate smoke and gas concentrations along the trajectory of a smoke plume.

Box models do not calculate trajectories of

particles but assume smoke fills a box, such as a

confined basin or valley, and concentrations

vary over time as smoke enters and leaves the

box. Grid models are like expanded box models

in that every grid cell acts as a confined box.

Because trajectories are not explicitly computed,

box or grid models may include other enhancements, such as complex computations of chemical interactions. Currently, only dispersion and

box models have been adapted for wildland

smoke management applications. Work is

underway to adapt grid models to smoke problems and this will help in estimates of regional

haze because grid models can simulate large

domains and usually include critical photochemical interactions. The following summary

of numerical models currently used by smoke

managers is updated from an earlier review by

Breyfogle and Ferguson (1996).

Dispersion Models – Dispersion models track

trajectories of individual particles or assume a

pattern of diffusion to simplify trajectory calculations. Particle models typically are the most

accurate way to determine smoke trajectories.

They are labor intensive, however, and more

often used when minute changes in concentrations are critical, such as when nuclear or toxic

components exist, or when flow conditions are

well bounded or of limited extent (e.g., PBPiedmont by Achtemeier 1994, 1999, 2000).

Diffusion models commonly assume that concentrations crosswind of the plume disperse in a

bell-shape (Gaussian) distribution pattern. Both

plume (figure 9.1a) and puff (figure 9.1b)

patterns are modeled. The plume method

assumes that the smoke travels in a straight line

under steady-state conditions (the speed and

direction of particles do not change during the

period of model simulation). SASEM (Sestak
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2001 Smoke Management Guide 9.0 – Dispersion Prediction

and Riebau 1988), VSMOKE (Lavdas, 1996),

and VSMOKE-GIS (Harms and Lavdas 1997)

are examples of plume models. Plume models

most commonly are applied in regions of flat or

gently rolling terrain but can be used whenever a

plume is expected to rise above the influence of

underlying terrain. The puff method simulates a

continuous plume by rapidly generating a series

of puffs (e.g., NFSpuff: Harrison 1995; Citpuff:

in TSARS+ by Hummel and Rafsnider 1995;

and CALPUFF: Scire and others 2000a).

Therefore, like particle models, puff models can

be used at times when trajectory winds change,

such as during changeable weather conditions or

in regions where underlying terrain controls

smoke trajectory patterns. Because particle

trajectory models and Gaussian diffusion models use coordinate systems that essentially

follow particles/parcels as they move

(Lagrangian coordinates), sometimes they are

referred to as Lagrangian dispersion models.

Particle and puff models must have high spatial

and temporal resolution weather data to model

changing dispersion patterns. This requires at

least hourly weather information at spatial

resolutions that capture important terrain features (usually less than 1km). For this reason,

particle and puff models currently used for

smoke management include a weather module

that scales observations or input from external

meteorological information, to appropriate

spatial and temporal resolutions. For example,

TSARS+ is designed to link with the meteorological model NUATMOS (Ross and others

1988) while CALPUFF is linked to CALMET

(Scire and others 2000b). NFSpuff (Harrison

1995) and PB-Piedmont (Achtemeier 1994,

1999, 2000) contain internal algorithms that are

similar to CALMET and NUATMOS. Most

weather modules that are attached to particle

and puff models solve equations that conserve

mass around terrain obstacles and some have

additional features that estimate diurnal slope

winds and breezes associated with lakes and

oceans at very fine scales.

Unlike most particle or puff models, plume

models assume that mixing heights and trajectory winds are constant for the duration of the

burn. Therefore, they do not require detailed

weather inputs and are very useful when meteorological information is scarce. Plume models,

however, will not identify changing trajectories

or related concentrations if weather conditions

fluctuate during a burn period. Also, when

smoke extends beyond a distance that is reasonable for steady-state assumptions, which typically is about 50 km (30 miles), plume

approximations become invalid. When terrain

or water bodies interact with the plume, steadystate assumptions become difficult to justify, no

matter how close to the source. Despite the

limitation of plume models in complex terrain,

they can be useful if plumes are expected to rise

above the influence of terrain or if plumes are

confined in a straight line that follows a wide

valley when dispersion does not extend beyond

the valley walls.

Box and Grid Models – The box method of

estimating smoke concentrations assumes

instantaneous mixing within a confined area,

such as a confined basin or valley (figure 9.1c).

This type of model usually is restricted to

weather conditions that include low wind

speeds and a strong temperature inversion that

confines the mixing height to within valley

walls (e.g., Sestak and others, unpublished;

Lavdas 1982). The valley walls, valley bottom,

and top of the inversion layer define the box

edges. The end segments of each box typically

coincide with terrain features of the valley, like

a turn or sudden elevation change. Flow is

assumed to be down-valley and smoke is

assumed to instantaneously fill each box segment. The coordinates used to calculate box

dispersions are fixed in space and time and thus

called Eulerian coordinates. The box method

provides a useful alternative to Gaussian diffu-
Chapter 9 – Dispersion Prediction Systems 2001 Smoke Management Guide

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Figure 9.1. Schematic diagrams of numerical dispersion models; (A) Gaussian plume, (B) Gaussian

puff, and (C) box.

A.

B.

C.

valley wall

valley bottom

inversion height

valley wall

down-valley flow
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2001 Smoke Management Guide 9.0 – Dispersion Prediction

sion models when understanding patterns of

smoke concentrations in an isolated valley

become critical.

Many grid models are called Eulerian grids

because of their fixed coordinate system. The

fixed coordinates make it difficult for grid

models to track the impact of individual plumes

but allows for easier evaluation of cumulative

impacts from several plumes or chemical interactions of particles and gases within plumes.

This makes grid models especially useful for

evaluating the impact of smoke on regional

haze. Work is underway to adapt at least two

grid models (REMSAD: Systems Applications

International 1998; and CMAQ: Byun and

Ching 1999) for wildland fire applications.

REMSAD has very simple chemistry thus is

desirable for use in large domains or over long

time periods. The CMAQ model is more fully

physical and part of the EPA’s Models 3 project,

which is a “one-atmosphere” air quality modeling framework designed to evaluate all potential

impacts from all known sources. At this time

grid models require experienced modelers to

initialize and run. Smoke managers, however,

may be asked to provide input for grid models

and could begin seeing results that influence

application of regional haze rules.

Uncertainty

All prediction systems include some level of

uncertainty, which may occur from the meteorological inputs, diffusion assumptions, plume

dynamics, or emission production. Many

dispersion models and methods have been

compared to observations of plumes from point

sources, such as industrial stacks, or tightly

controlled experiments (e.g., Achtemeier 2000).

In these cases, the greatest error usually occurs

because of inaccuracies in the weather inputs;

either from a poor forecast or an insufficient

number of data points. If trajectories can be

determined correctly then dispersion and resulting down-wind concentrations from point

sources are relatively straightforward calculations. This is because emission rates and subsequent energy transmitted to the plume from

industrial stacks, or controlled experiments,

usually are constant and can be known exactly.

It is expected that the largest source of uncertainty in modeling smoke concentrations from

wildland fires is in estimating the magnitude

and rate of emissions. Highly variable ignition

patterns and the condition and distribution of

fuels in wildland fires create complex patterns

of source strength. This causes plumes with

simultaneous or alternating buoyant and nonbuoyant parts, multiple plumes, and emission

rates that are dependent on fuel availability and

moisture content. Few comparisons of observations from real wildland fires to dispersion

model output are available. Those that do exist

are qualitative in nature and from the active

phase of broadcast-slash burns (e.g., Hardy and

others 1993), which tend to generate relatively

well-behaved plumes.

To calculate the complex nature of source

strength, components of heat and fuel (particle

and gas species) must be known. For simulating

wildland fires, additional information is required

on: 1) the pattern of ignition, 2) fuel moisture by

size of fuel, 3) fuel loading by size, 4) fuel

distribution, and 5) local weather that influences

combustion rates. Much of this information is

routinely gathered when developing burn plans.

Peterson (1987) noted that 83% of the error in

calculating emissions is due to inaccurate fuel

load values. Therefore, even the best burn plan

data will introduce a large amount of uncertainty

in predicted dispersion patterns.

The shift from burning harvest slash to using

fire in natural fuel complexes for understory

renovation and stand replacements has intro-
Chapter 9 – Dispersion Prediction Systems 2001 Smoke Management Guide

– 170 –

duced another degree of uncertainty by the

existence of decaying fuel and isolated concentrations of deep duff that have previously been

neglected in pre-burn inventories. This has

prevented emission models from accurately

estimating the contribution of smoldering

combustion, which is common in the porous

elements of rotten wood and deep duff. Until

this omission is corrected, users must manipulate source-strength models into expecting

smoldering by inputting very long ignition

periods and low fuel loads, which simulate the

independent smoldering combustion that occurs

in porous material.

Currently variable-rate emissions are determined by approximating steady-state conditions

in relatively homogeneous burning segments of

a fire (e.g., Sandberg and Peterson 1984;

Ferguson and Hardy 1994; Lavdas 1996; Sestak

and Riebau 1988) or by allowing individual fuel

elements to control combustion rates (e.g.,

Albini and others 1995; Albini and Reinhardt

1995; Albini and Reinhardt 1997). The steadystate method has been adapted for many of the

currently available puff, plume, and box models

and is most useful when the pattern and duration

of ignition are known ahead of time, either

through planning or prediction. The fuelelement approach shows promise for calculating

emissions simultaneously with ignition rates

(fire spread) and may become particularly useful

for coupled fire-atmosphere-smoke models,

which currently are being developed.

Principal components (plume rise, trajectory,

and diffusion) of all numerical dispersion

models assume functions that are consistent

with standard, EPA approved, industrial stack

emission models. The models themselves,

however, may or may not have passed an EPA

approval process. Primary differences in the

physics between the models appear to be the

degree to which they fully derive equations. All

models include some empirical coefficients,

approximations, or parameterized equations

when insufficient input data are expected or

when faster computations are desired. The

degree to which this is done varies between

models and between components of each model.

Note that it is not clear whether fully physical

calculations of plume rise and dispersion are

more accurate than approximate calculations in

biomass burning because of the considerable

uncertainty in the distribution and magnitude of

available fuels in wildland areas.

Output

Useful output products for smoke managers are

those that relate to regulatory standards, show

impact to sensitive receptors, and illustrate

patterns of potential impact. Regulatory standards require 24-hour averaged and 24-hour

maximum surface concentrations of respirable

particles at sensitive receptors. In addition,

surface concentrations of carbon monoxide

(CO), lead, sulfur oxides (SOx), ozone (O3),

nitrous oxides (NOx), and hydrocarbons (e.g.,

methane, ethane, acetylene, propene, butanes,

benzene, toluene, isoprene) are needed to

conform to health regulations. Quantifying the

impact on regional haze is becoming necessary,

which requires an estimate of fine particles,

carbon gases, NOx, O3

, relative humidity, and

background concentrations. Safety considerations require estimates of visibility, especially

along roads (Achtemeier et al. 1998) and at

airports. In addition to quantitative output, it is

helpful to map information for demonstrating

the areal extent of potential impact because even

the smallest amount of smoke can affect human

values, especially when people with respiratory

or heart problems are in its path. For example,

studies have shown that only 30 to 60 μg/m3 in

daily averaged PM10 (particulate matter that is

less than 10 micrometers in diameter) can cause

increases in hospital visits for asthma (Schwartz
– 171 –

2001 Smoke Management Guide 9.0 – Dispersion Prediction

et al. 1993; Lipsett et al. 1997). These values

are less than 1/3 of the national ambient air

quality standard (U.S. Environmental Protection

Agency 1997). Sometimes the mere presence of

smoke, regardless of its concentration, is enough

to force alteration of a burn plan.

The old adage, “you can’t get out what you

don’t put in,” aptly describes the output of

dispersion prediction systems. In a geometric

screening system (Wade 1989), only place of

impact can be approximated because elemental

constituents of the source emissions are not

considered. The value in screening processes of

this type, however, is that they allow an objective, first-guess estimate of smoke impacts so

alternative measures can be taken if needed.

Also, the process can be done on a map that

illustrates potential receptors and estimated

trajectory for others to see and discuss. Depending on the state or tribal implementation

plan, a geometric screening may be all that is

needed to conform to regulatory standards.

Numerical models disperse gases and particulates that are available from a source-strength

model, which uses measured ratios of emissions

to amount of fuel consumed (emission factors).

Emission factors vary depending on fuel type,

type of fire (e.g., broadcast slash, pile, or undisturbed) and phase of the fire (e.g., flaming or

smoldering). Currently, emission factors

available for wildland fire include total particulate matter (PM), particulate matter that is less

than 10 micrometers (μm) in diameter (PM10),

particulate matter that is less than 2.5 μm in

diameter (PM2.5), carbon monoxide (CO),

carbon dioxide (CO2

), methane (CH4), and nonmethane hydrocarbons (NMHC). Emission

factor tables (AP-42) are maintained by the U.S.

Environmental Protection Agency (1995).

At this time, emissions of lead and SOx from

biomass fires are considered negligible. Emission factors of NOx are uncertain and have not

been quantified to a satisfactory level. It is

assumed that ozone is not created at the source

but develops downwind of the source as the

plume is impacted by solar radiation. Currently,

aside from grid models, only one dispersion

model (CALPUFF: Scire and others 2000a)

includes simple photochemical reactions for

calculation of down-wind ozone.

Desired attributes within a dispersion prediction

system vary in complexity by several orders of

magnitude. To help potential users determine

which systems may best apply to their specific

need, three levels of complexity were estimated

for each desired attribute as shown in table 9.3.

The 1st level is the simplest; usually producing

generalized approximations. At the 3rd level,

attributes are determined with the best available

science and often include a number of perspectives or options for output.

Using the estimated levels of complexity from

table 9.3, it becomes possible to rank dispersion

prediction systems for each potential application. For example, if graphical output is available, the location of impact can be determined.

If surface concentrations of particles and gases

are available, then the system can be used to

determine health and visibility impacts. A quick

estimate of visibility may require only a 1st level

of complexity, while precise visibility determinations may require more complex approaches.

A summary of attributes for each dispersion

prediction system is provided in table 9.4. The

numbers in the attribute columns refer to an

estimated level of complexity from 1 to 3 as

summarized in table 9.3. Ease of use is a

subjective determination based on the work of

Breyfogle and Ferguson (1996). It considers the

number and type of inputs, the availability of

inputs, required user knowledge, and effort

needed to produce useful results. Because

calculating a ventilation or clearing index is

simply a product of two numbers, dispersion

indexes typically are computed by others, and
Chapter 9 – Dispersion Prediction Systems 2001 Smoke Management Guide

– 172 –

 

Table 9.3. Desired attributes of dispersion prediction systems are compared to estimated levels

of complexity.

both commonly are available through fire

weather or air quality forecasts, they are considered very easy to use.

Several methods/models can show cumulative

impacts from a number of fires by generalizing

the atmosphere’s capacity to hold the total

emissions (index values) or by displaying

multiple plumes at once (VSmoke-GIS if separate projects are used as overlays, NFSpuff,

TSARS+, and CALPUFF). The ability to

numerically determine the cumulative impact,

however, requires concentrations of intersecting

plumes to be added together. Currently

CALPUFF (Scire and others 2000a) is capable

of additive concentrations.

Only two of the currently available models are

specific to a geographic area. They are NFSpuff

(Harrison 1995) and PB-Piedmont (Achtemeier

1994, 1999, 2000) that were built for ultimate

ease by including digital elevation data so the

user would not have to find it or adjust for

different formats. Early versions of the NFSpuff

model contain only elevation data from Washington and Oregon while later versions include

all of the western states. The PB-Peidmont

model includes data for the piedmont regions of
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2001 Smoke Management Guide 9.0 – Dispersion Prediction

Table 9.4. Dispersion prediction systems designed for wildland fire applications. Attributes are ranked

by their level of complexity, with 1 being simplest and 3 being most complex, where a dash indicates

that the attribute is unavailable. Ease of use is ranked from 1 being the easiest to 10 being the most

difficult.

southeastern United States. Other models do

not require elevation data (e.g., SASEM and

VSmoke) or allow the input of elevation data

from anywhere as long as it fits the modelspecified format (e.g., VSmoke-GIS, TSARS+,

and CALPUFF). While there is some concern

that version 1.02 of the Emission Production

Model (EPM: Sandberg and Peterson 1984) is

specific to vegetation types in Washington and

Oregon, it has been adapted for use in the

southeastern U.S. through VSmoke (Lavdas

1986) and can be adjusted to function elsewhere

in the country (e.g., SASEM: Sestak and Riebau

1988). Newer versions of EPM (Sandberg

2000) and the BurnUp emissions model (Albini

and Reinhardt 1997) are not geocentric but to

date neither has been incorporated into any

available dispersion prediction system.

Summary

For many projects a simple model often provides as good information as a more complex

model. Regulations, however, may dictate the

level of modeling required for each project.

Other times, community values will determine

the level of effort needed to demonstrate compliance or alternatives. Also, skills available to

set up and run models or the availability of

required input data may affect whether a prediction system is necessary and which one is most

appropriate.

Because regulations vary from state to state and

tribe to tribe and because expectations vary

from project to project there is no simple way to

determine what dispersion prediction system is

best. It is hoped that the information in tables

9.3 and 9.4 can be used to help assess the value

of available methods and models. For example, if a simple indication of visibility impacts is required, plume models can be used or

visual indexes can be approximated from
Chapter 9 – Dispersion Prediction Systems 2001 Smoke Management Guide

– 174 –

concentrations out of box, plume, or puff

models. If more detailed visibility impacts are

required, a sophisticated puff model should be

used. Whatever the situation, whether smoke

dispersion prediction systems are used for

screening, planning, regulating, or simply game

playing, it is helpful to remember their

strengths and weaknesses.

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for predicting smoke movement. South. J.

Appl. Forest. 18: 60-64.

Achtemeier, G.L. 1999. Smoke Management:

Toward a Data Base to Validate PB-Piedmont -

Numerical Simulation of Smoke on the Ground

at Night Proceedings of the 1999 TAPPI

Internatinal Enviromental Conference, April

18-21, 1999, Nashville, Tennessee, Opryland

Hotel, Vol. 2.

Achtemeier, G.L. 2000. PB-Piedmont: A numerical

model for predicting the movement of biological material near the ground at night. In:

Proceedings of the 24th conference on agricultural and forest meteorology; 14-18 August

2000; Davis, CA. Boston, MA: American

Meteorology Society: 178-179.

Achtemeier, G.L., W. Jackson, B. Hawkins, D.D.

Wade, and C. McMahon. 1998. The smoke

dilemma: a head-on collision! Transactions of

the 63rd North American Wildlife and Natural

Resource Conference. 20-24 March 1998.

Orlando FL. 415-421.

Albini, F.A., J.K. Brown, E.D. Reinhardt, and R.D.

Ottmar. 1995. Calibration of a large fuel

burnout model. Int. J. Wildland Fire. 5(3):

173-192.

Albini, F.A. and E.D. Reinhardt. 1995. Modeling

ignition and burning rate of large woody

natural fuels. Int. J. Wildland Fire. 5(2): 81-91.

Albini, F.A. and E.D. Reinhardt. 1997. Improved

calibration of a large fuel burnout model. Int.

J. Wildland Fire. 7(2):21-28.

Breyfogle, Steve and S. A. Ferguson. 1996.User

assessment of smoke-dispersion models for

wildland biomass burning. U.S. Department of

Agriculture, Forest Service, Pacific Northwest

Research Station, Portland, OR. PNW-GTR379. 30 pp.

Byun, D.W. and Ching, J.K.S., editors. 1999.

Science Algorithms of the EPA Models-3

Community Multiscale Air Quality (CMAQ)

Modeling System. U.S. Environmental Protection Agency, Office of Research and Development. EPA/600/R-99/030. pages unknown.

Ferguson, S.A; Hardy, C.C. 1994. Modeling Smoldering Emissions from Prescribed Broadcast

Burns in the Pacific Northwest. International

Journal of Wildland Fires 4(3):135-142.

Ferguson, S.A.; S. McKay; D. Nagel; T. Piepho;

M.L. Rorig; and C. Anderson. 2001. The

potential for smoke to ventilate from wildland

fires in the United States. In Proceedings of the

4th Symposium on Fire and Forest Meteorology, 13-15 November 2001, Reno, Nevada.

Paper No. 4.6.

Hardy, C.C.; Ferguson, S.A.; Speers-Hayes, P.;

Doughty, C.B.; Teasdale, D.R. 1993. Assessment of PUFF: A Dispersion Model for Smoke

Management. Final Report to USDA Forest

Service Pacific Northwest Region. Fire and

Environmental Research Applications, USDA

Forest Service, PNW Research Station, 32 pp.

Harrison, H. 1995. A User’s Guide to PUFFx: A

Dispersion Model for Smoke Management in

Complex Terrain. WYNDSoft Inc., 42 pp.

Hummel, J.; Rafsnider, J. 1995. User’s Guide:

TSARS Plus Smoke Production and Dispersion

Model, Version 1.1. National Biological

Service and the Interior Fire Coordination

Committee. 107 pp.

Harms, Mary F.; Lavdas, Leonidas G. 1997. Draft:

User’s Guide to VSMOKE-GIS for Workstations. Research Paper SRS-6. Asheville, NC:

U.S. Department of Agriculture, Forest Service,

Southern Research Station. 41 p.

Lavdas, L.G. 1982. A day/night box model for

prescribed burning impact in Willamette Valley,

Oregon. Journal of Air Pollution Control

Agency, 32:72-76.
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Lavdas, L.G. 1986. An Atmospheric Dispersion

Index for Prescribed Burning. U.S. Department

of Agriculture, Forest Service, Southeastern

Forest Experiment Station. RP- SE-256. 35

pp.

Lavdas, L.G. 1996. VSMOKE User’s Manual. U.S.

Department of Agriculture, Forest Service,

Southern Research Station. GTR-SRS-6. 147

pp.

Lipsett M., Hurley S., Ostro B. 1997. Air Pollution

and Emergency Room Visits for Asthma in

Santa Clara County, California. Environmental

Health Perspectives. 105(2):216-222.

Ottmar, R.D., M.F. Burns, J.N. Hall, and A.D.

Hanson. 1993. CONSUME User’s Guide.

Gen. Tech. Rep. PNW-GTR-304. U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station. Portland, OR.

117 pp.

Peterson, J.L. 1987. Analysis and reduction of the

errors of predicting prescribed burn emissions.

Master of Science thesis. University of Washington, Seattle, Washington. 70 pp.

Ross, D.G.; Smith, I.N.; Mannis, P.C.; Fox, D.G.

1988. Diagnostic wind field modeling for

complex terrain: model development and

testing. Journal of Applied Meteorology,

27:785-796.

Reinhardt, E.D., R.E. Keane, and J.K. Brown. 1997.

First Order Effects Model: FOFEM 4.0 User’s

Guide. Gen. Tech. Rep. INT-GTR-344. U.S.

Department of Agriculture, Forest Service,

Intermountain Research Station. Ogden, UT.

65 pp.

Sandberg, D.V.; Peterson, J. 1984. A source

strength model for prescribed fires in coniferous

logging slash. Presented at the 1984 Annual

Meeting, Air Pollution Control Association,

Pacific Northwest Section, 1984 November 12-

14, Portland, Oregon. 10 pp.

Sandberg, D.V. 2000. Implementation of an improved Emission Production Model. Abstract.

Joint Fire Science Program Principle

Investigator’s Meeting. 3-5 October 2000,

Reno, NV.

Schaaf, M.D., J. Nesbitt, and J. Hawkins. 1999. An

introduction to smoke emissions and dispersion

modeling. National Interagency Fire Center,

Great Basin Training Unit, 17-19 March, 1999,

Boise Idaho. CH2Mhill, Portland, OR.

[unpaginated].

Schwartz J, Slater D, Larson T.V, Pierson W.E,

Koenig J.Q. 1993. Particulate air pollution and

hospital emergency room visits for asthma in

Seattle. Am Rev Respir Dis. 147(4):826-831.

Scire, J.; Strimaitis, D.G.; Yamartino R.J.; Xiaomong

Zhang. 2000a. A User’s Guide for CALPUFF

Dispersion Model (Version 5). Earth Tech, Inc.,

Concord, Massachusetts. 512 pp.

Scire, J.; Robe, F.R.; Fernau, M.E.; Yamartino, R.J.

2000b. A User’s Guide for CALMET

Meterorological Model. Earth Tech, Inc.,

Concord, Massachusetts. 332 pp.

Sestak, M.L.; Marlatt,W.E.; Riebau, A.R. Unpublished. Draft VALBOX: Ventilated Valley Box

Model; U.S. Bureau of Land Management, 32

pp.

Sestak, M.L.; Riebau, A.R. 1988. SASEM, Simple

Approach Smoke Estimation Model. U.S.

Bureau of Land Management, Technical Note

382, 31 pp.

South Carolina Forestry Commission. 1996. Smoke

Management Guidelines for Vegetative Debris

Burning Operations: State of South Carolina.

SCFC 3rd Printing. 19 pp.

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Guide to the Regulatory Modeling System for

Aerosols and Deposition (REMSAD).

SYSAPP98-96/42r2, prepared for the U.S.

EPA under contract 68D30032. Available on

U.S.EPA website at

<www.epa.gov/scram001/>.

USDA Forest Service, Southern Forest Experiment

Station. 1976. Southern forestry smoke

management guidebook. U.S. Department of

Agriculture, Forest Service, Southern Forest

Experiment Station. SE-10. 55 pp.
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U.S. Environmental Protection Agency. 1995.

Compilation Of Air Pollutant Emission Factors,

Volume I: Stationary Point and Area Sources,

(AP-42). Fifth edition. Office of Air Quality

Planning and Standards Office of Air and

Radiation, U.S. Environmental Protection

Agency, Research Triangle Park, NC 27711.

[unpaginated].

U.S. Environmental Protection Agency. 1997.

National Ambient Air Quality Standards for

Particulate Matter; Final Rule. 40 CFR Part 50

[AD-FRL-5725-2] RIN 2060-AE66. Federal

Register. 62(138): 102 pp.

Wade, D.D. 1989. A Guide for prescribed fire in

southern forests. National Wildfire Coordinating Group, Prescribed Fire and Fire Effects

Working Team, Boise Interagency Fire Center,

ATTN: Supply, 3905 Vista Avenue, Boise, ID

83705. NFES #2108. [U.S. Department of

Agriculture, Forest Service, Southeastern

Forest Experiment Station. Tech. Pub. R8-TP

11.] 56 pp.
– 177 –

2001 Smoke Management Guide 10.0 – Monitoring

AIR QUALITY MONITORING

Chapter 10
Chapter 10 – Air Quality Monitoring 2001 Smoke Management Guide

– 178 –
– 179 –

2001 Smoke Management Guide 10.0 – Monitoring

Air Quality Monitoring for Smoke

John E. Core

Janice L. Peterson

Introduction

There are several reasons why wildland fire

managers may want to conduct an ambient air

quality-monitoring program. These include:

• smoke management program evaluation

purposes,

• to fulfill a public information need,

• to verify assumptions used in Environmental Assessments,

• to assess potential human health affects in

communities impacted by smoke,

• and to evaluate wildland burning smoke

impacts on State and Federal air quality

laws and regulations.

Both visibility data and PM10/PM2.5 concentration data are useful to smoke management

program coordinators for assessing air quality

conditions if the information is provided in realtime. Fire managers may also be interested in

monitoring impacts on visibility in Class I areas.

Whatever the objective may be, care must be

taken to match monitoring objectives to the right

monitoring method. Monitoring locations,

sampling schedules, quality assurance, and

monitoring costs are elements that must also be

considered.

Particulate Monitoring Techniques

Particulate monitoring instruments generally use

one of two particle concentration measurement

techniques: gravimetric or optical. Gravimetric

or filter-based instruments collect particulates

on ventilated filters. The filters are later

weighed at special laboratory facilities to determine the mass concentration of particulate

collected. Gravimetric monitoring techniques

have been used for years to quantify mass

concentration levels of airborne particulate

matter. Filter-based sampling is labor intensive.

Filters must be conditioned, weighed before

sampling, installed and removed from the

instrument, and reconditioned and weighed

again at a special facility. Results may not be

available for days or weeks. Also, airflow rates

and elapsed sampling time must be carefully

monitored and recorded to ensure accurate

results. Filter-based techniques integrate

samples over a long period of time, usually 24-

hours, to obtain the required minimum mass for

analysis. Gravimetric monitoring is best for

projects where high-accuracy is needed and the

time delay in receiving the data is not a problem. State monitoring networks designed to

detect violations of air quality standards rely

largely on gravimetric monitors. Specific

monitoring devices must be approved by EPA

for this task and are called Federal Reference

Monitors (FRM’s).
Chapter 10 – Air Quality Monitoring 2001 Smoke Management Guide

– 180 –

Optical instruments measure light-scattering

(nephelometers) or light-absorbing (aethalometers) characteristics of the atmosphere. This

measurement can then be converted to obtain an

estimate of the concentration of airborne particulates. Optical instruments offer several

advantages over gravimetric methods, including

real-time readings, portability, low power

consumption, and relatively low cost. Optical

instruments have the disadvantage of being

generally less accurate than gravimetric instruments at estimating particulate mass concentration. Optical instruments are best for projects

where real-time or near-real time data is needed,

where a high degree of accuracy is not a requirement, and if instrument portability and ruggedness is desirable.

Proper conversion of the light scattering measurement collected by nephelometers to an

estimate of particle concentration requires

development of customized conversion equations. The light scattering value measured

depends on particle size distribution and optical

properties of the specific aerosol mix in the area

of interest. The light scattering value measured

varies as a function of the relative proportions of

fine particles (including smoke) and coarse

particles (such as soil dust). As a result, optical

instruments should be calibrated against a colocated FRM in the same area, and pollutant

mix, in which they will eventually operate. A

formula is then developed to properly convert

scattering to a particulate mass per unit volume

(μg/m3

) estimate.

In a recent monitoring instrument evaluation

study, sixty-six laboratory measurements were

made with the MIE DataRam, the Radiance

Research nephelometer, and an EPA FRM

sampler where the instruments were exposed to

pine needle smoke (Trent and others 1999).

Results from these tests concluded that both

nephelometers overestimated mass concentrations of smoke when using the scattering to

mass conversion factors provided by the manufacturer. A follow-up study (Trent and others

2000) compared optical instruments from

various manufacturers (Radiance, MIE, Met

One, Optec, and Andersen) to FRM instruments

both in the field and laboratory and developed

preliminary custom calibration equations (figure

10.1). The report provides an estimate of a

conversion equation for each instrument tested

Figure 10.1. Three of the nephelometers tested during the Trent and others (2000) study include

the MIE DataRam, the Radiance Research nephelometer, and the Met One GT-640.
– 181 –

2001 Smoke Management Guide 10.0 – Monitoring

but also recommends that optical instruments be

field calibrated for a type of fire event, and that

meteorological conditions and existing levels of

ambient particles be included. Specific conditions to consider during calibration are age of

the smoke, type of fire (flaming or smoldering),

fuel moisture, relative humidity, and background

particle concentration without smoke from the

fire. Figure 10.2 shows the correlation found

between PM2.5 measurements made with an

EPA FRM gravimetric instrument vs. results

from an MIE DataRam nephelometer (Trent and

others 2000).

Wildland Fire Smoke

Monitoring Objectives

Gathering PM10/PM2.5 air quality data downwind from a prescribed burn or wildfire is an

important fire manager goal in some areas. This

data may be used as an input to smoke management decision-making, and may or may not

involve immediate public release of estimated

pollutant levels and health warnings. This

monitoring can be conducted at a few sensitive

locations within a relatively small area during

specific events such as a planned large-scale

understory burn, or used as a permanent part of

smoke management effectiveness monitoring.

Real-time data access, ease of use, and ruggedness are all generally required so optical instruments are most appropriate (table 10.1).

Monitors are often equipped with data loggers

and modems to permit downloading of the data

over a telephone line or via radio modem. In the

near future, technology will be available to

make air quality monitoring data from remote

sites accessible over the Internet. The USDA

Forest Service, Missoula Technology and

Development Program with Applied Digital

Security, Inc have developed a satellite-based

data retrieval system. Appropriately outfitted

Figure 10.2. Comparison of PM2.5 measurements made with a gravimetric Federal Reference

Monitor vs. an MIE DataRam nephelometer (Trent and others 2000).
Chapter 10 – Air Quality Monitoring 2001 Smoke Management Guide

– 182 –

Table 10.1. Equipment appropriate for smoke monitoring differs by program objective.
– 183 –

2001 Smoke Management Guide 10.0 – Monitoring

instruments will send packets of 5-minute

average particulate concentrations each hour by

satellite to a stored database to be viewed and

retrieved through a Web site.1

A second smoke monitoring objective may be to

gather data on prescribed fire smoke impacts at

sensitive locations over a much longer period

for purposes of comparison with ambient air

quality standards (NAAQS). In these cases,

immediate data access is of secondary importance to gathering data that approximates or is

equivalent to the high-accuracy official Federal

Reference Method (FRM) instruments used by

air regulatory agencies. A popular option is the

small, portable, battery powered MiniVol sampler although these are not official EPA FRM

designated monitors. The lag-time limitation

may be overcome by using one of two EPAapproved continuous air monitoring devices

(TEOM or Beta Attenuation Monitors [BAM])

__________________________________

1 MTDC Air Program News Issue 1. August 2001. Available at: http://fsweb.mtdc.wo.fs.fed.us/programs/wsa/

air_news/issue1.htm

Figure 10.3. A typical IMPROVE monitor installation.

but this equipment is costly and requires a high

degree of technical skill to operate (table 10.1).

Visibility protection is another monitoring

objective for fire managers when wildland

burning smoke may impact nearby Class I areas.

For visibility monitoring, information is not

only needed on PM10/PM2.5 concentrations but

aerosol chemical composition and particle light

scattering and absorption as well. Since aerosol

chemical analysis (speciation) monitoring

requires filter-based methods and extinction

measurements require in-situ real-time methods,

a combination of techniques are used. Monitoring is typically conducted throughout the year

over long time periods to establish trends. In as

much as data consistency with the national

visibility programs is also important, specialized

instruments designed and deployed by the

Interagency Monitoring of Protected Visual

Environments (IMPROVE) Network (Malm
Chapter 10 – Air Quality Monitoring 2001 Smoke Management Guide

– 184 –

2000) should be used whenever possible

(figure 10.3). Monitoring the visual quality of

a vista, called scene monitoring, is often done at

the same time using 35mm cameras. Digital

camera systems can be used at sites where

real-time web access to the scene is desirable

(table 10.1).

Further monitoring guidance is available on the

Internet at the EPA Air Monitoring Technology

Information Center (AMTIC) web site (http://

www.epa.gov/ttn/amtic) and the EPA Visibility

Improvement site (http://www.epa.gov/oar/vis/

index.html).

Monitoring Locations & Siting

Samplers used for smoke impact monitoring are

normally placed at smoke sensitive locations

that have the greatest likelihood of impact.2

This may be a private residence, within a nearby

community, or at a county fair. Care must be

taken to ensure that the instrument is located in

an open, exposed location removed from local

pollution sources such as dirt roads, burn barrels, or woodstoves that would influence the

data. The sampler should be located two or

more meters above ground at a secure location.

Power availability and access are often controlling considerations (CH2MHill 1997).

Visibility monitoring sites must be representative of the Class I area of interest and are therefore best located within the area’s boundary or,

in the case of wilderness areas, as close to the

boundary as possible. Since visibility data is

used to represent conditions over sub-regional

spatial scales, special care is needed in siting to

avoid local source influences. The IMPROVE

network has recently been expanded with

representative monitors for each of the 156

Class I areas in the country. Siting of the instruments was accomplished with state and Federal

Land Manager input.

Sampling Schedules

The timing, duration, and frequency of sampling

depend on the program objective. Continuous,

hourly data is needed to monitor smoke impacts

from several days prior to burn ignition to a day

or two after the event. In contrast, PM10

NAAQS compliance monitoring using filterbased instruments is conducted once every six

days in attainment areas. In a nonattainment

area, daily sampling is required for cities with

more than a million people and every three days

otherwise. Filter-based measurements made as

part of the IMPROVE visibility monitoring

network are made every third day to reduce

costs and operational requirements. Continuous

monitoring instruments always operate 24 hours

per day. Although sampling duration and

frequency decisions are often based largely on

operating costs and technician time requirements, measurements made as part of the IMPROVE network or for NAAQS compliance

determinations must follow the protocols outlined in EPA regulations found on the AMTIC

web site.

2 For NAAQS compliance monitoring, refer to the EPA Monitoring Network Siting Guidance found on the EPA

AMTIC web site at. http://www.epa.gov/ttn/amtic.
– 185 –

2001 Smoke Management Guide 10.0 – Monitoring

Quality Assurance

Data integrity is essential in any monitoring

program. Every monitoring project should have

a documented quality assurance plan. In addition to the maintenance and calibration measures outlined by the manufacturer of the

instruments being used, additional quality

assurance measures may also be included in the

plan if the monitoring data are of an especially

important nature. These include auditing procedures conducted by the state/local air quality

agency to verify proper instrument siting,

calibration and data capture as well as traceability of measurement standards to the National

Bureau of Standards (NBS) (EPA 1984). Methods of calculation and data processing should

also be audited. Fire managers may wish to

confer with their state/local air agency to assure

that monitoring results are valid.

Monitoring Costs

Monitoring is expensive. In addition to the

capital cost of the instruments, costs for equipment installation, electrical, maintenance,

calibration standards, supplies, shipping, data

analysis, and reporting must also be considered.

In the case of filter-based particulate sampling,

laboratory costs for filter weighing and chemical

analysis must also be included. On-going

annual operating costs for technician time to

service the instruments is a major expense that

often drives the monitoring system design.

Literature Citations

CH2MHill. 1997. When and how to monitor

prescribed fire smoke: a screening procedure.

Prepared for the USDA Forest Service, Pacific

Northwest Region, Portland, OR. Contract No.

53-82FT-03-2. 49p. Available at: http://

www.fs.fed.us/r6/aq.

Environmental Protection Agency. 1984. Quality

assurance handbook for air pollution measurement systems. EPA-600/9-76-005. US Environmental Protection Agency, Office of Research

and Development. Washington DC.

Malm, William C. 2000. Spatial and seasonal

patterns and temporal variability of haze and its

constituents in the United States – Report III.

ISSN: 0737-5352-47. Cooperative Institute for

Research in the Atmosphere. Colorado State

University. Fort Collins, CO 80523.

Trent, Andy; Thistle, Harold, Fisher, Rich; [and

others]. 1999. Laboratory evaluation of two

optical instruments for real-time particulate

monitoring of smoke. Tech. Rep. 9925-2806-

MTDC. Missoula, MT: U.S. Department of

Agriculture, Forest Service, Missoula Technology and Development Center. 14p.

Trent, Andy; Davies, Mary Ann; Fisher, Rich; [and

others]. 2000. Evaluation of optical instruments

for real-time, continuous monitoring of smoke

particulates. Tech. Rep. 0025-2860-MTDC.

Missoula, MT: U.S. Department of Agriculture,

Forest Service, Missoula Technology and

Development Center. 38p.
Chapter 10 – Air Quality Monitoring 2001 Smoke Management Guide

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– 187 –

2001 Smoke Management Guide 11.0 – Emission Inventories

EMISSION INVENTORIES

Chapter 11
Chapter 11 – Emission Inventories 2001 Smoke Management Guide

– 188 –
– 189 –

2001 Smoke Management Guide 11.0 – Emission Inventories

Emission Inventories

Janice L. Peterson

An inventory or estimate of total statewide (or

some other geographically distinct unit) annual

emissions of criteria pollutants is a necessary

part of understanding the burden on the air

resource in an area and taking appropriate

control actions. Emission inventories are a basic

requirement of state air resource management

programs and are a required element of State

Implementation Plans. Emission inventories

help explain the contribution of source categories to pollution events, provide background

information for air resource management,

provide the means to verify progress toward

emission reduction goals, and provide a scientific basis for state air programs. An accurate

emissions inventory provides a measured, rather

than perceived, estimate of pollutant production

as the basis for regulation, management action,

and program compliance. Emission inventories

should include all important source categories

including mobile, area, and stationary and are

not complete unless difficult-to-quantify sources

like agricultural burning, backyard burning,

rangeland burning, and wildland and prescribed

burning are each addressed.

Wildland and prescribed fires are extremely

diverse and dynamic air pollution sources and

their emissions can be difficult to quantify.

Design and development of an emission inventory system is primarily the responsibility of

state air regulatory agencies. But cooperation

and collaboration between air regulatory agencies and fire managers is required to design an

effective and appropriate emission inventory

system. Wildland fire managers should have the

knowledge and data necessary to calculate

emissions from their burn programs and be

prepared to work with the state in developing

emission inventory systems for wildland fire.

At the most basic level, estimation of wildfire

emissions requires knowledge of area burned,

fuel consumed, and a fuel-appropriate emission

factor. The estimate of emissions is made

through simple multiplication of area burned

(acres or hectares) times fuel consumed (tons per

acre or kilograms per hectare) times an emission

factor assigned with knowledge of the fuel type

(lbs/ton or g/kg) (figure 11.1). Resulting emissions are in tons or kilograms.

Greater accuracy, precision, and complexity can

be achieved through increasingly detailed knowledge of these basic parameters. For example,

area burned is estimated pre-burn in many

existing reporting systems; if area burned is

reassessed post-burn the accuracy of the emission inventory will increase. Accuracy and

precision will also be improved if fuel consumed

can be estimated with knowledge of pre-burn

loading and consumption of fuels in each of

many possible categories based on fuel type,

size, and arrangement; and with knowledge of

fuel moisture conditions, weather parameters,

and application of emission reduction techniques. A more precise emission factor can be

assigned with knowledge of burning conditions

that can shift fuel consumption from the less

efficient smoldering combustion phase into the

more efficient flaming phase (figure 11.2).
Chapter 11 – Emission Inventories 2001 Smoke Management Guide

– 190 –

Figure 11.1. Basic information components needed to estimate the quantity of

emissions from an individual wildland burn and compile an emissions inventory.

Figure 11.2. Detailed information about fuel loading and consumption by size class plus information to predict

consumption by phase of combustion can increase the accuracy and precision of estimates of emissions from

prescribed wildland fire for an emissions inventory (Modified from Sandberg [1988]). The ranges given in the

figure cover the majority of fuel loading and consumption situations in wildland fuels but do not define the

extremes. Numerous exceptions could likely be found in practice.
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2001 Smoke Management Guide 11.0 – Emission Inventories

Sources of Prescribed Burning

Activity Level Information

States with incomplete or no centralized burn

reporting requirements will need to go to the

burners themselves to quantify activity level.

Federal agencies generally keep fairly accurate

records of burning accomplished in a given time

period and can also provide estimates of wildfire

acres. Federal agencies that may need to be

contacted in a given state or area include the

Bureau of Land Management, Bureau of Indian

Affairs or individual Tribes, National Park

Service, Forest Service, and Fish and Wildlife

Service. In some areas other federal agencies

may need to be contacted. Such as the Department of Energy, Department of Defense, Natural

Resources Conservation Service, Agricultural

Research Service, U.S. Geological Survey, or

the Department of Reclamation along with

managers of National Preserves and National

Monuments.

Specific state agencies with a forestry, wildlife,

conservation, or natural resource management

mandate are another source of activity level

information. They may use prescribed burning

themselves and may compile burning statistics

for state lands and sometimes also for private

lands. Private land owners, especially those

managing timber-lands should be contacted as

should The Nature Conservancy and the

Audubon Society.

In some areas, especially where prescribed

wildland burning is infrequent, the only source

for activity level information may be a gross

estimate for all prescribed fires for an entire

state or area. This can sometimes be obtained

from a single federal or state agency, or sometimes from an academic institution.

Type of Burn

Prescribed burning can be divided into categories depending on the arrangement of the fuels.

Fuel arrangement can help predict total fuel

consumption and the proportion consumed in

the flaming vs. smoldering phases. Broadcast

burning refers to fuels burned in place. This

term can be used to describe natural woody

fuels scattered under a stand of trees, woody

debris scattered at random after a timber sale,

brush burned in place, or grass. Fuels can also

be concentrated into piles before burning. In

addition to pile and broadcast burning, other

general prescribed-fire-type categories that may

be used include range, windrow, right-of-way,

spot, black line, jack-pot, and concentration.

Knowledge of the type of burn is valuable for

estimating emissions as it can affect the accuracy and correct interpretation of estimates of

area burned, fuel consumed, and assignment of

an appropriate emission factor.

Area Burned

Area burned is generally the easiest parameter to

obtain from fire managers. One caution is that

area burned is often estimated prior to prescribed burning and not updated with the results

of the burn, which may be smaller or larger (in

the case of an escaped fire) than originally

estimated. Also, area burned may reflect the

area treated or the area within the wildland fire

perimeter, rather than the area actually blackened by fire. The wildland fire perimeter may

be considerably larger than the area actually

blackened by fire. For example, a study of the

Yellowstone fires of 1988 found that about 65%

of the wildfire perimeter area within the park

was actually blackened (Despain and others

1989), the remaining 35% was in unburned

islands. In the case of prescribed fire, land
Chapter 11 – Emission Inventories 2001 Smoke Management Guide

– 192 –

managers may consider a larger area to have

been treated or to have benefited by the fire than

was actually blackened by flames. Compiling

an accurate emission inventory requires actual

acres (or hectares) blackened for an accurate

estimate of emissions. Caution should be used

with estimates of area burned, as this parameter

is more prone to systematic overestimation than

any other component of emissions estimation.

Fuel Consumed

Fuel consumed is generally estimated via a twostep process; first fuel loading is estimated, then

a percent consumption is applied to calculate

fuel consumed. At the most basic level, a single

value for both total fuel loading and consumption can be used (for example 20 tons of fuel of

which 50 percent consumed). In reality, a

fuelbed is a complex mix of various sizes of

woody fuels (tree boles, branches, and twigs),

needle and/or leaf litter, decayed and partly

decayed organic matter and rotten material

(generally called duff or rot), and live fuels like

brush, forbs, and grass. Each of these fuelbed

components contributes to the total loading and

is consumed to a greater or lesser extent. For

example 100 percent of woody fuels less than 1

inch in diameter may burn whereas just 30

percent of those greater than 3 inches in diameter burn. In addition, some emission reduction

techniques are specific by fuelbed component.

Use of a single estimate of total fuel loading and

consumption will fail to capture this. To gain

accuracy in the emissions inventory and the

ability to track the use and effectiveness of

emission reduction techniques, further detail

concerning fuel loadings by fuelbed component

would ideally be tracked.

One simple method for obtaining a gross estimate of fuel loading is through the use of standardized fuel models. The most widely used

example is the array of National Fire Danger

Rating System (NFDRS) fuel models (Deeming

and others 1977). These 20 models are standardized descriptions of different fuel types that

can be used with some applicability to virtually

all wildlands in the US. The NFDRS fuel

models were designed as predictors of fire

danger rather than to characterize the wide

range of potential wildland fuel loadings as

would be ideal for compilation of an emissions

inventory. Another commonly used set of fuel

models is based on predicting fire behavior.

Thirteen fire behavior fuel models are described

in Anderson (1982). Since both the NFDRS

and fire behavior fuel models were designed for

purposes other than accurate fuel loading

estimation, these models should be used with

caution. In addition, the use of standardized

fuel models to estimate fuel loading means that

efforts to reduce fuel loading for emission

reduction purposes prior to prescribed burning

cannot be tracked or reflected in the emissions

inventory.

Other more detailed standardized fuel models

called fuel characteristic classes (FCC’s) are

under development (Sandberg and others 2001)

that are expected to greatly improve fuel loading estimates when they reach widespread use.

It is estimated that there will be a core set of 48

to 64 FCC’s in common usage with as many as

10,000 available in total describing the vast

range of fuel types and conditions that can exist

in wildlands across the country.

The most accurate method of estimating fuel

loading is to have fire managers measure it in

the field. Field estimation also enables

reflection of the effect of emission reduction

techniques on fuel loading. The most accurate

method of estimating fuel consumption is

through modeling (field measurement being

unreasonably difficult in virtually all cases). In
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2001 Smoke Management Guide 11.0 – Emission Inventories

the west, two fuel consumption models are

commonly used for this: the First Order Fire

Effects Model (FOFEM) (Reinhardt and others

1997) and Consume (Ottmar and others 1993).

These two models can provide very good estimates of fuel consumption if some basic knowledge of factors influencing fuel loading and

moisture are known.

Estimating fuel loading and consumption for

wildfire is much more difficult than for prescribed fire. For one thing, large wildfires often

burn through many different fuel types where

fuel loading can range from just a couple of tons

per acre to over 100 tons per acre. Also, the

science of predicting fuel consumption and

emissions from a fire burning in tree crowns is

extremely weak. The fuel type available from

wildfire report forms is generally for the point

of ignition rather than a reflection of fuel on

the majority of acres burned.

Emission Factors

Wildland and prescribed-fire emission factors

are contained in the EPA document AP-42 (EPA

1995) and in table 5.1 in the Smoke Source

Characteristics chapter. Accuracy may be

gained in an emissions inventory through

knowledge of the portion of fuel consumed in

the two primary consumption phases: flaming

and smoldering. Flaming consumption emits far

less emissions per unit of fuel consumed than

smoldering consumption. Estimation of the

flaming vs. smoldering ratio can be obtained

through fuel consumption modeling and with

knowledge of some influencing factors such as

rate of ignition, fuel moisture conditions, and

days since rain.

Federal Agency Reporting

The Forest Service, Bureau of Land Management, Fish and Wildlife Service, National Park

Service, and Bureau of Indian Affairs all have

mandatory reporting requirements for wildland

and prescribed fires although at present, they are

all somewhat different. These reports contain

some of the basic information needed to compile an emissions inventory. Within the next

couple of years, all federal agencies will be

moving toward a consolidated fire reporting

database through implementation of the Federal

Fire Policy.

Record keeping by state and private landowners

is much more variable and may or may not be

available to states wishing to compile an emissions inventory.

Forest Service

Forest Service forms FS-5100-29 (wildland

fire) and FS-5100–29T (prescribed fire) require

some of the basic inputs needed to compile an

emissions inventory. The wildland fire report

form requires reporting of acres burned within

the fire perimeter regardless of landowner plus

National Fire Danger Rating System (NFDRS)

fuel model. It is significant to note that the

instructions for estimating acres (USDA Forest

Service 1999) specify reporting of all acres

within the fire perimeter, unfortunately this

value is not likely to equal acres blackened by

fire. The number of acres blackened will

always be less than the number of acres within
Chapter 11 – Emission Inventories 2001 Smoke Management Guide

– 194 –

the fire perimeter so use of this value without

some adjustment will result in a serious

systematic overestimation of acres actually

burned and therefore of smoke produced. The

NFDRS fuel model reported is the one in which

the fire was burning at the time and place where

another required element, the fire intensity

level, was observed so it may or may not be

representative of the majority of acres burned.

Individual fire reports are collected throughout

the year and can be analyzed through an electronic system called FIRESTAT (USDA Forest

Service 1999).

Data collected by the Forest Service about

prescribed burning that is useful for compiling

an emissions inventory includes the prevailing

NFDRS fuel model; the total acres plus the

percent of acres burned; the preburn loading of

dead fuels 0-3 inches in diameter; 3+ inches in

diameter, and live; and the percent of these fuels

that consumed. The prescribed fire report

allows more accurate estimation of emissions

since the percent of acres burned is reported and

fuel loading and consumption is estimated in

three categories. The Forest Service reporting

system does not include estimates of duff

consumption which can contribute as much as

50 percent of the emissions from a prescribed

burn in certain areas under dry conditions,

though is generally much less than that.

Fish and Wildlife Service

The Fish and Wildlife Service also has mandatory fire reporting requirements and uses a

system called the Fire Reporting System (FRS)

for data collection. The FRS requires reporting

of project area size plus the actual burned area

or acres blackened for both wildland and prescribed fire. It also allows multiple entries for

NFDRS fuel model and links a specific area

burned to each. Fuel loading is assigned based

on NDFRS defaults in seven categories: dead

woody fuels of diameter 0-1/4”, 1/4-1", 1-3",

3+; herbaceous; live woody; and duff. Users

then specify percent consumption for each

fuelbed category. Custom fuel models may also

be defined. Data collected as part of the FRS

provides very good information for estimating

emissions from both wildland and prescribed

fire on Fish and Wildlife Service burns though

this is a very small part of total burning in most

areas of the country with notable exceptions in

the Southeastern states and Alaska.

Bureau of Land Management

The BLM reporting requirements include

estimation of area burned for wildland and

prescribed fire, less any unaltered areas as an

estimate of acres blackened. The fire behavior

fuel model that best represents the fuels in the

burn area is required as is the NFDRS fuel

model in the vicinity of the fire origin. The

model representing fuels in the burn area is

more appropriate for emissions estimation. In

addition, for prescribed fire up to two firebehavior fuel models can be selected and the

percent of the burned area assigned. Fuel

loading (tons per acre) and consumption (percent) can be reported in each of six fuel size

classes: 0-1", 1.1-3", 3.1-9", greater than 9",

shrub and herb, and litter and duff. If actual

field data for fuel loading and consumption is

not available, the most appropriate standard fuel

loading and consumption range can be selected.

Fuel loads can be assigned as light, average, or

heavy for the fire behavior fuel model type and

fuel consumption can be assigned as light,

average, or heavy making some customization

of the standard fuel models possible. The BLM

reporting system also accommodates the unique

requirements of estimating loading and consumption of prescribed burning of debris piles.
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2001 Smoke Management Guide 11.0 – Emission Inventories

National Park Service

The NPS has mandatory fire reporting requirements but the information collected is of little

use for emissions estimation, especially for

wildland fire. For wildland fires, acres burned is

required but the instructions don’t specify

whether perimeter acres or acres blackened is to

be reported. The only required description of

vegetation assigns one of three categories:

commercial forest land, non-commercial forest

land, or non-forest watershed which provides

little or no information for estimating fuel

loading and consumption. There is an optional

field for input of NFDRS fuel model but how

often this is used is unknown. Prescribed fire

and wildland fire for resource benefit requires

input of both NFDRS fuel model and a fire

behavior fuel model.

Bureau of Indian Affairs

Fire reporting requirements for the BIA are

similar to those for the NPS (see discussion

above). One minor difference exists in the

reporting of prescribed and wildland fire for

resource benefits, where a fire behavior model

may be input (but is not required). Further, a

fire danger rating (NFDR) fuel model cannot be

input.

Choosing the Appropriate

Accuracy and Precision in an

Emissions Inventory

The appropriate accuracy and precision for a

state emissions inventory should be designed

through analysis of the importance of the source

in the affected area (sub-state, state, or multistate area). Variables influencing the importance of prescribed burning as a source can be

assessed through addressing issues such as:

• whether there are current impacts from

prescribed fire or wildfire smoke,

• the aggressiveness of state goals for

emission reduction and air quality improvement,

• the trend in burning in the local area and

the rate of increase or decrease,

• a professional or financial motivation by

burners to track and/or reduce emissions,

• the need to associate wildland fire emissions with specific air pollution episodes.

Tables 11.1 and 11.2 summarize information

needed for a prescribed burning emissions

inventory and for a wildland fire emissions

inventory. Each table lists the categories of

information needed to inventory emissions,

proposes a minimum requirement for a basic

inventory, and lists options for increasing the

accuracy and precision of the inventory which

may be desirable if wildland fire in the area of

interest is of concern or controversial.1

Data requirements for producing an emissions

inventory for either prescribed burning or

wildland burning are very similar. They both

require information about the time period of the

burn, the location, the area actually burned, a

description of the fuelbed, how much fuel

burned, and site specific information for assigning an emission factor. A prescribed burning

___________________________________

1 Sandberg, David, V.; Peterson, Janice. 1997. Emission inventories for SIP development. An unpublished technical support

document to the EPA Interim Air Quality Policy on Wildland and Prescribed Fires. August 15, 1997. (Available from the authors or

online at http://www.epa.gov/ttncaaa1/faca/pbdirs/eisfor6.pdf ).
Chapter 11 – Emission Inventories 2001 Smoke Management Guide

– 196 –

Ta

ble 11.1. Summary of information needed to compile a prescribed fire emissions in

ventory and options for increasing accuracy.
– 197 –

2001 Smoke Management Guide 11.0 – Emission Inventories Ta

ble 11.2. Summary of information needed to compile a wildland fire emissions in

ventory and options for increasing accuracy
Chapter 11 – Emission Inventories 2001 Smoke Management Guide

– 198 –

emissions inventory includes extra information

about the type of burn or fuelbed arrangement

plus the purpose of the burn. These are optional

data items that may be useful in some cases. A

wildland burning emissions inventory includes

information about the control strategy used to

fight the fire.

Literature Citations

Anderson, Hal E. 1982. Aids to determining fuel

models for estimating fire behavior. USDA For.

Serv. Gen. Tech. Rep. INT-122. Intermt. For.

And Range Exp. Stn., Ogden, Utah. 22p.

Deeming, John E., Robert E. Burgan, and Jack D.

Cohen. 1977. The National Fire-Danger Rating

System – 1978. USDA Forest Service Gen.

Tech. Rep. INT-39. Intermt. For. And Range

Exp. Stn., Ogden, Utah. 63 p.

Despain, Don; Rodman, Ann; Schullery, Paul;

Shovic, Henry. 1989. Burned area survey of

Yellowstone National Park: the fires of 1988.

Yellowstone National Park, WY: U.S. Department of the Interior, National Park Service,

Yellowstone National Park. 14 p.

Environmental Protection Agency. 1995. Compilation of air pollutant emission factors AP-42.

Fifth Edition, Volume 1, Chapter 13.1: Wildfires

and prescribed burning. Supplement B, October

1996. U.S. Environmental Protection Agency,

Research Triangle Park, NC.

Ottmar, Roger D.; Burns, Mary F.; Hall, Janet N.;

Hanson, Aaron D. 1993. CONSUME users

guide. Gen. Tech. Rep. PNW-GTR-304. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research

Station. 17 p.

Reinhardt, Elizabeth D.; Keane, Robert E.; Brown,

James K. 1997. First Order Fire Effects Model,

FOFEM 4.0 user’s guide. GTR IMT-GTR-344.

Sandberg, David V. 1988. Emission reduction for

prescribed forest burning. In: Mathai, C.V.;

Stonefield, David H., eds. Transactions—

PM10: implementation of standards: An

APCA/EPA International Specialty Conference;

1988 February 22-25; San Francisco: 628-645.

Sandberg, David V.; Ottmar, Roger D., Cushon,

Geoffery H. 2001. Characterizing fuels in the

21st century. International Journal of Wildland

Fire 10:1-7.

USDA Forest Service. August 1999. FIRESTAT 5.0

User’s Guide. Fire and Aviation Management.

Washington DC.
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2001 Smoke Management Guide 12.0 – Administration and Assessment

ADMINISTRATION AND ASSESSMENT

Chapter 12
Chapter 12 – Administration and Assessment 2001 Smoke Management Guide

– 200 –
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2001 Smoke Management Guide 12.0 – Administration and Assessment

Smoke Management Program

Administration and Evaluation

Peter Lahm

Smoke management program administration can

range from activities conducted at the local burn

program level to a multi-state coordinated effort

to manage smoke. The EPA Interim Air Quality

Policy on Wildland and Prescribed Fires (Interim Policy) (EPA 1998) recommends that

smoke management programs be administered

by a central authority with clear decisionmaking capability. As smoke management

programs range from voluntary efforts to mandatory regulatory driven programs, the administration will vary accordingly1

. On the more

local level, the programs may be administered

by a group of land managers or private landholders seeking to coordinate burning efforts to

avoid excessive smoke impacts. Mandatory

regulatory driven smoke management programs

tend to be administered by tribal/state/district air

quality regulatory agencies or state forestry

entities. The administration of smoke management programs allows for a number of different

approaches to meet EPA objectives and to

maintain cooperative and interactive efforts to

manage the dual objectives of good air quality

and land stewardship.

The Interim Policy also recommends periodic

evaluation of smoke management programs to

ensure that air quality objectives are being met.

From the land management point of view, these

same reviews are critical to assessing whether

land management objectives are being met

under the smoke management program. EPA

also recommended periodic evaluation of smoke

management rule or regulation effectiveness as

part of its Interim Policy. For programs that are

under scrutiny by a concerned public or are

growing rapidly, continuous evaluation should

also be considered. All smoke management

efforts—from formal interagency smoke management plans to less structured efforts to

address smoke from individual fire operations—

can benefit from continuous and periodic evaluation. If a smoke management program changes

size, jurisdiction, or regulatory responsibilities,

the level of effort applied to managing smoke

should also change. To keep a program ahead of

growing air quality concerns, a continuous effort

to evaluate smoke management effectiveness is

useful. This evaluation is also critical for local

unit programs that are under formal state or

tribal smoke management plans. The evaluation

process has applicability to all types of fire,

including wildland fire under suppression,

wildland fire use and prescribed fire.

1 Examples of specific state smoke management programs are provided in chapter 4, section 4.2.
Chapter 12 – Administration and Assessment 2001 Smoke Management Guide

– 202 –

Smoke Management Program

Administration

Administration of a smoke management program is frequently a function of the size of the

burn program using a metric such as acres

burned or emissions generated, coupled with the

complexity of the local air quality issues. Fire

programs located in areas that are not rife with

Class I areas, PM10 non-attainment areas, or

smoke-sensitive transportation corridors are

commonly under voluntary smoke management

programs and may be locally administered.

These types of programs may be focused on

concerns of local area impacts such as nuisance

or transportation safety and can be well addressed through local level coordination among

burners. State forestry agencies and their

respective districts are frequently central points

for dissemination of information; many examples of this type of program can be found in

the southeastern states.

As air quality complexity rises with potential

smoke impacts on non-attainment areas or Class

I areas, legal requirements also rise, and frequently trigger a more centralized regulatorybased smoke management program. Attendant

with the increased program requirements is the

commensurate increased cost of the program.

Direct costs of smoke management program

administration are frequently recovered through

the charging of fees to burners. Fees are frequently based on emissions production or

tonnage of material to be consumed and are

used to offset an authority’s program administration costs. The increased indirect cost of

frequent reporting requirements and other

permitting tasks such as modeling of impacts

and smoke management plan preparation are

frequently overlooked. The most common

centralized program approach is administered

by the state or tribal air quality authority and

can be found in such states as Colorado. States

such as Florida and Oregon have opted to use

their forestry agencies to help directly manage

their smoke management programs. Oversight

by the respective air quality regulatory authority

is usually a part of such a program. There is an

option for interagency approaches to smoke

management program administration. This

approach blends the lines between air quality

regulatory agencies and land managers. Personnel from a land management agency may be

out-stationed to the respective air quality regulatory authority to assist in the smoke management program administration. The states of

Utah and Arizona use this approach respectively

and have avoided program management fees in

this fashion. This approach can also foster good

inter-agency communication and development

of joint air quality and land management objectives for smoke management programs.

The future of smoke management program

administration will be a reflection of the implementation of the Regional Haze Rule (40 CFR

Part 51), which creates a paradigm in which air

quality impacts are viewed in a regional sense

rather than by locality or state. Tribal smoke

management programs are being rapidly developed and will help support this regional approach. The establishment of multi-state smoke

management jurisdictions is rapidly becoming a

reality with a joint effort by Idaho and Montana

being a recent example. The PM2.5 and ozone

standards will also support this type of approach

as the impacts of smoke are viewed as a longrange transport issue. The inclusion of all

sources of fire emissions, such as agricultural

burning and wildland burning, into a singular

smoke management program is also a future

direction in these programs, and can already be

found in the Title 17 Rule in California.
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2001 Smoke Management Guide 12.0 – Administration and Assessment

Evaluation of Smoke

Management Programs

Size of Program — In lieu of any other parameter that can describe the activity level of a burn

program, the number of acres can be used to

trigger level of effort for smoke management

and subsequent evaluation of smoke effects. As

mentioned elsewhere, the representation of fire

activity in terms of emissions is more effective

for air quality purposes. In lieu of emissions,

fire size and fuel type can be used for triggering

different smoke management requirements.

Small burns located in remote areas with low

emissions may not dictate any evaluation greater

than tracking the activity level and date of burn.

However, more complex situations such as a

burn of several days’ duration with heavy

emissions located in the wildland/urban interface should be tracked more extensively for

smoke management effectiveness. This same

complex situation may track the effectiveness of

emission reduction practices. It may be beneficial if the criteria are established in consultation

with the local or state air regulatory agency. For

federal agencies, these criteria can also be

linked to the management plan’s monitoring

program. A post burn analysis of the smoke

management plan and the burn’s smoke effects

can be extremely valuable to all concerned

parties.

Intensity and Duration of Smoke Effects —

The intensity and duration of smoke impacts are

critical parameters that can represent a variety of

smoke management effectiveness measures.

Duration of smoke impacts upon the public, a

non-attainment area, a transportation corridor or

Class I area can be tracked and assessed through

direct air quality monitoring.2

 The public can be

tolerant of one day of heavy levels of smoke,

however consecutive day impacts may lead to a

rash of complaints. The criteria for evaluating a

program may be to assess the number of consecutive days/hours of impact to a specific area.

The intensity level of smoke impact also plays a

role, as short bursts of high levels of smoke

punctuated by clear air is frequently tolerable by

receptors. An application of this type of criteria

exists in Oregon where number and intensity of

smoke intrusions is tracked annually. This type

of criteria is applicable to individual incidents as

well.

Methods of tracking the intensity and duration

of smoke impact include:

• Number and type of public complaints

(citizen, doctor, hospital, etc.);

• Intrusion of smoke into designated smoke

sensitive areas through specific air quality

measurement;

• Violations or percent increase of criteria

pollutants attributable to smoke;

• Visibility impacts (local and regional).

As the National Ambient Air Quality Standards

(NAAQS) include both short term and annual

standards, the full impact of smoke on the

NAAQS may not be readily determined until

well after the burn season is completed, which

further supports the importance of incorporating

evaluation into a smoke management program.

Impacts on visibility were previously viewed on

an annual basis, however that has changed to

tracking impacts on Class I areas to determine

effects on the 20% clearest and 20% dirtiest

days. These methods for tracking and evaluation should be established prior to the event or

as part of the overall smoke management program as they can take significant planning or

coordination. Pre-planning for the air quality

element of the Wildland Fire Situation Analysis

used by federal agencies for wildland fires
Chapter 12 – Administration and Assessment 2001 Smoke Management Guide

– 204 –

(USDI and USDA Forest Service 1998) can also

be beneficial as the public, air quality regulatory

community, and land management entity has the

opportunity to increase acceptance of smoke

effects.

The evaluation criteria should be as quantitative

as possible in light of the complexity of the burn

or program and the air quality concerns of the

area. Proximity to non-attainment or Class I

areas should automatically trigger some programmatic evaluation. Visibility should be

considered in terms of plume blight, regional

haze and impacts on safety (transportation).

Conversely, a small incident with a small quantity or short duration of emissions in an area

with few air quality concerns should not warrant

extensive programmatic or individual incident

evaluation effort. Again, advance coordination

with concerned parties can help determine this

varying level of effort.

If an incident or program results in a smoke

intrusion above a pre-defined level such as

number of complaints or presence of smoke in

an avoidance area, the cause should be evaluated

as soon as possible. The breakdown of the

smoke management plan for an incident is

equivalent to the breakdown of the fire behavior

prescription for the burn. Smoke management

contingency programs are another element of a

smoke management program included in the

Interim Policy (EPA 1998). Factors such as

weather/smoke dispersion forecasting or fuel

condition changes can lead to such a smoke

intrusion and need to be evaluated quickly

following a failure of the system in order to be

addressed in a proactive fashion. Determination

of what caused the adverse air quality impact

allows for growth of the program through

implementation of changes to avoid future

recurrence. If a program or incident was conducted such that no smoke criteria were exceeded, evaluation of the factors which led to

success are also valuable in building confidence

among cooperating parties. The development of

an annual report which outlines the air quality

effects of a burning program or the smoke

management program demonstrates the commitment to addressing both land management and

air quality objectives and can show significant

and useful trends to concerned parties. The

knowledge that smoke impacts are being addressed effectively in terms of specific criteria is

valuable when working with the concerned

public and media.

Sources for Evaluation — Evaluation can be

the assessment of air quality monitoring data

collected by the land manager or utilization of

existing air quality networks as operated by a

regulatory agency (state/district/county/EPA/

tribe). The meteorological conditions under

which burns occur is another criteria that can be

evaluated to help assess the smoke management

program. For complex smoke areas, the use of

digital camera points could allow distribution of

the real-time images over the Internet to concerned parties, including the public. The concerned public can also be directly queried as to

the level of smoke levels and duration of effects.

Annual Evaluation — One of the most effective means of evaluating the smoke management

program is to hold periodic meetings amongst

the concerned parties such as the burners,

regulators and potentially-concerned public.

The frequency of such reviews should depend

on the air quality complexity and smoke impacts. Many statewide smoke management

programs meet annually to review the years’

activities, successes and problems. These

meetings could include review of activity/

emissions of burners, record-keeping efforts,

effects tracked through the previously mentioned methods, and discussion of program

logistics and costs. This same review meeting is

also an opportune time to plan for future
– 205 –

2001 Smoke Management Guide 12.0 – Administration and Assessment

changes, discuss emerging issues, and conduct

training if needed. The Interim Policy (EPA

1998) also urges such an evaluation process

occur annually. These annual sessions may be

an effective way of addressing an Interim Policy

goal of assessing the adequacy of the rules and

regulations pertaining to smoke management for

a respective state, tribe or other managing entity.

Reflecting the state of the smoke management

program, whether statewide or at the land

manager level, through the issuance of an

annual program report on smoke management

can be another technique for assessing the

program and informing the public of the investment into smoke management.

Continuous Evaluation — If a specific incident were to have significant adverse effects, it

might trigger immediate review to prevent a

repeat occurrence. This immediate incident

assessment can be an effective way of addressing pressing public concerns that may have

arisen due to the impacts. During a wildland

fire use incident, daily conference calls amongst

the land manager and the regulatory agencies

which discuss acres/fuels/emissions or qualitative smoke behavior can be very effective at

addressing smoke concerns. This real-time

evaluation can prevent conflict over smoke

impacts and can ensure accurate information be

provided to the public as well as incorporated

into the message transmitted to the media by the

respective agencies.

Incident debriefings should consider air quality

effects and how they were addressed. In wildland fire use, there is a continuous evaluation of

air quality as part of the Wildland Fire Situation

Analysis (USDI and USDA Forest Service

1998). Establishment of criteria for evaluation

of air quality effects prior to the actual event or

implementation of a program can allow for

greater buy-in by potentially affected parties

when the fire occurs. Criteria for evaluation

should also include indicators of success.

Literature Citations

Environmental Protection Agency. 1998. Interim air

quality policy on wildland and prescribed fires.

Office of Air Quality Planning and Standards,

Research Triangle Park, NC 27711. 39p.

40 CFR Part 51. Vol. 64 No. 126. Regional Haze

Regulations – Final Rule. July 1, 1999.

USDI and USDA Forest Service. 1998. Wildland

and prescribed fire management policy—

implementation procedures reference guide.

National Interagency Fire Center, Boise, ID. 81

pp. and appendices.
Chapter 12 – Administration and Assessment 2001 Smoke Management Guide

– 206 –
2001 Smoke Management Guide Glossary

– 207 –

APPENDIX
Appendix A – Glossary 2001 Smoke Management Guide

– 208 –
2001 Smoke Management Guide Glossary

– 209 –

Appendix A

Glossary of Fire and Smoke

Management Terminology

The terms listed below were either taken from existing glossaries or developed specifically for this

Guide. Where terms were taken from an existing glossary or document, the source reference is indexed

in brackets (e.g. [source number]), with full reference citations provided at the end of the glossary.

Note: Although the referenced definitions in this glossary were taken from other sources, the editors

have revised or changed many of them from their original version.

Absorption coefficient A measure of the ability of particles or gases to absorb photons; a number that is proportional to the number of photons removed from the sight

path by absorption per unit length. (See Extinction coefficient). [2]

Activity fuel Debris resulting from such human activities as road construction, logging, pruning, thinning, or brush cutting. It includes logs, chunks, bark,

branches, litter, stumps, and broken understory trees or brush.

Activity level Fuels resulting from, or altered by, forestry practices such as timber

harvest or thinning, as opposed to naturally created fuels. [1]

Adiabatic lapse rate Rate of decrease of temperature with increasing height of a rising air

parcel without an exchange of heat at the parcel boundaries. (See Dry

adiabatic lapse rate, Saturated adiabatic lapse rate, and Atmospheric

stability).

Advection The transfer of atmospheric properties by the horizontal movement of air,

usually in reference to the transfer of warmer or cooler air, but may also

refer to moisture. [1]

Aerial ignition Ignition of fuels by dropping incendiary devices or materials from aircraft. [1]

Aerosol A suspension of microscopic solid or liquid particles in a gaseous medium, such as smoke and fog. [2]
Appendix A – Glossary 2001 Smoke Management Guide

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Air mass An extensive body of air having similar properties of temperature and

moisture. [1]

Air pollution The general term referring to the undesirable concentration of substances

(gases, liquids, or solid particles) to the atmosphere that are foreign to the

natural atmosphere or are present in quantities exceeding natural concentrations. [1]

Air quality The composition of air with respect to quantities of pollution therein;

used most frequently in connection with “standards” of maximum acceptable pollutant concentrations. [1]

Allowable emissions The emissions rate that represents a limit on the emissions that can occur

from an emissions unit. This limit may be based on a federal, state, or

local regulatory emission limit determined from state or local regulations

and/or 40 Code of Federal Regulations (CFR) Parts 60, 61, and 63. [3]

Ambient air Any unconfined portion of the atmosphere: open air, surrounding air. [4]

Ambient standards Specific target threshold concentrations and exposure durations of pollutants based on criteria gauged to protect human health and the welfare of

the environment. Ambient standards are not emissions limitations on

sources, but usually result in such limits being placed on source operation

as part of a control strategy to achieve or maintain an ambient standard.

[3]

Anthropogenic Produced by human activities. [2]

Area sources A source category of air pollution that generally extends over a large

area. Prescribed burning, field burning, home heating, and open burning

are examples of area sources. [1]

Atmospheric inversion (1) Departure from the usual increase or decrease with altitude of the

value of an atmospheric property (in fire management usage, nearly

always refers to an increase in temperature with increasing height). (2)

The layer through which this departure occurs (also called inversion

layer). The lowest altitude at which the departure is found is called the

base of the inversion. (See Atmospheric stability; Temperature inversion;

Mixing height; Mixing layer; Stable atmosphere; Unstable atmosphere;

Subsidence inversion) [1]
2001 Smoke Management Guide Glossary

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Atmospheric pressure The force exerted by the weight of the atmosphere, per unit area. At sea

level the atmospheric pressure fluctuates around 1013 millibars (mb). At

5,000 feet (~1,500 m) above sea level the atmospheric pressure fluctuates

around 850 mb. (See Standard atmosphere).

Atmospheric stability The degree to which vertical motion in the atmosphere is enhanced or

suppressed. (See Atmospheric inversion; Temperature inversion; Mixing

height; Mixing layer; Stable atmosphere; Unstable atmosphere). [1]

Attainment Area An area considered having air quality as good as or better than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean

Air Act. Note that an area may be in attainment for one or more pollutants but be a nonattainment area for one or more other pollutants. (See

Non-attainment area). [3]

Avoidance A smoke emission control strategy that considers meteorological conditions when scheduling prescribed fires in order to avoid incursions into

smoke sensitive areas. [1]

Background level In air pollution control, the concentration of air pollutants in a definite

area during a fixed period of time prior to the starting up, or the stoppage,

of a source of emission under control. In toxic substances monitoring,

the average presence in the environment, originally referring to naturally

occurring phenomena. [1]

Best Available Control An emission limitation action based on the maximum degree of

Measures (BACM) emission reduction (considering energy, environmental, and

economic impacts) achievable through application of production

processes and available methods, systems, and techniques. [4]

Burn severity A qualitative assessment of the heat pulse directed toward the ground

during a fire. Burn severity relates to soil heating, large fuel and duff

consumption, consumption of the litter and organic layer beneath trees

and isolated shrubs, and mortality of buried plant parts. [1]

Carbon dioxide (CO2) A colorless, odorless, nonpoisonous gas, which results from fuel combustion and is normally a part of the ambient air. [1]

Carbon monoxide (CO) A colorless, odorless, poisonous gas produced by incomplete fuel combustion. Carbon monoxide is a criteria pollutant and is measured in parts

per million. (See Criteria pollutants).
Appendix A – Glossary 2001 Smoke Management Guide

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Carcinogen Any substance that can cause or contribute to the production of cancer.

[1]

Clean Air Act A federal law enacted to ensure that air quality standards are attained and

maintained. Initially passed by Congress in 1963, it has been amended

several times. [1]

Combustion efficiency The amount of products of incomplete combustion released relative to

amounts produced from theoretically perfect combustion, expressed as a

dimensionless percentage. Because perfect combustion produces only

CO2 and water, its combustion efficiency is 1.0. In combustion of

wildland fuels, combustion efficiency can roughly range from as high as

0.95 (for flaming combustion) to as low as 0.65 (for smoldering combustion).

Condensation nuclei The small nuclei or particles with which gaseous constituents in the

atmosphere (e.g., water vapor) collide and adhere. [2]

Consumption The amount of a specified fuel type or strata that is removed through the

fire process, often expressed as a percentage of the preburn weight. [1]

Convection column The rising column of gases, smoke, fly ash, particulates, and other debris

produced by a fire. The column has a strong vertical component indicating that buoyant forces override the ambient surface wind. [1]

Convergence The term for horizontal air currents merging together or approaching a

single point, such as at the center of a low-pressure area producing a net

inflow of air. The excess air is removed by rising air currents. Expansion of the rising air above a convergence zone results in cooling, which

in turn often gives condensation (clouds) and sometimes precipitation.

[1]

Criteria Pollutants Pollutants deemed most harmful to public health and welfare and that can

be monitored effectively. They include carbon monoxide (CO), lead

(Pb), nitrogen oxides (NOx ), sulfur dioxide (SO2), Ozone (O3), particulate matter (PM) of aerodynamic diameter less than or equal to 10 micrometers (PM10) and particulate matter of aerodynamic diameter less

than or equal to 2.5 micrometers (PM2.5). [3]

Deciview A unit of visibility proportional to the logarithm of the atmospheric

extinction. (See Extinction coefficient; Visibility; Visual range). [2]
2001 Smoke Management Guide Glossary

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De minimis level A level of emission or impact that is too small to be considered of concern. From the Latin phrase “de minimis non curat lex,” meaning the law

is not concerned with trifles.

Dew point Temperature to which a specified parcel of air must cool, at constant

pressure and water-vapor content, in order for saturation to occur. The

dew point is always lower than the wet-bulb temperature, which is always

lower than the dry-bulb temperature, except when the air is saturated and

all three values are equal. Fog may form when temperature drops to

equal the dew point. (See Dry-bulb temperature; Wet-bulb temperature).

[1]

Dormant season burning Prescribed burning conducted during the time of year when vegetation is

not actively growing. In some parts of the country, dormant season burns

are typically less intense than growing season burns.

Drift smoke Smoke that has drifted from its point of origin and is no longer dominated by convective motion. May give false impression of a fire in the

general area where the smoke has drifted. [1]

Dry adiabatic lapse rate Adiabatic cooling in a dry atmosphere. Usually about -5.5 degrees

(DALR) Fahrenheit per 1,000 feet (~-10 degrees centigrade per kilometer).

(See Adiabatic lapse rate; Saturated adiabatic lapse rate).

Dry-bulb temperature Originally, the temperature measured with a mercury thermometer whose

bulb is dry. Commonly it is a measure of the atmospheric temperature

without the influence of moisture. (See Wet-bulb temperature; Dew

point).

Duff The partially decomposed organic material above mineral soil that lies

beneath the freshly fallen twigs, needles, and leaves and is often referred

to as the F (fermentation) and H (humus) layers. Duff often consumes

during the less efficient smoldering stage and has the potential to produce

more than 50 percent of the smoke from a fire.

Ecosystem health A condition where the parts and functions of an ecosystem are sustained

over time and where the system’s capacity for self- repair is maintained,

allowing goals for uses, values, and services of the ecosystem to be met.
Appendix A – Glossary 2001 Smoke Management Guide

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Ecosystem maintenance A prescribed fire or wildland fire managed for resource benefits that is

burn utilized to mimic the natural role of fire in an ecosystem that is currently

in an ecologically functional and fire resilient condition. [5]

Ecosystem Processes The actions or events that link organisms and their environment, such as

predation, mutualism, successional development, nutrient cycling, carbon

sequestration, primary productivity, and decay. Natural disturbance

processes often occur with some periodicity

Ecosystem Restoration The re-establishment of natural vegetation and ecological processes that

may be accomplished through the reduction of unwanted and/or unnatural levels of biomass. Prescribed fires, wildland fires managed for resource benefits and mechanical treatments may be utilized to restore an

ecosystem to an ecologically functional and fire resilient condition. [5]

Extinction coefficient A measure of the ability of particles or gases to absorb and scatter photons from a beam of light; a number that is proportional to the number of

photons removed from the sight path per unit length. (See Absorption

coefficient; Deciview; Visibility; Visual range). [2]

Effective windspeed The mid-flame windspeed adjusted for the effect of slope on fire spread.

[1]

Emission factor (EFp) The mass of particulate matter produced per unit mass of fuel consumed

(pounds per ton, grams per kilogram). [1]

Emission inventory A listing, by source, of the amount of air pollutants discharged into the

atmosphere of a community. [3]

Emission rate The amount of an emission produced per unit of time (lb./min or g/sec).

[1]

Emission reduction A strategy for controlling smoke from prescribed fires that minimizes the

amount of smoke output per unit area treated. [1]

Emission Standards A general type of standard that limit the mass of a pollutant that may be

emitted by a source. The most straightforward emissions standard is a

simple limitation on mass of pollutant per unit time (e.g., pounds of

pollutant per hour). [3]
2001 Smoke Management Guide Glossary

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Extinction The attenuation of light due to scattering and absorption as it passes

through a medium. [2]

Federal Class I area In 1977, Congress identified 156 national parks, wilderness areas, international parks and other areas that were to receive the most stringent

protection from increases in air pollution. It also set a visibility goal for

these areas to protect them from future human-caused haze, and to

eliminate existing human-caused haze, and required reasonable progress

toward that goal. [5]

Fine fuel moisture The moisture content of fast-drying fuels that respond to changes in

moisture within 1 hour or less; such as, grass, leaves, ferns, tree moss,

pine needles, and small twigs (0-1/4" or 0.0-0.6 cm). (See Fuel moisture

content; One-hour timelag fuels). [1]

Fire-adapted ecosystem An ecosystem with the ability to survive and regenerate in a fire-prone

environment.

Fire-dependent An ecosystem that cannot survive without periodic fire.

ecosystem

Fire exclusion The policy and practice of eliminating fire from an area to the greatest

extent possible, through suppression of wildland fires and a lack of fire

use.

Fire regime Periodicity and pattern of naturally occurring fires in a particular area or

vegetative type, described in terms of frequency, biological severity, and

area extent. [1]

Fire regime groups Classes of fire regimes grouped by categories of frequency (expressed as

mean fire return interval) and severity. Refers specifically to five groups

used in Federal policy and planning: 0-35 years, low severity; 0-35 years,

stand replacement; 35-100 years, mixed severity; 35-100 years, stand

replacement; 200+ years, stand replacement. (See Fire return interval;

Fire regime).

Fire return interval Mean fire return interval. A mean, area-weighted time (in years) between

successive fires for a respective area (i.e., the interval between two
Appendix A – Glossary 2001 Smoke Management Guide

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successive fire occurrences); the size of the area must be specified.

Fire severity (See Burn severity.)

Fire use The combination of wildland fire use and prescribed fire application to

meet resource objectives. [6]

Fireline intensity The rate of heat release per unit time per unit length of fire front. Numerically, it is the product of the heat yield, the quantity of fuel consumed in the fire front, and the rate of spread. [1]

Flaming combustion Luminous oxidation of gases evolved from the rapid decomposiphase tion of fuel. This phase follows the pre-ignition phase and precedes the

smoldering combustion phase, which has a much slower combustion rate.

Water vapor, soot, and tar comprise the visible smoke. Relatively efficient combustion produces minimal soot and tar, resulting in white

smoke; high moisture content also produces white smoke. (See Soot;

Smoldering combustion phase). [1]

Forest floor material Surface organic material, including duff, litter, moss, peat, down-dead

woody pieces.

Forest residue Accumulation in the forest of living or dead (mostly woody) material that

is added to and rearranged by human activities such as harvest, cultural

operations, and land clearing. (See Activity fuel). [1]

Fuel loading The amount of fuel present expressed quantitatively in terms of weight of

fuel per unit area. This may be available fuel (consumable fuel) or total

fuel and is usually dry weight. [1]

Fuel moisture content The quantity of moisture in fuel expressed as a percentage of the weight;

derived by weighing fuel sample both before and after thorough drying at

(nominally) 212 degrees F (100 degrees C). (See Fine fuel moisture). [1]

Fuel reduction Manipulation, including combustion, or removal of fuels to reduce the

likelihood of ignition and/or to lessen potential damage and resistance to

control. [1]

Fuel size class A category used to describe the diameter of down dead woody fuels.

Fuels within the same size class are assumed to have similar wetting and

drying properties, and to preheat and ignite at similar rates during the

combustion process. [1]
2001 Smoke Management Guide Glossary

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Fuel treatment Manipulation or removal of fuels to reduce the likelihood of ignition and/

or to lessen potential intensity, rate of spread, severity, damage, and

resistance to control. Examples include lopping, chipping, crushing,

piling and burning. [1]

Fuel type An identifiable association of fuel elements of distinctive species, form,

size, arrangement, or other characteristics that will cause a predictable

rate of spread or resistance to control under specified weather conditions.

[1]

Glowing combustion Oxidation of solid fuel accompanied by incandescence. All

phase volatiles have already been released and there is no visible smoke. This

phase follows the smoldering combustion phase and continues until the

temperature drops below the combustion threshold value, or until only

non-combustible ash remains. (See Combustion; Flaming combustion

phase; Smoldering combustion phase). [1]

Growing season burning Prescribed burns conducted during the time of year when vegetation is

actively growing, or when leaves have matured but not fallen.

Hazard reduction Any treatment of living and dead fuels that reduces the threat of ignition

and spread of fire. [1]

Haze A sufficient concentration of atmospheric aerosols to be visible. The

particles are so small that they cannot be seen individually, but are still

effective in visual range restriction. (See Visual range; Extinction; Absorption coefficient; Regional haze). [2]

Heat release rate (1) Total amount of heat produced per unit mass of fuel consumed per

unit time. (2) Amount of heat released to the atmosphere from the

convective-lift fire phase of a fire per unit time. [1]

Hydrocarbons Compounds containing only hydrogen and carbon. [2]

IMPROVE Interagency Monitoring of Protected Visual Environments. A cooperative

visibility monitoring effort, using a common set of standards across the

United States, between the EPA, Federal land management agencies, and

state air agencies. [5]
Appendix A – Glossary 2001 Smoke Management Guide

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Integrating nephelometer An instrument that measures the amount of light scattered (scattering

coefficient) and can be used to measure particulate matter concentrations

from fires. [2]

Inversion (See Atmospheric inversion) [2]

Isothermal layer A layer of finite thickness in any medium in which the temperature

remains constant.

Landscape An area composed of interacting and inter-connected ecosystems that are

repeated because of the geology, landform, soils, climate, biota, and

human influences throughout the area. A landscape is composed of

watersheds and smaller ecosystems.

Lead (Pb) A criteria pollutant, elemental lead emitted by stationary and mobile

sources can cause several types of developmental effects in children

including anemia and neurobehavioral and metabolic disorders. Nonferrous smelters and battery plants are the most significant contributors to

atmospheric lead emissions. (See Criteria pollutants). [3]

Litter The top layer of forest floor, composed of loose debris of dead sticks,

branches, twigs, and recently fallen leaves or needles; little altered in

structure by decomposition. (See Duff; Forest floor material). [1]

Mass fire A fire resulting from many simultaneous ignitions that generates a high

level of energy output. [1]

Mean fire interval (See Fire return interval)

Micron Micrometer (mm)—a unit of length equal to one millionth of a meter; the

unit of measure for wavelength and also for the mean aerodynamic

diameter of atmospheric aerosols. [2]

Mixing height Measured from the surface upward, the height to which relatively vigorous mixing occurs in the atmosphere due to turbulence and diffusion.

Also called mixing depth. [1]

Mixing layer That portion of the atmosphere from the surface up to the mixing height.

This is the layer of air within which pollutants are mixed by turbulence

and diffusion. Also called mixed layer. (See Ventilation Index). [1]
2001 Smoke Management Guide Glossary

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Mopup Extinguishing or removing burning material near control lines, felling

snags, and trenching logs to prevent rolling after an area has burned, to

reduce the chance of fire spreading beyond the control lines, or to reduce

residual smoke. [1]

Mosaic The central spatial characteristic of a landscape. The intermingling of

plant communities and their successional stages, or of disturbance (especially fire), in such a manner as to give the impression of an interwoven,

“patchy” design. [1]

National Ambient Air Maximum recommended concentrations of criteria pollutants

Quality Standards to maintain reasonable standards of air quality. (See criteria

(NAAQS) pollutants). [3]

National Wildfire National interagency operational group authorized by the U.S.

Coordinating Group Secretaries of Agriculture and Interior and the National Associa-

(NWCG) tion of State Foresters, designed to coordinate fire management programs

of participating federal, state, local and private agencies to avoid wasteful

duplication and provide a means of constructive cooperation.

Natural background An estimate of the visibility conditions at each Federal Class I area

condition that would exist in the absence of human-caused impairment. [5]

Nitrogen dioxide (NO2) The result of nitric oxide combining with oxygen in the atmosphere. A

major component of photochemical smog. [1]

Nitrogen Oxide[s] (NOx) A class of compounds that are respiratory irritants and that react x with

volatile organic compounds (VOCs) to form ozone (O3). The primary

combustion product of nitrogen is nitrogen dioxide (NO2). However,

several other nitrogen compounds are 2 usually emitted at the same time

(nitric oxide [NO], nitrous oxide [NO], etc.), and these may or may not

be distinguishable in available test data. [3]

Non-attainment area An area identified by an air quality regulatory agency through ambient

air monitoring (and designated by the Environmental Protection Agency),

that presently exceeds federal ambient air standards. (See Attainment

area). [1]

Nuisance smoke The amount of smoke in the ambient air that interferes with a right or

privilege common to members of the public, including the use or enjoyment of public or private resources.
Appendix A – Glossary 2001 Smoke Management Guide

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One-hour timelag fuels Fuels consisting of dead herbaceous plants and roundwood less than

about one-fourth inch (6.4 mm) in diameter. Also included is the uppermost layer of needles or leaves on the forest floor. Fuel elements of this

size usually respond to changes in moisture within one hour or less,

hence the term 1-hr timelag. (See Fuel moisture content; Fine fuel moisture). [1]

One-hundred-hour Dead fuels consisting of roundwood in the size range of 1 to 3

timelag fuels inches (2.5 to 7.6 cm) in diameter and very roughly the layer of litter

extending from approximately three-fourths of an inch (1.9 cm) to 4

inches (10 cm) below the surface. Fuel elements of this size usually

respond to changes in moisture within about one hundred hours or 3 to 5

days, hence the term 100-hr timelag. (See Fuel moisture content). [1]

One-thousand-hour Dead fuels consisting of roundwood 38 inches in diameter and the

timelag fuels layer of the forest floor more than about 4 inches below the surface. Fuel

elements of this size usually respond to changes in moisture within about

one thousand hours or 4 to 6 weeks, hence the term 1000-hr timelag.

(See Fuel moisture content). [1]

Ozone (O3) A criteria pollutant, ozone is a colorless gas, ozone is the major component of smog. Ozone is not emitted directly into the air but is formed

through complex chemical reactions between precursor emissions of

volatile organic compounds (VOCs) and NOx in the presence of sunlight.

(See Criteria pollutants). [3]

Particulate matter Any liquid or solid particle. “Total suspended particulates” as used in air

quality are those particles suspended in or falling through the atmosphere. They generally range in size from 0.1 to 100 microns. [1]

Piling-and-burning Piling slash resulting from logging or fuel management activities and

subsequently burning the individual piles. [1]

PM10 Particulate matter of mass median aerodynamic diameter (MMAD) less

than or equal to 10 micrometers. A measure of small solid matter suspended in the atmosphere that can penetrate deeply into the lung where

they can cause respiratory problems. Emissions of PM10 are significant

from fugitive dust, power plants, commercial boilers, metallurgical

industries, mineral industries, forest and residential fires, and motor

vehicles. (See Criteria pollutants). [3]
2001 Smoke Management Guide Glossary

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PM2.5 Particulate matter of mass median aerodynamic diameter (MMAD) less

than or equal to 2.5 micrometers A measure of fine particles of particulate matter that come from fuel combustion, agricultural burning,

woodstoves, etc. Often called respirable particles, as they are more

efficient at penetrating lungs and causing damage. (See Criteria pollutants). [3]

Point sources Large, stationary, identifiable sources of emissions that release pollutants

into the atmosphere. Sources are often defined by state or local air regulatory agencies as point sources when they annually emit more than a

specified amount of a given pollutant, and how state and local agencies

define point sources can vary. [3]

Precursor emissions Emissions from point or regional sources that transform into pollutants

with varied chemical properties. [2]

Prescribed fire Any fire ignited by management actions to meet specific objectives. A

written, approved prescribed fire plan must exist, and NEPA requirements must be met, prior to ignition. This term replaces management

ignited prescribed fire. [6]

Prescribed natural fire Obsolete term. (See Wildland fire use) [6]

Prescription A written statement defining the objectives to be attained as well as the

conditions of temperature, humidity, wind direction and speed, fuel

moisture, and soil moisture, under which a fire will be allowed to burn.

A prescription is generally expressed as acceptable ranges of the prescription elements, and the limit of the geographic area to be covered. [1]

Prevention of Significant A program identified by the Clean Air Act to prevent air quality

Deterioration (PSD) and visibility degradation and to remedy existing visibility problems.

Areas of the country are grouped into 3 classes that are allowed certain

degrees of pollution depending on their uses. National Parks and Wilderness Areas meeting certain criteria are “Class I” or “clean area” in that

they have the smallest allowable increment of degradation. [1]

Reasonably Available Control measures developed by EPA that apply to residential

Control Measures wood combustion, fugitive dust, and prescribed and silvicultural

(RACM) burning in and around “moderate” PM10 nonattainment areas. RACM is

designed to bring an area back into attainment and uses a smoke management program that relies on weather forecasts for burn/no-burn days.
Appendix A – Glossary 2001 Smoke Management Guide

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(See Best Available Control Measures [BACM]). [1]

Regional Haze Visibility impairment caused by the cumulative air pollutant emissions

from numerous sources over a wide geographic area. (See Haze).

Relative humidity (RH) The ratio of the amount of moisture in the air, to the maximum amount of

moisture that air would contain if it were saturated. [1]

Residual combustion (See Smoldering combustion phase)

phase

Residual smoke Smoke produced by smoldering material. The flux of smoke originating

well after the active flaming combustion period with little or no vertical

buoyancy, and, therefore, most susceptible to subsidence inversions and

down-valley flows. (See Nuisance smoke). [1]

“Right-to-burn” Law A state law that provides liability protection for prescribed burners,

providing they meet specified training and planning criteria. The degree

of liability protection varies by state.

Saturated adiabatic Adiabatic cooling in an atmosphere that is saturated with moislapse rate (SALR) ture. Usually about -3.0 degrees Fahrenheit per 1,000 feet (~-5.5 degrees

centigrade per kilometer). (See Adiabatic lapse rate; Dry adiabatic lapse

rate).

Scattering (light) An interaction of a light wave with an object that causes the light to be

redirected in its path. In elastic scattering, no energy is lost to the object.

[2]

Secondary aerosols Aerosol formed by the interaction of two or more gas molecules and/or

primary aerosols. [2]

Slash (see Activity fuel) [1]

Smoke concentration The amount of combustion products (in micrograms per cubic meter)

found in a specified volume of air. [1]

Smoke intrusion Smoke from prescribed fire entering a designated area at unacceptable

levels. [1]
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Smoke management The policies and practices implemented by air and natural resource

managers directed at minimizing the amount of smoke entering populated areas or impacting sensitive sites, avoiding significant deterioration

of air quality and violations of National Ambient Air Quality Standards,

and mitigating human-caused visibility impacts in Class I areas.

Smoke management A standard framework of requirements and procedures for manprogram (SMP) aging smoke from prescribed fires, typically developed by States or

Tribes with cooperation from stakeholders.

Smoldering combustion Combined processes of dehydration, pyrolysis, solid oxidation,

phase and scattered flaming combustion and glowing combustion, which occur

after the flaming combustion phase of a fire; often characterized by large

amounts of smoke consisting mainly of tars. Emissions are at twice that

of the flaming combustion phase. (See Combustion; Flaming combustion

phase, Glowing combustion phase). [1]

Soot Carbon dust formed by incomplete combustion. [4]

Stable atmosphere A condition of the atmosphere in which vertical motion in the atmosphere is suppressed. Stability suppresses vertical motion and limits

smoke dispersion. In a stable atmosphere the temperature of a rising

parcel of air becomes cooler than its surroundings, causing it to sink back

to the surface. Also called stable air. (See Atmospheric stability; Unstable atmosphere).

Standard atmosphere A horizontal and time-averaged vertical structure of the atmosphere

where standard atmospheric pressure at sea level is 1,013 mb, at 5,000

feet (~1,500 m) it is 850 mb, at 10,000 feet (~3,000 m) it is 700 mb, and

the standard atmospheric pressure at 20,000 feet (~6,000 m) is 500 mb.

Actual pressure is nearly always within about 30% of standard pressure.

(See Atmospheric pressure).

State Implementation Plans devised by states to carry out their responsibilities under the

Plan (SIP) Clean Air Act. SIPs must be approved by the U.S. Environmental Protection Agency and include public review. Same as Tribal Implementation

Plan (TIP). [5]

Subsidence inversion An inversion caused by settling or sinking air from higher elevations.

(See Atmospheric inversion; Temperature inversion).
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Sulfur dioxide (SO2) A gas (SO2) consisting of one sulfur and two oxygen atoms. Of interest

because sulfur dioxide converts to an aerosol that is a very efficient at

scattering light. Also, it can convert into acid droplets consisting primarily of sulfuric acid. (See Criteria pollutants). [2]

Sulfur oxides (SO) A class of colorless, pungent gases that are respiratory irritants and

precursors to acid rain. Sulfur oxides are emitted from various combustion or incineration sources, particularly from coal combustion. [3]

Temperature inversion In meteorology, a departure from the normal decrease of temperature

with increasing altitude such that the temperature is higher at a given

height in the inversion layer than would be expected from the temperature below the layer. This warmer layer leads to increased stability and

limited vertical mixing of air. [2]

Ten-hour timelag fuels Dead fuels consisting of roundwood 1/4 to l-inch (0.6 to 2.5 cm) in

diameter and, very roughly, the layer of litter extending from immediately below the surface to 3/4 inch (1.9 cm) below the surface. Fuel

elements of this size usually respond to changes in moisture within about

ten hours or less than a day, hence the term 10-hr timelag. (See Fuel

moisture content). [1]

Total fuel All plant material both living and dead that can burn in a worst-case

situation. [1]

Tribal Implementation Plans devised by tribal governments to carry out their responsiPlan (TIP) bilities under the Clean Air Act. TIPs must be approved by the U.S.

Environmental Protection Agency and include public review. Same as

State Implementation Plan (SIP). [5]

Understory burn A fire that consumes surface fuels but not overstory trees (in the case of

forests or woodlands) and shrubs (in the case of shrublands).

Unstable atmosphere A condition of the atmosphere in which vertical motion in the atmosphere is favored. Smoke dispersion is enhanced in an unstable atmosphere. Thunderstorms and active fire conditions are common in

unstable atmospheric conditions. In an unstable atmosphere the temperature of a rising parcel of air remains warmer than its surroundings,

allowing it to continue to rise. Also called unstable air. (See Atmospheric stability; Stable atmosphere).
2001 Smoke Management Guide Glossary

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Ventilation index An index that describes the potential for smoke or other pollutants to

ventilate away from its source. Also called clearing index. It is the

product of mixing height and the mean wind within the mixed layer

(trajectory wind).

Visual range Maximum distance at which a given object can just be seen by an observer with normal vision. [1]

Volatile Organic Any compound of carbon, excluding carbon monoxide, carbon

Compounds (VOC) dioxide, carbonic acid, metallic carbides or carbonates, and ammonium

carbonate that participates in atmospheric photochemical reactions. [3]

Wet-bulb temperature Originally, the temperature measured with a mercury thermometer whose

bulb is wrapped in a moist cloth. Commonly it is a measure of the

atmospheric temperature after it has cooled by evaporating moisture.

(See Dry-bulb temperature; Dew point).

Wildland Fire Any non-structure fire, other than prescribed fire, that occurs in the

wildland. This term encompasses fires previously called both wildfires

and prescribed natural fires. [6]

Wildfire An unwanted wildland fire. This term was only included [in the new

Federal policy] to give continuing credence to the historic fire prevention

products. This is NOT a separate type of fire under the new terminology.

[6]

Wildland Fire (See Wildland Fire Use) [6]

Managed for Resource

Objectives

Wildland Fire Use The management of naturally ignited wildland fires to accomplish specific pre-stated resource management objectives in predefined geographic

areas outlined in Fire Management Plans. Wildland fire use is not to be

confused with “fire use,” which is a broader term encompassing more

than just wildland fires. [6]

Wildland Urban The line, area, or zone, where structures and other human develInterface (WUI) opment meet or intermingle with undeveloped wildland or vegetative

fuel.
Appendix A – Glossary 2001 Smoke Management Guide

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Literature Citations

1. National Wildfire Coordinating Group. 1996.

Glossary of wildland fire terminology. PMS

205. Boise, ID: National Wildfire Coordinating

Group, National Interagency Fire Center. 162

p.

2. Malm, William C. 1999. Introduction to

visibility. Cooperative Institute for Research in

the Atmosphere. NPS Visibility Program,

Colorado State University, Fort Collins, CO:

79 p.

3. U.S. Environmental Protection Agency. 1999.

Handbook for criteria pollutant inventory

development: a beginner’s guide for point and

area sources. EPA-OAQPS-454-99-037.

Research Triangle Park, NC. U.S. Environmental Protection Agency, Office of Air Quality

Planning and Standards.

4. Terms of Environment. [online]. 1998. U.S.

Environmental Protection Agency, Office of

Communication, Education, and Public Affairs.

Available: URL http://www.epa.gov/

OCEPAterms/intro.htm [2001, Dec.].

5. Policy for categorizing fire emissions. [online].

2001. Natural Background Task Team, Fire

Emissions Joint Forum, Western Regional Air

Partnership. Available: URL [2001, Nov.].

6. USDI and USDA Forest Service. 1998. Wildland and prescribed fire management policyimplementation procedures reference guide.

National Interagency Fire Center, Boise, ID. 81

pp. and appendices.