The: staff of the Southern Fomst Fim Labratory resptfully dedicP-iLes this work 

to the memory of Rob& W. Cooper whose guidance and inspiration long helpd to 

b~ng science to the art of prescribed burning in the South. 

HOW THIS BOOK WAS WRITTEN 

Contributions from many scientists were required to complete this Guidebook. These contributors 

are listed as authors of the individual Chapters, and they take sole responsibility for technical content. 

Advice on overall content and applicability for users was provided by a group of eomprlers. The senior 

compiler worked directly with the authors to achieve a team product. 

The compilers were: 

SENIOR COMPILER 

Hugh E. Mobley, Technical Specialist 

Southeastern Area, State and Private Forestsy 

USDA Forest Service 

Atlanta, Georgia 

ASSOGIATE COMPILERS 

Charles R. Barden, Executive Director 

Texas Air Control Board 

Austin, nxas 

A. Bigler Crow, Professor of Forestry 

Louisiana State University 

Baton Rouge, Louisiana 

Damin E. Fendec Director of Land Management 

International Paper Company 

Mobile, Alabama 

David M. Jay, Director 

Division of Fire Management 

Region 8, USDA Forest Service 

Atlanta, Georgia 

Ralph C. WinkworLh, Di~ctor 

Division of Forest Resources 

Raleigh, North Carolina 

Additional contributions in the form of technical reviews and assistance have helped to shape the 

final result. me~e are acknowledged in a Special Acknowledgments Section following the Glossary. 
USDA Forest Seruice General Technical Report S E-I0 

December 19 76 

SOUTHERN FORESTRY 

SMOKE MANAGEMENT 

GUIDEBOOK 

bs 

Southern Forest Fire Laboratory Personnel 

Southeastern Forest Experiment Station 

U. S. Department of Agriculture - Forest Seruice 

Sou theus tern Forest Experiment Stat ion 

Asheuille, North Carolina 

and 

Southern Forest Fire Laboratory 

Macon, Georgia 
ABSTRACT 

A system for predicting and modifying smoke concentrations from prescription 

fires is introduced. While limited to particulate matter and the more typical 

southern fuels, the system is for both simple and complex applications. Forestry 

smoke constituents, variables affecting smoke production and dispersion, and new 

methods for estimating available fuel are presented. 

KEIYWORDS: Air quality, pollution, prescribed burning, smoke management, 

particulate matter, smoke concentrations, emission factors, components of forestry smoke, fuel loading. 
TABLE OF CONTENTS 

page 

PERSPECTIWS ...................................................................... v 

CHAPTER I: SMOKE MANAGEMENT . WHAT IS IT? ................. 1 

Purpose of These Guidelines ............................................................... 1 

A Source of More Information .............................................................. 1 

What's in This Guidebook .................................................................. 1 

There are Alternatives .................................................................... -2 

CHAPTER 11: CONTENTS AND EFFECTS OF FOREST 

FIRE SMOKE ......................................................................... 9 

he1 ..................................................................................... 9 

Burning Process ......................................................................... 10 

Primary Products ........................................................................ 11 

Secondary Products ...................................................................... 14 

Particulate Matter ....................................................................... 14 

CHAPTER 111: AIR QUALITY ADMINISTRATION .................. 23 

The Federal Clean Air Acts ............................................................... 23 

A Review of Key Sections of the 1970 Clean Air Act (PL 91-604) 

Applicable to Forestry Prescribed Burning ............................................... 23 

State and Local Air Quality Regulations ................................................... 24 

Air Quality Control Regions and Maintenance Areas ........................................ 25 

Prevention of Significant Deterioration .................................................... 26 

A Voluntary Decision Procedure Proposed for Forestry Smoke Management ................... 26 

CHAPTER IV: FUELS. FIRE BEHAVIOR. AND EMISSIONS ...... 29 

Variables Affecting Emissions and Fire Phases ............................................. 29 

Heat Release Rate to the Atmosphere ...................................................... 33 

Particulate Matter Emission Rate ......................................................... 33 

Grass With Pine Overstory Fuel Type ...................................................... 35 

Pine Needle Litter and Light Brush Fuel Types ............................................. 36 

Emission Factor for Slash and hblolly Pine Litter and Light 

Brush Fuel Types ...................................................................... 38 

Palmetto-Gallberry With Pine Overstory Fuel Type ......................................... 39 

Pine Logging Debris Fuel Type ............................................................ 41 

Conclusions ............................................................................. 44 

CHAPTER V: SMOKE TRANSPORT AND DISPERSION ........... 45 

Phenomena Affecting Smoke Transport and Dispersion ..................................... 45 

Pollution Climatology .................................................................... 48 

Mathematical Models .................................................................... 49 

Adaptation of the Turner Workbook Methods to a Model for 

Managing Smoke hm Prescribed Fire in the South ...................................... 51 

Long-Range Transport ................................................................... 54 

Limitations of the Mathematical Model .................................................... 54 

CHAPTER VI: HOW TO MANAGE SMOKE .............................. 57 

Part 1 . Planning for Smoke Management .................................................. 57 

Part 2 . Decision Logic .................................................................... 58 

Decision-Logic Stage No . 1: Initial Screening ............................................... 61 

Decision-Logic Stage No . 2: Rate Determinations for: 

Palmetto-Gallberry Fuel Type .......................................................... 71 

Grass With Pine Overstory Fuel Type .................................................... 75 

Pine Needle Litter and/or Light Brush ................................................... 79 

Unpiled Logging Debris ................................................................ 85 

Decision-Logic Stage No . 3: Long-Range Margin ........................................... 89 

Decision-Logic Stage No . 4: Matching Prescriptions to Typical Cases ......................... 91 

Decision-Logic Stage No . 5: Plots of Concentration, Comparisons, 

Modifications, and Multiple-Source Analysis ............................................. 99 

Decision-Logic Stage No . 6: Automatic Data Processing Assisted 

Analysis ............................................................................. 107 

Part 3 . Tables ........................................................................... 109 

GLOSSARY .......................................................................... 133 

METRIC CONVERSION AM) PREFIX LE ........................ 137 

SPECIAL ACKNOWLEDGMENTS .......................................... 139 

PERSPECTIVES 

The air we breathe is essential to our lives and 

well-being. Forests are also important to our wellbeing. This Guidebook was prepared because the 

fires used in forest management can temporarily 

reduce air quality. Possible air quality impacts are 

discussed in detail, and ways are suggested to 

minimize unwanted atmospheric consequences 

when using fire in the forests. Procedures and suggestions to follow should be viewed as an opportunity to apply the best available knowledge, consistent with current need. In some locales, this 

need may be for use of only the more simple procedures. Complex air quality problems in other 

locales are likely to call for application of complex 

procedures. We have attempted to provide for both 

needs. 

When compared with other sources of emissions, smoke from forestry burning has been 

regarded by regulatory agencies as only locally important. Its components are thought of as natural, 

occur from other sources as well, and may even be 

deemed inevitable if we accept prescribed fire as 

merely a practical substitute for wildfire. The 

ecological necessity for fire in some forests and the 

use of controlled fire to avoid the devastation of 

wildfires are strong arguments for its prescription. 

Forest pathologists recognize fire as a needed 

sanitation measure in some situations. On the 

other hand, because some smoke components are 

toxic, because they may interact unfavorably with 

one another and with other chemicals in the atmosphere, and because they can also impair safe or 

esthetic visibility, alternatives to open burning are 

sometimes strongly advocated. Also, burning 

forest fuels, like all carbonaceous fuels, produce 

traces of such implicated carcinogens as 

benzo(a1pyrene. Because not all health-related 

threshold levels have been established, a first reaction could be to avoid all open burning. 

In truth, knowledge of interrelating synergistic 

effects and of general human susceptibility to airborne toxins is still too imperfect to suggest 

elimination of all smoke as attainable, or even 

necessary. And while heavy debate continues over 

safe or no-effect proposals, a seemingly rational 

control approach may emerge. Rather than attempt to regulate emissions merely on the basis of 

our rapidly improving detection (i.e., analytical) 

capability, it is suggested that acceptable levels for 

naturally occurring, physiologically active pollutants be related to their ambient (or background) 

levels. 

This is not to say alternatives to open burning 

are not preferred when possible. Neither is it intended as anything but a strong message to apply 

a meaningful principle: 

AVOID OVERLOADING 

NATURAL, CLEARANCE 

MECHANISMSBOTH PULMONARY AND ENVIRONMENTAL 

By applying this principle, prolonged toxic contact 

and possibly increased physiologic effect on 

humans can be avoided. We believe that some 

smoke from forest management can be accepted in 

trade for benefits to the forest and for prevention of 

uncontrolled and overloading emissions from 

wildfire. 

This Guidebook provides for the needs of both 

air and forest resource stewardship, and it is 

offered for local interpretation and use. It is 

offered, too, in the expectation that the health and 

well-being of the populace will be a primary concern of forestry smoke managers. 

JOHN M. PIEROVICH 

Program Manager 

Southern Forest Fire Laboratory 

CHAPTER I 

SMOKE NAGEMENT - T IS IT? 

Hugh E. Mobley, nchnical Specialist 

Southeastern Area - State and Priuate firestry 

USDA Flnrest Seruice 

Macon, Georgia 

PURPOSE OF THESE A SOURCE OF MORE 

GUIDELINES INFORMATION 

This Guidebook is designed to help you determine in advance: 

IVIZAT YOUR FIRE WILL PUT INTO THE 

AIR 

WiYERE THIS MATERUL WILL GO 

?V.HAT WILL H;.1PPEN IIYI) IT 

T EFFECT IT WILL IrL4Vi41 

IVIZAT YOUCANDOABOUTIT 

. . .and doing something about it to minimize environmental impact is smoke management. 

As this Guidebook is being written, a parallel 

Forestry Smoke Management Sourcebook is also 

being developed. This Guidebook provides a great 

deal of information to practitioners in condensed 

form, while the Sourcebook will provide much additional information to key specialists. Any 

references made to the Sourcebook are intended to 

let you know that additional information is 

already available - at least in manuscript form. 

The first edition of the Sourcebook will probably be 

distributed in 1977 to regional and areal levels of 

the Forest Service and to State Foresters in a 

looseleaf format. 

Fire in the forest-natural, accidental, or 

deliberate- has been an important process in the 

ecology of the south for thousands of years, WHAT'S IN THIS 

especially in the fire subclimax pine stands of the 

Coastal Plains. The use of prescribed fire to ac- GUIDEBOOK 

complish specific forest management objectives is 

now regarded as an indispensable tool of the forest A lot of information is presented for the first 

manager (~~bl~~ and others 1973). may, nearly time in this Guidebook. Much is based on limited 

3 million acres a year are burned by prescription in data and will be subject to updating. New inforthe Southern United States. In the past, the mation 

forest manager had only a minimum of information to help him determine what smoke from a 

prescription fire would do to visibility or to the atmosphere. 

This Guidebook was developed for southern 

forest-land managers who prescribe fires, and for 

public agencies that are ~spnsible for maintaining air quality in southern rural areas where 

forests are burned. What is presented is based 

upon the best available technology. Because 

knowledge is presently incomplete, the scope is 

limited to: 

A broad breakdown of important southern 

fuels 

Single pmscription fires 

A system for estimating total fuel loading 

A system for estimating available fuel 

Particulate matter emission factors for major 

fuel types and burning techniques 

A procedure for detemining particulate matter production rate 

A proedure for predicting smoke concentrations at any target area. 

All are described in Chapters IV and I? This information is put together in a step-by-step decisionlogic framework in Chapter VI that can be used 

to predict what smoke from a planned burn will do 

to the immediate airshed, and how it will affect 

visibility at any point downwind. 

Predictions of particulate matter emissions Although much more information can be 

only. found in the Soumebook that is being developed, 
Chapter I1 summarizes what is presently known 

about the components of smoke plumes and their 

effects. Chapter I11 briefly reviews the Clean Air 

Acts and resulting Federal standards, State 

regulations that pertain to forestry burning, and a 

proposed method for determining a voluntary 

limit on emissions. 

THERE ARE 

ALTERNATIVES 

FIRE 

Burning may be for more than one purpose; 

but because reasons vary by treatment, the discussions that follow are categorized by specific treatment objectives. In each of the following sections, 

a brief discussion of the need to meet the objective 

is also provided. 

Reduction of Hazardous F'uels 

Flammable vegetation and litter accumulate 

land managers want to reduce cornpet- rapidly in pine forests. This material is fuel for ing vegetation or debris, they have various treat- wildfires, and excessive accumulation must be conment alternatives: open burning, mechanical trolled to minimize losses and damages. men fire 

treatment, chemical application, close utilization, is prescribe, to reduce hazardous fuel accumulaand doing nothing. No One 'ystem Or type of tions, the stand is virtually fireproofed for the next 

ment will meet allneeds. The common treatments year or two. ~~~l begins to accumulate im- and considerations affecting their choices are mediate~% but wildfires that do occur are of lower Y' summarized in table 1. intensity and much easier to control; they burn 

Three special categories of alternatives need less area and cause less damage to the forest. In 

further discussion: fire, utilization, and no treat- the South, prescribed fire is used primarily for this 

ment. Purpose. 

Figure 1. - Natural accumulations of understory vegetation are burned by prescription to reduce 

fire hazard. 
Table 1. --Considerations in reducing forest debris by different treatments1 

Considerations : Prescription burning Chemicals : Forced-air burners 

Adverse effect Produces smoke 

on air 

Adverse effect 

on water xone2 

Adverse effect 

on soil PJegligible2 

Chemical drift in 

foliar application 

Very little visible emissions 

May contaminate3 Negligible2 

Negligible2 Some compaction4 

Erosion Possibly on steep slopes5 ~e~ligible" Possibly on steep slopes4' ' 

Overstory Negligible2 Negligible2 Skin trees4 

Energy use None None to very little Very high 

Portability 

at site Yes 

Transportation Crew truck 

requirements 

Yes None 

Crew truck &/or tank truck Lowboy & tractor (2 units) 

Spray unit if used 

costs6 20~ to $2.50/acre (avg. $1) $20 to $45/acre (avg. $25) $5 to $lO/ton of material 

Site preparation up to $6/acre treated 

Effectiveness Effective 

under stands 

Effectiveness EXfective only on 

in the open small material 

Advantages Inexpensive 

Fast 

Multiple benefits 

Effective on all sizes Not effective 

(live vegetation only) 

Not effective on 

dead material 

Effective 

Versatile Can handle large boles 

Can treat any size material 

Disadvantages Air pollution Public disapproval Need support equipment 

Usable days are limited Regulated Costly 

Not effective on large Possible offsite effects Cannot treat understory 

material Volume not reduced 

Increased fire hazard 

Best use Hazardous fuel reduction Timber stand improvement Change in land use 

Wildlife habitat improvement or conversion Site preparation 

Grazing improvement Right-of-way clearing 

continued 
Table 1. --Considerations in reducing forest debris by different treatments1 (continued) 

Rotary-blade : Dozing or shearing ' Considerations : Drum choppers : choppers : Total-tree chlppers : and root raking A 

Adverse effect Only exhaust Only exhaust Only exhaust Only exhaust on air emissions emissions emissions emissions 

Adverse effect Kegligible2 Negligible" Sedimentation if Xegligible" 

on water on slope 

Adverse effect Possible 

on soil compaction 

Some compaction Compaction and Some compaction 

removal of topsoil 

Eroslon Moderate to _ Possibly on Very susceptible5 Possibly on 

steep siopesa steep slopes6 steep slopes4~ 

Overstory Skin tree boles Xone 

& damage roots 

Excessive damage Skin trees4 

Energy use High High High Very high 

Portability 

at site Limited in stands Limited in stands Limited in stands Kone 

Transportation 

requirements Lowboy S; tractor Lowboy & tractor Lowboy & tractor Lowboy E; tractor (2 units) 

costsG $30 to $50/acre $10 to $20/acre $50 to $125/acre About $101 ton of 

material treated 

Effectiveness Very limited Limited 

under stands Damage overstory 

Cannot be used Not effective 

Effectiveness Effective 

in the open 

Effective on small Effective 

material 

Effective 

Advantages Effective in Effective on small Leaves ground clean Salable product 

logging resldue standing material Can handle large boles 

Thorough treatment 

Disadvantages Damages leave trees Limited where Debris left Need support equipment 

Blades tend to break can be used Erosion Initial investment 

on rocky ground Costly Cannot treat understory 

Cannot treat 

understory 

Best use Site preparatron Maintenance of Change in land use Pulpwrood logging 

openings and Site preparatron Change in land use 

rights-of-way 

'.Adapted from Earrlson (19'75). 

"fmproper use could cause some adverse effects. 

3~f long-term chernrcals are used or if treatment 1s close to stream or reservoir. 

*Support equlprnent . "These treatments are not feasrble on steep slopes due to erosion and/or excessive cost- -and 

generally not needed. 

E~osts are usually higher In Predmont areas. 
Figure 2. - Wildlife favor the newly sprouting vegetation that appears after a prescribed burn. 

Wildlife Habitat Improvement 

As shrubs mature, the amount of food available to wildlife declines. Fires are often prescribed 

by wildlife biologists to improve wildlife habitat. 

Unpalatable brush and litter are removed, allowing production of palatable new plants and 

sprouts. Seeds and insects are also more plentiful 

on burned areas. 

competition and prepare a proper site for tree seeding or planting. Mechanical treatments alone may 

create large, unmanageable accu-mulations of 

debris that occupy space needed for growing trees. 

This debris can tie up nitrogen needed by the new 

stand for a prolonged period. Furthermore, 

mechanical treatment alone often fails to expose 

the soil properly. On the other hand, burning alone 

is not very effective either-except when the 

Site Preparation volume of debris is very low. Where the volume of 

logging debris is large, fire is often used in conLitter and debris must be removed to reduce junction with mechanical treatment. 

Control of Undesirable Species 

In the absence of fire, most pine sites in the 

South tend to succeed to a climax type of scrub 

hardwoods. If these species are prmitted to invade and compete with overstory pine, production 

is impaired and regeneration is very difficult. 

Complete elimination of understory brush is 

not ecologically desirable or economically practical. It can be controlled with fire, however, if done 

while the understory is small. The resulting 

sprouts and growth of annuals provide good food 

and improved habitat for wildlife as well. 

Disease Control 

?b control brownspot needle blight (Scirrhia 

acicola lDearn.1 Siggers) in longleaf pine (Pinus 

palustris Mill.) seedlings, the infected needles 

must be removed without damaging the bud. Fire 

is the only known practical way to properly remove 

the brownspot-infected needles of longleaf pines. 

Long experience with fire for this purpose has 

made it possible to do so without killing the bud. 

Improve Forage for Grazing 

Cattlemen produce beef on forested ranges. 

However, native grasses in the timber understory 

are smothered by shrubs and inferior hardwoods. 

Periodic, low-intensity fires control competition 

and maintain the grass species. In addition, the 

grass produced after such burning is especially 

nutritious and palatable for cattle. 

Other Objectives 

Other treatment objectives are to fireproof 

stands before initiating naval stores operations, to 

enhance esthetic appearance, and to improve accessibility for timber operators and hunters. 

UTILIZATION 

After allocating sufficient woody material to 

protect the soil from erosion, moisture loss, and unwanted loss of nutrients, most managers of commercial woodland would like to utilize all the remaining woody material for production of energy 

or as a raw material. Progress is being made in this 

Figure 4. - Whole-tree chipping may be a practical alternative to burning in some places. 

7 
direction. In the South, merchantable pine trees 

are often utilized down to diameters of 2 to 4 inches. This is not usually the case, however, with 

or forest areas being cleared for other 

uses. 

One utilization system that looks promising 

is total-tree chipping. This system employs large, 

transportable chippers mounted on semitrailers. 

These will accept whole trees (limbs, leaves, and 

bark), cutting them into chips which can be blown 

into a truck and hauled to a pulpmill. No appreciable logging debris is left on areas logged in this 

manner. The investment cost and use of energy 

are high, but these disadvantages are offset where 

there is a market for such chips that contain bark 

and leaves. Some southern pulpmills can now accept substantial amounts of this type chipped 

material. Where such markets exist, total-tree 

chipping may be a better alternative than 

prescription burning. ?I, meet energy needs, totaltree chippers can also be used to produce fuel for 

boilers. Studies and limited use are already underway. 

Utilization of the small shrubs, brush, litter, 

and leaves within timber stands does not look 

promising. Volumes are too low and scattered to 

justify the cost of harvesting the material from 

among tree stems. Neither is there a developed 

Competition of unwanted plant species 

reduces timber growth. 

Failure to prepare a site may make establishment of a new commercial timber stand 

difficult or impossible. 

Wildlife habitat and food sourees may disappear. 

Palatable grass for cattle will be reduced or 

eliminated. 

In stands of longleaf pine seedlings, mortality from brownspot disease will be increased. 

Accessibility for hunting, timber management, and naval stores activites will be 

reduced. 

Damage, as well as pollution of air and water, 

from wildfires will probably increase 

drastically - especially in areas of high fire 

occurence. 

LITERATIJRE CITED 

market for most of this material. Pine needles can Mobley, Hugh E., Robert S. Jackson, William E. Balmer, and 

be sold for mulch when located close to others 

metropolitan areas or nurseries. 1973. A guide for prescribed fire in southern forests. 

Southeast. Area, State & Priv. For.-2, 40 p. 

NO TREATMENT USDA For. Serv., Southeast. Area, State & ~riv. 

For.. Atlanta. Ga. 

Choosing no treatment as an alternative- Harrison, Robin T. 

letting nature take its course-certainly has no 1975. Slash. . . equipment and methods for treatment immediate adverse effects on the quality of air, and utilization. Equip. Dev. & Test Rep. 7120-7, soil, or water. However, there can be other conse- 47p. USDA For. Serv. Equip. Dev. Center, San 

quences : Dimas, Calif. 

Figure 5. - Unless its growth is controlled in some manner, 

understory vegetation will take over desirable pine sites. 
CHAPTER I1 

AND EFFECTS OFFOREST 

FIRE SMOKE 

Charles D. Rngren, Physical Scientist 

Charles K. McMahon, Research Chemist 

Paul W Ryan, Research Forester 

Southern Forest Fire Laboratory 

Southeastern Forest Experiment Station 

USDA Forest Service 

Macon, Georgia 

The components of smoke are determined by 

the fuel and the process that converts this fuel to 

smoke. We therefore begin this Chapter with a 

description of the chemical elements of wood and 

the fuel. We then describe the process that first 

separates, and then recombines, these elements 

into the constituents of smoke. Although there are 

only a few major chemical elements in wood, the 

complex burning process results in numerous combinations and thereby generates a large number of 

chemical compounds. 

We will then describe the products emitted 

from forest fires and their effects. Most investigators have measured only the major combustion 

products: carbon dioxide (COz), carbon monoxide 

(CO), total hydrocarbons (HC) , and particulate 

matter. A few have measured nitrogen oxides 

(NOx), organic acids, and aldehydes. The effects of 

forest fire smoke on man and his environment 

have not been measured directly. However, since 

the components of this smoke are similar to those 

of smoke from other combustion sources, we will 

draw information on effects from studies of individual components. 

In the last section, we discuss particulate 

matter at some length. We provide detail on 

polycyclic organic matter (POMI and on physical 

characteristics. Size is perhaps the most important physical property of particulate matter. This 

size distribution is a good indicator of the potential 

for causing both health and visibility problems. 

FUEL 

ing land clearing and logging. Wildfires, which 

are often more intense than prescribed fires, may 

consume the foliage and small limbs of tree 

crowns, all litter layers, and organic soil. When 

burned, these fuel elements emit smoke with a 

chemical character that is basically determined 

by the chemical character of the fuel. Therefore, 

our discussion will start with an examination of 

the chemical character of forest vegetation. 

CHEMICAL ELEMENTS 

OF WOOD 

Chemical analysis of wood shows that it is 

composed of about 50 percent carbon, 6 percent hydrogen, 44 percent oxygen, and a fractional percent of what are called trace inorganic components. Surprisingly, there is only a minor 

difference in the major components between 

various wood species. The variability among trace 

components such as ash and nitrogen is greater. 

Ash content varies from 0.2 to over 0.9 percent for 

wood species in the United States. For nitrogen, 

the variation can be tenfold; for example, ponderosa pine (Pinus ponderosa Laws.) ranges from 

0.13 percent nitrogen in boles to 1.04 percent 

nitrogen in growing needles. 

More than half of the elements in the periodic 

table have been found in plants. At least 27 elements were identified in certain samples of white 

pine (Pinus strobus L.) wood and others doubtless 

occur in very small quantities. 

Many of these elements are commonly recogThe fuels of prescribed fires in the South, de- nized growth nutrients. Those occurring in fairly 

scribedingreaterdetailinChapterIV,aremostly largequantitiesarecalled themajor or 

understory foliage, small branches, and the upper macronutrients: nitrogen, phosphorus, potassium, 

layers of ground litter. 1Cb a lesser extent, fuels also calcium, magnesium, and sulfur. Elements reinclude the large branches and treetops left dur- quired in smaller quantities are the minor or 
micronutrients: iron, manganese, zinc, copper, 

boron, and molybdenum. This list may be expanded further as more is learned about plants. 

Table 2 shows an example of the type and concentration of trace elements. 

Table 2. - Relative amounts of various elements found 

in dried leaf tissue of healthy plantsl' 

Nitrogen 

Potassium 

Calcium 

Magnesium 

Phosphorus 

Sulfur 

Iron 

Boron 

Manganese 

Zinc 

Copper 

Molybdenum 

Element 

Percent 

- 11 F'rom Kramer and Kozlowski (1960). 

Content 

the xylans, mannans, and glactans - plus related 

substances such as the uronic acids and their 

derivatives. No single, structural formula can be 

presented for this group; in fact, objections are 

oftezl raised to the use of the collective term 

hemicellulose. The hemicellulose content of wood 

varies from 15 to 25 percent, depending on species. 

The lignin portion of wood is quite different 

chemically from cellulose and hemicellulose. It 

consists of polymeric, aromatic materials characterized by the presence of phenolic hydroxyl 

groups. Lignin includes a variety of substances 

that have similar chemical compositions, but may 

have structural differences. The basic building 

block of lignin is the phenyl propane unit. The lignin content varies from about 23 to 33 percent in 

softwoods, and from about 16 to 25 percent in 

hardwoods. 

Content 

percentage 

BURNING PROCESS 

How the components of smoke are generated 

from burning forest vegetation is best understood 

by recognizing that fire is a two-stage process of 

pyrolysis and combustion. Although both stages 

occur simultaneously, pyrolysis occurs first; it is 

consideration of trace components may the initiating stage of chemical decomposition at 

seem trivial and unnecessary at first glance. Trace temperatures- It is most often viewed as a 

components, however, can cause major environ- heat-absorbing (endothermic) reaction that conmental problems. example, the emission of verts large molecules into smaller ones. Fuel elesulfur oxides (regarded as a major pollutant) ments are separated into char, vapors, and highresults from relatively minor amounts of sulfur in molecular-weight . , hydrocarbons and particulate 

coal, oil, and other fossil fuels. matter. 

Combustion is the burning or rapid oxidation 

CHEMICAL COMPOUNDS of the pyrolysate vapors escaping from the surface 

of the fuel. Defined in the most rigorous sense, 

IN WOOD combustion is a relatively fast, heat-releasing (exNinety to ninety-five percent of the dry 

weight of wood is composed of three polymeric cellwall constituents: cellulose, hemicellulose, and 

lignin. The other 5 to 10 percent includes constituents often listed as extractables or extraneous 

components. The extraneous components consist 

of several hundred individual chemical compounds that vary greatly between species, within 

species, and even within parts of the tree. In this 

group we find terpenes, tannins, resins, oils, pectins, gums, free organic acids, and minerals. 

Wood contains between 41 and 53 percent 

cellulose. The composition of cellulose is quite 

uniform and independent of source; it consists of 

several hundred glucose-type carbohydrate units 

linked in a polymeric chain. Hemicellulose includes all noncellulosic polysaccharides such as 

othermic), chemical reaction among pyrolysate 

vapors and oxygen. 

Pyrosynthesis is a third activity that is a part 

of both the pyrolysis and combustion stages. It 

forms large and complex organic compounds fronn 

smaller free-radical hydrocarbons in the hightemperature and low-oxygen regions of the fuel 

and combustion zone. The formation of these cornpounds occurs in any combustion of carbonaceous 

fuel, and is due more to combustion characteristics than fuel characteristics. 

Brown and Davis (19731, Browne (1963), and 

Murty Wury (1972) have described what takes 

place during combustion of forest fuels. Combining their views, we can recognize three distinct 

phases of decomposition within fuel particles that 

are consumed. These phases - pre-ignition, flaming, and glowing -occur both sequentially and 

simultaneously in a moving fire front. 
PRE-IGNWION PHASE 

(PYROLYSIS PREDOMINATING) 

In this phase, the fuel is heated; volatile components move to the surface of the fuel and are expelled in the surrounding air. Initially, these 

volatiles contain large amounts of water vapor 

and some noncombustible organic compounds. As 

temperatures increase, hemicellulose, followed by 

cellulose and lignin, begin to decompose and 

release a stream of combustible organic products 

(pyrolysates). Because these gases and vapors are 

hot they rise, mix with the oxygen in the air, and 

ignite - producing the second phase. 

FEAMING PHASE 

(GAS-PHASE OXIDATION 

PREDOMINATING) 

In the second phase, the temperature rises 

rapidly from the heat of exothermic reactions. 

Pyrolysis continues, but it is now accompanied by 

rapid oxidation, or flaming, of the combustible 

gases being evolved in high concentrations. Carbon monoxide, methane, formaldehyde, organic 

acids, methanol, and other highly combustible hydrocarbon species are being fed into the flame 

zone. The products of the flame zone are predominantly carbon dioxide and water vapor. The water 

vapor here is not a result of dehydration as in the 

pre-ignition phase, but rather a major product of 

the oxidation of the fuel constituents. 

Some of the pyrolyzed substances cool and 

condense without passing through the flame zone; 

others pass through the flames but only partially 

oxidize, producing a wide range of products. Many 

products of low molecular weight (methane, propane, etc.) remain as gases after cooling. Others, 

with higher molecular weights, cool and condense 

to form small, taw, liquid droplets and solid soot 

particles as they move from the combustion zone. 

These condensing substances, along with the 

rapidly cooling water vapor that is being evolved 

in copious amounts, form the smoke that accompanies all forest fires. 

Pyrosynthesis also occurs during this phase. 

Low-molecular-weight hydrocarbon radicals condense in the reducing region of the flames, leading 

to the synthesis of relatively large molecules such 

as the polynuclear aromatic hydrocarbons. 

GLOWING PHASE (SOLID 

OXIDATION PR-MINATING) 

In the final phase of combustion, the exposed 

surface of the char left from the flaming phase is 

oxidized, producing a characteristic glow: This continues, as long as temperatures remain high 

enough, until only small amounts of noncombustible minerals remain as gray ash. Many times the 

arrangement of the burning material is such that 

temperatures cannot be maintained, and black 

char is left instead of gray ash. 

he1 particles are not always consumed in a 

moving fire front. Because of the size, condition, or 

arrangement of these particles, some are 

pyrolyzed but not oxidized and others are only partially consumed before the flame is extinguished. 

From the heat still available after the flaming 

phase, these particles emit large amounts of 

smoke. Still other particles continue in flaming 

combustion after the flaming phase has ended. As 

a result dehydration, pyrolysis, solid oxidation, and 

scattered flaming often occur simultaneously during this last phase. Where this condition exists, 

this last phase is called smoldering. 

In subsequent Chapters, two fire phases are 

described: one with convective lift and one without. These phases are related to the activity of the 

convection column and not to the pre-ignition, 

flaming, glowing, and smoldering phases just described. In the convective-lift phase most emissions are entrained into a definite convection column. In the no-convective-lift phase, most emissions are not entrained into a definite convection 

column. The smoldering phase described in this 

Chapter occurs in both the convective-lift and noconvective-lift phases. 

The discussion that follows covers the gases, 

vapors, and suspended particulate matter found in 

forestry smoke. Because of the special importance 

of particulate matter, a separate section will follow 

the more general discussions of primary and secondary emissions. 

PRIMARY PRODUCTS 

The burning of forest fuels emits hundreds, if 

not thousands, of chemical compounds into the atmosphere. An appreciation of the complexity of 

smoke can be obtained by a quick glance at 

research on the chemical characterization of 

tobacco smoke. As of 1968, over 10,000 publications had reported the identification of over 1,200 

chemical compounds. 'Ib date, over 200 compounds 

have been identified in woods smoke. 

Amounts of carbon dioxide and water vapor 

emitted are indicators of burning efficiency. The 

more efficient the combustion, the more C02 and 

water vapor produced. As combustion efficiency 

decreases, the proportion of undesirable emissions 

increases. Efficiency varies with the fuel moisture, 

fuel loading, type of fire (heading versus backing), 
and to a lesser extent, weather conditions. Perhaps 

the most dramatic finding to date is that heading 

fires produce approximately three times more particulate matter than backing fires. Wet fuels produce substantially more particulate matter than 

dry fuels. 

Scientists have shown that mounts of emissions per ton of fuel consumed (emission factors) 

vary widely (table 3). In most cases, investigators 

pounds and the particles. Both temporary and 

lasting effects must be considered. The potential 

for a lasting effect is reduced by the detoxification 

capability of the body organs. Even compounds 

that can act synergistically to cause cell damage 

at levels below the threshold effect of each compound alone are a threat only in dosages above the 

body's capacity for detoxification. 

Table 3. - Range of emission factors for components of forest fire smoke, 

with effect potentials 

Carbon dioxide 

Water vapor 

Carbon monoxide 

Total suspended 

particulate matter 

Total hydrocarbons 

Other organics 

Nitrogen oxides 

Sulfur oxides 

20- 180 

10- 40 

Unknown 

Components Effect potentials 

31 NegligibleRange of emission factors 

(pounds produced per ton 

of fuel consumed) 

No direct 

Visibility 

Health 

Visibility & health 

Visibility & health/ 

Visibility & healthg 

Visibility & health? 

Health 

- 

- 11 Values higher than 1 ton occur because of the chemical combination of carbonaceous constituents 

with oxygen in air to produce carbon dioxide. 

- 2/ Includes effects from secondary photochemical products. 

- 31 A possible exception in the high-sulfur peat or "muck" soils. 

measured only C02, CO, total hydrocarbons (HC), 

and particulate matter. In a very few instances 

they measured nitrogen oxides, aldehydes, and 

organic acids. Data on the latter groups are insufficient to estimate their emission factors with 

reasonable accuracy. Most studies have been 

limited to those emissions that are currently 

covered by the National Ambient Air Quality 

Standards. 

In forest fires, the two products of complete 

oxidation - carbon dioxide (CO z) and water 

vapor-make up over 90 percent of the mass emitted. The other 10 percent includes virtually all of 

the smoke and potential problem compounds. Products of major concern are carbon monoxide, particulate matter, gaseous hydrocarbons, other 

organic compounds, and the nitrogen oxides. 

The effects of smoke from forest fires on man 

and his environment cannot yet be directly 

measured. We can only consider the potential 

effects of components known to exist in this 

smoke. The components that are potentially most 

harmful to humans are the volatile organic comCARBON DIOXIDE (C02) 

Carbon dioxide is an odorless and colorless 

nontoxic gas formed abundantly in nature by the 

decomposition of organic substances. It is exhaled 

by man and animals during breathing and absorbed from the air by plants for use in photosynthesis. Its only potential as a pollutant is as a 

contributor to the overall greenhouse effect that 

may be causing a rise in the Earth's air temperatures. 

WATER VAPOR (H2 0) 

Water vapor is important because it can affect 

visibility near a fire, and because it interacts with 

the other combustion products to reduce combustion efficiency It is theoretically possible to produce 1,720 pounds of water from. a ton of fuel at a 

moisture content of 30 percent. Six hundred 

pounds are unbound, or free water, and 1,120 

pounds are from the combustion reaction. 
CARBON MONOXIDE (CO) 

Carbon monoxide is a colorless and odorless 

toxic gas. Although concentrations of this gas can 

be quite high (100 to 200 ppm) right at the fireline, 

measurements on low-intensity prescribed fires 

show that normal atmospheric dilution processes 

are quite rapid-reducing this level to below 10 

ppm approximately 100 feet downwind. Although 

the subject has been studied in depth and is still 

debated, reviews of the literature by Hueter and 

others (19721, Bartlett (19731, and Horvath (1973) 

indicate that the concentrations would probably 

have to exceed 10 ppm for a lengthy period to produce serious effects. 

HYDROCARBONS (HC) 

Hydrocarbons are organic compounds containing only carbon and hydrogen in the molecule. 

Two groups of hydrocarbons are particularly important potential pollutants : the low-molecularweight olefins or unsaturated hydrocarbons and 

the high-molecular-weight, aromatic-type hydrocarbons. Methane, ethylene, and acetylene are 

the predominant low-molecular-weight hydrocarbons in forest fire smoke, comprising as much as 

50 percent of the total. Lesser amounts of ethane, 

propane, propylene, methyl and ethyl acetylene, 

and butene and butane isomers have also been 

found. Characterization of the high-molecularweight hydrocarbons to date is too fragmented 

and incomplete to draw any meaningful conclusions. 

Hueter and others (1974) report that the hydrocarbons propylene, acetylene, and ethylene are 

known to Sect plants. However, the amount of 

propylene in smoke is too small to be of direct concern, and both propylene and acetylene are considerably less phytotoxic than ethylene. Also, exposure from forest fire smoke is believed likely to 

be of too short a duration for any appreciable direct 

adverse effect from ethylene. 

OTHER ORGANIC 

COn!lPOUNDS 

In addition to the hydrocarbon organic compounds, there are literally hundreds of other 

organic gases and vapors in forest fire smoke. 

Figure 6 is a chromatogram of organic vapors 

36 72 

IOOM GLASS SCOT OV-IOI 

PEAK 

2 

28 

2C 

3 

3A 

3 8 

4 A 

4 8 

8 

8A 

10 

15 

16 

17 

20 

21 

22 

23 

24 

COMPOUND 

isopentam 

I-pantone 

f uron 

a-pentone 

isoprene 

acetone 

isoproponol 

cycbpentadiene 

dtacetyl 

I- hexene 

methyl vinyl ketone 2- methylfuron 

n- hexana 

2,4- haxadiene 1,3,5-hexatrienr 

3-methylhtanal 

benzene 

cyclohaxana 

4- methylpentem 

28-dimethylpantans 

I-hYn~-2-dimethylCyclopentono 

TIME (MINUTES) 

PEAK COMPOUND 

24A sabaklohyde (tent.) 26 23-dimethylfuran 26A n-heptone 27 a-2- heptone 

29 2-vinylfuran 

31 2.3-dimethyl-2- 

pentans 

32 2.4- dimethylhexone 36 toluacw, 

39 I-octena 40 2,3- dimthylhexo- 1.4- diem 

41 n-octane 

42 2.3.5-tridhylfuran 44 furfural 49 ethyl benzene 

50 e-xylane 

X)A 2-propiony Ifuran (tent.) 

52 styrene 

53 Q-XY~~W 

COMPOUND 

8- nonane 

2- isopropylfuran 

anisole 

2-methyl-5- isapropany lfuran 

cumsna 

n- decane 

camphene (tent.) 

a- propylbenzane 

m-ethyltoluene 

e- ethy ltoluenr 

I - decene benzofurar 

m- diethylbenzene 

limonene 

Fa-dimethylstyrene 

n- undecana 

n- dodecane 

Figure 6. - Chromatogram of organic vapors in loblolly pine smoke. Each peak represents a 

separate compound. 
sampled from a laboratory fire of loblolly pine 

(Pinus taeda L.1 needles. Each peak represents a 

separate compound. This display includes only 

some of the organic compounds in smoke-principally those with 4 to 12 carbon atoms. Included 

in this fraction are many oxygenated compounds-mostly organic acids, aldehydes, and 

furans-plus many high-molecular-weight 

aliphatic and aromatic hydrocarbons. Several lowmolecular-weight and oxygenated species, 

especially the carboxylic acids (formic and acetic 

acids, etc.) and the reactive aldehydes (formaldehyde, acetaldehyde, acrolein, etc.) have been 

reported as minor, but significant, constituents of 

woods smoke. 

In extensive reviews of the health effects of 

volatile organic compounds, Balchum (1973) and 

Hueter and others (1974) point to the lower 

molecular-weight and more soluble aldehydes - such as formaldehyde-as irritants to the mucous 

membranes of the eyes and upper respiratory 

tract. Formaldehyde irritates the eyes, nose, and 

throat at levels of 0.01 to 1.0 ppm, causes discomfort at 2.0 to 3.0 ppm, and can only be tolerated for 

PO to 30 minutes at 4.0 to 5.0 ppm. The higher 

molecular-weight and less soluble aldehydes are 

deep-lung irritants, 

Balchum (1973) and Hueter and others 

(1974) have found that the unsaturated aldehydes 

are several times more irritating and toxic than 

the saturated aliphatic aldehydes. Within the 

saturated and unsaturated aldehydes, toxicity increases with decreasing molecular weight. For example, unsaturated acrolein can cause moderate 

irritation of the eyes and nose within 5 minutes at 

levels as low as 0.25 pprn and becomes intolerable 

at 5.0 pprn within this same time. In contrast, 

saturated acetaldehyde does not become an irritant until it reaches a concentration of 50 ppm, far 

above anticipated levels, 

OXIDES OF NITROGEN (NO,) 

Oxides of nitrogen (NOx) include both nitric 

oxide (NO) and nitrogen oxide fNO2). NO is a colorless gas that, in contact with air, forms NO2, a 

ddish-brow gas. The normal mechanism for the 

fomation of oxides of nitrogen in combustion is 

through fixation of atmospheric nitrogen and oxygen in the burning zone, principally at temperatures above 1,600' C. This is above temperatures normally occurring in prescribed forest 

fires. However, these temperatures could be 

achieved in piled slash or wildfires. 

Nitric oxide can also be formed at lower temperatures in the presence of hydrocarbon-fkee radicals (Ay and Sichel 1976). Significant amounts of 

nitric oxide may be formed in this way in forest 

fires. Nitrogenous compounds in forest fuels are 

another potential source of oxides of nitrogen in 

emissions. Information on nitrogen oxide emission 

rates from forest fires is scanty and inconclusive. 

NO 2 is about four times more toxic than NO 

and exerts its primary effect on the lungs. 

However, based on the reviews of Hueter and 

others (1973) and Shy (19731, concentrations far 

exceeding those expected of a forest fire are required for direct effects on man. The real importance is in the formation of a whole train of secondary products. 

SULFUl3 OXIDES (SO,) 

Sulfur oxides are probably produced only in 

negligible quantities because most forest fuels 

contain less than 0.2 percent sulfur. Sulfur oxides 

have not yet been detected in forest fire smoke. A 

notable exception is certain organic soils in 

Florida which have a sulfur content of about 4 percent and are under current investigation. 

SECONDARY 

PRODUCTS 

We have briefly reviewed the major findings 

on primary or fire-produced emissions and their 

effects. As smoke plumes travel through the atmosphere, secondary products can be generated 

through mixing of primary effluents or photochemical activity. Evans and others (19741, for example, reported formation of ozone in the upper 

layer of a smoke plume when it was irradiated 

with sunlight. Some secondary products are more 

harmful than the primary products, and some are 

harmless. 

Health effects due to the interaction of particulate matter and sulfur dioxide have been found in 

numerous air pollution studies (Engel and others 

1971, National Academy of Sciences 1973 and 

1975). Our current studies, while only yielding 

tentative results, tend to confirm that these and 

other secondary reactions will take place. 

PARTICULATE 

MATTER 

In this Guidebook, particulate matter is 

defined as any dispersed aggregate matter, solid or 

liquid (other than water), that for practical purposes is larger than about 0.002 micron in 

diameter, but smaller than 500 microns in 

diameter. The size, shape, porosity, density, and 
other physical properties of particulate matter are 

highly variable. Aerosol, another often-used term, 

is considered here to mean small, airborne particulate matter. 

Particulate matter remains suspended in the 

atmosphere for periods of a few seconds to several 

months, Suspended particulate matter is that portion which, hause of its small size (Gelow 5 to 10 

microns in diameter), is transported long distances in the atmosphere and has the greatest potential for environmental impact. Suspended particles are of greatest concern in smoke management. 

The most obvious environmental effect of 

smoke from prescribed forest fires is a reduction in 

visibility. This effect is caused by the particles that 

absorb and scatter light, washing out the contrast 

that exists between the source and its background. 

These particles can also scatter the sunlight that 

illuminates the air between the source and the 

receiver, again washing out the contrast zs distance increases. This temporary reduction in 

visibility can hinder safe operation of aircraft and 

automobiles or the enjoyment of scenic vistas. 

The soiling ability of larger carbon-type particles is another environmental effect of forest 

Figure 7. - A reduction in visibility is the most obvious adverse effect of smoke on the environment. 

A term that is increasing in popularity and 

significance is fine particulate matter (or sometimes, respirable suspended particulate [RSPI) 

which comprises particles blow 2 to 3 microns. 

These have an especially long residence time in 

the atmosphere, contribute to smog formation, 

and penetrate deeply into the lungs. Also, they 

may act synergistically with gases or other particles. 

fires; but in prescription burning, these particles 

tend to fall out of the smoke column close to the 

fire rather than adding to the general pdlution 

level. 

According to the review of Engel and others 

(19711, particulate matter may contribute to accelerated corrosion of metals upon which they are 

deposited by sorbing corrosive chemicals from the 

atmosphere. Almost all of this information comes 
from studies of urban versus rural areas where 

gaseous pollutants in the urban areas are adding 

to the corrosion. 

Health effects of particulate matter are determined by three properties: size, sorption, and 

chemical composition. Sizes of particles are important because of their relation to different parts of 

the respiratory system. The three main parts of 

the respiratory system are the nasopharyngeal, 

tracheobronchial, and pulmonary. Of these, the 

upper two contain cellular tissue with hairlike 

outgrowths (cilia! covered with mucus, and the 

lower one contains moist cellular tissue covered by 

a surface-active material to prevent the collapse of 

the air sacs at the end of respiration. Through inertial impaction and gravitational settling, the 

larger particles are deposited in the upper two 

parts of the system and then expelled. As the size 

decreases below 5.0 microns in diameter, increasing numbers are deposited in the lower respiratory 

tract -including over 50 percent of those between 

0.01 and 0.1 micron that penetrate this far. Many 

forest fire smoke particles, as shown in the physical properties subsection, have a potential for 

being deposited deep in the lungs. 

Sorptive properties of particles make them 

potential carriers of toxic material. In a review of 

the effects of particles on health, Engel and others 

(1971) found that formaldehyde, which does not itself readily penetrate the upper respiratory tract, 

is carried to the lungs by adsorption to small particles -causing increased toxic effect. In their 

review of hydrocarbons, Hueter and others (1974) 

found that the toxicity of acrolein and formaldehyde (both constituents of forestry smoke), 

when in the presence of certain inert aerosols, appeared more toxic to mice. 

Particulate matter can consist of just a few 

easily analyzed solid inorganic compounds as in 

some industrial smoke, or it can consist of several 

hundred liquid and solid compounds in a complex 

organiclinorganic matrix as in certain natural 

aerosols. Examples of natural particulate matter 

are: (1) the coarse, inorganic mineral dust particles derived from windblown soil, (2) the inorganic 

sea-salt particles emitted from the oceans, (3) the 

powderlike, organic pollens from plants, and (4) 

the organic aerosols produced by forest fires. 

Solvent extractions with benzene have traditionally been used to estimate the amount of 

organic compounds in particulate matter. The 

benzene soluble organic (BSO) fraction of particulate matter from fires in various southern fuels 

has been found to range from 40 to 75 percent. 

Some of this variation is due to the type of fire. In 

comparison, the average BSO fraction of ambient 

air particulate matter is about 8 percent. 

The BSO percentage, while a measure of the 

organic content of particles, gives no information 

about the individual organic compounds. Very little of the chemical analysis required for this has 

been accomplished for forest fire particles. 

However, a considerable amount of analysis of the 

smoke in flavoring food, from tobacco, and from 

burning building materials has been completed. 

Those analyses that covered the burning of 

cellulose, hemicellulose, and lignin have identified 

several hundred organic compounds in the particulate matter. These compounds, expected to be a 

part of forest fire smoke, are categorized in the 

general classes: organic acids, alcohols, aldehydes, 

furans, ketones, and aromatic compounds. The 

aromatic compounds include the esters, phenols, 

and polycyclic organic matter. 
POLYCYCLIC ORGANIC 

MATTER 

Polycyclic organic matter (POhl) is of special 

interest in smoke management because it is a 

class of compounds containing many 

physiologically active substances. Benzo (a) pyrene 

(BaP) and other implicated carcinogens are 

usually found in POM. 

POM is formed by the pyrosynthesis of small 

carbon fragments into large hydrocarbon 

molecules in the low-oxygen region of combustion 

processes. It is found in virtually all burning 

which involves carbonaceous fuels. Production of 

POM is more dependent on the conditions of the 

fire than the type of carbonaceous fuel. For example, inefficient, residential coal furnaces produce 

substantially more benzo (a) pyrene per unit of fuel 

consumed than do more efficient coal furnaces in 

power plants (National Academy of Sciences 

1972). 

In recent laboratory experiments, BaP concentrations were measured in the smoke from 

burning slash pine (Pinus elliottii Engelm.) needles. With the laboratory burning tray on a slope 

of 50 percent, heading and backing fires (two replicates) were set at three loadings (pounds per 

square foot) each. 

Heading fires, as expected, usually produced 

more particulate matter per ton of fuel at a given 

fuel loading (table 4). Backing fires, however, produced substantially more benzo (a) pyrene, 

especially at light loadings. 

Within heading fires, the smoldering phase 

produces higher amounts of both BaP and particulate matter than the corresponding flaming phase 

(table 5). 

The differences in BaP production can be explained partly by the conditions required for its 

formation -moderately high temperatures, low 

oxygen, and long residence times in the reaction 

zone. Carbon fragments in the slow-moving, backing fires (especially the light loadings) remained 

under these optimum formation conditions substantially longer than in the heading fires. Within 

heading fires the carbon fragments in the 

Table 4. - Benzo(a) pyrene (BaP) and total suspended 

particulate matter (TSP) from burning pine 

needles I/ 

Emissions 

Type of fire I 

Pounds wer 

and 

fuel loading 

(pounds per 

square foot) 

Backing: 

Light (0.1) 3,500 2 2 

Medium (0.3) 560 8 

Heavy (0.5) 240 5 

Benzo(a)~~rene 

Heading: 

Total 

suspended 

particulate 

matter 

Light (0.1) 38 22 

Medium (0.3) 40 88 

Heavy (0.5) 100 129 

I/ Fuel moisture content for all fires ranged from 18 to 27 

percent. 

21 Nanograms of benzo(a) pyrene per gram of fuel burned. A 

nanogram is 0.000000001 gram. 

31 Pounds of total suspended particulate matter per ton of 

fuel burned. 
smoldering phase, even though at less than optimum BaP formation temperatures, are subject 

to these conditions for substantially longer 

periods than in the corresponding flaming phase. 

The bnzo(a)pyene levels shown in tables 4 

and 5 are generally in the ranges reported 

elsewhere for open burning of landscape refuse, 

grass clippings, leaves and branches (National 

Academy of Sciences 19721, and hardwood leaves 

(Jones 1975). The one exception is the value we observed for lightly loaded backing fires. That value 

is abut 10 times what we might have expected 

from reading earlier study results. 

Table 5. - Benzo(a) pyrene (BaP) and total suspended 

particulate matter (TSP) from flaming and 

smoldering phases of burning pine needlesg 

Total 

fuel loading suspended 

square foot) matter 

Pounds per 

- nglg 2f - ton 31 

Flaming: 

Light (0.1) 33 

Medium (0.3) 17 

Heavy (0.5) 36 

Smoldering: 

Light (0.1) 100 59 

Medium (0.3) 55 143 

Heavy (0.5) 140 192 

- 11 Fuel moisture content for all fires ranged from 18 to 27 

percent. 

21 Nanograms of benzo(a1pyrene per gram of fuel burned. A 

nanogram is 0.000000001 gram. 

- 31 Pounds of total suspended particulate matter per ton of 

fuel burned. 

General conclusions about benzo(a)pyrene in 

forestry smoke cannot be drawn at this time. The 

levels we found in our limited number of laboratory fires were very low to moderate. Our data may 

indicate, however, that one should be cautious in 

declaring backing fires to be the cleanest. It is true 

that backing fires can be expected to produce a 

lower volume of all particulate matter than heading fires. But, it appears that some backing fires 

can be expected to produce more BaP than heading fires. 

PHYSICAL PROPERTIES 

The particulate fraction of forest fire smoke is 

highly variable. As we have shown, this high 

variability is not only in the mass produced but 

also in the size, shape, porosity, density, and other 

physical properties of individual particles. Particles are responsible for two major smoke problems: 

respiratory effects and visibility reduction. 

Respiratory effects have been discussed previously. 

Visibility reduction is caused by the scattering of light by the particles. All particles do not 

scatter light to the same degree. Those having 

diameters within the wavelength of visible light, 

between 0.3 and 0.8 micron, cause the maximum 

scattering. Unfortunately, these sizes of particles 

remain suspended in the air the longest. 

Particle Formation 

The majority of particles in forest fire smoke 

are formed from the gaseous organic compounds 

produced by pyrolysis and combustion. Nucleation,condensation, and coagulation form both liquid and solid particles ranging upward in size 

from about 0.002 micron. hrn 60 to 70 percent of 

the total particles produced are liquid, These are 

formed into a spherical shape by the condensation 

of organic vapors and range from the highly 

volatile and short lived to the long lived, tarry, and 

viscous. Figure 8 is a photomicrograph that shows 

both the spherical. liquid particles and the irregular solid particles. 

Figure 8. - Liquid particles are spherical, whereas solid particles are irregularly shaped. 

Characterizing particle shapes often helps in 

evaluating environmental effects. 
Solidparticlescreatedbythecornbustionproc- clesrangefrom0.01micronto5micronsin 

ess, particularly the smaller ones, can also diameter. Fkquently, the small particles will bind 

assume a spherical shape. More commonly, together to produce larger agglomerates that vary 

however, they assume other forms that appmxi- in shape from roughly circular to long, slender, 

mate flattened discs, angular cubes, and long, chainlike masses. Figure 9 is a scanning electron 

chainlike agglomerates. Sizes of the solid parti- micrograph illustrating these agglomerated particles. 

Figure 9. - A scanning electron micrograph shows angular nature of solid primary particles 

and the aggregation of small particles into long, chainlike masses. 
Particles are also formed by the mechanical 

action of turbulent forces present in the fire zone. 

These forces simply break up the fire-weakened 

fuel and lift small pieces into the heated air column over the fire. Initially, mechanically formed 

particles are fewer in number but usually are 

larger and have more mass than the chemically 

produced ones. Figure 10 shows this type of particle. 

Figure 10. - A large, mechanically formed par - ticle. Notice that plant structures can still 

be identified. 

Mass Distribution 

Particles are produced in a wide range of 

sizes. The amount of particulate matter in each 

size category is called the size distribution, which 

can be expressed as mass or number of particles. 

We report both mass and number distributions 

because some effects are more closely related to 

mass distribution and others to number distribution. In addition, no existing instrument can 

measure the full range of sizes. Expensive instruments are available to measure very small particles; they usually record number distributions. 

Commonly available instruments for measuring 

larger particles usually record mass distributions. 

A particle's mass, in combination with its size 

and shape, determines its aerodynamic size. Aerodynamic size equates an irregular shape to a 

sphere and can be much different than physical 

size. The solid and liquid particles in figure 8, 

although of obviously different physical sizes, are 

the same aerodynamic size. Aerodynamic size is 

more closely related to particulate matter dispersion and respiratory effects, while physical size is 

more related to visibility effects. 

We sampled the aerodynamic mass size distribution of particulate matter frorn several experimental backing fires in slash pine and palmetto-gallberry fuels of Georgia and Florida. About 

70 percent of the particle mass from the slash pine 

fires was less than 0.4 micron in diameter, and 95 

percent was less than 1 micron. Similar results 

have been reported from other studies in the 

United States and elsewhere. In the smoke frorn 

Douglas-fir (Pseudotsuga rnenziesii [Mirb.] Franco) 

fires in the Northwest, 69 percent of the particle 

mass was found to be less than 0.3 micron and 82 

percent less than 1 micron (Sandberg and Martin 

1975). Additional information collected with a 

scanning electron microscope showed that most 

single, spherical particles were about 0.1 micron in 

diameter. Particulate matter in the smoke from 

burning rice residue was found to have mass median diameters that range from 0.1 to 0.3 micron 

(Goss and Miller 1973). Reports from Australia 

and England show that woods smoke particles are 

about 0.1 micron in diameter (MacArthur 1966 

and Foster 1960). 

Number Distribution 

A recently developed instrument has given us 

the opportunity to measure the lower range of particle distribution. It was used in field experiments 

during the 1974-75 fire season. These distributions (fig. 11) are from fires in longleaf-slash pine 

needles in Louisiana, a sawgrass stand in the 

Everglades of Florida, light brush under a loblolly 

pine stand in Georgia, and light brush under a 

loblolly pine stand in North Carolina. Samples 

were collected at distances from the fire site of 0.3 

mile to 3.5 miles, except in Florida where the distance was 12 miles. 

Certain properties of the size distributions of 

particles can be discovered by comparing the number distributions (fig. 11) with the mass distributions (fig. 12). Merging values from the two distributions, we found that the average diameter of 

particles in forest fire smoke is approximately 0.1 

micron, and that this average is approximately the 

same for fires in all fuel types. 

In general, only particles smaller than 10 

microns can be expected to pose problems at distances greater than l/z to 1 mile from the source of 

production. Particles larger than 10 or 20 microns 

will usually be removed from the atmosphere by 

gravitational forces within this distance. There 

are, of course, exceptions caused by extreme 
9 9.99 

NUMBER 

DISTRIBUTION 

9 9.9 

9 9.8 

DERIDDER, LA. * NEW BERN, N. C. 

O FT. LAUDERDALE, FL. 

@ ROUND OAK, GA. 

PARTICLE DIAMETER, MICRONS 

Figure 11. - Size distribution for particles 

smaller than about 0.5 micron. Distribution 

is based on numbers of particles. 

windspeeds or by specialized particle growth conditions high in the atmosphere. Particles found by 

aimraft samplings of fomt fire smoke plumes are 

rarely larger than 10 microns. 

LITERATURE CITED 

Ay, J. H., and M. Sichel 

1976. Theoretical analysis of NO formation near the 

primary reaction zone in methane combustion. 

Combust. & Flame 25(1):1-15. 

Balchum, Oscar J. 

1973. Toxicological effects of ozone, oxidant, and hydrocarbons. Proc. Conf. Health Effects Air 

Pollut.:489-503. NAS-NRC, Washington, D.C. 

Bartlett, Donald, Jr. 

1973. Effects of carbon monoxide on human 

physiological processes. Proc. Conf. Health 

Effects Air Pollut.:103-126. NAS-NRC, Washington, D.C. 

Brown, Arthur A., and Kenneth I? Davis 

1973. Combustion of forest fuels, p. 155-182. In Forest 

fire: control and use. 2d ed. McGraw-Hill Book 

Co., Inc., New York. 

Browne, E L. 

1963. Theories of the combustion of wood and its control. USDA For. Serv., For. Prod. Lab. Pap. 2136, 

59 p. Madison, Wis. 

Engel, Ronald E., H. Wilfried Goerke, Rauf Saygin, and 

others 

9 9.99 

DISTRIBUTION 

9 9.8 

c * 99 I 

PARTICLE DIAMETER, MICRONS 

Figure 12. - Distribution of particles larger than 

0.4 micron. Distribution is based on mass. 

1971. Air quality criteria for particulate matter. 

NATO, Comm. Challenges Modern Soc., N. 8, 

257 p. Brussels, Belgium. 

Evans, Leslie E, Nicholas K. King, David R. Packham, and 

others 

1974. Ozone measurements in smoke from forest fires. 

Environ. Sci. & Tech. 8(1):75-76. 

Foster, W W: 

1960. The size of wood smoke particles. Int. J. Air 

Pollut. 3:89-96. 

Goss, J. R., and G. E. Miller, Jr. 

1973. Study of abatement methods and meteorological conditions for optimum dispersion of particulates from field burning of rice straw. Spring 

open field burning trials. U.S. Dep. Commez, 

Natl. Tech. Inf. Serv. PB-235-796, 47 p. 

Springfield, Va. 

Horvath, Steven M. 

1973. Effects of carbon monoxide on human behavior. 

Proc. Conf. Health Effects Air Pollut.:127-144. 

NAS-NRC, Washington, D.C. 

Hueter, E Gordon, H. Wilfried Goerke, Necip A. Berksan, and 

others 

1973. Air quality criteria for nitrogen oxides. NATO, 

Comm. Challenges Modern Soc., N. 15, 213 p. 

Brussels, Belgium. 
Hueter, FI Gordon, H. Wilfried Goerke, Necip A. Berksan, and 

others 

1974. Air quality criteria for photochemical oxidants 

and related hydrocarbons. NATO, Comm. 

Challenges Modern Soc., N. 29,365 p. Brussels, 

Belgium. 

Hueter, F. Gordon, H. Wilfried Goerke, Ayson Muezzinoglu, 

and others 

1972. Air quality criteria for carbon monoxide. 

NATO, Comm. Challenges Modern Soc., N. 10, 

264 p. Brussels, Belgium. 

Jones, I? W. 

1975. Final report on leaf burning emission program. 

Battelle Columbus Laboratories, Contract No. 

63-02-1409, Task 28, Columbus, Ohio. 

Kramer, Paul J., and Theodore T. Kozlowski 

1960. Physiology of trees. McGraw-Hill Book Co., Inc., 

642 p., New York. 

MacArthur, D. A. 

1966. Particle sizes in bush fire smoke. Aust. 

For.:274-278. 

Murty Kanury, A. 

1972. Ignition of cellulosic solids - a review. Fire Res. 

Abstr. & Rev. 14(1) :24-52. 

National Academy of Sciences 

1972. Particulate polycyclic organic matter. Work performed pursuant to Contract No. CPA 70-42 

with Environmental Protection Agency. 361 p., 

Washington, D.C. 

National Academy of Sciences 

1973. Sulfur oxides and particles. Proc. Conf. Health 

Effects Air Pollut. (Sess. 2) : 173-460. Washington, D.C. 

National Academy of Sciences 

1975. Air quality and stationary source emission control. Prepared for Committee on Public Works, 

U.S. Senate, 94th Congress, 1st Session. 909 p. 

Washington, D.C. 

Sandberg, D. V., and R. E. Martin 

1975. Particle sizes in slash fire smoke. USDA For. 

Serv. Res. Pap. PNW-199, 7 p. Pac. Northwest 

For. & Range Exp. Stn. Portland, Oreg. 

Shy, Carl M. 

1973. Human health consequences of nitrogen dioxide: a review. Proc. Conf. Health Effects Air 

Pollut.:363-405. NAS-NRC, Washington, D.C. 
CHAPTER I11 

AIR QUALITYADMINISTRATION 

Andrew Searcy, Ji, Operations Research Analyst 

Southern Forest Fire Laboratory 

Southeastern Forest Experiment Station 

USDA Forest Service 

Macon, Georgia 

This Chapter reviews the legislation and 

regulations passed to maintain air quality. It also 

introduces a voluntary decision procedure proposed for forestry smoke management. 

THE FEDERAL CLEAN 

AIR ACTS 

Interest in Federal clean air legislation began 

to accelerate in 1955 when Congress provided for 

investigations into the nature and extent of the 

Nation's air pollution problems. With the passage 

of the Clean Air Act of 1963 (PL 88-2061, Congress 

encouraged the first air pollution abatement programs by providing Federal funds to assist in 

State and local control efforts and by establishing 

limited authority to abate interstate air pollution. 

Amendments to the 1963 Act in July 1967 increased the powers of the Secretary of the Department of Health, Education, and Welfare to implement air pollution abatement programs anywhere 

in the United States. The amendments included 

provisions to: 

Request injunctions to abate emissions 

Designate air quality control regions 

Establish air quality standards for the above 

regions in the absence of effective State 

action 

Enforce the above standards 

Establish interstate air quality planning 

commissions; in lieu of action by the affected 

States (Stern 1971). 

The Clean Air Act of 1970 greatly increased 

Federal powers and responsibilities. Section 101, 

paragraph fb) of the 1970 Clean Air Act lists as its 

while at the same time encouraging additional 

State and local regulations. 

A REVIEW OF KEY 

SECTIONS OF THE 1970 

CLEAN AIR ACT 

(PL 91-604)APPLICABLE 

TO FORESTRY 

PRESCRIBED BURNING 

SECTION 108: 

AIR QUALITY CRITERIA 

The Environmental Protection Agency Administrator is directed to identify and publish a 

list of air pollutants. Included in this list is particulate matter, 

SECTION 109: 

NATIONAL AMBIENT AIR 

QUALITY STANDARDS 

The EPA Administrator is required to establish national primary and secondary ambient air 

quality standards for the pollutants identified in 

Section 108. The primary standard is set at a level 

necessary to protect the public health, while the 

secondary standard is set at a level to protect the 

purpose: public welfare from any known or anticipated ad- 

"To protect and enhance the quality of the verse effects of a pollutant. %ble 6 lists the levels 

Nation's air resources so as to promote the public of pollutants thus far identified by the standards 

health and welfare and the productive capacity of as being adequate to protect the public health and 

its population" (U.S. Code: 42 U.S.C. S. 18571, welfare. 
Table 6. - National primary and secondary ambient air quality standards 

Ppm 

35.0 

9.0 

3/0.24 

I Averaging Pollutant 1 standard time 

Annual maximum21 

Annual maximuma 

Frequency 

parameter Concentration 

Carbon 

monoxide 

Primary and 

secondary 

Hydrocarbons Annual maximum 2' 

(nonmethane) 

Primary and 

secondary 

Nitrogen 

dioxide 

Primary and 

secondary 

Annual arithmetic 

mean 

Photochemical Annual maximum% 

oxidants 

Primary and 

secondary 

Annual maximum3 

Annual geometric 

mean 

Particulate 

matter 

Primary 

2/ Annual maximum - Annual geometric 

mean 

Secondary 

Annual maximum3 

Annual arithmetic 

mean 

Sulfur 

dioxide 

Primary 

Secondary Annual maximum2 

1/ Adapted from Federal Register (1971). 

- 5 Not to be exceeded more than once per year. 

- 3/ As a guide in devising implementation plans for achieving oxidant standards. 

- 41 As a guide to be used in assessing implementation plans for achieving the annual maximum 24-hour standard. 

SECTION 110: SECTION 114: 

INSPECTIONS, MONITORING, 

AND ENTRY 

Onsite inspection of emission sources is 

authorized (U.S. Environmental Protection Agency 1970). 

STATE AND LOCAL 

AIR QUALITY 

IMPLEMENTATION PLANS 

Each State must develop and submit for 

Federal approval a comprehensive plan identifying the strategy that the State intends to follow in 

order to attain and maintain the National Ambient Air Quality Standards. A State may revise 

its State Implementation Plan (SIP) at any time 

and, in turn, may be required to revise its plan by 

the Environmental Protection Agency (EPA) if it 

is found to be substantially inadequate. 

REGULATIONS " 

SECTION 113: ~ost States have granted variances from air 

pollution control rules-to valid forestry burning FEDERAL ENFORCEMENT practices. This could be done under the provisions 

 hi^ section also for ~~d~~~l enfoKe- of the Clean Air Act because these operations have 

merit of an SIP where violations appear to be not been identified as a major source of particulate 

caused by a State's failure to enforce its own SIP matter. 

The EPA can initiate court actions against l/ Portionsof this Section werecontributed by Joan B. Boilen, Attorney, polluters violating an applicable provision of an SIP ~egai~upport ranch, U. S. Environ. rot. Agency, Reg. IV, Atlanta, Ga., 1975. 
When emissions from major sources are 

reduced, lesser sources may be expected to receive 

more attention. Control of major sources alone 

may not be sufficient to achieve local ambient 

standards. Then, reduction of emissions from 

minor sources may be required. Some southern 

States are bringing prescription burning under 

control by requiring permits, and some have 

specified certain conditions limiting open burning. A few counties have curtailed all open burning. 

The following are examples of some of the 

more stringent State regulations affecting forestry prescription burning in the South: 

In Arkansas, open burning is prohibited 

within specified distances of certain population centers except for fires used for purposes 

of forestry management, provided fires are 

set and burned when winds are blowing 

away from populated areas. 

In Florida, open burning is allowed between 9: 00 a.m. and 1 hour before sunset with 

permission of the State Division of Forestry, 

or at other times when allowed by the Division and when dispersion of air pollutants is 

reasonably assured. 

In Georgia, counties with populations 

exceeding 65,000 allow open burning only if 

adequate disposal facilities are not reasonably available. In all counties, no smoke of a 

shade darker than a No. 2 on a Ringelmann 

chart (a means by which opacity of smoke 

plumes is judged by visual observation) is 

permitted - except for a reasonable period to 

get the fire started. 

In South Carolina, open burning 

specifically for forestry management is excepted from a general ban when practices acceptable to the State Board of Health and 

Environmental Control are followed, and 

when no undersirable levels of pollutants 

are or will be created. 

In Tennessee, forestry prescription 

burning exceptions include provisions that 

no public nuisance is created, and that no 

land, air, or water traffic hazard is created. 

Distances from certain specified land-use 

areas kg., li2 mile from a secondary highway) are also imposed as restrictions on 

burning. 

The importance of having an up-to-date 

knowledge of traditional State and local air 

quality regulatory requirements is evident from 

these examples. In addition, the forestry smoke 

manager needs firsthand knowledge of specific 

concerns in each Air Quality Control Region 

(AQCR) and in any Air Quality Maintenance 

Area (AQMA) where he works. 

AIR QUALITY 

CONTROL REGIONS 

AND MAINTENANCE 

AREAS " 

The primary air quality ahinistrative area 

is the Air Quality Control Region (AQCR). These 

areas were designated on the basis of geographical 

and meteorological considerations, as well as political boundaries. For this reason, they may transcend Scate or county borders. 

Initially, in 1971 these AQCR's were classified 

Priority I, 11, or I11 based upon existing air quality 

to assist States in planning. In each AQCR the 

sources of air pollution were identified and control 

measures adopted that, after analysis, were felt to 

be sufficient to provide for attainment of the National Ambient Standards upon implementation. 

In 1973, a court decision required EPA to disapprove all State Implementation Plans (SIP'S) 

for not providing for maintenance of the ambient 

standards beyond the attainment date of 

mid-1975. The court held that SIP'S had addressed 

the growth of pollution sources and their related 

air emissions only until the time when standards 

would be attained, and not beyond. Further, the 

court made clear the Clean Air Act required the 

development of a plan that included provisions for 

continuing attainment and maintenance of the 

ambient standards well beyond the attainment 

date. In response to the court's decision, EPA 

developed procedures for each State to use in 

assessing the maintenance issue. Each State was 

asked to review the air quality within its jurisdiction and identify those areas (usually counties) 

that, due to anticipated growth, had the potential 

to violate the ambient standards during the 

forthcoming 10-year period. These areas were 

identified as Air Quality Maintenance Areas 

(AQMA's) . 

In most cases, the area designated as an 

MMA is only a portion of an AQCR. Usually the 

AQMA is urban as well as the surrounding area 

expected to be affected by the same growth potential. Designation of the AQMATs was completed in 

September 1975. Much emphasis has been placed 

on these AQMA's by each State in their reviews of 

growth and its impact on air pollution. The States 

are assessing strategies that, upon application, 

will provide continuous maintenance of the ambient standards. 

2/ Porticnsof this Sectma were contributed by William M, Burch, Chief, Air s trace^^ Dev, Sect., Air Programs Branch, Air and Hazardous Mater. Div, U.S. 

Envlmn. Pmt. Agency, Reg. 1'4 Atlanta, Ga., 1975. 
PREVENTION OF 

SIGNIFICANT 

DETERIORATION 

Additional court decisions involving interpretation of the Clean Air Act resulted in the 

development of the EPA propm to prevent significant deterioration (PSI)) of air quality. The 

Administrator put this program into effect on 

December 5,1974 (Federal Register 1974). 

These PSD regulations combined the concept 

of area classification with new source review procedures and the application of best available control technology. The preconstruction review of all 

new and modified sources now including 19 major 

categories (but not forestry burning) is designed 

to prevent their violating allowable increments of 

deterioration and to assure the employment of 

best available control technology (Federal 

Register 1975). States are being encouraged to accept a delegation of authority to implement this 

review process fully. 

While the regulations are directed to 

specifically named stationary sources, their importance to other sources lies in area classification 

by classes. 

The regulations stated that, effective January 6, 1975, all areas are designated Class I1 and 

restrict deterioration to that associated with normal, well-controlled growth. With the 1974 air 

quality regulations as a baseline, States may 

decide if areas should remain Class I1 or should be 

either Class I that restricts deterioration to a 

minimum, or Class I11 that levies no additional 

restrictions beyond State plan requirements and 

considers any deterioration as insignificant as 

long as no national standards are violated. These 

class designations differ from the priority 

classification discussed earlier in that they indicate levels of air quality to be maintained, whereas 

the priority classifications indicate the urgency to 

apply pollution abatement measures to the areas 

so designated. 

A VOLUNTARY 

DECISION PROCEDURE 

PROPOSED FOR 

FORESTRY 

SMOKE 

MANAGEMENT " 3/ Chtributed by Southern Forest Fire Laboratory personnel who developed 

the &ision-~o~ic presented in Chapter VI. 

Even though the main focus of air quality 

regulations has been on stationary and automotive so- of emissions, southern fomt managers 

have sought a method by which they may voluntarily help to avoid unwanted environmental consequences from prescription burning. In the preceding sections of this Chapter, we have reviewed 

an evolving framework of air quality administration. In Chapter I we discussed alternatives to 

burning, and in Chapter I1 we examined the 

characteristics of forestry smoke likely to bear on 

future increased regulatory interest, locale by 

locale. 

A single forestry burn will seldom be an important emitter more than a few hours on 1 day every 3 or 4 years. It may; however, contribute emissions of consequence to a given atmosphere when 

the pollution load is already high, or when concentrations temporarily exceed locally acceptable 

levels. Because they are based on long-term health 

studies, regulations and standards established for 

stationary and mobile sources of emissions do not 

lend themselves well to decision procedures for 

these transitory forestry sources. For example, 

standards are usually expressed as concentrations 

averaged over times longer than a forestry burn 

would last. Because of this, a time/concentration 

adjustment could be made which would still be 

within established standards; the adjusted concentration could, however, be intolerable when 

judged by other criteria such as highway safety or 

personal respiratory difficulties. 

In some areas of the United States, carrying 

capacity of the atmosphere is estimated within 

certain boundaries. This approach is called the 

"%k Concept" in that this supposed finite atmosphere is regarded as having limiting "walls" 

and a "lid." We have rejected this concept because 

it does not adequately represent actual dispersion, 

particularly in the initial stages. 

Our proposal will be fully presented in 

Chapter VI, after discussions in Chapters IV and 

V on the important variables affecting the procedure. We believe the proposal will lend itself well 

to self-regulation or to agency administration. It 

emphasizes decisions for the single forestry burn, 

but also recognizes multiple contributions from 

other forestry burning or fixed sources. A major 

gain in air quality will be achieved in some locales 

if the procedures for multiple-source forestry 

burns are applied by mutual agreement between 

burners. 

Currently the best available control technology (also used in many similar instances) is to 

limit the escape of particulate matter into the atmosphere, regardless of the size or chemical composition of the particulate matter. We have 
adapted this control technology to short- term or 

instantaneous concentrations. 

Very small chemically reactive particles have 

a greater potential to impair health than large 

chemically inert particles. Regulatory agencies 

are placing increased emphasis on controlling 

more harmful components. Limiting strategies 

under development will thus likely be more 

specific. 

While many tedious operations are needed for 

decisions in complex situations, the basic procedure involves just five main steps: 

1. Predicting a smoke plume trajectory 

2. Identifying key targets along this trajectory (in this text, targets denote locations where 

smoke concentrations are more likely to have unwanted effects; e.g.: an AQMA, a "sensitive" community, an airport, a road, a highway, a townsite, 

etc.) 

3. Selecting a maximum acceptable particulate matter concentration for each key target 

identified 

4. Determining the "background" pollutant 

level within the target area, then adding this to 

the prescribed fire concentration predicted to 

reach the zone where the target is identified 

5. Comparing the maximum acceptable concentration in No. 3 with the total concentration in 

No. 4. 

Selection of a maximum acceptable concentration in No. 3 above can be either as determined by a special ambient air quality requirement in effect or desired, or as dictated by a need to 

maintain a certain level of visibility. In the procedure described in Chapter VI, either type of 

value can be selected by the decisionmaker. There 

is an implication in the literature that public complaints are more closely associated with visibility 

reductions and with effects of visibility irnpairment on highway and air traffic safety. Decisionmakers arriving at acceptable concentrations may 

also be influenced by the current indication that 

visibility-determined concentrations for total suspended particulate matter are more stringent 

than those suggested by published human health 

effects (US. Department of Health, Education, 

and Welfare 1969). 

Figure 13, - A first step in smoke management is to identify potential targets - areas that might 

be adversely affected by the smoke from a prescribed burn. 

2 7 
LITERATURE CITED 

Federal Register 

1971. National primary and secondary ambient air 

quality standards. Fed. Regist. 36(84): 

8186-8201. 

Federal Register 

1974. Approval and promulgation of implementation 

plans. Fed. Regist. 39(235):42510-42517. 

Federal Register 

1975. Approval and promulgation of implementation 

plans. Fed. Regist. 40(176) :42011-42012. 

Stern, Arthur C. 

1971. Air and water pollution quality standards. Part 

1: Air pollution standards, p. 4-1 through 4-22. 

In Herbert E Lund ied.1, Industrial pollution 

control handbook. hilcGraw-Hill Book Co., Inc., 

New York. 

U.S. Department of Health, Education, and Welfare 

1969. Air quality criteria for particulate matter. Natl. 

Air Pollut. Control Adm. Publ. No. AP-49,211 p. 

Natl. Air Pollut. Control Adm., U.S. Dep. 

Health, Educ., and Welfare, Washington, D.C. 
CHAPTER IV 

FUELS, FFIRE BEHAVIOR, AAND EMISSIONS 

ar W Johnsen, Research Forester 

W Henry McNab, Research Forester 

Walter A. Hough, Research Forester 

M. Boyd Edwards, Jz, Research Botanist 

Southern Forest Ere Laboratory 

Southeastern Forest Experiment Station 

USDA Forest Service 

Macon, Georgia 

This Chapter prepares you to predict the 

amount of particulate matter emitted and the rate 

of heat release from deliberate burning of forest 

fuel. Making these predictions requires estimates 

of the amount of fuel that will burn, the rate at 

which fire will spread, the amount of particulate 

matter that evolves per ton of fuel burned (called 

emission factor), and the heat yield of the fuel. 

The material presented is organized as follows: 

variables affecting emissions and fire phases, heat 

release rate, emission rate, specific information by 

available fuel is needed in the emission rate and 

heat release rate equations, total fuel must be estimated before the available value can be calculated. 

Three layers of litter will eventually develop 

on an undisturbed forest floor: a top litter layer 

(L), a fermentation layer (F), and a humus layer 

(H). When sampling, the two upper litter layers 

(L + Ii') can be grouped. These L + F layers account 

for most of the fuel consumed during prescription 

burns (Hough 1968). During droughts, considerable humus can also bum. Live vegetation in the 

fuel types, and a conclusion. Although many fuel understory must also be accounted for since it will 

complexes are present in the Southeast, only the be consumed in varying degrees, depending on the 

major types in which most of the prescription bum- burning conditions. 

ing is done will be discussed, The identification of 

each fuel type is generally based on its vegetative RATE OF SPREAD 

cover and, Gsomktent, on the ecological province Rate of fire spread must be known to compute it occupies. The major fuel types discussed in sepa- particulate matter emission rate and heat 

rate sections are: grasses, pine needle litteq palmet- rate to the ahnosphere prescribed fire. to-gallberry, light brush, and pine logging debris. 

The rate at which fire advances through a 

VARIABLES 

AFFECTING 

EMISSIONS AND 

FIRE PHASES 

Emissions of particulate matter are influenced by many variables as are fire phases. 

These are reflected in fuel loading, rate of spread, 

burning method, and combustion stage. 

FUEL LOADING 

It is important to understand the difference 

between total fuel and mailable fuel. lbtal fuel is 

the entire accumulation of vegetative matter, living or dead, that could possibly bum if properly 

conditioned. Available fuel is that portion of the 

total fuel that will be consumed by a fire during 

the burning period following ignition. While 

forest fuel usually depends on windspeed and on 

size, arrangement, and moisture content of the 

surface litter and understory fuel. An exception is 

when the fire is backing against the wind. In that 

case differences in windspeed have a negligible 

effect on spread rate, and a windspeed of zero 

should be used when entering the rate of spread 

tables. 

Fire spread rates vary by fuel type because of 

differences in fuel type and arrangement. They 

are, therefore, discussed individually in the 

Guidebook. 

BURNING METHOD 

The burning method employed will depend 

upon the kind of area to be burned and the burning conditions. There are four main categories of 

burning method: 

L3aclztng.fires are those that are ignited on the 

downwind side of an area and permitted to 

spread (or "back") against the wind. 
Heding fires are ignited on the upwind side of 

an area and permitted to spread (or "head) 

with the wind. 

Sometimes, backing or heading fires are ignited in strips and allowed to burn together. 

Ring fires are ignited on all sides of an area to 

be burned. 

Area-cited fires or simultaneous-@ition fires 

are those that are ignited in many places at 

about the same time to result in many small 

fires burning together. 

Often, combinations of these categories are 

used. 

Burning is generally done in two kinds of 

areas. In the first, a tree overstory exists and considerable understory and/or litter are to be 

removed. The fuel is generally natural plant accumulations that increase with time, although 

logging residue from thinnings may also be present. In the second kind of area a tree overstory no 

longer exists, but there is fuel on the ground. This 

fuel results from clearcut logging or brush clearing. 

When burning under a tree overstory, timber 

managers must be sure their fires do not seriously 

damage or destroy crop trees. A manager usually 

waits for those days when winds are likely to remain steady for the burning period. He can then 

ignite the downwind side of his area and allow the 

fire to back slowly against the wind. If fuel loading 

is not excessive, intensity of a heading fire may be 

acceptably low. 

When burning areas free of an overstory, 

there is obviously no need for concern about 

damage to an overstory. The main purpose of such 

burns is to consume as much fuel as possible on 

the area. Only precautions to prevent fire escape, 

to minimize air pollution downwind, to avoid soil 

damage and unwanted runoff of ash, etc., need be 

considered. High-intensity heading fires are 

generally used when the fuel is dispersed over the 

area. Such fires will usually jump gaps in fuel continuity. 

There are times, especially in land-clearing 

operations, when much of the fuel exceeds 2 inches in diameter. If disposal of the large material 

by burning is desired, some form of piling is 

necessary. Concentrating the fine fuel with the 

large, allowing the entire mass to dry, and igniting 

the pile perimeters quickly to get rapid heat 

buildup will permit the large fuel elements to be 

ignited and eventually consumed. 

Burning method afFects rate of fire spread, 

rate of particulate matter emission, and amount of 

fuel consumed. In heading fires, a relatively large 

amount of fuel is consumed during the residual 

combustion stage, and more particulate matter is 

produced per unit of fuel burned. 

COMBUSTION STAGES 

We will discuss combustion in two main 

stages: advance-Font stage and residual stage. 

These stages may be broken down into substages 

to further characterize the fire behavior. For example, the advancing-fiont stage is usually a flaming 

Font, but can also be a smoldering hnt For the 

burning situations covered in this Guidebook, only 

the two main stages are important to determining 

separate emission factors (EF) and emission rates 

(ER) due to marked differences in quantities of 

particulate matter emitted in these stages. 

FIRE PHASES 

For convenience, we have separated fires into 

two phases: convective-lift phase and no-convectivelift phase. The convective-lift phase is when most 

emissions are entrained into a definite convection 

column because of heat being seleased frorn the 

fire. The no-convective-liftphase is when most emissions are not entrained into a definite convection . 

column. Heat release rate will be of consequence 

to the plume rise of the convective-liftphase, but of 

no consequence to the no-convective-lift phase. 

MINIMIZING DURATION OF 

THE NO-CONVECTIVE-LIFT 

FIRE PHASE 

Long-duration residual combustion involves 

humus, organic soil, and large fuel elements such 

as stumps, snags, and logs. Decaying stumps and 

snags exceeding 10 inches in diameter contribute 

most to long-duration residual combustion. Large 

pieces of sound wood are not easily ignited during 

the relatively brief exposure to the flaming front of 

a prescribed fire. When ignition does occur, the 

rapid departure of reinforcing heat from. surrounding sources causes quick flameout, and smoldering 

in sound wood is short lived. This Guidebook does 

not address the problem of long-duration residual 

combustion in detail because the great variability 

does not now permit a standard handling procedure. There are, however, some safeguards that 

can be observed to minimize troublesome emissions during the associated no-convective-lift 

phase of fires. 

Rate of stump deterioration following timber 

cutting was observed in the Coastal Plains of 

Georgia (unpublished data, Southeastern Forest 

Experiment Station). Data from this study permit 
estimation of the extent of rot in stumps if the 

time of cutting is known: 

Year after cutting Depth of decay 

(Inches) 

To minimize the amount and duration of 

residual combustion, take these actions: 

Fell dead snags. 

In cutting operations, keep stump height as 

low as possible to maximize moisture content 

of decaying stumpwood and speed decay 

Burn only when stump moisture content is 

high, as soon after a heavy rainfall as possible. 

Scatter large, sound wood material. 

As necessary, provide for mopup. 

TOTAL LITTER LAYER 

MOISTURE CONTENT 

Fuel moisture is constantly changing, and 

the changes must be monitored. Both wetting and 

drying moisture curves for 10-hour timelag fuels 

are contained in the National Fire-Danger Rating 

System (NFDRS) (Deeming and others 19721, but 

they do not apply to pine needle litter. The wetting 

cums are based on moisture absorbed by wood 

dowels that respond much slower than does pine 

needle litter. The drying curves approach 10 to 15 

percent moisture content in about 7 days-lower 

than measured moisture contents in heavy slash 

pine litter layers 7 days after a rain. Palmettogallberry, grass, and pine needle litter types all 

need more accurate litter moisture estimates. 

More appropriate curves were, therefore, 

developed using data from. experimentally burned 

plots in the South. 

Multiple-regression analysis showed that 

total litter layer moisture content could be predicted with acceptable accuracy from days since 

rain and total litter layer dry weight (Hough 

1976). In the presence of these variables, relative 

humidity did not improve predictions. Using 

Hough's (1976) equations, table 7 was developed 

to show rates of drying for litter. ?I, enter the table, 

one must know the age of rough and yesterday's 

total litter layer moisture content. The value 

shown in the table is subtracted from yesterday's 

value to estimate today's total litter layer 

moisture content. 

During wet, rainy periods forest litter 

moisture content increases. Moisture retention 

capacity of total forest litter layers has been found 

to be up to 300 percent of dry weight (Swank and 

others 1972, Metz 1958, Helvey 1964, Van Wagner 

1970). Metz found this maximum moisture content only after prolonged rainfall, indicating the 

importance of rainfall duration. This need was 

also shown by ~aul," who found that maximum 

water uptake for pine litter occurs in 10 to 12 

hours. A single curve of total litter layer moisture 

content versus duration of precipitation was used 

to construct a table that gives a reasonable estimate of moisture content increases in the litter 

fuel bed (table 8). 

4/ Paul, James T. 1967. Influenceof rateof rainfall on pine litter moisture 

content. Unpublished report. Southeast. For. Exp. Stn., Macon. (;a. 

Table 7. - Daily correction to the total litter layer moisture content for drying 

Age 

of 

mugh 

(years) 

Yesterday's total litter layer moisture content (percent) 

46- 

55 

, 

1- 

5 

11- 

15 

6- 

10 

56- 

65 

16- 

20 

66- 

89 

110- 

129 

90- 

109 

21- 

25 

31- 

35 

26- 

30 

130- 

164 

36- 

40 

165- 

199 

41- 

45 

200- 

200+ 
Table 8. - Correction to total litter layer moisture content for wetting due to precipitation 

Yesterday" total litter Iayer moisture content (percent) ii 

1/ A value of 250 percent is the practical maximum that should be used. If yesterday's total litter moisture content, plus the correction for precipitation exceeds 250, enter 250 on records. 

To use table 8, all that is needed is duration of when there has been abundant for Or 

rainfall and a value for yesterday's total litter more hours so that an initial value of 250 ~ment 

layer moisture content. me value taken from the for today's litter moi~~~ can assigned opposite 

table is added to yesterday's total litter layer the appropriate date and fuel loading class. Should 

moisture content to give the moisture content of a time of Year be selected for beginning to track 

the layer today. ~~i~f~ll duration should be ob- the total litter layer moisture when the chance for 

tained from nearby weather stations, or fmm fire- haYing 8 hours of continuous rain is remote, pick a 

danger rating stations that maintain rainfall day when at least 0.25 inch of rainfall occurs and 

duration recordsB A form (table 9) was designed to assign a litter moisture value of 100 for that day. 

keep track of daily changes in total litter layer If a number of stanch have diEerent ages of 

moisture content. This record should be stmted rough and are being considered for prescription 

Table 9. - Daily record of total litter layer moisture content -- 

Years Percent Time Time Hours Percent Percent Percent 

- + - + 

Daily record 

continues to 

end of month 
burning, the daily drymg rates will have to be HEAT RELEASE RATE maintained for each age class. 

Steps and tables needed to deteene total lit- TO THE ATMOSPHERE 

ter layer moisture content are: 

1. Obtain records of daily rainfall duration 

from the nea~st weather station or fim-dmger 

rating station. 

2. Beginning with the day of interest (today), search the records backward until a day is 

found on which rainfall duration exceeded 8 hours 

or at least inch of rain fell. 

3. hate that date on table 9 and enter 250 

or 100 in the "Way's" column for that day's litter 

moisture. 

4. Compute daily change in fuel moisture 

using instructions found on that form until today's date is reached. After these initial calculations are completed, it is suggested that daily 

calculations of total fuel moisture be made to 

maintain ia current record. 

5. When rain has fallen in the past 24 hours, 

go directly to Step 7. men it hm not, go to Step 6. 

6a. Record age of rough: years. 

b. Obtain yesterday's total litter layer 

moisture content from table 9. 

The rate of heat released to the atmosphere 

(HRR) by flames in an advancing-front combustion stage is needed to determine how high a 

smoke plume will rise during the convective-lift 

phase of the fire. Heat released from the residual 

stage of combustion is expected to be of importance in some situations, but is only negligible for 

those situations covered in this Guidebook. 

The total heat of combustion of ovendry forest 

fuel burned in a bomb calorimeter averages 8,600 

British thermal units (Btu) per pound and is a 

maximum value. Considerable heat is lost when 

these fuels are burned in the forest in their 

natural state. There, heat yield varies from 5,000 

to 7,000 Btu. Losses are due to such phenomena as 

incomplete combustion, radiation, and the presence of moisture in the fuel. Brown and Davis 

(1973) report that 6,300 Btu is a good average for 

fuel conditions and types of fire encountered when 

prescription burning southern fuels. Further 

details will be covered in the Forestry Smoke .Management Source book. 

The calculations for heat release rate (HRR) 

are: 

1. 7b simplify the heat release rate equation 

and provide the dimensional units used in Chapters V and VI, we have determined a factor that inc. Read correction factor due to drying cludes the heat yield constant and converts from 

from table 7. English to metric units-0.0012. 

d. Record factor in correction for daily drying column opposite today's date on table 9. 

e. Subtract drying correction from yesterday's litter moisture. 

f. Record answer in today's total litter 

moisture content column on table 9. 

7. To increase yesterday's total litter 

moisture content by a correction factor for rain: 

- 

a. Record rain duration for past 24 hours: 

hours. 

b. Obtain yesterday's litter layer moisture 

content from table 9: - percent. 

c. Read correction for rain in table 8. 

d. Record correction due to rain duration opposite today's date and proper age of rough on table 9. 

e, Add rain correction to yesterday's litter 

moisture. 

f. Record answer in today's total litter 

moisture content column on table 9. 

2. The heat release rate equation with this 

conversion factor is: 

HRR = 0.0012 yA wrL (1) 

where HRR = heat release rate to the atmosphere 

in megacalories per second 

%= fractional part of available fuel involved in the advancing-fmnt eombustion stage (range 0.01 to 1.00) 

w = weight of available fuel in tons per 

acre 

r = rate of spread in feet per minute 

L = length of fire front in feet. 

PARTICULATE MATTER 

EMISSION RATE 

The particulate matter emission rate (ER) is 

the weight of suspended particulate matter produced per unit length of line per unit of time. This 

rate is needed to determine how much will be 

transported and dispersed to targets downwind 
from a burn. An emission factor (EF) will be used 

in this calculation. Each fuel type has been 

assigned a constant emission factor that reflects 

its unique characteristics. Within fuel types, fuel 

arrangement and moisture patterns are know to 

influence the EE We do not have sufficient data to 

calculate such variations precisely, and the 

calculations would be cmbersome. 

The manner in which particulate matter 

evolves from a prescription burn can differ 

measurably, depending upon available fuel and 

the manner of burning. All backing fires, and 

those heading fires burning on areas having low 

fuel loadings (I- to 2-year-old roughs), consume 

most of the fuel in the advancing-front combustion stage. However, heading fires in older roughs 

or in broadcast logging debris consume only 50 to 

80 percent of the fuel during the advancing-front 

combustion stage. The available fuel remaining in 

heading fires is consumed in the residual combustion stage. In the case of heading fires in older 

roughs and logging debris, the^ is enough heat in 

the advancing-front combustion stage to entrain 

part of the residual stage emissions into a convection column; after the heat diminishes, emissions 

from the residual combustion stage become associated only with the no-convective-lift fire phase. 

Contributions of emissions from the two combustion stages to the convective-lift fire phase and 

to the no-convective-lift fire phase are summarized by fuel type and burning method (table 

10). More detailed information on emission factors 

(EF) is in separate sections to follow for each fuel 

type. 

Table 10. - Contribution of emissions from combustion stages to fire phases 

Grass with pine overstory: 

all burning methods 

Fuel type and burning method 

Pine needle litter andlor 

light brush with age of 

rough 2 years and less: 

all burning methods 

Pine needle litter and/or 

light brush with age of 

rough more than 2 years: 

backing fires 

Fire phases 

heading fires 

Convective-lift (CL) 

phase 

Palmetto-gallberry with age 

of rough 2 years and less: 

all burning methods 

No-convective-lift 

(NCL) phase 

Palmetto-gallberry with age 

of rough more than 2 years: 

backing fires 

heading fires 

Unpiled logging debris: 

all burning methods 

Advancing-front stage 

EF = 15 Iblton 

Advancing-front stage 

EF = 50 Iblton 

Advancing-front stage 

EF = 50 lblton 

Advancing-front stage 

EF = 50 lblton and 

Residual stage 

EF = 180 lblton 

Advancing-front stage 

EF = 25 Iblton 

Advancing-front stage 

EF = 25 lblton 

Advancing-front stage 

EF = 25 lblton and 

Residual stage 

EF = 125 lblton 

Advancing-front stage 

EF = 35 lblton and 

Residual stage 

EF = 180 lblton 

None 

None 

None 

Residual stage 

EF = 180 lblton 

None 

None 

Residual stage 

EF = 125 Iblton 

Residual stage 

EF = 180 lblton 
A factor of 570 is needed to convert from the 

familiar English units (pounds, acres, feet) used to 

describe our fuel, fire movement, and emission factor (EF) to the metric units needed in the emission 

rate (ER) dispersion equation in Chapters V and 

VI. 

The equation for the advancing-front combustion stage particulate matter emission rate 

(ERA) is: 

ERA= 570 yAwrEFA (2) 

where ERA= particulate matter emission rate in 

micrograms per meter-second 

yA = fractional part of available fuel involved in the advancing-front combustion stage (range 0.01 to 1.00) 

w = weight of available fuel in tons per 

acre 

r = rate of fire spread in feet per minute 

EFA = emission factor in pounds per ton for 

the advancing-front combustion 

stage. 

The particulate matter emission rate (ER R ) 

for the residual combustion stage can be calculated in the same manner as for the advancingfront stage of combustion: 

where ERR= particulate matter emission rate in 

micrograms per meter-second 

= fractional part of available fuel re- '' maining to be involved in the 

residual combustion stage (or 1 - yA) 

w = weight of available fuel in tons per 

acre 

r = rate of fire spread in feet per minute 

EFR = emission factor in pounds per ton for 

the residual combustion stage. 

For the convective-lift phase of heading fires 

where the total emissions must include those from 

both the advancing-front stage and the residual 

stage of combustion, a total emission rate is calculated as follows: 

ERA+R= ERA+ ERR (4) 

he1 types are discussed individually in the 

following sections. Since all of the referenced tables must be used in Chapter VI, they are presented therein for convenience of users, and will 

only be cited here to avoid repetition and save 

space. 

GRASS WITH PINE 

OVERSTORY 

FUEL TYPE 

DESCRIPTION 

Loblolly, slash, and longleaf pines in the 

South are normally associated with various 

grasses, most of which form bunches rather than 

turf. 

Figure 14. - Grass with pine overstory fuel type. 

35 
Grasses of the genus Andropogon-including 

broomsedge (A. uirginlcus L.), little bluestem(A. 

scoparius Michx.) , and slender bluestem !A, tener 

Muhl.1-are dominant on all of the moist sites 

where longleaf has been succded by slash and 

loblolly pines, or where sites have been extensively 

disturbed by cultivation or site preparation such 

as disking, chopping, and berfding (Crelen 1962). 

On drier, sandy sites where longleaf pines predominate, wiregrass (Aristida spp.) dominates the 

site. 

Where grass makes up a significant portion of 

the total fuel loading (estimated to exceed 50 percent by weight), and the presence of shrubs is insignificant, the fuel type will be designated 

"grass." Where a dense pine overstory exists, the 

fuel type is considered the same as a "pine needle 

litter type" after age of rough is more than 1 year. 

FUEL LOADING 

Grass fuels in forested stands are unique. The 

greatest accumulation occurs after the first growing season following a fire and continues to 

decrease thereafter. The decrease is due to the 

smothering effect of accumulating needles shed 

from a pine overstory and the shading effect of a 

developing brush understory. Total grass accumulation in tons per acre is presented in table 

VI-F-1, page 105, for easy use. For grass, available 

fuel will be considered equal to total fuel. The 

available fuel in any pine needle accumulation 

must also be estimated (table VI-F-5, page 109; or 

table VI-F-6, page 110; and table VI-F-7, page 

111). 

EMISSION FACTOR 

Evidence available from the experimental 

burning of many grass species suggests an emission factor of 15 (pounds of particulate matter per 

ton of fuel) for prescribed burning with heading or 

backing fires. We are assuming that most of this 

burning will take place when fuel moisture is between 4 and 15 percent (dry basis), and that all 

fuel is consumed during the advancing-front combustion stage. 

RATE OF SPREAD 

The estimating system that best represents 

measured rate-of-spread values in grass fuel was 

calculated from the Rothermel rate-of-spread 

equation using typical grass fuel characteristics 

(Rothermel1972). Calculated values have been 

converted to tabular form so that the only variables needed to determine the rate of spread are fine 

fuel moisture and windspeed (table VI-F-4, page 

108). Actual fuel moisture can be derived from table VI-F-2 (page 106) where the fuel moisture is 

shown to be a function of ambient temperature, 

relative humidity, and cloud cover. The windspeed 

used should be that at midfiame height. This value 

can be approximated by obtaining the value reported from a 20-foot tower at the nearest firedanger rating station and dividing that value by 4. 

Data from table VI-F-4 fpage 108) should be 

used only for sites with slopes of 20 percent or less. 

The table is suitable for the Coastal Plains of the 

South where most prescription burning is done. 

Fire travel in feet per minute from the table 

can be converted to miles per hour as follows: 

feet per minute mph = 88 

PINE NEEDLE LITTER 

AND LIGHT BRUSH 

FUEL TYPES 

The forest floor of pine stands having light 

brush understories may appear quite different 

from that of a pine stand without an understory, 

but knowledge gained from studying fuel buildup 

and fire behavior in these stands shows them to be 

very similar. They will, therefore, be treated as a 

single fuel complex, 

Pine Needle Litter 

In well-stocked pine stands, understory 

grasses and shrubs are drastically reduced after 

crowns close due to overhead shading from the 

pine canopy, competition from pine roots, and the 

blanketing effect of the shedding pine needles. 

The areas are generally parklike with a blanket 

of pine needles covering the soil surface. Understory shrubs that are present are sparsely scattered, 

and grass is found mainly in stand openings. 

This type usually develops where previously 

cultivated land has reverted to pine forest, and 

where sites have been carefully prepared by plowing, disking, or bedding prior to pine regeneration. 

Light Brush 

This type is found throughout the Piedmont 

and Upper Coastal Plain regions of the Southern 

States. The fuel mixture consists of grasses, forbs, 

pine needle litter (usually loblolly pine), deciduous 

shrubs, and small deciduous trees such as 

blackgum (Nyssa syluatica Marsh.), sweetgum (Liguidambar styractflua L.), red maple Cllcer rubrum 

L.1: oaks (@emus spp.), etc. There may also be 

some scattered nondeciduous shrubs, such as wax 

myrtle (Myrica cerifera L.) or holly (Ilex opaca 

Ait.). 
Figure 15. - Backing fire in pine needle litter fuel type. 

During the winter and early spring when McNab and Edwards (1976). For field use, the 

prescription burning is usually done, only the ovendry values are presented in table VI-F-5 (page 

naked stems of the shrubs are standing. All the 109). This table shows, for example, that in a 5- 

leaves have fallen and become part of the litter year-old rough where the stand basal area is 70 

layer - together with the grass, forbs, and pine square feet, there would be a total litter accumulaneedles. Most of the available fuel is in this layer. tion of 6.1 tons. 

FUEL LOADING 

Because rate of pine needle accumulation 

under slash pine stands differs considerably from 

accumulations under loblolly or loblolly-longleaf 

stands, separate tables for predicting fuel loading 

will be presented for each. 

Litter accumulation is the same whether an 

understory does or does not exist. In stands where 

no understory exists, only the litter fuel need be 

considered as total fuel for the area. Where understory fuels will be consumed by a prescribed burn, 

the two fuel fractions must be summed to estimate 

total fuel. 

Slash Pine Litter Total Fuel Estimate 

Slash Pine Litter Available Fuel 

Estimate 

The portion of total fuel that is available for 

consumption by a prescribed fire is directly correlated with the moisture content of the fuel. By 

estimating total loading from table VI-F-5 (page 

109) and deriving the total litter layer moisture 

content (percent), the amount of fuel available for 

burning can be read from the center of table VIF-7 (page 11 1). Tb use the table you must know the 

total litter layer moisture content, discussed 

under VARIABLES AFFECTING EMISSIONS 

AND FIRE PHASES. 

Loblolly Pine Litter And 

Light Brush Total Fuel Estimate 

Equations describing the relationships be- The primary fuel consumed during a 

tween litter accumulation on the forest floor, basal prescribed burn in this fuel type is loblolly pine 

area, and age of rough have been reported by needles, or a mixture of loblolly and longleaf or 
loblolly and shortleaf needles-possibly with some burned loblolly needle beds at a moisture content 

hardwood brush leaves. of 6 to 10 percent had an emission factor of 17 

High densities of young hardwood and brush pounds per ton of fuel consumed; but at a 19 perstems m present in type. During the ming cent moisture content, the value was 28 pounds. 

season, the brush is very evident due to the pres- Particulate matter emissions measured on 

ence of their green leaves; but during dormancy, several backing fires in slash pine plantations 

when all the leaves have been shed, only naked averaged approximately 50 pounds per ton of constems are evident. Although they are usually sumed fuel. This higher emission factor is thought 

killed by the heat, the stems are not generally con- to be due to differences in moisture content of 

sumed in prescribed burns. different litter layers. 

An insufficient number of loblolly pine plots 

were sampled to develop a total litter prediction 

equation as was done with slash pine litter. The 

slash pine litter model was tried for estimating 

loblolly litter accumulations using the loblolly 

stand parameters of basal area and age of rough. 

In every case, the slash pine model overestimated 

the actual loblolly weights. We decided to use the 

model and calculate an error factor by regression: 

Error factor = 1 + p.74 + 4.49 (age of rough) 

100 I 

Then, 

Slash pine litter weight Loblolly litter weight = Error factor 

Using values from slash pine litter data and 

the error factor equation, loblolly pine litter accumulations were computed and listed in table VIF-6 (page 110). Considerable estimation error may 

occur when using values in excess of 5 tons per 

acre because those values are extrapolated well 

beyond the weights actually measured on our 

limited sample plots. 

Loblolly Pine Litter and 

Light Brush Available 

Fuel Estimates 

Loblolly litter can now be determined from 

table VI-F-7 (page 111) using the total weight 

values derived from table VI-F-6 (page 110) and 

total litter layer moisture content as earlier discussed under VARIABLES AFFECTING EMISSIONS AND FIRE PHASES. 

EMISSION FACTOR FOR 

SLASH 

AND LOBLOLLY PINE LITTER 

AND LIGHT BRUSH FUEL 

TYPES 

Until further knowledge is gained to reconcile the differences in particulate matter emissions between laboratory and field burns, and to 

account for the effect of fuel moisture, an emission 

factor of 50 pounds of particulate matter per ton of 

needles consumed should be used. Most emissions 

are from the slow-moving flaming portion of the 

fire. 

Heading Fires 

Emissions from heading fires moving 

through pine needle fuel (ERA+R usually come 

from both the advancing-front combustion stage 

and the residual combustion stage that take place 

immediately after passage of the advancing front. 

Thus, ERA+^= ERA+ ER R . 

In the advancing-front stage the emission factor would be identical to that of backing fires, 50 

pounds per ton of fuel consumed; but the emission 

factor in the residual combustion stage could be up 

to 180 pounds. These data are based on the burning of small fuel beds in a laboratory, but are the 

best available. 

Where litter buildup is low, as in a 1- to 2-yearold rough, emissions from residual combustion are 

negligible and only advancing-front combustion 

need be considered. Such burns would have an 

emission factor of 50. 

RATE OF SPREAD 

Pine needle and low-brush fuel types are 

similar in fuel makeup and arrangement. Fire 

behavior will, therefore, be considered the same for 

identical fuel moisture and wind conditions. 

The best estimate of rate of fire spread in this 

fuel type was calculated with the Rothermel 

spread model (Rothermel 1972). Rates of fire 

spread are shown in table VI-F-8 (page 112). 

Particulate matter emissions from burning As in the grass model, rate of fire spread can 

pine needle litter were derived from laboratory be predicted by knowing only midflame windspeed 

and field experiments by Southern Forest Fire and fine fuel moisture (1-hour timelag) values. 

Laboratory personnel. This windspeed can be estimated by obtaining a 

value from a 20-foot, open-tower installation at a Backing Fires nearby fire-danger rating station and dividing 

As fuel moisture increases, so does emission that value by 4. Fine fuel moisture can be read 

of particulate matter. Backing fires in laboratory- from table VI-F-3 (page 107) as a function of only 
relative humidity. Rate of spread in feet per 

minute is read from table VI-F-8 (page 112). If 

desired, the rate of spread in feet per minute can be 

converted to miles per hour: 

feet per minute mph = 88 

PALMETTOGALLBERRY WITH 

PINE OVERSTORY 

FUEL TYPE 

DESCRIPTION 

The vegetation commonly referred to by 

southern forest fire control personnel as the 

palmetto-gallberry fuel type can vary widely in 

amount of vegetation and plant composition 

throughout its range. Saw-palmetto (Serenoa 

repens IBartr.1 Small) is native to the Lower 

Coastal Plain, extending south from Charleston, 

South Carolina, into the whole of Florida and west 

into southeastern Louisiana (Hilmon 1968). 

The gallberry (Ilex glubra lL.1 Gray) range 

overlaps the palmetto range, but is considerably 

more extensive, stretching fm Nova Scotia to 

Louisiana (Gleason 1968). Within the fuel type 

both shrub species are generally associated and 

predominate, although in south Florida the 

gallberry may be totally absent. 

Other shrub associates include blueberry 

( Vaccinium myrsinites Lam.), dwarf pawpaw 

Msimina parviflora [Michx.] Dunal.) , titi (Cyrilla 

racemiflora L.), dwarf candleberry (Myrica cerifera 

var. pumilu Michx.), tar-flower (Befaria racernosa 

Vent.), running oak (Quercus pumila Walter.), 

huckleberry (Gaylussaciu spp.) , fetterbush (Lyonia 

lucida [Lam.] K. Koch), pepperbush (Clethra 

acuminata var. tomentosa [Lam.] Michx.) , etc. 

The herbaceous stratum is made up primarily 

of grasses and dominated by wiregrass and broomsedge. 

The genera Aristidq Andropogon, Panicurn, 

and Rhynchospora comprise a major portion of the 

herbaceous weight on sites that are frequently 

burned. In parts of South Carolina, brackenfern 

Figure 16. - Palmetto-gallberry fuel type. 

39 
(Pteridium a~uilinum iL.1 Kuhn.) is the predominant herb, while tropical shrubs predominate in 

the south Florida Everglades. 

This fuel type is usually found under an overstory of loblolly, slash, or longleaf pine, and considerable quantities of pine needles are mixed 

with dead grass and other vegetative debris in the 

ground litter, All estimates of fuel buildup for this 

type assume the presence of a pine overstory. 

FUEL LOADING 

The palmetto-gallberry type has two levels of 

fuel: (1) the understory living vegetation and 

standing or logged debris and (2) dead material on 

the forest floor. Separate computations must be 

made for each level. 

Understory 

Weight of understory vegetation is related to 

time since last disturbance (age of rough) and 

vegetative height. Table VI-F-9 (page 113) shows 

weights of understory vegetation; but to use it, 

average height of representative understory 

vegetation must first be estimated. If, for example, 

understory height averages 4 feet and age of 

rough is 3 years, the weight of understory 

material would be 4.6 tons per acre. 

Available Litter he1 Estimate 

The litter buildup in a palmetto-gallberry 

fuel type is primarily influenced by the pine overstory and should be predicted from table VI-F-5 

(page 109) or VI-F-6 (page 110) using basal area of 

the stand and age of rough as inputs. 

Data from prescription-burned experimental 

plots containing aerial fuel in addition to pine litter were analyzed for fuel consumption. 

Differences between backing and low-intensity 

heading fires were not great, so all the data were 

combined. Data needed to estimate available fuel 

are: 

1. ntal standing understory vegetation (table VI-F-9, page 113) 

2. Total litter fuel (table VI-F-5, page 109) 

or VI-F-6 (page 110) 

3. Moisture content of the total litter layer 

from a worksheet (table 9) as shown in this 

Chapter, 

Tables 7 and 8 are used to determine the 

changes in moisture content of the total litter 

from normal drying, or from wetting by rain. 

Their use is explained on pages 31 and 32. 

The amount of available fuel consumed from 

the entire understory fuel bed (includes litter) is 

presented in table VI-F-10 (page 114). This table 

has six sections (10, 20, 40, 80, 120, and 160 percent) that represent the range of litter fuel 

moisture that would be expected when prescribed 

burning would be considered. The moisture interval is smaller at the lower moisture contents 

because the change in available fuel consumed is 

greatest at these lower moisture contents. Should 

the predicted moisture level not correspond to one 

of the moisture content sections listed (e.g., 50 percent instead of 40 or 80 percent), choose the section with the closest value (the 40-percent 

moisture content in this case), Limitations on the 

accuracy of estimates in the palmetto-gallberry 

fuel type depend primarily upon the accuracy of 

the litter and moisture content estimates. These 

estimates should, therefore, be made with care. 

EMISSION FACTOR 

The calculated emission factors from experimental field burns in Georgia ranged from 11.8 

(pounds of particulate matter per ton of consumed 

fuel) to 41.2. Based on these field experiments, an 

advancing-front particulate matter emission factor (EF of 25 pounds per ton of palmetto-gallber- A 

ry fuel burned is suggested for use with backing 

fires. This value is believed to be less than emissions from pine needle litter because fuel bulk density is lower and combustion is, therefore, more 

efficient. No measurements were made for heading 

fires in the type; if heading fires in 1- or 2-year-old 

roughs are contemplated, the same emission factor of 25 should be used. Emissions from the 

residual combustion stage are considered negligible for heading fires in young roughs. 

Heading fires in older roughs would evolve appreciable emissions during residual combustion in 

the litter layer; a much higher emission factor for 

this stage of combustion (EFR) of 125 pounds of 

particulate matter per ton of palmetto-gallberry 

fuel consumed is suggested for use. The emission 

rate (ERA+R) for the convective-lift fire phase of 

older rough heading fires is: 

ERA+R= ERA+ ERR 

RATE OF SPREAD 

Rate of fire spread in palmetto-gallberry fuel 

was estimated from measures of fuel and fire 

behavior in this fuel type. Hough and Albini 

(1976) describe the measurement and analytical 

procedures used to derive the rate-of-spread equations. If windspeed at midflame height and fine 

fuel moisture (table VI-F-3, page 107) are known, 

fire spread rate can be read directly from table VIF-ll? page 115. For backing fires, assume the 

windspeed is zero. 
Figure 17. - Emissions from the residual combustion phase in backing fires, and in heading fires 

with rough less than 2 years old, are negligible for the palmetto-gallberry fuel type. 

The proper value to be used for midflame tion of all small and much of the larger residue elewindspeed in table VI-F-11 (page 115) can be esti- ments (branches and tops exceeding 1 inch in 

mated by using values taken from a 20-foot, open- diameter), or it can be left scattered where the intower installation at the nearest fire-danger sta- dividual trees were felled to be consumed by a 

tion and dividing that value by 4. If desired, the broadcast burn of the area. The latter type burn 

rate of spread can be converted to miles per hour: usually consumes only residue less than 1 inch in 

feet per minute diameter. mph = 88 We have insufficient data to account for 

differences in emissions from piled debris because 

PINE LOGGING piling methods and pile conditions can vary 

widely. Therefore, this Guidebook will not have a 

DEBRIS FUEL TYPE section for piled debris. Further research in this 

fuel type is in progress. The Guidebook does, 

however, give a procedure for predicting particu- DESC~IF'TION late matter emission rate and heat yield from the 

burning of broadcast debris, This procedure is This type is made up of tree parts left On based upon very scant observations and little exan area following logging, plus a very disturbed perimental evidence, natural understory fuel. The debris consists 

mostly of the upper portion of the central bole, 

tree branches, and needles. Other residue could in- FUEL LOADING 

clude unmerchantable "whip" trees and hard- Residue weight may be estimated by several woods. methods. The traditional procedure is to gather all 

Logging debris can be burned in one of two material from many small sample plots, separate 

ways. The debris can be piled to permit consump- by size class, dry, and express weight on a unit area 
Figure 18. - Unpiled pine logging debris fuel type. 

basis. More recent estimating procedures are the broadcast burning a logged area. Note that the 

line intercept method (Van Wagner 1968) and the average d.b.h. of the logged stand has some effect 

planar intercept method (Brown 1971). These on the amount of residue that will be left on the 

methods are useful where the slash from several ground. If d.b.h. of the stand averaged 8 inches and 

species of trees is present. The techniques do not the species was loblolly, for every cord of timber 

require the collection of material, but considerable cut there is 0.15 ton of available residue on the 

field time and effort are still needed. ground. If average stand d.b.h. was 11 inches, 

A quicker and more economical is to there is 0.12 ton of available residue per cord. Total 

relate the quantity of crown residue left on the residue on an area is the product of tons of residue 

ground to average diameter at breast height Per cut VI-F-12, Page 116) and 

(debah.), basal area, and volume in the stand that cords cut On the area* dividing this EUiswer 

was cut. Two have been completed on the number of acres in the logged area, the 

amount of dry residue left on the forest floor residue weight is expressed in tons per acre. 

following standard logging of two major southern 

species. One involves loblolly pine residue ~%ras 

and Clark 1974) and the other slash pine residue 

(data on file at the Southern Forest Fire Laboratory). 

Logging debris that has been left undisturbed and is scattered over the entire logged 

area is generally burned with some form of heading fire. Such fires consume only fuel less than 1 

inch in diameter. Table VI-F-12 (page 116) depicts 

the amount of residue, in tons per cord cut (logged), that would generally be consumed when 

SPECIAL RULE OF THUMB 

Debris that has been left broadcast over a logged area is usually burned in one of two ways. It 

may be head fired from its upwind side toward the 

downwind side, which is usually backfired in advance. Primary fuel consumption is from the 

movement of the heading fire, and length of the active burning front for computing heat release rate 

(HRR) is easily ascertained. 
Ring firing may be used instead. This tech- downwind edge of the area and connect these two 

nique usually begins with the firing of the down- lines with diagonals from the extremities of each. 

wind side of the area, followed by the firing of the Where the diagonals intersect, label the point (x). 

two flanks simultaneously. Finally, the upwind Length of fired line for computation of HRR is the 

side is fired to totally encircle the area with fire. sum of scaled lines a to x and b to x. This is the enFire movement is towad the center of the area. try needed for Chapter VI. 

Determining the length of active fire for a 

ring-fired area poses problems. When there is wind EMISSION FACTOR 

movement, the heading portion of the fire is obviously active. But so are the flanks, and as the fire 

progresses all sides are shrinking in length. For 

purposes of this Guidebook, the movement of the 

backing fire will be ignored, even though this side 

of the fire is obviously contributing some heat and 

particulate matter to the reaction. Where ring firing. " is used and there is no wind, all fired sides probably move toward the center at an equal rate.- 

A rule of thumb has been developed for 

estimating a length-of-fired line value for computing HRR in Chapter VI. The procedure was 

developed in an attempt to make an allowance for 

the fire activity on the burning flanks. ?b complete 

the procedure, a scale map of the area to be burned 

is needed. On the map, draw a line perpendicular 

to the expected or planned wind direction along 

the upwind edge of the area to the extremities (fig. 

19, line a to b). Draw a second line (c to d) along the 

Emissions from fires moving through unpiled 

logging debris occur in two phases- the convective-lift phase and the no-convective-lift phase. 

Emissions during the convective-lift phase are 

from both the advancing-front combustion stage 

and the residual combustion stage behind the advancing front. 

Six to 18 months usually elapse between logging and burning. During this time much of the 

accumulated litter breaks down, leaving primarily 

the logged litter layer of residue over the soil. 

Upon firing, 75 percent OI\ = 0.75) of the available 

fuel is estimated to be consumed in the advancingfront combustion stage, leaving only 25 percent 

(yR = 0.25) to be consumed during the residual 

combustion stage. These proportions are based on 

data taken from sample areas of debris burned in 

the southern Piedmont of Georgia near Macon. 

Determination of representative emission fac- c tors for this fuel type must be partially subjective 

due to the limited data currently available. 

Results from the limited fuel beds burned in the 

laboratory indicate emission factors much below 

values expected, compared with values for the 

seemingly similar pine needle litter and palmettogallberry fuel types. The difference between expected results and laboratory results can be explained only by hypotheses that: (1) aerial distribution of pine logging debris may result in 

flame interactions that reduce particulate matter 

emissions, and (2) laboratory fuel beds used may 

not have been representative of area-wide fuel arrangements found in actual field situations for 

pine logging debris. 

Laboratory-derived particulate matter EF 

values of 5 and 75 pounds per ton of fuel for pine 

logging debris in the advancing-front and residual 

combustion stages, respectively, must be regarded 

as tentative until further laboratory and field 

work is completed. We are suggesting, therefore, 

that 35 and 180 pounds per ton of fuel be used for 

the advancing-front and residual combustion 

a stages, respectively. These more conservative EF 

values for unpiled pine logging debris are drawn 

from comparisons with other fuel types, but allow 

Figure 19. - Procedure for determining length of for possible interactions indicated by limited 

fired line for heat release rate (HRR) calcula- laboratory work to date. Use of these values will 

tions for ring fires in the logging debris fuel minimize the risk of unwanted environmental 

type- consequences until research is completed. 
When computing the emission rate to be used 

for the convective-lift fire phase for heading (or 

ring) fires (ERA+R) in this fuel type, the 

simultaneous activity of both stages of combustion are accountable. The equation is as follows: 

RATE OF SPREAD 

Observations of fire spread rate in this fuel 

type are limited. Until better data are available, 

the rate-of-spread curves in NFDRS Model C 

(Deeming and others 1972) fuel, with modifications (table VI-F-13, page 117), should be used. 

The only input variables needed to read rate 

of spread from table VI-F-13 (page 117) are fine 

fuel moisture (from table VI-F-3, page 107) and 

midflame windspeed. The midflame windspeed 

should be obtained by taking the value at the 

nearest fire-danger rating station having an 

anemometer mounted on a 20-foot tower and 

dividing that value by 2. A factor of 2 is used 

rather than 4 because of the effect of removing the 

overstory. If desired, rate of spread can be converted to miles per hour: 

mph = feet per minute 

88 

CONCLUSIONS 

Although many voids in knowledge exist, we 

have presented useful new information on rates of 

spread and available fuel. These data have been 

badly needed in the fuel types covered. 

In general, practices and fuel conditions that 

minimize particulate matter production from the 

burning of forest fuel are: 

1. Favoring backing fires where possible 

2. Cutting to low stumps and felling dead 

snags 

3. Burning when fuel moisture is low 

4. Minimizing amount of logging debris 

through utilization to small top diameters 

5. Burning scattered logging debris rather 

than piled debris. 

LITERATURE CITED 

Brown, James K, 

1971. A planar intersect method for sampling fuel 

volume and surface area. For Sci. 17(1):96-102. 

Brown, Arthur A., and Kenneth I? Davis 

1973. Combustion of forest fuels, p. 163. In Forest fire: 

control and use. 2d ed. McGraw-Hill Book Co., 

Inc., New York. 

Deeming, John E., James W. Lancaster, Michael A. 

Fosberg, and others 

1972. National fire-danger rating system. USDA For. 

Serv. Res. Pap. RM-84,165 p. Rocky Mt. For. & 

Range Exp. Stn., Fort Collins, Colo. 

Gleason, Henry A. 

1968. Illustrated flora of the northeastern United 

States and adjacent Canada. 2d ed., vol. 2,655 p. 

Hafner Publ. Co., Inc.,New York. 

Grelen, H. E. 

1962. Succession on cleared sandhills in northwest 

Florida. Am. Midl. Nat. 67:36-44. 

Helvey, J.D. 

1964. Rainfall interception by hardwood forest litter 

in the southern Appalachians. USDA For. Serv. 

Res. Pap. SE-8, 8 p. Southeast. For. Exp. Stn., 

Asheville, N.C. 

Hilmon, J. B. 

1968. Autecology of saw palmetto (Serenoa repens 

lBartr.1 Small). Ph.D. dissertation, 190 p. Dep. 

Botany, Duke Univ., Durham, N.C. 

Hough, W. A. 

1968. Fuel consumption and fire behavior of hazard 

reduction burns. USDA For. Serv. Res. Pap. 

SE-36,7 p. Southeast. For. Exp. Stn., Asheville, 

N.C. 

Hough, Walter A. 

In press. Estimating available fuel weight consumed 

by prescribed fires in the South. USDA For. 

Serv. Res. Pap. Southeast. For. Exp. Stn., 

Asheville, N.C. 

Hough, Walter A., and Frank A. Albini 

In press. Predicting fire behavior in palmetto-gallberry fuel complexes. USDA For. Serv. Res. Pap. 

Southeast. Fox Exp. Stn., Asheville, N.C. 

McNab, W. Henry, and M. Boyd Edwards, Jr. 

1976. Estimating forest fuel buildup. For. Farmer 

356) :6-7. 

Metz, Louis J. 

1958. Moisture held in pine litter. J. For. 56(1) :36. 

Rothermel, Richard C. 

1972. A mathematical model for predicting fire 

spread in wildland fuels. USDA For. Sew. Res. 

Pap. INT-115, 40 p. Intermountain For. & 

Range Exp. Stn., Ogden, Utah. 

Swank, Wayne T., Norbert B. Goebel, and Junior D. 

Helvey 

1972. Interception loss in loblolly pine stands of the 

South Carolina piedmont. J. Soil Water Conserv. 

27: 160-164. 

Taras, Michael A., and Alexander Clark 111 

1974. Aboveground biomass of loblolly pine in a 

natural, unevenaged sawtimber stand in 

central Alabama. TAPPI For. Biol. 

Conf:107-116. 

Van Wagner, C. E. 

1968. The line intersect method of forest fuel sampling. For. Sci. 14(1):20-26. 

Van Wagner, C. E. 

1970. An index to estimate the current moisture content of the forest floor. Dep. Fisheries For., Can. 

For.Serv. Publ. No. 1288,23 p., Ottawa, Ontario. 
CHAPTER V 

SMOKE TRANSPORT AND DISPERSION 

James A. Pharo, Research Meteorologist 

Leonidas G. Laudas, Research Meteorologist 

Philip M. Bailey, Physical Science Dchnician 

Southern Forest Fire Laboratory 

Southenstern Forest Experiment Station 

USDA Forest Service 

Macon, Georgia 

The purposes of this Chapter are: Consider a parcel of air heated to a certain 

To outline phenomena affecting transport 

and dispersion of smoke 

To introduce concepts of air pollution 

climatology important to scheduling burning 

operations when the probability of good 

smoke transport and dispersion is greatest 

Tb explain the bases we used to select and 

adapt mathematical models for predicting 

concentrations of smoke from forestry burning. 

The models described were adapted only for 

common forestry burning situations in the South, 

but with further adaptation they can be applied 

elsewhere. 

PHENOMENA 

AFFECTING SMOKE 

TRANSPORT AND 

DISPERSION 

It has been difficult to achieve a proper balance between too much and too little information 

for the wide spectrum of readers expected to use 

this Guidebook. For those who desire more background on basic weather variables, we suggest a 

text like Ere Weather (Schroeder and Buck 1970). 

ATMOSPHERIC STABILITY 

The definition of atmospheric stability as it 

affects smoke dispersion is the degree to which the 

atmosphere resists turbulence and vertical motion. In this discussion it is convenient to consider 

portions of air as parcels. Parcels of air do not have 

strict boundaries (as if encased in a wrapper); 

they tend to mix and take on the characteristics of 

their surrounding environment. 

temperature at-the Earth's surface. The more 

unstable the atmosphere, the more readily the less 

dense, heated air parcel will rise by convection. 

Similarly, a more dense, cooled parcel of air will 

descend more rapidly under unstable conditions. 

When a parcel of air is heated by a forest fire and 

carries smoke with it, the rate and height of its ascent are essential to our calculations of subsequent dispersion. 

Atmospheric stability is more properly 

defined by air temperature changes with height 

over a specific location. The adiabatic lapse rate, a 

temperature decrease of lo C per 100 meters (5.5' F 

per 1,000 feet), defines a neutral atmosphere and is 

the basic reference for other stability classifications. The atmosphere is unstable if its lapse rate 

is greater than neutral, and stable if less. Neutral 

conditions can usually be found below cloud bases 

during cloudy and windy conditions. An unstable 

atmosphere usually occurs in early afternoon on 

clear days with light winds. Stable conditions 

usually occur at night when the air is clear and 

the winds are light. 

TEMPERATURE INVERSIONS 

An inversion layer is a special case of the temperature-height relationship just discussed. ?'emperature in this layer increases instead of 

decreases with height. When our previously consided heated parcel of air encounters an inversion layer it soon stops rising. Because it cools 

quickly as it rises, the parcel reaches the same 

temperature as the very stable surrounding air. 

An inversion can thus be thought of as a Ztd on a 

smoke column. 

Forestry smoke managers should be careful 

to avoid low and intermediate level inversions in 

order to keep from having such a lid imposed upon 

the smoke from their burns. If the inversion layer 
Figure 20. - Major factors affecting smoke transport and dispersion include vertical plume rise, 

horizontal movement on an azimuth determined by the transport wind direction, and dispersion by physical forces such as atmospheric mixing. 

is very weak (i.e., not very thick in the vertical Mixing heights of less than 500 meters are often 

dimension and temperature increase with height associated with air pollution episodes. 

is not great), the heated air from a fire can sometimes penetrate this layer. When it does, the TRANSPORT WINDSPEED 

smoke then has a better chance for dispersion, but You have probably seen smoke columns that there is often a change in fire behavior. go up to one of the lids just described and then just Smoke from the no-convective-lift fire phase will 

smear out in all directions. This occurs when there not penetrate the inversion lid. It is, therefore, best is little or no transport wind. The smoke column to avoid prescribed burning when low inversion 

layers affecting the fire are predicted. that bends or shears is encountering wind as it 

rises. 

MIXING HEIGHT 

The temperature inversion is one kind of lid 

that traps smoke beneath it. Stable layers of less 

than inversron intensity are another form of lid. 

These lids determine mixing height. Mixing 

height is the atmospheric limit above which 

vigorous vertical mixing does not take place. It is a 

height at which airmass stability is sufficient in 

strength and depth to inhibit further upward 

transport of smoke. 

Windspeeds usually increase with height, except where funneling takes place near the ground 

(as through a mountain saddle or opening in the 

forest). 'llransport windspeed is the arithmetic 

average of all windspeeds within the mixing layer, 

including surface windspeed. Smoke concentrations usually decrease as transport windspeeds increase. Transport windspeeds of less than 4 meters 

per second are indicators of stagnant conditions 

which often result in air pollution episodes. 

Mixing height represents the top of the atmospheric volume available for dispersion. High 

TRANSPORT WIND 

mixing heights imply that large volumes of air are DIRECTION 

available for smoke dispersion. Thus, with higher Wind direction usually veers (changes to the 

mixing heights, smoke concentrations will be right) with height. Veering with height is imporless-especially at long distances from the fire. tant in determining where the smoke will go. The 
change in wind direction with height is due to fric- inland. This sea breeze effect is due to land surtion that causes ground-level winds to be deflected faces being warmer than the sea surface. Similar 

to the left in the Northern Hemisphere. As the circulations, much weaker and less widespread, 

heightabovetheEarthincreases,thereisa oftenoccuralongmarginsoflesserwaterbodies, 

decrease in friction. The rougher the surface, the and even open fields, that differ significantly in 

greater the change. Veering with height over temperature from adjoining land surfaces. 

even-aged pine stands on relatively level terrain is 

between 15 and 20 degrees in the first kilometer 

(3,281 feet) of height. Over markedly uneven-aged 

pine stands in rough terrain, it is as much as 40 to 

45 degrees. Changes in wind direction with height 

tend to be more pronounced at night than during 

the day because vertical motion is usually 

diminished at night. 

LOCAL-SCALE SYSTEMS 

Local-scale (sometimes called small-scale) 

systems are associated with fixed geographic 

features and do not travel from one location to 

another like high- and low-pressure systems. They 

often develop, persist, and dissipate in one small 

locale. Land and sea breezes are examples of this 

phenomenon. These breezes change stability, 

windspeed, and wind direction. 

Along coastlines on clear, summer days when 

early morning winds are light, onshore winds frequently develop by midafternoon -penetrating 

Mountain-valley or slope-valley wind is 

another example of a local weather phenomenon 

that can affect smoke transport and dispersion. On 

clear nights, high slopes cool by radiation; the air 

adjacent to them becomes colder and denser, and 

drains into the valley. The reverse of this drainage 

flow may occur during the day. 

These local-scale systems are important 

because they directly affect the dispersion of 

smoke by causing abrupt changes in local atmospheric stability and can influence the direction in which smoke will be transported. They are 

somewhat predictable-often site dependent. 

OBTAINING CURRENT AND 

FORECAST UTEATHER 

FOR APPLICATION 

Limits on values for the phenomena covered 

in the preceding section need to be specified in a 

fire prescription, then checked against current 

and forecast weather for a specific locale, and for 

specific times. 
National Weather Service Forecast Offices 

can supply the following information in spot 

forecasts: 

Mkh he@t (also referred to as height of the 

mixing layer) 

Surface windspeed (in the open at a height of 

10 meters) 

Damport windspeed 

Damport wind direction. 

Both transport windspeeds and mixing 

heights are reported in metric units. The probable 

transport wind velocity (direction and speed) is 

usually the vector-sum of reported or forecast 

winds through the mixing height. 

As of this writing, stability expressed in the 

Pasquill (1975) stability classes used in Chapter 

VI is not available through the National Weather 

Service. These values may eventually be provided, 

but until they are the smoke manager must predict the class from reported cloud cover and cloud 

he@t plus angle of the sun. A predicting method 

is provided in ?'able 11. 

POLLUTION 

CLIMATOLOGY 

Forestry smoke managers responsible for a 

large number of planned burns are urged in 

Chapter VI to develop schedules based upon the 

total number of days with good probability of 

satisfactory smoke transport and dispersion, as 

well as other burn objectives. %I do this requires 

an understanding of the climatology of pollution 

and a knowledge of available sources of appropriate climatologies. This leads us to consider again 

the phenomena affecting transport and dispersion 

discussed earlier. 

Climate, the synthesis of these conditions 

over a long time, should be used in formulating 

long-range prescribed burning plans. Climatic 

conditions to be considered in prescription burning plans include stagnation, mixing, windspeed, 

and wind direction frequencies. 

%I avoid high concentrations of smoke in sensitive areas, burning often has to be done when the 

Table 11. - Stability estimating method 2 

After Pasquill ( 19751, with insolation estimates incorporating shadow length or cloud cover after Lavdas (1976). 

Burns will be delayed in Decision-Logic Stage No. 1, Chapter VI. 

Shaded areas indicate categories for which typical cases are not presented in Chapter VI. 

How to use table: 

1. Locate main column head for day or night. Night applies from 1 hour before sunset to 1 hour after 

sunrise. 

2. Locate subcolumn head for cloud cover. 

3. If for day situation, locate sub-subcolumn head for 6-foot vertical standard shadow length, 

4. hate row for surface windspeed. 

5, In ro~r and under column, read stability class category. 

Example: Day with more than 50 percent low and mid clouds and shadow length less than 3.5 feet 

with windspeed 8 to 10 mph. Read stability category B-C. 

Surface 

windspeed 

DAY NIGHT 

50% or more cloud Clear or less than 

More than 50% 

low clouds 

. cover w/low and 50% cloud cover w/ 

Clear or 50% or 

less cloud cover wl 

low & mid clouds: 

or any high clouds 

More than 50% 

low and mid 

clouds 
wind is blowing in a particular direction. Forestry 

smoke managers can determine the probability 

that the wind will be blowing in the proper direction on a given day from summaries of prevailing 

seasonal wind directions. 

Needed climatological information may be 

found in the literature cited in this section. The 

Climatic Atlas of the United States (available 

from the National Climatic Center, Federal Building, Asheville, North Carolina 28801) is another 

comprehensive source. This publication gives 

monthly and seasonal averages and totals for most 

of the phenomena affecting transport and dispersion. Airport summaries of windspeed and direction frequencies are available from the National 

Climatic Center as well. 

Two primary factors that inhibit atmospheric 

dispersion are light winds and stable atmospheres. 

When these persist, stagnation occurs. High-pressure systems, or anticyclones, exhibit both of these 

characteristics. Korshover (1971) used 35 years of 

upper air observations to determine the relative 

occurrence of stagnant anticyclones. He found 

that stagnant conditions in the Southeast occur 

most frequently during late summer and fall. The 

maximum number of stagnant episodes lasting 4 

days or more occurred in north Georgia and in 

western North and South Carolina. 

Stagnant anticyclones are not the only 

systems that result in poor dispersion conditions. 

Dilution capacity of the atmosphere may be poor 

during other meteorological patterns, such as 

when inversions persist. Hosler (1961) reported 

the frequency of low-level (less than 500 feet) inversions over the Continental United States during a 2-year period. His findings agree well with 

Korshover's (1971) -inversions causing poor dispersion patterns in the Southeastern United 

States occur most frequently in the fall, but may 

occur in any season. 

Holzworth (1972), in his analysis of 5 years of 

National Weather Service data, presented mixing 

heights, windspeeds, and the resulting potential 

for urban air pollution tbughout the contiguous 

United States. His generalizations may be applied 

to rural atmospheres. 

MATHEMATICAL 

MODELS 

Different assumptions about governing processes and behavior have resulted in many 

different models for calculating dispersion. Some 

are different merely because of their intended application. Additional work will undoubtedly yield 

yet a wider variety from which to choose. In the 

discussions that follow, we will address the criteria 

we used for selecting a dispersion model-as well 

as the related approaches used in the decision logic 

in Chapter VI. We will also cover modifications imposed upon selected approaches, but will leave full 

development and defense of previously published 

equations to cited sources. 

Three general criteria were applied in selecting and adapting the model: 

1. Predictions close to the burn are the most 

critical, and the model must accurately reflect 

source and atmospheric variables. 

2. The model must be widely accepted by 

scientists in regulatory agencies. 

3. The model must permit either computer 

or desk-top calculations. 

In order to provide a practical predictive 

method for smoke concentrations at downwind 

locations, it has been necessary to assign fixed 

values for some factors. In Chapter IV two separate fire phases are described: the convective-lift 

and the no-convective-lift fire phases. While smoke 

entrainment will gradually increase then decline 

in the convective-lift phase, use of a steady state is 

believed to be realistic in order to make calculations manageable. In the no-convective-lift phase, 

emissions will gradually decline; but again, using 

a steady-state condition is necessary if anything 

but extremely complex equations calling for automatic data processing are to be applied. Similar 

steady-state compromises are applied in the final 

transport and dispersion model to be introduced in 

this section for use in Chapter VI. In addition to 

these practical considerations, current knowledge 

does not justify more sensitive, time-dependent 

adjustments at this time. 

PLUME RISE 

The height that the center of the smoke 

plume attains is called plume rise. During the convective-lift phase of combustion, heat released by 

the fire causes convective lift of emissions from the 

fire in a definite column. As this heat diminishes, 

the plume loses its columnar shape to a point 

where lift of emissions is mostly a result of vertical 

atmospheric mixing alone. Thus, while atmospheric stability is an important variable at all 

times, heat release rate, explained in Chapter Iv 

will be employed only for the convective-lift phase. 

Winds impinging upon the column during the convective-lift phase tend to bend or shear it, restricting the total possible plume rise. Plume rise, 

therefore, is a function of heat release rate, atmospheric stability, and transport windspeed. Inversions will also limit plume rise and are accounted for by stability. Mixing height becomes 
important after the initial convective lift, and is 

incorporated in the final dispersion model. 

In discussions with Dr. Gary A. Briggs of the 

NOAA Oak Ridge Laboratory, we elected to adapt 

the plume rise relations he developed for stack 

emissions handled as point sources. Briggs' (1969, 

1971, 19723 plume rise relationships fit satisfactorily for prescribed fires when his term QH is expressed as the total rate of heat release from the 

entire length of fired line, as determined by relationships explained in Chapter IV. Relationships 

were examined for stability classes A through F 

(Pasquill 1975). Equations (1) through (4) are 

used in calculating ultimate plume height, in 

which: 

H = height (in meters) 

QH= total heat release (in calories per second> 

u = transport windspeed (in meters per 

second). 

For stability classes A through D,and QHiess 

than 1.40 x lo6 cal/sec: 

For stability classes A through Dl and QH 

greater than 1.40 x 106 cal/sec: 

H = 0.0847 QH 3/5 u (2) 

For stability class E and all values of QH 

(temperature increase with height of 1°C per 100 

m assumed) : 

H = 0.917 QH 1/3 u -1/3 (3) 

For stability class F and all values of QH(tem - 

perature increase with height of 2.5"C per lOOm 

assumed) : 

H = 0.761 Q~ 'I3 u -'I3 

Equations (1) through (4) are used to calcu - 

late plume rise while the smoke rises for some distance as it travels downwind. Often ultimate 

height is not reached for several kilometers downwind. This distance is not affected by transport 

windspeed. Briggs' (1969) ultimate height for a 1 

megacalorie per second source is attained about 

480 meters (0.3 mile) downwind. From Briggs' 

work, downwind &stances to ultimate heights for 

sources releasing heat at different rates under 

stability classes A through D compare as follows: 

Heat release Approximate down- 

(Megacallsec) wind distances to 

ultimate heights 

(Miles) 

1 0.3 

10 0.8 

It can be shown that at one-third the downwind distance to ultimate height, one-half the 

ultimate height is consistently attained. For example, a 10 megacalorie per second fire with an 

ultimate plume rise limited to 250 meters will 

have attained a height of 125 meters at 0.27 mile 

downwind (i.e., 113 x 0.8 mile). 

When Briggs' (1969) equation (4.30) is applied, most southern prescribed fires are shown to 

be unable to penetrate a modest inversion of 1" C 

at 100-meter elevations or higher. 

Now we have a means to express the total 

height of the plume. That portion of the smoke observed to remain unentrained and traveling along 

the ground still remains to be accounted for. This 

phenomenon is experienced even during the hottest portion of the convective-lift phase in 

southern prescribed fires. Additional research is 

needed, but observations of the phenomenon on 

three experimental fires were used to arrive at a 

ratio of 60-rise to 40-no-rise for the amount left 

unentrained. This ratio was borne only by observations on a fourth experimental fire. 

The 60:40 ratio has thus been suggested for a 

limited number of both heading and backing fires. 

When heat release (HR, the heat released per unit 

of fired-line length, rather than the total heat 

release rate (HRR), or QH)is increased, the ratio 

can logically be expected to increase toward 100:0, 

provided stability and transport windspeed remain unchanged. For example, a campfire can be 

seen to lift all emissions by convection so long as 

its heat causes a dram from all portions of the fire. 

But the same fire, while still maintaining a convection column, will in time cease to draw smoke 

from its outer portions. Smoke from these portions 

will then tend to drift free from convective lift. 

This is essentially what takes place in most 

southern prescribed fires covered in the logic of 

Chapter VI. It seems likely additional research 

will lead to adjustments in the 60:40 ratio, 

In working with plume rise under unstable 

atmospheric conditions, the effect of vertical wind 

eddies that temporarily bring high smoke concentrations aloft closer to the ground have been 

evaluated. The largest vertical eddies occur when 

instability is greatest. Eddy sizes decrease as conditions become more nearly stable, and the plume 

rise fluctuations become less significant. These 

conditions have been found to be important to dispersion calculations for emissions from cool 

sources like elevated smoke stacks, but they have 

not been observed in our experimental fires in the 

Southeast. 

Tb summarize, two expressions have been introduced. These are the factor H for ultimate 
plume height, and the coefficient 0.6 for the 

amount of smoke entrained in the convection column of the convective-lift fire phase. Both will be 

noted as adaptations in the dispersion model to be 

discussed in following subsections. 

SELECTION OF A 

DISPERSION MODEL 

Forest managers have been exposed to the 

"tank concept" and to applications of a "box 

model" of dispersion. These names are sometimes 

incorrectly described as interchangeable. Before 

selecting any more complex model, it was thus 

necessary to assess possible adaptations of these 

two relatively simple approaches. 

The "tank concept" is a convenient way of 

thinking about a certain atmosphere's ability to 

"absorb" a specified level of air pollutants. The atmosphere, of whatever dimension, is thought of as 

a container with imaginary "walls" (such as 

mountains, but sometimes only arbitrary or political boundaries) and a "lid (such as imposed by an 

inversion or by the mixing height). It is assumed 

that smoke is distributed evenly, and that emissions can be accommodated until smoke concentrations reach an accepted maximum for the 

"tank'? as a whole. Unfortunately for a management 

use of this concept, however convenient it may be 

in gaining an initial grasp of air pollution problems, the real world of smoke transport and dispersion does not operate nearly so simply! Within the 

"tank," emissions from each source flow along an 

axis determined by the transport wind direction. 

Initial horizontal and vertical diffusion (dispersion) is defined by physical laws that do not result 

in uniform distributions of pollutant concentrations, even when the "tank" has real walls such as 

a valley or mountain canyon. The result is that 

along the path of the plume initial smoke concentrations will be greater than in the "tank" as a 

whole (a very undemocratic consequence for individuals along the plume's path if they are depending upon administrators of the "tank" to 

assure them their equal share of pure air). 

The term "box model" differs from the 

"tank concept" in that dispersion takes place 

along an axis determined by transport wind direction. Ilistribution, however, is considered to be 

uniform. This model has gained acceptance 

through application to dispersion problems in the 

Willamette Valley of Oregon (Reiquam 1970). A 

derivation labeled the "smoke-volume model" has 

been suggested by Williams (1974) for application 

to prescribed fires. This variant differs from the 

box model in that the plume is restricted by formulas b& upon measured heights and widths of 

experimental fires. The principal advantage of 

uniform distribution models is the ease with 

which calculations for different downwind distances can be accomplished. A potential for solution of long-range transport problems has been 

identified (Pasquill 1972). The chief disadvantage, 

however, is that because plume rise is not accounted foq the predicted ground-level concentrations due to a uniform vertical distribution are not 

valid for locations within the first 100 kilometers 

(62 miles) of sources. 

Wide acceptance has been gained for application of the Gaussian distribution to dispersion 

modeling. A statistical tool, the Gaussian distribution permits a general description of smoke plume 

dispersion over time. There have been numerous 

independent validations in both laboratory and 

field experiments (Hay and Pasquill 1957; Cramer, 

Record, and Vaughan 1958; and Barad and 

Haugen 1959). A workbook, published by the U.S. 

Environmental Protection Agency (Turner 19701, 

en joys widespread application by scientists working on dispersion. This approach employs Gaussian distribution, as well as a synthesis of the 

work of other accepted authorities. Methods of the 

Turner Workbook (1970) have thus been selected 

for use in this Guidebook. 

ADAPTATION OF THE 

TURNER WORKBOOK 

METHODS TO A MODEL 

FOR MANAGING 

SMOKE 

FROM PRESCRIBED 

FIRE IN THE SOUTH 

Our initial adaptation of the Turner 

Workbook is straightforward, with Equation (5) 

being the model used. Combinations of terms and 

derivations are after Turner (19701, except as 

adaptations are explained in the list of variables 

and coefficients (table 12). 
Table 12. -Variables and adaptive coefficients used in Equation (5). Other coefficients are from Turner (1970). 

Variable or 

coefficient Definition and discussion Units 

Centerline, ground-level concentration microgramslmeter 3 

Plume rise, adapted from Briggs (1969, 

1971,1972) and as recommended by 

Turner (see Plume Rise discussion) 

meters 

Length of fired-line adaptation meters 

Mixing height, the height in the atmos- meters 

phere to which turbulent mixing occurs 

Reflection numbers (as smoke bounces off 

the ground or stable layers) after Bierly 

and Hewson (1962) 

nondimensional 

Emission rate per unit length of firedline adaptation (equivalent to ER) 

Transport windspeed meterslsecond 

Variable crosswind distance from mid. meters 

point of fireline to the limits ~f: L/2uy 

Horizontal standard deviation of plume 

concentration distribution 

meters 

Vertical standard deviation of plume 

concentration distribution 

meters 

1.2 and 

1.6 

Adapted coefficients resulting from 

combination of terms with the 0.6 

coefficient for the 60- percent entrained and 40 - percent unentrained 

smoke covered under Plume Rise. 

nondimensional 

Besides being a complex series of terms, 

Equation (5) calls for certain inputs which are 

difficult to derive. Some simplifications can be 

achieved by solving for the relative concentrdtion, 

XU on the left-hand side. Transport windspeed, u, 4 

The first of these alternatives resulted in 

such an unwieldy set of tables, graphs, instructions, and intermediate calculations that it was 

discarded. Alternative No. 2 is in progress at this 

writing. Recognizing the value of close exposure 

to the actual procedures, and recognizing as well 

that some users would not have immediate access 

to automatic data processing, we have pursued 

alternative No. 3 in this Guidebook. 

and mixing height, M, are readily obtainable for 

field application, but the remaining three variables on the right-horizontal and vertical standard deviation of plume concentration distribution, o and cZ, and plume rise, H, all call for more 

Y 

than the equation itself. 

This need for further adaptation brought us 

to three alternatives: 

1. Using a computer program to generate a 

series of graphs or look-up tables 

2. Offering a computer program in a form 

that could be accessed by users 

3. Providing a combination of look-up tables 

and typical cases with predicted concentrations 

that could be adjusted to actual cases. 

PLOTTING RESULTS 

OF CALCULATIONS 

When ground-level dispersion patterns 

calculated with a modified Gaussian distribution 

model are plotted to scale, they will typically show 

curves like those of figure 21. 

Because of possible deviations of the actual 

wind direction from the forecast, and the need to 

avoid underestimating smoke impact at designated targets, the Gaussian model is not used in 

unmodified form for predicting downwind smoke 
' . 

\\ 

\' 

\ 

\ 

'\ 

L. 

Figure 21. - Ground-level dispersion patterns 

from a modified Gaussian distribution 

model. Concentrations are shown on a hypothetical scale of 100 for ease of visualizing 

changes. 

concentrations. Rather, a system that extends the 

centerline concentrations 30" to either side of the 

expected downwind direction is used. A possible 

promise of partially reducing this adrni ttedly conservative allowance, as well as others, lies in automatic data processing for predicting trajectories 

and concentrations on the day of burning. This 

promise lies in an ability to work with more 

massive data from localized weather forecasts 

which are adjusted over time as the smoke plume 

travels downwind. While the technology is available now, a conservative procedure must be suggested for use until adaptive work in progress can 

be completed. 

The presently suggested procedure calls for 

plotting the crosswind length of the line to be fired 

and plotting a downwind trajectory from the 

center point of that line. From the ends of the line, 

downwind trajectories are plotted as dashed lines 

for a distance of twice the crosswind length of the 

fired line. From these end trajectories, lines of the 

limits of possible smoke impact are drawn at 30" 

outward angles. The trapezoid-like figure that 

results depicts the area of probable smoke impact. 

Concentrations in the impact area are determined by striking arcs through the centerline trajectory at specified distances. At distances less 

than twice the crosswind line length, two arcs 

should be struck using the line end points as centers. The two end point arcs are then connected by 

a straight line passing through the trajectory centerline. Beyond two fired-line lengths downwind, 

this procedure may be satisfactorily approximated 

by simply drawing a single arc between the smoke 

impact limits with the middle of the crosswind 

line as the center for the arc. The resulting plot, 

like the one shown in figure 22, differs from figure 

21 by intention. This difference allows for a plot of 

predicted maximum concentrations by zones that 

extend through the centerline to either edge of the 

trajectory, thereby avoiding underestimates of 

concentration due to transient or unexpected 

wind or centerline shifts. 

Figure 22. - Plot of predicted centerline concentrations like those to be employed in 

Chapter VI. The "2Z' point indicates twice 

the fired-line length. 

When completed, these plots are used to obtain a total predicted concentration at any potential downwind target by adding the concentration 

within the zone defined by an arc to the "background" pollutant concentration at the potential 

target. This permits rapid comparison of total predicted concentrations with acceptable concentrations for all potential targets. 

A rule of thumb (No11 and others 1968) can be 

employed to estimate ''background" pollutant concentrations when these have not been quantified 

by other means. The rule is limited to relative 

humidities of 70 percent or less and to particulate 

'matter 0.3 micron in diameter and larger. 'Ib use 

the rule, 730 micrograms per cubic meter per mile 

are divided by the visibility in miles. For example, 
if the visibility is 5 miles, the "background pollutant concentration is estimated to be: 

LONG-RANGE 

TRANSPORT 

Transport of emissions beyond the 100 km (62 

miles) limit of the model employed becomes a new 

predictive problem. Because this problem is almost 

in a province of regional smoke management, we 

have made no attempt to provide any adaptation 

from among the best of several models under 

study at this time. We have, however, recognized 

the importance of the normally stable trend 

toward evening. At the same time, we have attempted to provide a margin of safety to help 

assure the manager that smoke from a single burn 

will not contribute to problems beyond 100 km. CIb 

do this, we devised a procedure called Long-Range 

Transport Margin which is incorporated in 

Chapter VI. 

BASIS FOR LONG-RANGE 

TRANSPORT MARGIN 

For fires in fuel types known to be relatively 

heavy emitters, when the convective-lift fire phase 

will extend beyond 3 hours before sunset, users 

will find themselves referred to figure VI-M-1 in 

Chapter VI. To use figure VI-M-1, a graphic intersection of the fire emission rate (ER) and 

transport windspeed is located. If the intersection 

is either to the left of, or upon, the sloping internal 

line 

8 2 qL - 7.5 x 10 microgramslm -sec, -- (6) 

u 

the burn may be considered safe. If the intersection is to the right of the line, the fire prescription 

should be modified. 

The principal consideration underlying this 

procedure is to avoid carrying concentrations of 

particulate matter in excess of 150 micrograms 

per cubic meter beyond 100 km when stable conditions can be expected. 

The following assumptions have been made 

in constructing figure VI-M-1: 

1. D stability 

2. No plume rise (because at 100 or more km 

a plume is well mixed within the mixing layer) 

3. Point source (source configuration is of no 

consequence at 100 km) 

4. Relative concentration, - Xu, at 100 km is 

qIJ 

2 x loq7 meter-2, which is consistent with 150 

micwams/m3; variables are the same as previously listed, 

LIMITATIONS OF THE 

MATHEMATICAL MODEL 

Of the essential model, Turner (1970) points 

out that it ". . . may provide best estimates but not 

infallible predictions.'' We offer the adapted model 

in this same frame of reference. In addition to 

other limitations mentioned in preceding discussions, it is particularly important to note that as 

the smoke disperses with time, stability and other 

weather variables will change. The present model 

does not account for these changes. We have, 

however, covered one procedure adapted from the 

model to provide a margin of safety for long-range 

transport. This procedure is made part of those in 

Chapter VI to partially compensate for changes in 

stability. Finally, the user of the procedures in 

Chapter VI must recognize limitations in the accuracy of weather forecasts. In making these best 

estimates the user is allowing for upward and 

downward mixing within a zone of concentration. 

As a consequence, not all potential targets will be 

receptors at any given instant. He is portraying 

the potential concentration at each target. 

LITERATURE CITED 

Barad, M. L., and D. A. Haugen 

1959. A preliminary evaluation of Sutton's hypothesis for diffusion from a continuous point 

source. J. Meteorol. 16(1): 12-20. 

Bierly, E. W., and E. W. Hewson 

1962. Some restrictive meteorological conditions to 

be considered in the design of stacks. J. Appl. 

Meteorol. l(3) :383-390. 

Briggs, G. A. 

1969. Plume rise. Air Resour. Atmos. Turbul. and 

Diffus. Lab., Environ. Sci. Serv. Adm., U.S. 

Atomic Energy Comm., 81 p., Oak Ridge, Tenn. 

Briggs, Gary A. 

1971. Some recent analyses of plume rise observations. In Proc. Sec. Int. Clean Air Congr., 

p. 1029-1032, Acad. Press, New York. 

Briggs, Gary A. 

1972. Discussion, chimney plumes in neutral and stable surroundings. Atmos. Environ. 

6(71:507-510. 

Cramer, H. E., E A. Record, and H. C. Vaughan 

1958. The study of the diffusion of gases for aerosols in 

the lower atmosphere. Final Rep., Contract 

AF19(604)-1058,70 p., Mass. Inst. of Tech., Dep. 

Meteorol., Cambridge, Mass. 
Hay, J. S., and E Pasquill Pasquill, E 

1957. Diffusion from a fixed source at a height of a few 

hundred feet in the atmosphere. J. Fluid Mech. 

2, Part 2, p. 299-310. 

Holzworth, George C. 

1972. Mixing heights, windspeeds, and potential for 

urban air pollution throughout the contiguous 

United States. U. S. Environ. Prot. Agency, Off. 

Air Programs, Publ. No. AP-101, 118 p., 

Research Triangle Park, N.C. 

Hosler, Charles R. 

1961. Low-level inversion frequency in the contiguous 

United States. Mon. Wea. Rev. 89(9) :319-339. 

Korshover, Julius 

1971. Climatology of stagnating anticyclones east of 

the Rocky Mountains, 1936-1970. NOAA Tech. 

Memo. ERL-ARL-34,27 p., U. S. Dep. Commer., 

Natl. Oceanic & Atmos. Adm., Silver Spring, 

Md. 

Lavdas, Leonidas G. 

1976. A groundhog's approach to estimating insolation. J. Air Pollut. Control Assoc. 26(8) :794. 

Noll, Kenneth E., Peter K. Mueller, and Miles Imada 

1968. Visibility and aerosol concentration in urban 

air. Atmos. Environ. 2(5) :465-475. 

1972. Factors determining pollution from local 

sources in industrial and urban areas. The 

Meteorol. Mag. 101 (1194) : 1-8. 

Pasquill, E 

1975. Atmospheric diffusion. 2d ed., p. 368. John 

Wiley and Sons, New York. 

Reiquam, W. 

1970. An atmospheric transport and accumulation 

model for airsheds. Atmos. Environ. 

4(3) :233-247. 

Schroeder, Mark J., and Charles C. Buck 

1970. Fire weather . . . A guide for application of 

meteorological information to forest fire control 

operations. USDA For. Serv. Agric. Handb. 360, 

228 p., USDA For. Serv., Washington, D.C. 

Turner, D. Bruce 

1970. Workbook of atmospheric dispersion estimates. 

U. S. Environ. Prot. Agency, Off. Air Programs, 

Publ. No. AP-26,84 p., Research Triangle Park, 

N.C. 

Williams, Dansy T. 

1974. A smoke volume model for prescribed fire. In 

Proc. Symp. on Atmos. Diffus. & Air Pollut.: 

Santa Barbara, Calif., p. 159-162. Publ. by Am. 

Meteorol. Soc., Boston, Mass. 

CHAPTER VI 

HOW TO MANAGE SMOKE 

John M. Pierouich, Program Manager 

Ragnar W Johansen, Research Forester 

Leonidas G. Laudas, Research Meteorologist 

Hugh E. Mobley, nchnical Specialist 

James A. Pharo, Research Meteorologist 

Charles D. Rngren, Physical Scientist 

Southern Forest Fire Laboratory 

Southeastern Forest Experiment Station 

U-SDA Forest Service 

Macon, Georgia 

This Chapter is written to help manage 

smoke from forestry prescription burning once the 

decision to burn has been made. No attempt is 

made here to evaluate alternatives to burning. 

Sometimes, the logic steps may lead to a suggestion that the decisionmaker take a new look at 

other possible treatments. We will first discuss the 

concepts of smoke management planning and 

then present a decision-logic procedure. Part 3 of 

this Chapter contains tables needed to follow some 

of the more complex logic. 

PART 1. 

PLANNING FOR 

SMOKE MANAGEMENT 

A written burning plan should be prepared in 

advance for each area to be burned. It should contain a scheduling system and prescription elements that aim at both accomplishment of objectives and avoidance of unwanted air quality 

effects. We suggest that, as used, the worksheets 

presented in Part 2 of this Chapter be attached to 

file copies of completed plans. 

SCHEDULING 

The number of days during a season with conditions fitting both resource management objectives and air quality objectives is limited. As a consequence, it is likely that the number of large 

burns will increase on the few days when both sets 

of constraints are met. Smoke from several forestry sources could tax the smoke-absorbing 

capacity of target-area atmospheres on these days. 

A need for systematic and careful scheduling of 

burns is called for. 

A scheduling system that minimizes the 

effects on air quality should include the following 

elements : 

An analysis of the number of days each year 

when weather is likely to meet both management objectives and air quality objectives 

The numbers, sizes, and locations of desired 

burns listed by priority and difficulty of 

burn -along with likely-best smoke plume 

trajectories 

A method of allocating available days to 

desired burns 

A procedure for selecting alternate burn 

tracts when unfavorable weather conditions 

prevent following the schedule 

An inventory of expected background particulate matter concentrations in areas likely to 

be downwind from prescribed burning operations. 

PLANNING 

CHECKLIST 

1. Follow a formally prepared plan. 

2. Be sure all legal requirements are met. 

3. Provide in advance for burning permit, 

receipt of weather forecasts, and prior measurement of variables like total litter layer moisture 

content. 

4. When windrowing and piling debris, 

provide for best drylng and avoid mixing with dirt. 

5. Follow a decision logic to determine the 

kind of day on which you should be able to burn 

with good smoke management. 
6. Use localized weather information, asking for spot fire-weather forecasts and updates. 

7. Burn when wind will not carry smoke 

into sensitive areas (targets). 

8. Seek unstable weather conditions, but 

not extremes. 

9. Avoid days with low morning transport 

windspeed (less than 4 mph) . 

10. Avoid days with low morning mixing 

heights (less than 500 meters). 

11. Seek dry fuel conditions, but not extremes. 

12. Seek low relative humidity, but not extremes. 

13. Be cautious of nighttime burning (if 

permitted). 

14. Be especially cautious when burning a 

large area or a heavy loading of fuel. 

15. Use firing technique that produces the 

least emissions. 

16. Be prepared to mop up stumps and 

snags, especially if large and decaying. 

17. Make last-minute check on weather 

conditions. 

18. Remember that fires have to be controlled, and timber should not be excessively 

scorched; as dispersal conditions improve, fire intensity increases. 

19. Be alert for a change in weather conditions. 

PRESCRIPTION ELEMENTS 

Combinations of the following fire prescription elements are necessary to plan for maintenance of air quality. Some variables that are 

foreign to foresters will be needed for smoke management. In the list of elements which follows, 

numbers in parentheses refer to the decision-logic 

stages where each is used: 

Fuel type (No. 1 and No. 2) 

Age of rough (No. 1 and No. 2) 

ntal litter layer moisture content (No. 2) 

Fine fuel moisture (No. 2) 

Firing pattern (No. 2) 

Length of fired line (No. 1 through No. 3) 

Relative humidity (No. 2) 

Air temperature (No. 2) 

Stability (No. 1 and No. 3) 

Mixing height (No. 1) 

Surface windspeed and direction (No. 1 

and No. 2) 

Transport windspeed and direction (No. 1, 

No.3, and No. 5). 

PART 2. 

DECISION LOGIC 

INTENDED USE AND 

LIMITATIONS 

You are now well aware of the large amount of 

information that must be integrated to determine 

if fire prescriptions will meet air quality objectives. ?b accomplish this task, we have developed a 

decision-logic system for applying the best 

knowledge available. The system applies the 

mathematical models and concepts discussed in 

Chapters IV and V: The criteria for the system are 

discussed in Chapter I11 under A VOLUNTARY 

DECISION PROCEDURE PROPOSED FOR 

FORESTRY SMOKE MANAGEMENT, starting 

on page 26. 

The system calls for the user to specify his 

own fire prescription elements and to adopt acceptable levels of total suspended particulate matter 

(TSP) for target areas downwind. While designed 

for advance planning, the system should also be 

used on the day of burning with actual and 

forecast values substituted for prescribed values. 

Our intent is to provide the easiest possible 

procedure to AVOID OVERLOADING NATURAL 

CLEARANCE MECHANZSIMS. A model is a representation of beliefs about a natural system, not 

necessarily what actually takes place. For manageability, models used for dispersion calculations 

and for heat release rate (HRR) and emission rate 

(ER) calculations are dependent only upon values 

expected as averages for steady-state conditions 

during two discreet fire phases. We have chosen 

this course rather than attempt to impose more 

realistic, but exceedingly complex, equations - 

allowing for changes in state during the life of the 

burn. For these reasons, the logic system's predictions may be incorrect at times even though the 

system applies the best available technology. 

OVERVIEW 

The system is divided into six stages to keep 

the user oriented as he progresses. It is designed 

for desk-top calculations. As presented here, 

system responses to variability have been compressed to facilitate use. For example, in one instance, many separate operations and at least 32 tables are represented by only a few typical cases. 

Stage No. 1 is for relatively simple screening 

of prescriptions. From it the user can decide to 

burn, not to burn, or to proceed with more detailed 

analyses in subsequent Stages. We expect that 

this first Stage will cover many prescription 

burns. Stages No. 2 through No. 5 apply to more 
complex situations where decisions are not immediately obvious. Stage No. 6 introduces automatic data processing options.51 

Stage No. 2 is the logic for determining fuel 

and fire characteristics so that emission rate and 

heat release rate can be calculated. Stage No. 3 

provides for dekmining a margin of safety for 

concentrations carried long distances. In Stage 

No. 4, the user matches his prescription variables 

to typical burning cases. Provision is made to correct for differences between presented and typical 

cases. Then, downwind concentrations of total suspended particulate matter can be calculated. In 

Stage No. 5, comparisons are made between predicted and user-specified total suspended particulate matter concentrations at targets. Decisions to 

be reached at this point are: to follow the burn 

prescription, to revise the prescription further, to 

find an alternative to burning, or to proceed with 

an analysis that requires automatic data processing. 

51 Programs will be provided in the Forestry Smoke Management 

Sourcebook. 

We recognize that small landowners will find 

Stages No. 2 through No. 5 especially bothersome 

without technical staff or assistance. An adaptation of Stage No. 1 has been published for their use 

in uncomplicated situations (bgren 1976). 

In more complex situations, there are no easy 

ways to determine smoke dispersion without automatic data processing. 

For those who do not have access to a computer, the desk-top decision-logic procedure will 

seem tedious. We believe it is the only way, 

however, to assure proper analyses, and we advocate its initial use even for those who have access 

to automatic data processing. 

USE OF WORKSHEETS 

Each Stage of the logic is presented in 

worksheet format. It is suggested that you make 

copies of these worksheets (yellow pages), Save 

one set of copies for future use as an original, then 

use extra copies as working papers to include with 

each burn plan and prescription. 

Worksheet Set 1, page 1 of 5 

DECISION-LOGIC STAGE #I: INITIAL SCREENING 

To use this decision logic you should have already prepared a written prescription, and you should be familiar with applicable air quality rules, 

regulations, and standards. If there are no obvious situations that preclude burning, you are ready to proceed, 

This Stage will help you decide if your prescription calls for a burn that 

is: 

possible without modification 

possible with modification 

not possible. 

We believe most prescribed fires will fall into the first two categories. 

Steps 

app l i 

folio 

1.2 and 1.3 contain questions to be answered YES or NO. If all 

cable questions are answered YES, the burning prescription can be 

wed without modification. Burning is still possible if all NO answers 

can be changed to YES by modifying the fire prescription; for example, by 

calling for another time to burn when mixing heights are more favorable, or 

when the transport wind direction will not carry smoke into target areas. 

If you answer NO and callnot modify the prescription to be able to answer 

YES, you should not burn unless you favorably complete a more detailed 

analysis in Stages #2 through #5. 

1.1 PREPARATION 

1. la Wind Direction and Targets: 

(1) Obtain map(s) covering improvements detail for 60 miles downwind from burn. Obtain azimuths of paths from burn prescription 

for both the convective-lift (CL) and the no-convective-lift (NCL) 

fire phases. Locate burn on map and, using protractor and straight 

edge, draw lines representing centerline of paths of smoke plume. 

Use two different colors to plot the two phases. Then check here 

and proceed. 

Prescription specifies: 

Convective-lift phase transport wind azimuth 0 

No-convective-lift phase transport wind azimuth 0 

(NCL is omitted for backing fires) 

(2) Now you must allow for the width of the fire and shifts of the 

smoke plume centerline. Plot as in figure A if the fire is 

represented by a small dot. If it is larger, plot as in figure 

B. 
\forksheet Set 1, page 2 sf 5 

Within the plotted areas, look for any improvements or other 

potential target (e,g.: tom, Air Quality Maintenance Area, 

highway, village, hospital, factory, residence, airfield, etc.) 

that you consider critical from an air quality standpoint. 

Then check here and proceed. 

(3) If in rare cases no potential targets are found, this logic need 

nod be applied, and you may burn without further use of the 

procedure. If any targets are identified, you should continue 

with the procedure. Attach your map(s) to this Worksheet and 

check one of the following: 

Target(s) identified, logic will be applied 

(go on to Step lh) 

No target(s) identified, logic need not be 

applied further (Stop) 

l.lb Fuel Type: 

(1) At this time, research is not sufficiently complete to cover 

other than the following fuel types. If your fuel type is 

other than the ones listed, you must decide if one of these is 

reasonably comparable to proceed through the rest of the logic 

using this type, or you must plan your prescription without aid 

of the logic system. 

Palmetto-gallberry 

Grass with pine overstoryPine needle litter 

Light brush 

Unpiled pine logging debris 

(2) Check the appropriate fuel type above if yours matches, or if 

you select a type as nearly comparable as you can. 

(3) If you selected a conparable type, circle the checkmark. 

(4) If you checked none of the types listed, you may wish to use 

this Stage #l Worksheet, but do so with special caution and 

do not attempt to use Stages #2 through #6. 
Worksheet Set 1, page 3 of 5 

(5) Now check one of the following: 

Type matches or comparable type selected, 

and logic will be applied 

Type does not match, and comparable type 

not selected 

but Stage P1 will be applied 

and Stage gl will not be applied 

1,2 CRITICAL TRAJECTORIES 

If a NO answer is given to any of the following questions, it is most 

desirable to prescribe a new transport wind direction to avoid target 

areas in question. Be sure to aka rework Step Z. Za to refTeet $he 

neQ prescribed a2imtl-t-hs. 

If you cannot prescribe a new wind direction you should proceed 

immediately with Stages #2 through #5, but be prepared to encounter 

downwind concentrations that may not be acceptable. 

1.2a Sulfur Dioxide Interactions: 

Does your trajectory avoid the chance that critical sources of 

atmospheric emissions containing SO2 will merge with the emissions 

from your burn. 

1.2b Unacceptable Background Level: 

Are all identified target areas likely to be free from other known 

air pollution problems at the time of burn? (Allow for other 

forestry burning. ) 

YES 

NO 

1.2~ Is the area within 3/4 mile of your burn free of targets? 

YES 

NO 

1.3 MINIMIZING RISK 

You should always determine if you can readily change your prescription to obtain a YES answer whenever you have checked NO in 

this set of questions. 

lSulfur dioxide, SO2, is believed by many authorities to become 

a more likely health hazard in the presence of particulate matter 

from any source. If local guidance on critical sources is not 

available to you, a good rule is to avoid all sources. 
Worksheet Set 1, page 4 of 5 

1.3a Is your fuel type other than logging debris? 

YES 

NO 

1.3b For all other fuel types if your rough is older than 2 years, is a 

backing fire prescribed and is total fuel loading less than 10 tons 

per acre? " 

YES 

NO " 

1.3~ Will the burn be conducted when background visibility is likely to be 

at least 5 miles at all points within the first 60 miles along the 

plotted trajectory? (Step 1. la) 

YES 

NO - 

1.3d Are all other known or expected sources of emissions (including 

other prescribed burns) displaced to the side of your plotted trajectory (Step 1. la) by a distance of at least one-half their downwind distance and are any targets in overlapping area farther than 

2 km (1.2 miles)? 

YES 

NO - 

1.3e Does your prescription call for the forecast mixing height to be 500 

meters or more? 

YES 

NO - 

1.3f Is the prescribed transport windspeed 4 or more meters per second? 

YES 

NO - 

1.3g If your plan calls for a night burn, have you prescribed a surface 

windspeed greater than 4 mph and a backing fire? 

YES 

NO - 

NOT APPLICABLE 

2 Go directly to Stage #2 since prescription cannot be changed. 

3 This question reflects the application of current best available technology in limiting total suspended particulate matter (TSP) 

regardless of chemical nature, 

64 
Worksheet Set 1, page 5 of 5 

1.3h If a burning permit is locally required, do your prescription elements match permit requirements and does your plan call for obtaining the required permit? 

YES 

NO 4 

NOT APPLICABLE 

NOTE: You now have a set of answers to help you screen your prescription. If you have completed the preparatory Steps in 

Steps 1.1 and have now answered YES to all questions asked in 

Steps 1.2 and 1.3, you do not need to go on to Stages #2 

through #5. Instead, it is likely your prescription will provide for good smoke management and you are ready to burn. 

If you have answered NO and cannot revise your prescription, 

you should not burn until you have favorably completed Stages 

#2 through #5 .5 

4~o not proceed to Stage #2 if permit is required and NO has 

been answered. 

CAUTION: Stages 112 through 116 are likely to yield DO NOT 

BURN decision advice if you are using any of the following: 

Less than 500 meters mixing height 

Less than 4 mph surface windspeed 

Less than 4 meters per second transport windspeed 

Background visibility on trajectory less than 5 miles. 

SPECIAL INTRODUCTION TO STAGES #2 THROUGH #5 

If an autQmatic data processing procedure for smoke management decisions is 

available to you, you should skip immediately to Stage #6. 

The following interrelated parameters are needed to predict total downwind 

concentrations that will be used for comparisons with acceptable concentrations. The variables used to derive them are provided. 

Parameter Variabl es 

Total litter layer Previous litter layer moisture content, age of 

moisture content rough, yesterday" duration of precipitation 

(see Chapter JV), 

Fuel loading Fuel type, age of rough, stand basal area, understory height (palmetto.onlyj, average d,b,h, 

(Logging residue only), cords cut (logging residue only). 

Available fuel Fuel type, fuel. Boading, totab fitter layer 

moisture content, 

Emission factor Fuel type, combustion stage, age of rough, 

burning method, 

Fire phase Heat release rate. 

Gomhstisn stage Fire behavio~ 

Fine fuel moisture Temperature, relative humidity, sky condition 

(grass only) 

Stand characteristics Pseburn inventory or preharvest inventory, 

Rate of spread Fine fuel moisture, windspeed at mii$flame height, 

fuel. tyge. 

Length of fired line Prescription, plot geometry (for ring fires only). 

Heat release rate Available fuel, rate of spread, length of fired 

l ine , 

Particulate matter Available fuel, rate of spread, emission factor, 

emission rate 

Mixing height Observed and forecast weather* 

Transport windspeed Observed and forecast weather* 

and direction 

Stability class If not forecast by the National Weather Service: 

solar angle (shadow length), cloud cover and 

height, 10-meter v~indspeed (see Chapter V), 

Target-area background Effects of other emissions sourcesconcentrations 
This decision logic does not apply to slopes greater than 20 percent. 

Two sets of reference figures and tables will be used in working through 

the logic stages. The first set (tables VI-F-1 through VI-F-13) is related 

to fuels and fire behavior and is printed on pink paper. The second set 

(tables VI-M-1 through VI-M-6 and figure VI-M-I) is related to meteorology 

and is printed on blue paper. Many ca.icu?ations are represented by 

these figures and tables. Derivations are explained in Guidebook Chapters 

IV and V. 

In preparing to use the Stages, it is iqortant to recognize two constraints 

in the system presented: 

1. For each fuel type, an average emission factor [EF) has been derived 

for the most likely fuel conditions. We know that moisture and other 

variables will affect the EF, but believe the current state of knowledge 

does not warrant further refinement in calculations at this time. 

2. The strategy here is ts limit concentrations of total suspended 

particulate matter (TSP). Future control strategies may include control 

sf specific components of smoke. 
Worksheet Set 2A, page 1 of 1 

DECISION-LOGIC STAGE $2: RATE DETEWINATIONS 

You have been directed here from Stage gl because one of your responses 

indicated a degree of risk calling for more complex analyses, and/or you 

were unable to modify your fire prescription. 

From the list of parameters In the Special Introduction preceding this Stage, 

you will have noted a number of new prescription elements. Your prescription 

will require more detail, and we suggest you prepare the prescription as you 

work through this and subsequent Stages--adding new variables as needed, 

CAUTION: Do not proceed unless your prescription calls for a relative humidity 

of less than 71 percent during the convective-lift and no-convective-lift 

phases. (Predictions above this humidity are not to be used and the logic does 

not apply.) 

A. DETERMINATION OF STAGE #2 WORKSHEET SET TO BE USED: 

The fuel type you selected in Step l.lb was (cheek one, then proceed to next 

step on indicated Worksheet Set) : 

Palmetto-gal lberry Go directly to Worksheet Set 2B 

Grass with pine overstory Go directly to Worksheet Set 2C 

Pine needle litter or light brush Go directly to Worksheet Set 2D 

Unpiled pine logging debris Go directly to Worksheet Set 2E. 

Worksheet Set ZB, page I of 4 

DECISION-LOGIC SmGE #2 APPLIED TO PALMETTO-GAELBERRY FUEL TYPE 

You Have Been Directed Here From Worksheet Set 2A 

2B- 1 FUELS 

2BJa Make the following entries from your inventory of the burn area: 

(1) Stand basal area is sq ftlacre 

(2) Age of rough is Yr 

(3) Predominant overstory timber species is (check one): 

Sfash pine 

Loblolly pine 

(4) Average height of understory component is ft 

2B. Ib With entries (I), (21, and (3) from above, use table VI-F-5 if 

the predominant species is slash pine, or use table VI-F-6 if the 

predominant species is loblolly pine, to detemine the total 

Litter %eight, entering the value here: 

28.1~ With entries (2) and (4) from above, use table VI-F-9 to determine 

the understory vegetative dry weight, entering the value here: 

tonlacre 

28-2 TOTAL LITTER LAVER MOISTURE CONTENT 

2B12a Prescribe a maximum total litter layer moisture content (TLLMC), 

(Review Southern Forestry Smoke Management Guidebook Chapter IV 

for procedure and requirements.) The TLLMC will be: 

2B.2b Assure that the burning plan provides for observing and recording 

actual TLLMC, Then return here, check, and proceed to next step. 

2B- 3 TOTAL AVAILABLE FUEL 

2B3a With the total litter weight you detemincd in Step 2B.lb, the 

understory vegetative dry weight you determined in Step ZB.lc, 

and the prescribed maximum TLLMC you entered in Step 2B.2a, use 

table VI-F-10 ts detemine the estimated total available fuel 

(litter and vegetation), entering the value here: 
Worksheet Set 2B, page 2 of 4 

2B.4 PINE NEEDLE MOISTURE CONTENT AND BURNING METHOD 

ZB.4a Make the following entries from your written prescription for subsequent use: 

klaximum relative humidity % *- 

Minimm windspeed (20-foot tower) ~h 

Burning method (check one) : 

Heading fire 

Backing fire 

2B.4b With the relative humidity entry from above, use table VI-F-3 to 

determine the pine needle litter moisture content, entering the 

value here: % 

2B.5 WIND EFFECT 

2B.5a If you have prescribed a heading fire, divide windspeed you 

entered in Step 2B.4a by 4 to arrive at an estimated midflame 

windspeed, entering the value here; if you have prescribed a 

backing fire, enter a zero here: mph 

2B.6 RATE OF SPREAD 

2B.6a With the pine needle litter moisture you determined in Step 2B.4b 

and the windspeed you determined in Step 2B.5a (the windspeed used 

here for a backing fire is always 0 ), use table VI-F-11 to 

determine rate of spread, entering the value here: 

2B.7 COMBUSTION STAGES 

2B. 7a Because a sizable fraction of the fuels, when heading fired, will 

remain to be consumed in the residual combustion stage after the 

advancing-front combustion stage passes, an adjustment is needed to 

proportion the amount of fuel available to each stage. A suggested 

advancing front:residual ratio of fuel consumed is 50:50. When 

backing fires are employed, almost all of the fuel is consumed 

during the advancing-front combustion stage, and a ratio of 1:O is 

appropriate. Now select the values you judge most appropriate and 

enter here: 

(If Decimal fraction of fuel consumed in advancing-front stage 

(y,) - 

(2) Decimal fraction of fuel consumed in residual stage (yR); 

(1.00 - yAl 
Worksheet Set 2B, page 3 of 4 

28.8 EMISSION FACTORS 

2B.8a The suggested TSP emission factors (EF) for the palmetto-gallberry 

type are: 

Emission factors (lbs/ton) 

Age of rough and burning Advancing-front stage Residual stage 

met hod EF~ EF~ 

s2 years backing or heading 

and >2 years backing 25 None 

>2 years heading 25 125 

Now, opposite your age of rough and burning method, either circle the 

EF value(s) to be used or enter new values if better data are available to you. 

2B.9 EMISSION RATES 

28.9a Perform the indicated multiplications by entering the values from the 

steps shown in the following equations. 

(1) Calculate ERA, the total suspended particulate matter (TSP) 

emission rate, for the advancing front combustion stage: 

ERA = 570 x x 

(Available fuel from (Rate of spread from 

Step 2B.3a) Step 2B.6a) 

X X 

(Consumption adjustment (EFA from Step 2B. 8a) 

(yA) from Step 2B. 7 (1)) 

- ERA - micrograms TSP/meter-second (ug TSP/m-sec) 

(2) If your prescription is for a backing fire in any age rough, 

or for a heading fire in rough 2 years old or less, skip 

directly to Step 2B.9b. 

If your prescription is for a heading fire in rough more than 

2 years old, calculate ERR, the TSP emission rate for the 

residual combustion stage: 
Worksheet Set 2B, page 4 of 4 

ER = 570 x x 

R mailable fuel from [Rate of spsead from 

Step 2B-32) Step 2B,6a) 

X X 

(Consumption adjustment (EFR from Step 2B. 822) 

[yR) from Step 2B. 7a(2)) 

(3) Now calculate ERA+R, the TSP emission rate for the convectivelift phase of headlng fires in rough older than 2 years: 

- ER"+R (ERA from St@+ [ERR from Step 

2B.Sra(l)) 2iae9a(2)) 

2B.9b If you were told to skip to this Step from Step 2Be9a(2), enter 

the value of ERA, from Step 2B.9a(l) in the blank below for 

ER~L> and NONE In ERNCL below, then skip directly to Step 28.10. 

If you calculated ER irr Step 2Be9a(3), enter the value for 

ERA+R in the blank b8f8w for ERC then enter the value for ERR 

from Step 2B.9a(2) in the blank below for ERNCL 

2B.10 HEAT RELEASE RATE 

2B.10a Make the following entry from your written prescription: 

Length of fired line ft 

2B.10b Using the length of fired line from the Step immediately above 

and the same weight of available fuel and rate-of-spread values 

just used in Step 2B.9a9 calculate the heat release rate (HRR) 

for the convective-lift phase of your fire. Heat release has 

negligible effect for the no-convective-lift phase. 

HRRCL = 0.0012 x x 

(Available fuel from (Rate of spread from 

Step 2B.3a) Step 2B.6a) 

X X 

(Consumption adjustment (Length of fired line 

(y ) from Step 2Be7a(1)) A Step 2B-10a) 

NOW SKIP DIRECTLY TO STAGE #3 
Worksheet Set 2C, page I of 4 

DECISION-LOGIC STAGE #2 APPLIED TO GRASS WITI-I PINE OVERSTORY FUEL TYPE - You Have Been Directed Were From Worksheet 2A 

26.3 FUELS 

2C.h Make the following entries from your inventory of the burn area 

for subsequent use: 

(1) Age of rough Yr 

127 Stand basal area sq ft/acre 

i3j Predominant overstory (check one) : 

Slash pine 

Loblolly pine 

2C.lb With entry (1) from above, use table VI-F-1 to determine the total 

available grass weight, entering the value here: 

2C. lc With entries (I), (21, and (3) from above, use table VI-F-5 if the 

predominant overstory is slash pine, or table VI-F-6 if the predominant overstory is Zobfol1y pine, to determine the total needle 

litter weight, entering the value here: 

2C.Id Compare the entry you made for the grass weight in Step 2C.lb with 

the entry you made for the needle litter weight in Step 2C.l~. Is 

the grass component greater? 

Yes then proceed to Step 2C.2 

No then skip directly to Worksheet 2D and reclassify fuel 

type as pine needle litter, the more applicable fuel 

type. 

2C.2 WINDSPEED AND RELATED PRESCRIPTION ELEMENTS 

2C.2a Make the following entries from your written prescription for 

subsequent use: 

Expected cloud cover (check one): Sunny 

C 1 oudy 

Minimum windspeed (20-foot tower) mphTem~erature 0 

I 

Maximum relative humidity % 

Burning method (check one): Heading fire 

Backing fire 
Worksheet Set 2C, page 2 of 4 

2C.2h If your prescription calls for a backing fire, skip directly to 

Step 26.3. 

If your prescription calls for a heading fire, divide windspeed 

you entered above by 3 to arrive at an estimated midflame windspeed, 

entering the value here: 

mph 

26.3 RATE OF SPREAD 

2C.3a Use the appropriate prescription entries in Step 2C.2a with table 

VI-F-2 to determine fine fuel moisture for dead grass, entering 

the tabular value here: 

2C.3h If you completed Step 2C.2b3 use the midflame windspeed, or for 

backing fires use a zero windspeed, along with this fine fuel 

moisture to determine the rate of fire spread for grass from table 

VI-F-4, entering the tabular value here: 

2Ce4 TOTAL LITTER LAVER MOISTURE CONTENT 

2C.4a Prescribe a maximum total litter layer moisture content (TLLMC) 

(review Southern Forestry Smoke Management Guidebook Chapter IV 

for procedure and requirements). The maximum TLLMC will be: 

26.4b Assure that the bum plan provides for observing and recording 

actual TLLMC. Then return here, check, and proceed to next step: 

2C.5 AVAILABLE LITTER FUEL 

2C.k With the total litter weight (needle fuel) you determined in Step 

2C.lc and the prescribed TLLMC you entered in Step 2C.4a, use table 

VI-F-7 to deternine the available fuel in pine needle and associated 

vegetative litter other than grass, entering this value here: 
Worksheet Set 2C, page 3 of 4 

2C. E COMBINED T2YAh AIJAILABLE FUEL 

;2(1,6: '.dd the total available gr;:ss ~=:zigl-it from Steep 2Llb to the available 

litter FieH frox Ste~ 2i1,5.*, i.nter.ing the total here: 

--$A P 0 T 25& * -, %sslCsN FACTORS AN2 RATES FGi? GRASS 

3CJa An enission factor (EF) of li p~unds per ton of fuel consumed is 

suggested for grass fuels from experiments to date. Using this 

or other informatior; avaa?,;Pbie to you, select an EF appropriate 

to )'our prescribed burn, entering the value here: 

EF = Ib'ton of fuel 

ZC.7b Using the determined values from the Steps shown in the following 

equation, calculate an emission rate (ER) by performing the 

indicated mu$tipiicatisns: 

ERA = 570 x x 

(Cmbined total avail- (Rate of spread front 

able fuel from Step Step 26-3b) 

2C. 6a) 

-- 

X 

[EF from Step 2Ce7a) 

2C.7~ Since tllere is no appreciable residual combustion stage (and thus 

no no-convective-lift fire phase) for this fuel type with all 

burning methods, the advancing- front emission rate (ERA) is 

equivalent to the convective-lift (CL) fire phase. For this 

reason, enter the ERA value you determined in Step ZC.7b in the 

blank below: 

2G .8 HEAT RELEASE RATE 

2C.8a From your written prescription, enter here the length of fired 

line : 
Worksheet Set 2C, page 4 of 4 

26.a Calclrla"L the heat release rate [I-IRR) for your fire by enwering 

the determined values from the Steps shown in the following 

equation and performing the indicated multiplications: 

HRR =@,00%%x GL X 

(Combined total available (Rate of spread from 

fuel. from Step 2C.6a) Step 2@,3b) 

x 

(Length of fired Pine 

from Step 2C.8a) 
Worksheet Set 2D, page 1 of 5 

DECISION-LOGIC STAGE #2 APPLIED TO PINE NEEDLE LITTER AKDIOR LIGHT BRUSH 

You Have Been Directed Here From iyorksheet Set 2A, or by fuel type 

reclassification from Worksheet Set 2C 

20. I FUELS 

2D. la (1) If you have been directed here from Worksheet Set 2A, skip 

directly to Step 2D.lb. 

(2) If you have been directed here from Worksheet Set 2C, bring 

forward your entries from that Worksheet as follows: 

Total available grass weight ton / acre 

(from Step 2C. lb) 

Pine needle total litter weight ton/acre 

(from Step 2Celc) 

(3) Now skip directly to Step 2D.2. 

2D.lb Make the following entries from your inventory of the burn area 

for subsequent use: 

(1) Stand basal area is sq ft/acre 

(2) Age of rough is Yr 

(3) Predomj.nant overstory is (check one): Slash pine -- 

Loblolly pine 

2D. lc With the entries (I), (2), and (3) from above, use table VI-F-5 if the 

predominant species is slash pine, or use table VI-F-6 if the predominant 

species is loblolly pine, to determine the total litter weight, entering 

the value here: 

2D.2 TOTAL LITTER LAYER MOISTURE CONTENT 

2D.2a Prescribe a maximum total litter layer moisture content (TLLMC) 

(review Southern Forestry Smoke Management Guidebook Chapter IV 

for procedure and requirements). The TLLMC will be: 

2D.2b Assure that the burn plan provides for observing and recording actual 

TLLMC. Then return here, check, and proceed to next step: 
Worksheet Set 2D, page 2 of 5 

2D.2~ You will now use either the pine needle total litter weight from Step 

ZD.la(Z), if you completed this Step, or use the total litter weight 

from Step 2D.lc, if you completed this Step. With the value for 

total litter weight and the prescribed maximum TLLMC you entered in 

Step ZD.Za, use table VI-F-7 to determine the available litter fuel, 

entering the value here: 

2D.3 RATE OF SPREAD 

2D.3a Make the following entries from your written prescription: 

Relative humidity % 

Windspeed (20-foot tower) mph 

 urni in^ method (check one) : £leading fire 

Backing fire 

2D.3b With the relative humidity entry from above, use table VI-F-3 to 

determine the pine needle litter moisture content, entering the 

value here: 

2D.3~ If you have a prescribed heading fire, divide windspeed you entered 

in Step 2D.3a by 4 to arrive at an estimated midflame windspeed, 

entering the value here; or if you have prescribed a backing fire, 

enter a zero: 

2D.3d With the pine needle litter moisture content you determined in Step 

2D.3b and the windspeed you determined in Step 2D.3~ (the windspeed 

used here for a backing fire is always - 0 ), use table VI-F-8 to 

determine rate of spread, entering the value here: 

2D.4 COMBUSTION STAGES 

2D.4a Because a sizable fraction of the fuels, when heading fired, will 

remain to be consumed in the residual combustion stage after the 

advancing-front combustion stage passes, an adjustment is needed 

to proportion the amount of fuel available to each stage, Limited 

laboratory data suggest the advancing-front:residual ratio of fuel 

consumed is 50:50. When backing fires are employed, almost all of 

the fuel is consumed during the advancing-front combustion stage 

and a ratio of 1:O is appropriate. Now, select the values you 

judge most appropriate and enter here: 

(1) Decimal fraction of fuel consumed in advancing-front stage 

(yA1 : 

(2) Decimal fraction of fuel consumed in residual stage (yR) 

(1.00 - YA): 
Worksheet Set 2D, page 3 of 5 

2D. 5 EM I SS I ON FACTORS 

2D.5a The suggested total suspended particulate matter (TSP) emission 

factors (EF) for the pine needle/light brush fuel type are: 

Emission factors (lbs / ton) 

Age of rough and burning Advancing-front stage Residual stage 

method EF~ EF~ 

~2 years backing or heading 

and >2 years backing SO None 

>2 years heading 50 180 

2D.6 EMISSION RATES 

2D.6a If you completed Step 2D.la, add the total available grass weight in 

Step 2D.la(2) to the available litter fuel you determined in Step 

2D.2~~ entering the sum in the blank space below. 

If you completed Step 2D.lb, enter only the available litter fuel you 

determined in Step 2D.2~ in the blank space below. 

Total fuel available: tonlacre 

2D.6b Perform the indicated multiplications by entering the values from the 

Steps shown in the following equations. 

(1) Calculate ERA, the total suspended particulate matter (TSP) emission 

rate (ER) for the advancing-front combustion stage: 

ERA = 570 x x 

(Total fuel available (Rate of spread from 

from Step 2D.6a) Step 2D.3d) 

X X 

(Consumption adjustment (EFA from Step 

(yA) from Step 2De4a(l)) 2D.Sa) 
Worksheet Set 2D, page 4 of 5 

(2) If your prescription is for a backing fire in any age rough, or 

for a heading fire in rough 2 years old or less, skip directly 

to Step 2D.6~. 

If your prescription is for a heading fire in rough more than 

2 years old, calculate ERR, the TSP emission rate (ER) for the 

residual combustion stage: 

ERR = 570 x X 

(Total fuel available (Rate of spread from 

from Step 2D. Sa) Step 2D.3d) 

X X --- (Consumption adjustment (yR) (EFR from Step 

from Step 2Da3a[2)) 2D. 52.) 

(3) Now, calculate ER $'R' the TSP emission rate (ER) for the conveetivelift phase of hea'lng fires in rough older than 2 years: 

ER, ,, = + -- (ERA from Step (ERR from Step 

21>.6b(l)) 2D.6b(2)) 

2D.6~ If you were told to skip to this Step from Step 2Dehb(2), enter the 

value of ERA from Step 2De6b(l) in the blank below for EllCL9 and NONE 

in ERNCL3 below, then skip directly to Step 2D.7. 

If you calculated ERA+R in Step 2D.6b(S), enter the value for ERA+R 

in the blank below for ERCL9 then enter the value for ER from Step 

2D. 6b(2) in the blank below for ERkTPr : 

R 

2D. 7 HEAT RELEASE RATE 

2D.7a Make the following entry from your written prescription: 

Length of fired line f t 

2D.7b Using the length of fired line from the Step immediately above and 

the same weight of available fuel and rate-of-spread values just 

used in Step 2D.6b9 calculate the heat release rate [HRR) for the 

convective-lift phase of your fire. (Heat release has negligible 

effect for the no-convective-lift phase.) 
Worksheet Set 2D, page 5 of 5 

HRRrL = 0.0012 x x 0 (Available fuel from (Rate 06 spread from 

Step 2B, 6a) Step 23,36) 

X X 

(Consmpt ion adjustment (yA) (Length of fired l ine 

from Step 2D,4a(l)] from Step 2D.7a) 

NOW SKIP DIRECTLY TO STAGE #J 

Worksheet Set 2E, page I sf 4 

DECISIOK-LOGIC STAGE $2 APPLIED TO UNPILED LOGGING DEBRIS 

You Have Been Directed Fere From PJorkskeet Set 2A 

2EJ FUELS 

2E.13 Enter here fur subseqcent Jse the following information frsm ycbr 

inventory of the burn area: 

(Bf Average d,b,h. in cut timber stand inches 

(2) Species of timber cut (check one) : Loblolly pine 

Slash pine 

(33 Total number cords remsved from area 

(4) Total acres in burn 

2E.lb Using the diameter and species entries you made in Step 2E.la 

(I) and (21, turn to table VI-F-12 to obtain the tons of logging 

residue fuel 2 inch in diameter and less per cord for your bum 

area, entering here: 

tonlcord cut 

2E.I.c Now, using entries you made in Step 2E.I.a (3) and (41, divide the 

total number of cords removed entry by the total acres entry, 

then enter the result here: 

-- cord ~~~/acre 

2E.ld ?:ow, multiply the ton/cord cut entry you determined in Step 25.lb 

5 ;is number of cord cutlacre you determined in Step 2E.l~ to 

caiculate the available fuel per acre, entering the product here: 

2E. 2 FUEL CONSUMPTION 

2E.2a Lacking a more precise means to directly express a rate of fuel 

consumption for this fuel type, rate of fire spread for the fine 

fuels that dominate its initial spread will be used as a yardstick, 

and then adjusted. For ths purpose, enter here the following 

elements affecting spread in fine fuels from your written 

prescription: 

(?) Maximum relative hkamldlty % 

(2) Surface windspeed (20-foot tower) -p V%-n 

2E.?b Using the relative humidity entry from Step 2E.2a (I), turn to 

table VI-F-3 to determine the pine needle moisture content, 

entering this value here: 

Pine needle moisture content s%, 
Worksheet Set 2E, page 2 sf 4 

2E.2~ Convert your surface windspeed entered in Step ZE.2a (2) to midflame 

windspeed by dividing by 2 .5 Then turn to table VI-F-13 and use this 

conve-r."ld windspeed value with the pine needle fitter moistwe value 

you detenined in Step 2E.2b to determine rate of spread, entering 

the value here: 

2Ee3 COMBUSTION STAGES 

2E.3a Because fire spread in fine fuels is only a yardstick by which to 

gauge emissions and heat yield, and because a sizable amount of 

the fuels will remain to smolder during the residual combustion 

stage, an adjustment is needed to proportion the amount of fuel 

available to each stage. Limited data suggest a.1, idvancing-front: 

residual ratio of 75:25 for fuel consumed, With this and other 

data available to you, select the values you judge most 

appropriate and enter here: 

(1) Decimal fraction of fuel consumed in advancing-front 

stage (Y 1 

(2) Decimal fraction of fuel consumed in residual stage 

OR) ; (1.00 - advancing-front stage) -- 

2E.4 EMISSION FACTORS 

2E.4a A total suspended particulate matter (TSP) emission factor (EFA) of 

35 pounds per ton of fuel consumed is suggested for the advanc~ngfront stage. The suggested EFR for the residual stage is 180 pounds 

TSP per ton of fuel consumed. As covered in Chapter IV, these values 

are appseci.ably higher than iabcratary-determined values, but are 

suggested at this time as a conservative representation of the best 

overall infomat ion available. 

From this information, select emission factors JEF) for your prescribed burn and enter here: 

% factor of 2 is used rather than 4, as in understory burns, 

because harvesting has removed sheltering trees. 
Worksheet Set 2E, page 3 of 4 

2E. 5 EMISSION RATES 

2E.5a Using the determined values from the Steps shorn in the equations 

that follow, calculate emission rates (ER) by performing the 

indicated multiplications: 

(1) For the advancing-front stage: 

ERA = 570 x x 

(Available fuel from (Rate of spread from 

Step 2E.l.d) Step 2E.263) 

X X 

[Consumptio~~ adjustment (yA) (EFA from Step 

from Step 2E,3(1)) 2E.4a(P)) 

ER = pg TSPfm-sec 

A- 

(2) For the residnal stage: 

Ek = 570 x x 

R (Available fuel from (Rate of spread from 

Step 2E.l.d) Step 2E.2~) 

x X 

(Consumption adjustment (yR) (EF from Step 

from Step 2E.3a(2j) 2~!4a(2)) 

(3) Now, calculate ER , the TSP emission rate for the convectivelift phase of youQfRfire: 

h"A+R (ERA from Step (ERR from Step 

zE.sa(l)) 2E.5a(2>) 

2E.5b Enter again in the ERC blank below the value of ER you just 

calculated in Step 2~.ka(3). Then enter in the blank the 

value of ER you calculated in Step 2Ee5a(2). R 
Worksheet Set 2E, page 4 of 4 

2E.6 FIRING PATTERN AND FIRED-LINE LENGTH 

2i.53 From your written prescription, enter here your prescribed primary 

firing pattern (check one, then go to indicated Steps): 

Ring firing (if checked, skip to Step 2E.b~) 

Heading firc (if checked, proceed to Step ZE.hh) 

2E.Sb Use planned length of fired line without further adjustment, 

entering length from your written prescription here: 

Now skip directly to Step 2E.7. 

2E.b~ Determine an equivalent to fired line length by following the 

rule-of-thumb procedure outlined in the Southern Forestry Smoke 

Management Guidebook Chapter IV. Enter the equivalent determined 

here : 

2EJ HEAT RELEASE RATE 

2E.7a Using the determined values from the Steps shorn in the equation 

that follows, calculate the convective-lift phase heat release 

rate (HRR ) by performing the indicated multiplications. (Heat 6% release is of negligible effect for the no-convective-lift phase.) 

HRR = 8.0012 x GL (Available fuel from x (Rate of spread from 

Step 2E.ld) Step 2E,2c) 

x X 

(Consumption adjustment (yA) (Length of fired line 

from Step 2E.3ajl)) from Step 2E.6b or 

or 2E. 6c) 

NOW 60 DIRECTLY TO STAGE #3 
Worksheet Set 3, page 1 of 2 

DEGLS I@!<-LOGIC STAGE #3 : LONG-RAPt;GE hIARGIK 

You Have Been Directed Here from Stage g2 

FUEL TYPE 

3.1 Is the fuel type selected to describe your burn unpiled 

pine logging debris 0-8- ~;ai:r;etzro-galLberr;~~ oi;c 2 )-ears old, ~r 

for other fuel types will your convective-lift : -e phase 1 .:t 

to a time 3 hours before >anset? 

KO -- (skip directly to Stage 43) 

YES Isroceed to Step 32al 

3.2 DETERbfINATION OF TOTAL ENISSION RATE, qL 

3.2a Enter here again the length of fired line (or its equivalent if 

determined in Step 2E.6~): 

Now convert this length in feet to length in meters (multiply feet 

by 8.3048), entering the converted length here: 

3.2b Refer back to your Worksheet Set 2S or 2E for the value of ERNCL 

(which equals q), entering this value again here (if EllNCL not 

calculated, substitute ERCL): 

3,2c 3hrPtiply the entry for L in meters [not feet] from Step 3,224. times 

ERNCL in Step 3.2b for a value of qL, entering the result here: 

3,3 SAFETY MARGIN 

3.3a From your written prescription, enter here the transport windspeed: 

3.3b (1) Usingthe metric value qL you entered in Step 3.2~ and the 

transport windspeed you entered in 3.3a, refer to figure VI-M-I 

to determine if the intersection sf these two values is in the 

safe or urzsafe portion of the grap"il. 

If saf~, it is likely your fire will not result in a long-range 

(>I00 km or 62 miles) concentration greater than 150 py/rn3. 

Which did you determine? 

Safe (skip directly to Stage $4) 

Unsafe (proceed to Step J,3b(2)) 
Worksheet Set 3, page 2 of 2 

3.3b (2) Because your long-range transport calculation indicates a risk 

that the concentration will exceed 150 ug/m3 at or beyond 100 km 

(62 miles), you are redirected to Stage P1 to rewrite the prescription, NOTE: If possible, change time of burn for fuel 

types other than palmetto-gallberry or unpiled pine logging 

debris, or kt may be desirable to modify the prescribed length 

of fired-line or equivalent as a quick way of reducing the qL 

value, but bear in mind that -chis will also reduce the HRRCL 

value with an effect on plume rise, considered later, 
Worksheet Set 4, page P of 7 

DECISION-LOGIC STAGE #4: MATCHING PRESCRIPTIONS TO TYPICAL CASES 

You Have Been Directed Here from Stage #3 

4.1 SELECTION OF TYPICAL CASE 

4,la To arrive at a set of easily used typical cases rather than an extremely large number of complex tables and computations, it has 

been neGessary to fix certain variables, To use the procedure, you 

must now either conform your written prescriptions to at- least equal 

those variables that are fixed or you must make a series of adjustments to the typical-case concentrations in order to match your burn 

situation. All adjustments and all prescribed elements that are more 

favorable to dispersion than tpical will result in overestimates of 

tabular concentrations (i.e., the estimates are conservative), 

E: In this and all succeeding steps, complete no-convective-lift 

phase only for those burning situations for which you calculated an 

ERNCL in Stage 82. 

Turn now to table VI-M-l to find the typical case (by fuel type) most 

closely matching yours, entering the case number here: 

Convective-lift phase 

(Typical case no.) 

No-convective-lift phase 

(Typical case no.) 

4.2 MATCHING FIXED PRESCRIPTION ELEMENTS 

4.2a In this Step, you will have a match to start with, will modify your 

prescription to match fixed variables, or will indicate a match 

cannot be made, For each of the following, enter your prescribed 

value : 

Convective-lift phase6: Stability class 

Mixing height m 

No-convective-lift phase: Stability class 

Mixing height m 

4.2b For each of the following, indicate which answer applies. 

(1) Column 2: Stability class must be at least as good as shown in 

table VI-kl- I. Indicate how your prescription matches 

(check one in each phase): 

 or actual day of burn, if National Weather Service is not furnishing stability class, see Southern Forestry Smoke Management Guidebook Chapter V for a method of determining stability class in the 

field. 

7~ote stability classes decrease in ability to help smoke dispersion 

as these scale from A to B (i.e., A is better than B, etc.). Classes 

shown as typical are more likely to be encountered, 
Worksheet Set 4, page 2 of 7 

C~nvective-lift xo-cor;ectiye- : -j ft 

phase phase 

Matched or is better - 

Made to match 

Is not as good as and 

caI:& at be ~ade to 

match ---- 

(2 Column 3, hiixlng height ~:use be higher than or atleast ~~~fi

300 rnctcrs sf ",e value shown as tygical in table Vv"-R-l l, 

Indicate hox year prescription natches (check one in e5:i.s. phase): 

Convect ivc- lift No-can~:zctlve-Sift 

phase phase 

Hatched or is better 

Made to match 

Is not as good as and 

cannot be made to 

mat eh. - 

4-2c IT: bath [I) and (2) sf Step 4,2bb, did you check that a match could be 

made? (check only one) : 

ES [both matched or made to match) -. 

Skip to Step 4.33 

NO (one or both variables cannot be made to match) --- 

If a match cannot be made, we recommend that you arrange for a computerassisted analysis "i'r determining the best csmbimation of prescription 

elements. Is this possible? 

YES (If this is possible, proceed directly to Stage #6] 

KO (If not possible, you will run a risk of causing or contributing to a psllution episode under your present prescription, 

An alternative to burning is recomended,] 

4-3 OTHER VARIABLES AND CORRECTION FACTORS 

433 Each ofthe following variables can be made to match the tpical case 

by correction factors, First enter here for subsequent use the values 

shown in your written -prescsi@on for transpsrt windveed: 

Convective-lift phase m/sec No-convective-lift phase m/ sec 
Worksheet Set 4, page 3 of 7 

4.3b Now enter the crosswind length of fired line from pur prescription. 

(i'162'B: Do not use the fired-line equivale~t for logging debris from 

Step 2E.6~ here. For this calculation, the crosswind width of the 

fired area is needed in order to arrive at plume width.) 

And then convert -chis value to meters bj- multiplying feet by 0.3048, 

entering the conversion here: 

4.3~ Enter here values from that portion of Stage $2 you completed: 

fP) Convective-lift phase heat release rate 

(2) Emission rates (ER) 

4.3d In this Step, you will derive individual correction factors for each 

of the above variables by comparing your entries with typical values 

in table VI-M-P, (These will be used to the nearest i/lOth in 

Step 4.4a to develop a single correction factor.) 

(1) TRANSPORT WINDSPEED. Calculate a correction factor for transport 

windspeed by dividing the table VI-M-1 typical-case value by the 

value you entered in Step 4.33, entering the result here (if values 

are equal, enter 1-0): 

Convective-lift phase No-convective-lift phase 

(2) HEAT RELEASE RATE. Is the heat release rate (HRRC ) you entered in 

Step 4.3~ equal to or greater than the table VI-M-k column #4 

typical case? (check one) : 

If YES, > 

- .-, enter 1.0 below 

If NO, < enter a worst-case correction factor of 1.4 below 

Correction factor 

(3) COKVECTIVE-LIFT PHASE EbIISSION RATE. Calculate a correction factor 

for convective-lift phase emission rate (ERCL) by dividing your ERCL 

from Stage P2 by the table VI-M-1 typical case EllCL, entering the 

result here (if your ERCL is the same as the typical case ERCL, enter 1 fi>* 

Correction factor = - 

(Stage #2 ERCL) (Typical ERCL) 
Worksheet Set 4, page 4 of 7 

(4) NO-CONVECTIVE-LIFT PIZASE EMISSION RATE, Calculate a correction 

factor for the no-convective-lift phase emission rate (ERxCL) 

by dividing your ERNCL from Stage #2 by the table VI-M-1 

typical case ERN L, entering the result here (if your ERKCL is 

the same as the Eypical case ER NGL" enter 1.0) : 

Correction factor = - - (Stage 42 ERNCL) (Teical ERNCL) 

(5) FIRED-LINE LENGTH. Is the crosswind length of fired line in 

Step 4.3b(2) less than or equal to the table VT-hi-1 column #5 

typical-case length? 

If YES, check here then enter 1.0 for a correction factor for 

all distances in the spaces below 

If NO, check here then turn to table VI-M-6 and list in the 

spaces below the given correction factors for each distance 
Worksheet Set 4, page 5 of 7 

Downwind Distances Crosswind fired-line length 

4.4 COMBINING CORRECTION FACTORS AND MAKING CORRECTIONS 

4.4a Now calculate combined correction factors (nearest l/lOth) to be used 

at each distance for each fire phase as follows: 

(1) Enter here and multiply the following convective-lift phase factors: 

X X - 

(Transport windspeed (HRRCL factor (ERCL factor (Result , CL phase) 

factor from Step from Step from Step 

4.3d(l)) 4.3d(2)) Step 4.3d(J)) 
Worksheet Set 4, page 6 of 7 

Then use the convective-lift phase multiplication result 

immediately above to multiply each line-length correction 

factor listed in Step 4.3d(5), entering the final multiplication result in column (I31 of the blank table that follows 

Step 4.4b. 

(2) If you are carrying forward a no-convective-lift phase, 

enter here and muftiply the following no-convective-lift 

factors : 

X - 

(Transport windspeed (ERNCL factor (Result, NCL phase) 

factor from Step from Step 

4.3dfl)) 4.3d(4)) 

Then use the no-convective-lift phase multiplication result 

immediately above to again multiply each line-length correction 

factor listed in Step 4.3d(5), entering the final multiplication 

result in column (D) of the blank table which follows Step 4.4b. 

4.4b Use the same typical-case numbers you entered in Step 4.la to again 

refer to table VI-M-1, column 8, for the appropriate concentration 

tables to use next. Enter here the tables to be used. 

Convective-lift-phase concentration table VI-MNo-convective-lift phase concentration table VI-MNext use the concentration tables you just selected as follows for the 

worktable immediately below: 

(1) Opposite each distance, and in the column that fits your burning 

situation, read the typical-case concentration, entering it in 

column (C) for convective-lift phase, or in column (E) for noconvective-lift phase of the worktable which follows. 

(2) Now multiply each typical-case concentration entry in the 

following worktable by its correction factor, and enter the 

result in the corrected concentration columns, (C') (E' ) , for 

convective-lift and no-convective-lift phases, respectively, 

in the worktable. 
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Worksheet Set 5, page I of 8 

DECISION-LOGIC STAGE #5: PLOTS OF CONCENTRATPOK, COMPARISONS, bfOD%FI@AT%ONS, 

BWLTIPLE-SOURCE ANALYSIS 

5.1 PLOTTING ZONES OF CONCENTRATION 

5.la Using a drawing compass, set it to scale for each distance in 

Column (A) of the Piarktable you just completed in Step 4.4b, 

an$ strike distance arcs OM the trajectory plots you made on 

the map in Seeps 1,141) and (2) as follows : 

Until the distance from the fire is twice the length of the 

fired line, strike two arcs--one centered at each end of the 

fired line--then connect them by a straight line parallel to 

the fired Ikne. After the distance from the fire is twice 

the fired-line length, strike only one arc centered at the 

intersection sf the fired line with the plume centerline, 

NOTE: If target backgrounds are low and multiple fires are 

not expected, you need to plot arcs only to the distances 

where your corrected concentrations (Step 4.43, Columns (C'f 

and (Eq)) will be of importance. If important distances Eire 

within 7 kilometers, a. paat on a separate, large-seaPe map 

will be desirable. 

5.lb Now use the same two colors for the combustion stages that you 

used in Step l.la to write the corrected concentrations from 

the Worktable in Step 4.4b on your map at each corresponding 

distance arc. A completed trajectory plot with zones on concentration will look like this: 

5.2 COMPARING CRITICAL TARGET ACCEPTABLE CONCENTRATIONS WITH 

PREDICTED TOTAL CONCENTRATIONS 

5.2a Starting in the map area with the highest zone of concentration 

and working toward zones of lower concentrations, select the 

most critical targets expected to experience the concentrations 

plotted. List these selected targets one at a time in Column 

(A) of the Worktable immediately below, entering the corresponding 

values the table calls for ad the time you list each target, 

The following instructions apply to determining values for entries 

called for by the Worktable, 
Worksheet Set 5, page 2 of 8 

ue. --For 

targets directly on an arc, use the concentration zone value shown 

with the arc, For targets falling between two arcs, always use 

the higher of the two concentrations unless you interpolate 

logarithically, 

Entrxes In thls column must be for the time of year For which 

a planned burn prescription is being applied to this isgic 

procedure or must be actu~ These can be obtained, in sonre 

cases, from air quality pel ~nnel; or lacking this help, a rule 

of thumb will give you an expected particulate matter coricentration based upon the expected visibility [which can be drawn 

from experience, airport climatological records, or local 

residents). It is based upon the relationship: 

730 vg-miles/m3 5 miles of visibility = TSP concentration in 

Ltg/m3 

Some typical values are: 

25-mile visibility = 29 ug/rn" 220-mile visibility = 36 pg/m3: 

15-mile visibility = 49 sg/'m3; 10-mile visibility = 73 jg/m3; 

5-mile visibility =I46 sg/m\ ;-mile visibility =365 pg/m3. 

Colwnn (D) - Predicted Total Concentration,--The entry for this 

column is simply the sum of the value enrered in Colmn (B) and 

the value entered in Column (61, 

.--This entry is 

best obtained from local air quality personnel. Lacking this 

help, it is suggested you use a visibility criterion and the 

same rule of thumb as was suggested in the Column (C) instructions 

above. In this case, you set the minimum visibility you believe 

will be acceptable (CAUT/Ofl: This is reportedly rarely less than 

5 miles), then enter the corresponding concentration. EWfPLE: 

10-mile visibility is believed to be the minimum below which 

public complaints will he raised; then the corresponding maximum 

acceptable concentration entry is 73 pg/rn3, (730 : 10). 
Worksheet Set 5, page 3 of P 
Worksheet Set 5, page 4 of 8 

5,2b Now compare the Column (E) entries with both the convective-Lift 

and no-convective-lift phase entries in Column {D), 

Is the predicted total concentration less than the maximum 

acceptable concentration for zell entries? (check for each phase) 

Convective-lift phase 

Yes 

So 

No-convective-lift phase 

Yes 

Ns 

Not applicable 

5.2~ (1) If you checked YES for applicable phases above and do not 

anticipate that other burns may contribute to concentrations 

in target areas, check here and STOP using logic at this 

point, PROCEED WITH YOUR BURK. 

(2) If you checked YES for applicable phases above but anticipate 

other prescribed burns may contribute to concentrations in 

target areas and want to run a further analysis, check here 

and skip to Step 5,4, 

OW, if you do not want to skip to Step 5-4 check here and 

STOP using logic, 

PROCEED WITH YOUR BURN ONLY IF YOU WANT TO RISK POSSIBLE 

TARGET-AREA CONCENTMTIONS IN EXCESS OF DESIRED NET. 

(3) If you checked NO in either phase, proceed to Step 5.3. 

5-3 DETERMINING WHICH PRESCRIPTION VARIABLES TO MODIFY 

5.3a Look back to the Worktable you completed in Step 5.2a for the 

worst case (Lee: greatest amount Column fD) exceeds Column (Ef), 

Now divide the Column (D) entry by the Column (E) entry, entering 

the result of division here: 

(I.] If the result of division is less than 2, your chance of making 

a desk-top revision of your prescription for an acceptable 

concentration is good, Check here and skip directly to 

Step 5,3b. 

(2) If the result of division is less than 5, there is a chance 

of making an acceptable revision of your prescription--but 

repeated trials are likely to be needed, and a Stage #6 analysis 

will be most desirable, 
Worksheet Set 5, page 5 of 8 

If you can arrange for assistance with a Stage #G automatic 

data processing analysis, check here and STOP further work on 

Phase #5, 

If you cannot arrange for assistance, you may elect to try 

a desk-top revision and should skip directly to Step 5.33 

after checking here, 

If you cannot arrange for assistance and do not elect to 

try a desk-top revision, skip directly to Step 5.3g after 

checking here. 

(3) If the result of division is greater than 5, skip directly 

to Step 5.3g after checking here. 

5*3b If your prescription calls for a heading fire, first consider 

revising the prescription to call for a backing fire. Check 

here, then proceed to Step 5.3~ BEFORE modifying your prescription. 

5.3~ Examine the correction factors you calculated in Stage #4, 

entering a check here for each that is greater than 1.0. 

Transport windspeed 4,3d (1) 

Length of fired line 4.3d(Z) 

WRR~~ 4, Jd(3) 

ER~~ 4.3d(4) 

ER~~~ 4.3d(53. 

Not applicable 

Not applicable 

If any of the above checked factors include transport ivindspeed 

and/or fired-line length factors, you will next want to modify 

your prescription to lower these. The fired-line length correction 

factor is lowered by shortening the prescribed fired-line length. 

The transport windspeed correction factor is lowered by increasing 

the prescribed speed. NOTE: For this analysis, it will not 

benefit your calculations to reduce rhe fired-line length belo& 

that used in the tjpical case (see table VI-M-1). Check here, 

then proceed to Step 5.3e BEFORE modifying your prescription. 
Worksheet Set 5, page 6 of 8 

5-32 If your exceeded allowable concentration is only in the convectivelift phase and your heat release rate correction factor is checked 

in Step 5-3c, "chis is the next prescriptSon item to consider 

modifying. Before deciding to do so, make sure the emission rate 

correction factor IS NOT also cheeked. HRRCL is best increased, 

resulting in a lower correction factor, by increasing rate of 

spread (~hich is a knction of lower fine fuel moisture and 

higher surface windspeed). These, however, will all increase 

emission rate, which can offset your gains, Check here and then 

proceed to Step 5-3f BEFORE modifying your prescription. 

5.3f Now, having considered the instructions in Steps 5.3b through 

533, list here any variables you intend to modify in your 

prescription. Then use a colored pencil to enter new values 

in the prescription and in the preceding Stages #2 through #5, 

Steps 5.1 and 52, reworking all dependent calculations and 

comparisons until you have again arrived at Step 5.3. If there 

are no variables that can be modified, enter NONE, then proceed 

to Step 5,3g, 

Variables to be modified 

CAUTION: Do not simply modify the prescription and then use 

new correction factors in Stage #4. Many of the 

variables are interdependent, resulting in offsetting 

changes. Hopefully, after reworking Stages #2 

through 84 and Steps 5.1 and 5.2, you will be able 

to skip to Step 5.3 on the next pass through! 

5,3g You have arrived at this Step either because of too great a 

difference between predicted total concentration and 

maximum acceptable concentration, or because of computational 

difficulties that cannot be remedied. 

If this is the case, you may wish to consider exploring exceeded 

maximum acceptable concentrations at some targets for a very 

short time period, By limiting the dimension of the burn area 

which is on the same azimuth as the transport wind direction, 

the duration is limited. For exmple: Wind at right angle to 

road. A 200-foot-wide burned area will at least provide a good 

fuel break. If instead of burning the entire tract you burn to 

a 200-foot limit, the time of high smoke concentration will be 

shortened and you may be able to work with local authorities to 

provide traffic control for safety on the road for the short 

period this size burn would take to burn out. Other than this, 

you may need to select a treatment alternative other than fire. 
Worksheet Set 5, page 7 of 8 

Enter your decision here and STOP using the logic procedure: 

5.4 RUDIMENTARY MULTIPLE-SOURCE ANALYSIS 

5.423 This Step is for conducting a rudimentary multiple-source 

analysis if there is a likelihood that more than your 

prescribed burn will contribute to target concentrations. 

For all such suspect simultaneous sources, foliow this 

procedure : 

(1) For each, plot the trajectory and 30" deviations as 

you did in Steps 1. la (1) and (2). 

For all those where the 30' deviations overlap with 

those from this burn, it will be most desirable to 

have available completed, separate analyses such as 

this. If not available, use either the final trajectory plots from Step 5.lb of this burn again, or 

simply use the unadjusted values from a typical case 

(see table VI-M-1 and corresponding tables), whichever 

comes closest. 

(3) With the new burn trajectorgis) plotted to show arcs 

as zones of concentration, as you did for this burn. 

you can now sum the zones in all overlapping areas 

to prepare a mutual targets worktable in the same 

format as you did in Step 5.Sa for this burn alone. 

EXAMPLE: 
Worksheet Set 5, page 8 of 8 

1x1 this example, the applicable concentration zone values, relating 

two neighbors' burns to your burn, become: 
DECISION-LOGIC STAGE #6: AUTOhLkTIG DATA PROCESSING ASSISTED mALUSXS 

This Stage is under development at this time and will be issued later. 

The following is a brief outline of what is planned: 

1. A proarm in FORTRAN for use on any compatible computer.--This 

program will he printed as a "'separateu that can be inserted into 

copies of the Sourcebook. With the program, rapid reiterations 

sf combinations of variables now made by hand in Stages W2 through 

#5 will be possible, Hence, the user will be able to quickly 

select the best sf his pseseription options, Instructions for use 

will also be printed as a f%separatc8' that can be inserted into 

copies of the Guidebook, 

2. An ada~tatiou of the above program fofor use in a centrat computer.-- 

Data from spot weather forecasts would bc entered, along with user 

inputs to determine likely downwind concentrations, 

3. A refined system for analyzing the effects of mttiple forestry 

emissions sourees on air qzsality. 

PART 3. TABLES F-13, printed on pink paper) in Chapter IV and 

meteorology tables and figure (tables VI-M- 1 

The tables that follow are for use with the thmugh ~j--M-6 and fig. VIM-1 printed on blue 

Steps in the preceding instructions. Sources of paper) in Chapter V. For the convenience of users 

these table ore &SCUES~~ in prweding chapters - and to permit periodic updating, each table is prefuel and firpi- beha"tior tables (VI-F-I. through TI- sented on a separate page. 

Table %'I-F-2. - Fine fuel moisture content of dead grass (1-hour timelag) 

Clisud cover Relative humidity 

Sunny: 

Cloudy: 

70-89 5 6 7 8 9 10 10 11 12 ! 3 

l-/Adapted from Deeming and others (19721. 

Purpose. - To compute the fine fuel molsture content of dead grass 0 25 ~nch and less rn 

diameter. 

Procedure. - Use "cloudy" if there 1s 60 to 90 percent cloud cater, dn ovrrcdst copt-r~ng more 

than 90 percent of the sky, fog showers, or thundcrstnrrns 12 the vic~n~ty, or ~f the observat~on is being 

taken before 10 OCi J m or af tel 3 00 p rn local stdnddrd t~rne ""Sunny" covers all other condlt~ons 

Table VI-F-4. - Expected rate of fire spread in grass fuels 21 2 as a function of midflame 

windspeed and fine fuel moisture eontent where land slopes do not exceed 20 percent 

Fine fuel moisture (percent) 

Feet per minute - - - - 

4 3 

- 1/ Adapted from Rotherrnel (1972). 

2i Factors used in Rothermel's 11972) equation. - 

Wo = 0.088 lb/ft2 MCE = 30 

i 1 t , - 4 6 % I * - # 2- f < -i ti ' - 

r,ciarest Yb-:oot, 01 i ri-i,(,-rrci .~lstaiitrt,inr, dud d1v:ri:ng that value by 4. 

Table VB-F-6. - Total litter weight under loblolly pine stands as aEected by stand basal area 

and age of rough 

Stand 

basal area 

(square feet 

Age of rough (yeassf 

Table VI-F-8. - Expected rate of fire spread in pine needle and low brush fuels?/ 21 as a function of midflame windspeed and pine needle litter moisture content where land slopes 

do not exceed 20 percent 

(miles per hour) 

----------- Feetperminute 

- l/ Adapted from Rothermel ( 1972). 

2/ Factors used in Rothermel's (1972) equation: - 

Wo = 1.25 tonjacre = 0.057 1b/ft2 MCE = 0.40 

d = 0.25 (3 inches) WS = 0, 1,2,3,4,5,6 

s/v = 1,500 MC = 6,8, 12,16,20 

mc = 0.04 (min. content) 

sc = 0.01 

HV = 8,000 

DEN = 26 

- 3/ Under a tree canopy, midflame windspeed can be estimated by using windspeed values from the 

nearest 20-foot, open-tower installation and dividing that value by 4. 

Table VI-F-10. - Estimated total available fuel (litter + vegetation) as a function of total litter layer moisture content, 

total litter weight, and understory vegetative dry weight 

10 PERCENT TOTAL LITTER LAYER MOISTURE CONTENT 

Understory 

vegetative dry 

weight 

(tons per 

acre) 

20 PERCENT TOTAL LITTER LAYER MOISTURE CONTENT 

40 PERCENT TOTAL LITTER LAYER MOISTURE CONTENT 

Total available fuel (litter + vegetation) 

Total litter weight in tons per acre 

80 PERCENT TOTAL LITTER LAYER MOISTURE CONTENT 

120 PERCENT TOTAL LITTER LAYER MOISTURE CONTENT 

1 

160 PERCENT TOTAL LITTER LAYER MOISTURE CONTENT 

2 3 4 5 6 8 10 12 14 16 

Table VI-F-12. - Available fuel 1 inch in diameter and less in the unpiled pine logging debris 

type 

I 

Average d.b.h. 

in cut stand 

Undisturbed logging residue 

I I 

---- Tons per cord cut - - - - 

5 - 0.47 

(inches) Loblolls I Slash 

Table VI-M-1. - Summary of variables used in compiling typical case examples in tables VI-M-2 through VI-M-5 

__ 

Meters Megacallsec Meters - Mlsec pg/M-sec 

1 Grass: 

Backing fire C 1,500 14.112 800 8 37,800 VI-M-2 

2 Grass: 

Heading fire C 1,500 75.624 400 8 403,200 VI-M-2 

3 Pine needle litter: 

Backing fire C 1,500 4.704 400 8 84,000 VI-M-3 

4 Pine needle litter: 

Heading fire 

CL phase C 1,500 11.76 400 8 966,000 VI-M-3 

NCL phase C 1,500 0 400 8 756,000 VI-M-3 

5 Palmetto-gallberry: 

Backing fire C 1,500 37.632 800 8 168,000 VI-M-4 

6 Palmetto-gallberry: 

Heading fire in 

2-year-old rough C 1,500 137.984 800 8 616,000 VI-M-4 

7 Pine logging debris: 

In winter 

CL phase C 1,500 211.68 500 (eq.) 8 5,745,600 VI-M-5 

NCL phase C 1,500 0 500 (eq.1 8 3,628,800 VI-M-5 

8 Pine logging debris: 

In summer 

CL phase B 2,000 70.56 500 (eq.) 5 1,915,200 VI-M-5 

NCL phase B 2,000 0 500 (eq.) 5 1,209,600 VI-M-5 
Table VI-Md. - Particulate matter concentrations at various distances downwind for typic 

cases No* 1 and No. 2 

downwind 

0.10 203 

.13 2,161 

164 

.I6 1,751 

133 

.20 1,48 1 

108 

.25 1,149 

8 7 

.32 

931 

7 1 

.40 

754 

58 

.50 

611 

4 7 

.63 

495 

39 

.79 

400 

3 1 

1.00 

31 9 

26 

1.30 

249 

2 1 

1.60 

188 

18 

2.00 

138 

17 

2.50 

98 

15 

3.20 

68 

12 

4.00 

47 

10 

5.00 

33 

8 

6.30 

24 

5 

7.90 

19 

4 

10.00 

15 

3 

13.00 

11 

2 

16.00 

8 

2 

20.00 

6 

1 

25.00 

4 

1 

32.00 

3 

0 

40.00 

2 

0 

50.00 

2 

0 

63.00 

2 

0 

79.00 

1 

0 

100.00 0 1 1 
Table VI-M-3 - Particulate matter concentrations at various distances downwind for typical 

cases No. 3 land No. 4 

Distance 1 Heading fire 
Table VI-M-4. - Particulate matter e3 

eases l% 

oncentrations at various distances downwind for typical 

- To. 5 and No. 6 

Distance 

dournwind Heading fire 

in 2-year-ofd roughs 

0.10 901 - 

3,302 

.13 730 2,675 

.16 591 2,167 

.20 479 

.25 

1,756 

388 1,422 

.32 314 1,152 

.40 256 

.50 

933 

206 

'63 

756 

167 

.79 

612 

135 

1 .00 110 496 

1.30 90 402 

1.60 72 325 

2.00 57 26 1 

2.50 45 206 

3.20 3 7 157 

4.00 3 1 116 

5.00 25 83 

6.30 19 59 

7.90 14 43 

10.00 10 3 2 

13.00 7 25 

16.00 5 20 

20.00 3 15 

25.00 2 10 

32.00 2 8 7 

40.00 1 

50.00 1 6 

63.00 

5 

1 4 

79.00 1 

100.00 1 3 3 
Table VI-M-5. - Particulate matter concentrations at various distances downwind for typical 

cases No. 7 and No. 8 

n summer 
Table Vl-M-fS. - F5md-line lewb comec$jo~ faehrs 

continued 
Table VI-MS. - Fired-line length correction factors (Ccmtinued) 
q xL-TOTAL EMISSION RATE x lo8 (MICROGRAMS/SECOND) 

Figure VI-M-1. - Plot of total emission rate (qL1 versus transpofi windspeed (u) ; (qL = 7.5 x 108 jtg/m2 -secf .lb help determine if a - 

U 

fire might deliver 150 micmgrams of particulatr? matter per cubic meter of air to a location 60 or more miles domwind, locate 

the intersection of your total emission rate (emission rate (ER) x fired-line length (L) with your transport windspd. For example, a fire with an ER of 1,200,000 gglm-see and a 400 m line has a total ER of 480,000,000 pglsec (i.e., 4.8 x 108 ~glsee). 

Such a fire is unsafe if the transport windspd is 5 rnlsec, but safe if it is 10 mlsec. (See example plotted as A and 3, respectively.) 
LITERATURE CITED 

Blackman; W. H. 

1971. Equilibrium moisture content of common fine 

fuels found in southeastern forests. USDA For. 

Serv. Res. Pap. SE-74,8 p. Southeast. For. Exp. 

Stn., Asheville, N.C. 

Deeming, John E., James W. Lancaster, Michael A. 

Fosberg, and others 

1972. National fire-danger rating system. USDA For. 

Serv. Res. Pap. RM-84, 165 p. Rocky Mt. For. & 

Range Exp. Stn., Fort Collins, Colo. 

Hough, Walter A,, and Frank A. Albini 

In press. Predicting fire behavior in palmetto-gallberry fuel complexes. USDA For. Serv. Res. Pap. 

Southeast. For: Exp. Stn., Asheville, N.C. 

McNab, W. Henry, and M. Boyd Edwards, Jr. 

1976. Estimating forest fuel buildup. For. Farmer 

35(5) :6-7. 

Metz, Louis J. 

1958. Moisture held in pine litter. J. For. 56(1):36. 

Rothermel, Richard C. 

1972. A mathematical model for predicting fire 

spread in wildland fuels. USDA For. Serv. Res. 

Pap. INT-115, 40 p. Intermountain For. & 

Range Exp. Stn., Ogden, Utah. 

GLOSSARY 

Advancing-front combustion stage. - The 

period of combustion when a fire is spreading, usually accompanied by flaming combustion that releases heat that sustains the 

convection column. 

Aerosol. - See Particulate matter. 

Age of rough. - Time in years since the forest 

fuel was last reduced. 

Ambient air. - Literally, the air moving around 

us; the air of the surrounding environment. 

Available fuel. - The portion of the total combustible woody material that fire will consume under given conditions. 

Backing fire. - A fire spreading against the 

wind. Flames tilt away from direction of 

spread. 

Basal area. - The area of the cross section of a 

tree stem near its base, generally at breast 

height and inclusive of bark. 

Bound water. - Bound moisture. Moisture that 

is intimately ass~eiated with the finer wood 

elements of the cell wall by molecular sorption. 

Breast height. - On standing trees, a standard 

height (4-112 feet) from ground level for 

recording diameteq girth, or basal area. 

Broadcast burn. - The burning of forest residue 

scattered over an area. 

Char. - Charcoal. The residue from the destructive distillation of wood or animal matter 

with exclusion of air; contains carbon and 

inorganic matter. 

Clearcutting. - Strictly, the removal of the entire standing crop. 

Climax. - The culminating stage in plant succession for a given environment, the vegetation being conceived or having reached a 

highly stable condition. 

Coagulation, - A separation or precipitation 

from a dispersed state of suspended particles 

resulting from their growth. 

Combustion. - The burning or rapid oxidation of 

the pyrolysate vapors escaping from the surface of the fuel. 

Condensation. - (1) The linking together of two 

or more molecules, resulting in the formation of long-chain compounds. (2) The process bf forming a liquid from its vapor. 

Convection column. - That portion of a smoke 

plume sharply defined by the buoyant forces 

of heated air and effluents. 

Convective-lift fire phase. - The phase of a fire 

when most of the emissions are entrained 

into a definite convection column. 

Cord. - A unit of gross volume measurement for 

stacked round or cleft wd; i.e., based on external dimensions. A standard cord contains 

128 stacked cubic feet and generally implies 

a stack of 4 x 4 fet vertical cross section x 8 

feet long, with a small percent extra in 

height to allow for settlement. 

Crop tree. - Any tree forming, or selected to 

form, a component of the final crop. 

Decomposition. - The more or less permanent 

breaking down of a molecule into simpler 

molecules or atoms. 

Denitrification. - Reducing nitrates to nitrites, 

nitrous oxide, or nitrogen under anaerobic 

conditions. 

d.b.h. - Diameter at breast height (4-lf2 feet 

above ground level). 

Diffusion. - In meteorology, the exchange of 

fluid parcels (and hence the transport of conservative properties) between regions in 

space, in the apparently random motions of a 

scale too small to be treated by the equations 

of motion. 

Dispersion. - In air pollution terminology, 

loosely applied to the removal (by whatever 

means) of pollutants from the atmosphere 

over a given area; or the distribution of a 

given quantity of pollutant throughout an 

increasing volume of atmosphere. 

Eddy. - Any circulation drawing its energy from 

a flow of much larger scale, and brought 

about by pressure irregularities as in the lee 

of a solid obstacle. 

Effluent. - The mixture of substances, gases and 

liquids, and suspended matter, discharged 

into the atmosphere (or ground, river, ocean) 

as the result of a given process. 

Emission. - Pollutants released to the atmosphere from any combustion process. 

Sometimes used synonymously with 

effluent, but it is more applicable to atmospheric discharges. 

Emission factor. - The quantity of pollutant 

released to the atmosphere per unit weight 

of dry fuel consumed during combustion 

(pounds per ton). 

Emission rate. - The quantity of pollutant 

released to the atmosphere per unit of time 

per unit length of fire front, 
Fermentation layer. - The layer consisting of 

partly decomposed organic matter. The 

structure of the plant debris is generally 

well enough preserved to permit identification of its source. 

Fine fuel. - Flash fuels. F'uels; e.g., grass, ferns, 

leaves, draped (i.e., intercepted when falling) 

needles, tree moss, and some kinds of light 

slash, that ignite readily and are consumed 

rapidly by fire when dry. 

Fire behavior. - The manner in which fuel ignites, flame develops, and fire spreads and exhibits other phenomena. 

Firing technique. - A method of igniting a 

wild landarea to consume the fuel in a 

prescribed pattern; e.g., heading or backing 

fire, spot fire, strip-head fire, and ring fire. 

Flaming combustion. - Luminous oxidation of 

the gases evolved from the decomposition of 

the fuel. 

Flaming phase. - That phase of a fire where the 

fuel is ignited and consumed by flaming 

combus tion. 

Fossil fuels. - Coal, oil, and natural gas; so called 

because they are the remains of ancient 

plant and animal life. 

Free water. - Free moisture. In wood, moisture 

contained in the cell cavities and intercellular spaces and held by capillary forces only. 

Fuel loading. - The amount of fuel present expressed quantitatively in terms of weight of 

fuel per unit area. This may be available fuel 

or total fuel and is usually dry weight. 

Fuel type. - An identifiable association of fuel 

elements of distinctive species, form, size, arrangement, or other characteristics, that 

will cause a predictable rate of fire spread or 

difficulty of control, under specified weather 

conditions. 

Glowing phase. - That phase of a fire where the 

char left from the flaming phase is consumed by solid oxidation. 

Heading fire. - A fire spreading with the wind. 

Flames tilt in the direction of spread. 

Heat release rate to the atmosphere. - The 

amount of heat released to the atmosphere 

from the advancing-front combustion stage 

of a fire per unit of time. 

Heat yield. - ?'o a very close approximation, the 

quantity of heat per pound of fuel burned 

that passes through a cross section of the 

convection column above a fire that is burning in a neutrally stable atmosphere. 

Herbaceous. - Soft and green, containing little 

woody tissue. 

Hydrocarbons. - A general term for organic 

compounds that contain only carbon and hydrogen in the molecule. They are divided into 

saturated and unsaturated hydrocarbons, 

aliphatic (paraffin or fatty), and aromatic 

(benzene) hydrocarbons. 

Humus. - (1) A general term for the more or less 

decomposed (plant and animal) residues in 

the soil; litter, therefore, being excluded. (2) 

More specifically, the more or less stable fraction from the decomposed soil organic 

material, generally amorphous, colloidal, 

and dark colored. 

Inversion. - Temperature inversion. A layer in 

which temperature increases with altitude. 

Litter. - The uppermost layer, the L-layer, or 

organic debris on a forest floor; i.e., essentially the freshly fallen or only slightly 

decomposed vegetable material -mainly 

foliate (leaf litter)-but also bark fragments, twigs, flowers, fruits, etc. 

Micron. - One millionth of a meter, a 

micrometer. 

Mixing. - A random exchange of fluid parcels on 

any scale from the molecular to the largest 

eddy. 

Mixing height. - The height to which relatively 

vigorous mixing occurs (meters). 

Model. - A mathematical or physical system, 

obeying certain specified conditions, whose 

behavior is used to understand a physical, 

biological, or social system to which it is 

analogous in some way. 

Moisture content. - The amount of water present in a material; e.g., wood or soil, 

generally expressed as a percent of the 

material's ovendry weight. 

National Fire-Danger Rating System. - The 

method currently used by the USDA Forest 

Service and other Federal, State, and county 

agencies to uniformly describe the cumulative effects of weather on wildfire behavior. 

Naval stores. - A term of historical pedigree, 

still applied to the products of the United 

States resin industry, nowadays particularly 

to turpentine and resin, but also to pine tars 

and pitch. 

No-convective-lift fire phase. - The phase of a 

fire when most emissions are not entrained 

into a definite convective column. 
Nucleate. - Tb form into or around a nucleus, as 

in the formation of particulate matter. 

Organic soil. - Any soil or soil horizon consisting chiefly of, or containing at least 30 percent of organic matter; examples are peat soil 

and muck soil. 

Ovendry. - Of wood dried to constant weight in a 

ventilated oven at a temperature above the 

boiling point of water, generally 103 ~f: OC. 

Overstory. - That portion of the trees, in a forest 

of more than one story, forming the upper or 

uppermost canopy layer; e.g., frequent 

emergents in multi-storied tropical forests 

or, in a two-storied forest, seed bearers over 

regeneration and standards over coppice. 

Particulate matter. - Any liquid or solid particles suspended in or falling through the atmosphere. 

Total suspended particulate matter (TSP) 

is that portion of the total particulate matter 

that, because of its size (below 5 to 10 

microns in diameter), is transported long distances in the atmosphere and has the 

greatest potential for environmental impact. 

Respirable suspended particulate matter 

(RSP) is that portion of the total particulate 

Plume. - The segment of the atmosphere occupied by any of the emissions from a single 

source. A convection column, if one exists, 

forms a specific part of the plume. 

Point source. - See Source. 

Pollutant. - With respect to the atmosphere, any 

substance within it that is foreign to the 

natural atmosphere or that exceeds its 

natural concentrations in the atmosphere. 

The universal connotation is that a pollutant 

is potentially deleterious. 

Polymer. - A complex molecule formed from the 

combination of several molecules and having the same empirical formula as the simple ones. 

Pre-ignition phase. - That phase of a fire when 

the fuel is heated to ignition temperature. 

Prescribed burning. - Controlled application of 

fire to wild land fuels in either their natural 

or modified state, under such conditions of 

weather, fuel moisture, soil moisture, etc., as 

allows the fire to be confined to a predetermined area and at the same time to produce 

the intensity of heat and rate of spread required to further certain planned objectives 

of silviculture, wildlife habitat management, grazing, fire hazard reduction, etc. 

matter that, because of its size (below 2 to 3 Pyrolysis. - The thermal or chemical decomposi- microns in diameter), has an especially long tion of fuel at an elevated temperature. residence time in the atmosphere and 

penetrates deeply into the lungs. Aerosol is 

used interchangeably for the smaller airborne particulate matter by many 

authorities. However, aerosols are more precisely defined as particles in a gaseous 

Rate of spread. - The amount that a fire extends 

its horizontal dimensions within a unit of 

time. This can be expressed as forward rate 

of spread of the advancing fire front, area 

rate of spread, or perimeter rate of spread. 

medium. Residual combustion stage. - The smoldering 

zone behind the zone of an advancing fire Particulate mass concentration. - The front. 

amount of particulate matter per unit 

volume of air (p g/m 3 ) . Respirable suspended particulate matter 

(RSP). - See Particulate matter. 

Perturbation. - Any departure introduced into 

an assumed steady state of a system. 

Photochemical process. - The chemical 

changes brought about by the radiant 

energy of the sun acting upon various polluting substances. The products are known as 

photochemical smog. 

Photosynthesis. - The building up of organic 

compounds, particularly carbohydrates, in 

green cells, from C02 in the presence of Hz0 

and light, the energy of the latter being 

transformed by chlorophyll and enzymes. 

Physiological. - Relating to the functions of 

plant or animal as a living organism. 

Rough. - An accumulation of living or dead 

material that is susceptible to burning. 

Smoke management. - Conducting a 

prescribed fire under fuel moisture and 

meteorological conditions, and with firing 

techniques that keep the smoke's impact on 

the environment within acceptable limits. 

Smoldering phase. - The combined processes of 

dehydration, pyrolysis, solid oxidation, and 

scattered flaming often occurring after the 

flaming phase of a fire. Often characterized 

by emissions of large amounts of smoke. 

Soluble. - That can be dissolved; capable of passing into solution, as sugar is soluble in water. 
Sorption. - The uptake and retention of one 

substance (the sorbate) at the sdie (adsorption) or in the interior (absorption) of 

another (the sorknt). 

Sowce. - A point, line, area, or volume at which 

mass or energy is add4 to a system, either 

insmlaneously or continuously Conversely, 

at a sink, mass or energy is removed. Examples of soums in the context of air pollution 

are as follows : a smoke stack is a point source; 

a freeway or aircraft trajectory is a line 

source, 

Surfaice fuel. - The loose surface litter on the 

forest floor, normally consisting of fallen 

leaves or needles, twigs, bark, cones, and 

small branches that have not yet decayed 

sufficiently to lose their identity. Also 

grasses, shrubs less than 4 feet in height, 

heavier branchwood, down logs, stumps, 

seedlings, and forbs interspersed with or partially replacing the littet: 

Synergism. - The cooperative action of separate 

substances which, together, have greater 

total effect than the sum of their individual 

effects, 

Target. - Any place at which adverse effects of 

smoke concentrations may be experienced. 

Temwrate zone. - Either of two zones of the 

Earth between the Tropics and the Polar circles. 

Thermal energy. - Heat energy 

Total fuel. - The total combustible woody 

material. 

Total suspended particulate matter (TSP). - See Particulate matter. 

Toxic. - Relating to a harmful effect by a 

poisonous substance on the human body by 

physical contact, ingestion, or inhalation. 

Transport windspeed. - A measure of the 

average rate of the horizontal transport of 

air within the mixing layer (meters per second>. 

Turbulence. - A complex spectrum of fluctuating, disordered motion superimposed on the 

mean flow of a liquid or gas. 

Understory. - Any plants growing under the 

canopy formed by others - more particularly-herbaceous and shrub vegetation 

under a brushwood or tree canopy. 
METRIC CONVERSION AND PREFIX TMLE 

Metric Conversion 

From Symbol To Symbl Multiply by 

hngth 

Inches in Centimeters cm 2.54 

Cen timebrs cm Inches in. 0.393'9 

Feet ft Meters m 0.3048 

Meters rn Feet ft 3.281 

Miles mile Kilometers km 1.609 

Kilometers km Miles mile 0.6214 

Area 

Acres acre Square meters m2 4047 

Square meters m2 Acres acre 0.00025 

Acres acre Hectares ha 0.4047 

Hectares ha Acres acre 2.471 

Cubic inches in 3 Cubic centimeters cm3 16.39 

Cubic centimeters em3 Cubic inches in3 0.061 

Cubic feet ft 3 Cubic meters m3 0.0283 

Cubic meters 1113 Cubic feet ft 3 35.31 

Mms 

Pounds lbs Grams g 453.6 

Grams g Pounds f bs 0.0022 

Pounds lbs filograms kg 0.4536 

Kilograms kg Pounds Ibs 2,205 

Short tons sh' ton Metric tons rn, ton 0.9072 

Metric tons m. ton Short tons sh. ton 1.102 

SP~ 

Feetlminute ftlmin Meterslminute mlmin 0.3048 

Meterslminute m/min Feetlminute ftlmin 3.281 

Mileshour mph Kilometershour kmkr 1.609 

Klometers/hour kmkr Mileshour mph 0.621 4 

Temprature 

Fdrenheit "F Celsius "C 

Celsius "C Fahmnhei t "F 

Energy 

5/9 after 

subtracting 32 

9/5 then 

add 32 

British thermal units Btu Calories cal 252.0 

Calories cal British thermal units Btu 0.004 
Prefix 

Multiple Prefix 

gigs 

mega 

kilo 

hecto 

deka 

deci 

centi 

milli 

micro 

nano 

Symbol 
SPECIAL ACKNOWWDGMENTS 

While the authors accept full responsibility 

for t h e i r f i n a l products, we all gratefully 

acknowledge the contributions of the following individuals in reviewing portions of this Guidebook. 

A. I! Brackebusch, National Fire Specialist 

State and Private Forestry 

USDA Forest Service 

Craig C. Chandler, Director 

Forest Fire & Atmospheric Sciences 

Research 

USDA Forest Service 

Sharon R. Miller, Chairman 

Smoke Management Research Coordinating 

Committee and 

Director, Forest Management & Research 

The Chesapeake Corporation 

Perspectives 

Edward W. Burt 

Source Receptor Analyses Branch 

Region IV 

U.S. Environmental Protection Agency 

Dr. E. V: Komarek, Director 

Tall Timbers Research Station 

Dr. Paul Urone, Professor 

Environmental Engineering Sciences 

University of Florida 

Walt Myers, Editor 

Forest Farmer Magazine 

Chapter I: Smoke Management - What Is It? 

W. D. Baughman, Assistant Wbodlands Manager 

Westvaco Corporation 

Dr. Charles W. Philpot, Assistant Station Director 

Pacific Southwest Forest & Range Experiment 

Station 

USDA Forest Service 

Ronald J. Strauss, Fire Management Staff Officer 

National Forests in Mississippi 

Chapter 11: Contents and EXects of Forest Fire 

Smoke 

Dr. Alfred H. Ellison, Deputy Director 

Environmental Sciences Research Laboratory 

U.S. Environmental Protection Agency 

Lee Monteith, Senior Chemist 

Department of Environmental Health 

University of Washington 

Dr. Charles W. Philpot, Assistant Station Director 

Pacific Southwest Forest & Range Experiment 

Station 

USDA Forest Service 

Dr. Paul Urone, Professor 

Environmental Engineering Sciences 

University of Florida 

Chapter 111: Air Quality Administration 

William M. Burch, Chief 

Air Strategy Development Section 

Region IV 

U.S. Environmental Protection Agency 

James N. Hale, Environmental Administrator 

Air Quality Management 

Florida Dep. of Environmental Regulations 

Harry E Wieshahn, Engineer 

Division of Air Pollution Control 

Tknnessee Dep. of Public Health 

Chapter IV: Fuels, Fire Behavior, and 

Emissions 

Dr. Frank A. Albini, Research Mechanical 

Engineer 

Northern Forest Fire Laboratory 

Intermountain Forest & Range Experiment 

Station 

USDA Forest Service 

John E. Deeming, Project Leader 

Northern Forest Fire Laboratory 

Intermountain Forest & Range Experiment 

Station 

USDA Forest Service 

Dr. David Sandberg, Assistant Professor 

School of Forestry 

Colorado State University 

Chapter V: Smoke Transport and Dispersion 

Dr. Gary A. Briggs, Research Meteorologist 

Atmospheric Turbulence & Diffusion Laboratory 

Environmental Research Laboratories 

National Oceanic & Atmospheric Administration 

Edward W. Burt 

Some Receptor Analyses Branch 

Region IV 

U.S. Environmental Protection Agency 

Douglas G. Fox, Project Leader 

Rocky Mountain Forest & Range Experiment 

Station 

USDA Forest Service 

Lewis H. Nagler, Regional Meteorologist 

Region IV 

U.S. Environmental Protection Agency 

Charles E Roberts, Senior Research Meteorologist 

Forest Fire & Atmospheric Sciences Research 

USDA Forest Service 

Dr. D. Bruce Turner, Chief 

Environmental Applications Branch 

National Environmental Research Center 

U.S. Environmental Protection Agency 
Dansy T. Williams, Research Meteorologist 

Southeastern Forest Experiment Station 

Southern Forest Fire Laboratory 

USDA Forest Service 

Chapter W: How to Manage Smoke 

Brian E Anholt, Operations Research Analyst 

Pacific Northwest Forest & Range Experiment 

Station 

USDA Forest Service 

Marty Fox, Chief Forester 

Federal Paperboard Company 

Wally Lancaster, Fire Specialist 

Boise Interagency Fire Center 

USDA Forest Service 

Charles Maynard, Fire Control Research 

Coordinator 

Division of Forestry 

Florida Department of Agriculture & Consumer 

Services 

Lmbert H. Romem, Chief 

Forest Pmkction 

Louisiana Forestry Comission 

In addition to the above named reviewers, the 

authors wish to thank all other members of the 

std at the Southern Forest Fire Laboratory for 

their helpful advice and other assistance while the 

Guidebook has been in progress. 
ERRATA SHEET 

SOUTHERN FORESTRY SMOKE MANAGEMENT GUIDEBOOK 

To save space and avoid duplication, tables necessary for making predictions 

are printed only on the colored sheets. The descriptions (or. white sheets) of 

the use of these tables contain page references that are incorrect. The correct 

paging for work tables is: 

Table number 

VI-F- 5 

VI-F-6 

VI- F- 7 

VI- F- 8 

m-F-9 

m-F-10 

VI-F- I1 

VI- F- 12 

VI-F- 13 

Page 








U.S. FORE'~~Y 

CENTENNIAL