California Environmental Protection Agency

Air Resources Board 

Staff Report: 

Initial Statement of Reasons

for the Proposed Airborne Toxic Control Measure

to Reduce Emissions of Toxic Air Contaminants from

Outdoor Residential Waste Burning

Release Date:

January 4, 2002
State of California

California Environmental Protection Agency

AIR RESOURCES BOARD

STAFF REPORT: INITIAL STATEMENT OF REASONS

FOR PROPOSED RULEMAKING

Public Hearing to Consider

ADOPTION OF THE PROPOSED AIRBORNE TOXIC CONTROL MEASURE

TO REDUCE EMISSIONS OF TOXIC AIR CONTAMINANTS

FROM OUTDOOR RESIDENTIAL WASTE BURNING

To be considered by the Air Resources Board on February 21, 2002, at:

California Environmental Protection Agency

Air Resources Board

Coastal Hearing Room

1001 “I” Street

Sacramento, California

Air Resources Board

P.O. Box 2815

Sacramento, California 95812

This report has been prepared by the staff of the California Air Resources Board. 

Publication does not signify that the contents reflects the views and policies of the Air

Resources Board, nor does mention of trade names or commercial products constitute

endorsement or recommendation for use.
State of California

California Environmental Protection Agency

AIR RESOURCES BOARD

PROPOSED AIRBORNE TOXIC CONTROL MEASURE

TO REDUCE EMISSIONS OF TOXIC AIR CONTAMINANTS

FROM OUTDOOR RESIDENTIAL WASTE BURNING

Staff Report

Prepared by:

Planning and Technical Support Division:

Christina Suarez-Murias

Bruce Oulrey

Patrick Gaffney

Tony Servin, P.E.

Stationary Source Division:

Greg Harris

Michele Houghton

Michelle Komlenic

Reviewed by:

Karen Magliano, Manager, Particulate Matter Analysis Section

Robert Effa, Chief, Air Quality Data Branch

Robert Fletcher, Chief, Planning and Technical Support Division

January 2002
TABLE OF CONTENTS

EXECUTIVE SUMMARY.................................................................................ES-1

I. INTRODUCTION.................................................................................... I-1

II. PUBLIC OUTREACH AND REPORT PREPARATION .......................... II-1

III. PHYSICAL CHARACTERISTICS, SOURCES, AND AMBIENT

CONCENTRATIONS OF DIOXINS AND OTHER TOXIC AIR

CONTAMINANTS.................................................................................. III-1

IV. SUMMARY OF RESIDENTIAL WASTE BURNING PRACTICES

AND EMISSIONS..................................................................................IV-1

V. POTENTIAL HEALTH IMPACTS FROM RESIDENTIAL WASTE

BURNING...............................................................................................V-1

VI. THE PROPOSED CONTROL MEASURE AND ALTERNATIVES ........VI-1

VII. ECONOMIC IMPACTS OF THE PROPOSED AIRBORNE TOXIC

CONTROL MEASURE .........................................................................VII-1

VIII. ENVIRONMENTAL IMPACTS OF THE PROPOSED AIRBORNE

TOXIC CONTROL MEASURE ............................................................VIII-1

IX. REFERENCES......................................................................................IX-1

APPENDIX A: Proposed Regulation Order: Airborne Toxic Control Measure to

Reduce Emissions of Toxic Air Contaminants from Outdoor

Residential Waste Burning

APPENDIX B: Risk Assessment Modeling Results

APPENDIX C: Air Dispersion Modeling Results

APPENDIX D: Glossary and Acronyms
ES-1

EXECUTIVE SUMMARY

Residential waste burning is the practice of outdoor burning of household wastes

associated with one and two family homes.1 These household wastes include materials

such as garbage, paper, cardboard, cloth, and processed wood. Typically, 55 gallon

metal drums, known as burn barrels, are used for this burning. The smoke and ash

created by these fires contain many harmful pollutants, including polychlorinated

dibenzo-p-dioxins and dibenzofurans (collectively referred to as dioxins), polycyclic

aromatic hydrocarbons (PAHs), benzene, 1,3-butadiene, and polychlorinated biphenyls

(PCBs), as well as particulate matter. 

The main focus of the proposed ATCM is to address public exposure to dioxins,

although emissions of other toxic air contaminants and particulate matter will also be

reduced. The Air Resources Board (ARB) has identified dioxins as the most potent

toxic air contaminant identified to date, based on its potential to cause cancer and

affect immune systems (ARB, 1986). Concerns about children’s exposure to burn

barrel emissions is particularly high due to the Office of Environmental Health Hazard

Assessment’s (OEHHA) recent identification of dioxins and PAHs as two of the initial

five toxic air contaminants that may cause children to be especially susceptible to

illness (OEHHA 2001d). 

 

Dioxins are formed through the incomplete combustion of materials containing carbon

and chlorine. Residential waste materials such as plastics and paper contain both of

these substances, and therefore form dioxins when burned. The relatively low

temperatures present in the burn barrels during combustion are particularly conducive

to dioxin formation. Dioxins can contaminate air, water, food, and soil where they may

last in the environment for many years. Dioxins can also accumulate in the fat of fish

and animals, and are then passed on to people when contaminated food is eaten. 

Because dioxins can be passed through mothers milk, children are especially

vulnerable. Children may also be more sensitive to dioxin exposure because of their

rapid growth and development (U.S. EPA 2001b).

Currently, eight districts prohibit the burning of residential waste other than natural

vegetation. Natural vegetation is not included because the amount of dioxins

generated is substantially less than household wastes and the form of the dioxins

generated is less toxic (OEHHA, 2001e). In the remaining 27 air pollution control

districts or air quality management districts (air districts), some form of burning of

residential waste other than natural vegetation is allowed in all or part of the air district. 

Six air districts allow all forms of residential waste to be burned, including household

garbage, in all or part of the air district. The remaining 21 air districts prohibit the

burning of household garbage, but allow the burning of other materials such as paper or

cloth. The portions of these 27 air districts where non-vegetative burning is allowed

represent approximately seven percent of the State's population.

 

 

1 Health and Safety Code section 41800 prohibits the use of fire to dispose of waste at other than one or

two family dwellings.
ES-2

In order to reduce the public health impacts of residential waste burning, we are

proposing an airborne toxic control measure (ATCM) to regulate both the materials that

can be burned and the method of burning. The ATCM would eliminate the burning of

residential waste other than natural vegetation, and the use of burn barrels across the

State. Exemptions would be granted for some regions of the State based on specified

criteria including availability of waste disposal services, distance to approved landfills

and transfer stations, and population density. The following sections provide additional

information on the development of the proposed regulation and its impacts.

1. What authority does the ARB have to control emissions of toxic air

contaminants?

This control measure is developed under the authority of the California Toxic Air

Contaminant Identification and Control Program, established under California law by

Assembly Bill 1807 and set forth in Health and Safety Code sections 39650 through

39675. The Board identified dioxins as a toxic air contaminant (TAC) and potential

human carcinogen at its July 1986 Board hearing (ARB, 1986). The Board determined

there was not sufficient scientific evidence available to identify a threshold level of

exposure below which no adverse health effects are likely to occur. Other substances

that are produced during the burning of residential waste include benzene, 

1,3-butadiene, PAHs, and PCBs. The ARB has also formally identified these

compounds as TACs (ARB, 1984; ARB, 1992; ARB, 1993a).2

Following the formal identification of a substance as a TAC, Health and Safety Code 

section 39665 requires the ARB, with the participation of the air districts, and in

consultation with affected sources and interested parties, to prepare a report on the

need and appropriate degree of regulation for that substance. Once the ARB has

evaluated the need and appropriate degree of regulation for a TAC, Health and Safety

Code section 39666 requires the ARB to adopt ATCMs to reduce emissions of that

TAC. When adopting ATCMs, Health and Safety Code section 39666 requires that any

control measure for a TAC without a Board-specified threshold level be designed to

reduce emissions to the lowest level achievable through the application of best

available control technology or a more effective control method if necessary to reduce

risk.

A needs assessment for dioxins was conducted between 1988 and 1990 as part of the

ARB's development of the ATCM for emissions of dioxins from medical waste

incinerators (ARB, 1990).3

 This staff report is a supplement to that original needs

assessment for dioxins based on new information about the potential emissions from

outdoor residential waste burning. The new information is based on data collected by

the United States Environmental Protection Agency (U.S. EPA). The U.S. EPA began a

reassessment of dioxins exposure and human health effects (U.S. EPA, 2001b). Based

on national inventories for 1987 and 1995, the U.S EPA reported that the burning of

residential waste represents one of the largest uncontrolled sources of dioxins in the

 

2 California Code of Regulations, title 17, sections 93000 and 93001.

3 California Code of Regulations, title 17, section 93104
ES-3

environment (U.S EPA, 2001a). The U.S. EPA has taken action to reduce emissions of

dioxins from medical waste incinerators and municipal waste incinerators under

sections 111 and 129 of the federal Clean Air Act.

2. How prevalent is the practice of residential waste burning and what are the

emissions of dioxins and other toxic air contaminants?

Due to the potentially overlapping nature of air district rules, local ordinances, and fire

agency prohibitions, it is difficult to estimate the true number of households burning

their residential waste in California. Information on waste disposal practices is also

limited in some areas, and the relationship between availability of service and an

individual household's decision to burn any or all of its waste is not always clear cut. 

For example, even though some households have regular waste pickup for their

household garbage, they may still be burning their paper and cardboard. Also, some

households that do not have waste pickup service dispose of their household waste by

means other than burning. However, based on discussions with air district staff and

waste management agencies, we have developed our best estimate of the number of

households that could be burning their non-vegetative waste in California. 

Approximately 82,000 households are located in the portions of the six air districts that

have no prohibitions on the materials that can be burned. In these six air districts, we

estimate that about 15,000 households may be burning their residential waste,

including household garbage. An additional 641,000 households are located in the

remaining 21 air districts where burning of other waste materials is allowed. We further

estimate about 93,000 households may be regularly burning materials such as

cardboard and paper in these 21 air districts. In general, these estimates are based on

our discussions with the affected air districts. In total, approximately 

108,000 households may be burning some or all of their residential waste. 

The U.S. EPA has developed emission factors for residential waste burning conducted

in burn barrels (U.S. EPA, 1997a; Lemieux 2000). Using these factors and an average

waste generation rate of 2,137 pounds of waste per household per year 

(CIWMB, 2000), the average household burning residential waste could generate

between 0.005 and 0.15 grams of total dioxins per year. Based upon these emission

levels, the U.S. EPA has reported that residential waste burning is one of the largest

uncontrolled source of dioxins in the United States (U.S. EPA 2001a). It is also

important to recognize that while these numbers appear small, dioxins in even small

quantities pose health hazards and there is no threshold below which exposure to

dioxins has been deemed safe.

3. What are the potential health impacts associated with exposure to dioxins and

other toxic air contaminants from residential waste burning?

Exposure to dioxins may result in both cancer and non-cancer health effects to the

individuals conducting the burning, as well as to surrounding residents. Non-cancer

effects from exposure to dioxins include headaches, dizziness, rapid heartbeat,
ES-4

damage to the immune system, and liver and kidney damage. Dioxins are the most

carcinogenic air pollutant identified by the ARB (ARB, 1986). Because dioxins can be

passed through mothers milk, young children are especially vulnerable. Children may

also be more sensitive to dioxin exposure because of their rapid growth and

development (U.S. EPA, 2001b). 

Health effects of other toxic air contaminants generated during residential burning such

as benzene, 1,3-butadiene, PAHs, and PCBs include skin, eye and respiratory irritation,

fatigue, neurological and immune system effects, and cancer. In addition to these

TACs, smoke from residential burning contains particulate matter that can worsen

existing disease conditions and can produce respiratory and cardiac effects, especially

among sensitive populations such as the elderly and the very young (Pope, 1999;

Samet, 2000). Particulate matter is a criteria pollutant with standards set by both the

State and federal government. As required by the Children’s Environmental Health

Protection Act (Senate Bill 25, Escutia, 1999), ARB and the Office of Environmental

Health Hazard Assessment (OEHHA) are reviewing the State PM10 standards for their

ability to adequately protect public health, including that of infants and children. 

Recommendations for revised standards will be presented to the Board in the spring of

2002.

The risk assessment conducted to assess the potential health impacts from residential

waste burning found potential cancer risks ranging between less than 10 to about

2,300 chances in a million at the near-source location (a near-source location is defined

as a minimum modeled distance of 20 meters from the burning activity). The lower end

of this range includes the potential cancer risk from inhalation, soil ingestion, skin

absorption, and breast milk exposure pathways (OEHHA, 2001c). The upper end of the

range estimates potential cancer risks across all included exposure pathways (i.e., the

four minimum pathways discussed above plus crop, meat, and milk ingestion). 

The dioxins emitted from the burning of residential waste materials can have nearsource impacts on individuals in a household conducting the burning and on nearby

neighbors. As discussed previously, the impacts on young children are of special

concern. In addition, there is also a broader community impact from the dioxins

generated from this source. Dioxins are ubiquitous throughout the environment, due to

the cumulative emission impacts from many sources, including residential waste

burning. Dioxins emitted from a source have a half-life in the atmosphere of several

days (Balkanski et al., 1993). Eventually, the dioxins in the air are deposited onto

vegetation, waterways, and the soil. Once there, dioxins are highly persistent, with the

half-life in the soil surface estimated at 9 to 15 years, and in the soil subsurface at 25 to

100 years (Paustenbach et al., 1992). Dioxins can also accumulate in the fat of fish

and animals, and are then passed on to people when contaminated food is eaten. It is

estimated that 90 percent of dioxin intake for a typical person comes from dietary intake

of animal fats (Gilman & Newhook, 1991).

A more detailed discussion of health impacts is presented in Chapter V.
ES-5

4. What are the requirements of the proposed ATCM?

The proposed control measure would minimize emissions of dioxins and other toxic air

contaminants such as benzene, 1,3-butadiene, PAHs, and PCBs, and the criteria

pollutant, particulate matter, from residential waste burning by addressing both the

materials which can be burned and the method of burning. The proposed ATCM

prohibits the burning of residential waste, other than natural vegetation, anywhere in the

State except for areas that qualify for a temporary exemption based upon specified

criteria. The use of burn barrels would also be prohibited statewide, except in exempt

areas, as a means of ensuring that burn barrels are not used for the burning of

prohibited residential waste. The ATCM would require the use of ignition devices

approved by the Air Pollution Control Officer of the air district. It would also prohibit the

burning of allowable combustibles as defined in the regulation, unless it is a permissive

burn day in the air district where the residential burning takes place. The prohibitory

provisions of the regulation would be effective on July 1, 2003. During the time before

the prohibitions become effective, the ARB will work with air districts to carry out public

education and outreach efforts prior to implementation.

With the concurrence of the ARB, air districts may specify geographic areas that will be

exempt from the prohibitions in the ATCM if they meet specified criteria including, but

not limited to, all of the following:

1) no available waste pickup service, considering reasonable cost and

frequency of service; and

2) greater than a reasonable distance from an approved transfer station or

disposal facility or a communal or community dumpster, considering road

miles or time traveled, road conditions, terrain, weather conditions,

reasonable tipping fees, and hours of operation; and

3) low population density per census tract or other appropriate sub-unit of

the county area.

Those areas that meet these exemption criteria would be allowed to burn only those

materials that are currently allowed under air district rules, and would be allowed to use

burn barrels, or other incinerator type devices to dispose of the waste. Requests for

Exemptions would be submitted to the ARB by March 1, 2003. These exemptions

would be approved by both the Board of the air district and the Executive Officer of the

ARB. Exemptions must be justified and renewed every five years. 

5. What are the potential economic impacts of the proposed ATCM?

The proposed regulatory action may create some costs to the California Integrated

Waste Management Board for addressing potential impacts on waste diversion rates,

and the California Department of Forestry and Fire Protection for enforcement. The

proposed regulatory action may also result in nonmandatory costs to local agencies

responsible for waste management to the extent they choose to provide expanded

waste disposal services and to address waste diversion impacts. The proposed
ES-6

regulation may also result in some small, but unquantifiable, costs to air districts for

enforcement and public education and outreach. However, costs for public education

and outreach would be addressed through preparation of materials by the ARB. Most

air districts have enforcement programs due to existing rules addressing the burning of

residential waste. The proposed regulation is not expected to increase the enforcement

workload.

In developing this regulatory proposal, we evaluated the potential economic impacts

and/or benefits on businesses. The proposed regulatory action will not have a

significant adverse economic impact on businesses, including the ability of California

businesses to compete with businesses in other states. The proposed regulatory action

however, may provide increased business opportunities for waste pickup services,

landfill operators, and recycling center operators to provide expanded waste disposal

services. Some of these may be small businesses. Additional discussion of potential

economic impacts is provided in Chapter VII.

6. Will consumers have to pay more for waste disposal due to the proposed

ATCM?

Consumers who are currently burning their residential waste may have to pay more to

dispose of these materials. The proposed ATCM will require them to obtain waste

management services or to self-haul their waste to landfills or transfer stations. In

some areas, new waste service routes may need to be developed. In other areas, new

customers may be added to existing routes. The increased cost will vary depending

upon the costs of obtaining waste management service in their area.

We estimate that a consumer who did not previously contract for waste service could

incur new yearly costs for waste pickup of $96 to $420. These costs would be less for

households that already are disposing of a portion of their waste through waste pickup

service. Alternatively, some consumers may elect to self-haul their waste to landfills

and transfer stations. Staff estimates that a consumer who previously burned all of

their waste could incur yearly disposal costs of $78 to $520 for landfill or transfer station

tipping fees to self-haul their waste materials. Fuel costs to transport the waste could

amount to an additional $78 dollars per year per household. These costs could be

reduced in areas where recyclable materials, such as plastics and paper, are

separated, and which can often be dropped off for no cost. Consumers who had

previously been self hauling only a portion of their waste, and burning the rest, would

incur lower additional yearly costs.

7. What are the potential environmental impacts of the proposed ATCM?

The ARB is committed to evaluating community health impacts of proposed regulations,

and to addressing environmental justice concerns. Because some communities

experience higher exposures to toxic air pollutants due to cumulative impacts and other

factors, it is a priority of the ARB to ensure that full protection is afforded to all

Californians.
ES-7

The proposed ATCM is designed to reduce emissions of dioxins and other TACs from

residential waste burning, resulting in reduced exposures to these emissions for those

communities and individuals currently allowed to burn residential waste, with associated

lower potential health risks. The proposed ATCM will also reduce emissions of

particulate matter from residential waste burning.

The proposed ATCM was also evaluated in terms of potential impacts on waste

diversion rates, landfill capacities, illegal dumping, illegal waste storage, and increased

vehicle travel due to expanded waste service or self-hauling. In evaluating impacts, we

considered the role of exemptions in the proposed regulation. The goal of the

exemptions would be to allow burning in those areas where feasible alternatives to

waste disposal do not exist and where population density is low; therefore mitigating the

potential for adverse impacts in areas where they would be most likely to occur.

While the waste that is no longer burned will result in increased materials deposited at

landfills and have an impact upon waste diversion rates, these impacts can be

mitigated through efforts to decrease waste generation and increase recycling and

composting, and through a strong public education and outreach campaign regarding

the availability of alternative waste disposal options. In addition, some jurisdictions can

qualify for rural reduction programs with lower required diversion rates, or can develop

new baseline waste generation rates to better reflect the previously burned waste. 

Based upon the available information, ARB has determined that no significant adverse

environmental impacts should occur.

8. What public outreach was conducted in developing the ATCM?

For this assessment we developed an extensive outreach program that involved State

and local regulatory agencies, waste management agencies and service providers, fire

protection agencies, and other interested parties. These entities participated in the

development and review of the necessary surveys and draft reports, conference calls,

working group meetings, workshops, and the proposed regulation. Outreach efforts

also provided participants a forum in which to address their concerns. As part of this

process, ARB outreach activities included:

• conducting six public workshops in December 2001;

• scheduling an additional ten public workshops for January 2002;

• using newspaper advertisements and media advisories for workshops;

• mailing workshop notices to over 4,000 people;

• preparing and distributing two fact sheets;

• developing and maintaining a residential burning web site;

• holding over 20 individual meetings with waste management agencies, fire

protection agencies, air districts, and the Regional Council of Rural Counties;

and

• convening eleven meetings of the Residential Burning Working Group.
ES-8

RECOMMENDATION

We recommend that the Board adopt the proposed regulation set forth in Appendix A. 

The proposed regulation would eliminate residential waste burning, excluding natural

vegetation, and burn barrel usage except in some very rural areas of the State. The

proposed ATCM is based upon staff's evaluation of the best available control method

for dioxin emissions from this source. We considered the emissions and associated

health risks of residential waste burning, the availability and cost of alternative methods

of disposal, and the economic and environmental impacts of the proposed regulation. 

As a result of this evaluation, with the incorporation of recommended exemptions, staff

considers the proposed ATCM to be environmentally, technically, and economically

feasible, resulting in a safe, effective, and less-hazardous alternative to burning. 
I-1

I. INTRODUCTION

A. Overview

Residential waste burning, for the purpose of this document, is defined as the outdoor

burning of wastes, other than natural vegetation, generated by a single or two family

residence. The United States Environmental Protection Agency (U.S. EPA) has

identified residential waste burning as a major source of polychlorinated dibenzo-pdioxins and dibenzofurans (collectively referred to as dioxins). Dioxins in particular are

the most potent carcinogens identified to date by the Air Resources Board (ARB or

Board) as toxic air contaminants (TACs). In addition to dioxins, many other toxic air

contaminants are generated from residential waste burning, including polycyclic aromatic

hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), benzene, and

1,3–butadiene. These toxic air contaminants may result in substantial health impacts,

ranging from headaches, dizziness, rapid heartbeat, damage to the immune system, and

liver and kidney damage, to cancer. Because dioxins can be passed through mothers

milk, children are especially vulnerable. 

Particulate matter is also generated from residential waste burning. Most of the

particulate matter emitted from residential waste burning is small enough to be inhaled

and can be especially harmful to people with existing respiratory illness, the aged, and

the very young. Exposure to such particles may worsen existing disease conditions and

can produce symptoms ranging from breathing difficulties to increased respiratory

infection and even premature death (Pope, 1999; Samet, 2000).

The Board identified dioxins as a TAC and a potential human carcinogen at its July 1986

Board hearing (ARB, 1986). The Board determined that there was not sufficient

scientific evidence available to identify a threshold level of exposure below which no

adverse health effects are likely to occur. Once dioxins were identified as TACs in 1986,

the ARB was required under the Toxic Air Contaminant Identification and Control

Program to: 1) prepare a report on the need and appropriate degree of regulation for

the compounds, and 2) adopt regulations to reduce emissions of the compounds. 

These regulations are called airborne toxic control measures (ATCMs) or control

measures. In this report, we use the terms regulation, control measure, and ATCM

interchangeably. State law requires that such control measures for TACs without a

Board-specified threshold exposure level be based on the best available control

technology or a more effective control method in consideration of cost and risk.

This Initial Statement of Reasons for the Proposed Airborne Toxic Control Measure to

Reduce Emissions of Toxic Air Contaminants from Outdoor Residential Waste Burning

presents information on the toxic air contaminant identification and control process, the

report preparation process, and previous identification and control (regulatory) activities

for dioxins. We then present physical characteristics of dioxins and other TACs and

information on sources and ambient concentrations. This is followed by a discussion of

typical waste burning activities across the State, and information on exposure and health
I-2

effects for dioxins and other TACs. Finally, we present the proposed control measure,

and its health, economic, and environmental impacts.

B. Purpose

On March 23, 2000, the Board adopted revisions to the State’s Smoke Management

Guidelines for Agricultural and Prescribed Burning. At that time, the Board also directed

staff to assess the impacts of outdoor residential waste burning. We convened a

residential burning working group and performed a preliminary analysis of outdoor

residential waste burning. Our analysis included: 1) a survey of all the air districts in the

State to assess existing regulations and practices regarding residential waste burning

and burn barrel use; 2) a preliminary screening risk assessment to quantify health risks

associated with dioxins and other toxic compounds emitted from residential waste

burning; 3) meetings with the California Integrated Waste Management Board (CIWMB)

to assess existing waste management services across the State and the potential for

expanding service; and 4) discussions with fire management agencies within the State to

identify potential fire safety and resource management issues.

We presented our analysis to the Board at its June 28, 2001, meeting. Based upon the

prevalence of burning and the screening risk assessment, we recommended adding

residential waste burning to ARB’s Clean Air Plan and developing an ATCM. Two

witnesses, including the Chair of the California Air Pollution Control Officers Association

(CAPCOA), urged ARB to develop an ATCM to ban residential waste burning and the

use of burn barrels. As a result, the Board directed staff to proceed with developing an

ATCM and report back to the Board in 2002.

Following the June 28, 2001, Board meeting, we continued to refine our waste

burning/burn barrel use analysis. We contacted air districts, the CIWMB, and local

waste management agencies and service providers statewide to enlist their help with

characterizing the potential for and costs to expand waste management services. We

also worked with land management and fire safety representatives to address any

potential concerns they might have with banning waste burning and the use of burn

barrels.

C. Regulatory Authority

The California Toxic Air Contaminant Identification and Control Program (Program),

established under California law by Assembly Bill 1807 (Chapter 1047, Statutes of 1983)

and set forth in Health and Safety Code sections 39650 through 39675, is designed to

protect public health by reducing emissions of TACs. This law mandates the

identification and control of air toxics in California and complements the State’s criteria

air pollutant program. The identification phase of the Program requires the ARB, with

the participation of other State agencies, to evaluate the health impacts of, and

exposure to, substances and to identify those substances that pose the greatest health

threat as TACs. ARB’s evaluation is made available to the public and is formally

reviewed by the Scientific Review Panel (SRP) established under Health and Safety
I-3

Code section 39670. Following ARB’s evaluation and the SRP’s review, the Board

identified dioxins as TACs at its July 1986 Board hearing. The Board determined there

was not sufficient scientific evidence available to support the identification of a threshold

exposure level (ARB, 1986).

A threshold level can be defined as a level of pollutant exposure below which no adverse

health effects are likely to occur. In their evaluations of dioxins, staff from the California

Environmental Protection Agency’s Office of Environmental Health Hazard Assessment

(OEHHA) recommended that dioxins be treated as having no threshold exposure level

because: 1) all dioxins are potential human carcinogens, and

2) currently, there is insufficient evidence available to designate an exposure level below

which no significant adverse health impacts are anticipated.

Following the identification of a substance as a TAC, HSC section 39665 requires the

ARB, with participation of the air districts, and in consultation with affected sources and

interested parties, to prepare a report on the need and appropriate degree of regulation

for that substance. 

A needs assessment for dioxins was conducted between 1988 to 1990 as part of the

ARB’s development of the Airborne Toxic Control Measure for Emissions of Dioxins from

Medical Waste Incinerators (title 17, California Code of Regulations,

section 93104) (ARB, 1990). During that assessment, the ARB identified numerous

sources of dioxins, including incineration of medical waste, recycled waste oil,

hazardous waste, sewage sludge, municipal waste, and woodwaste. 

Subsequent to that report, the U.S. EPA also began a reassessment of dioxins exposure

and human health effects (U.S. EPA, 2001b). Based on national inventories for dioxins

representing 1987 and 1995, the EPA report suggested that the burning of household

waste is one of the largest uncontrolled sources of dioxin emissions in the environment.

D. Regulatory Activities

1. Airborne Toxic Control Measures

Once the ARB has evaluated the need and appropriate degree of regulation for a TAC,

State law (Health and Safety Code section 39666) requires the ARB to adopt regulations

to reduce emissions of the TAC to the maximum extent feasible in consideration of cost,

risk, and other factors specified in Health and Safety Code section 39665. To date, the

ARB has developed eleven ATCMs for a variety of TACs. In 1990, the ARB adopted a

control measure to reduce emissions of dioxins from medical waste incinerators by

99 percent. At that time, medical waste incinerators were one of the largest known

sources of dioxins in California. As a result of this regulation, the number of medical

waste incinerators in the State dropped sharply from about 150 to less than 15. In 1994,

the U.S. EPA adopted a control measure to regulate municipal waste incinerators by the

year 2000 (U.S. Federal Register, 1994). In California, there are only three operating

municipal waste incinerators. Each of these control measures incorporate the use of
I-4

best available control technology. In the case of dioxins, best available control

technology to minimize or eliminate the formation of dioxins is achieved through careful

control of combustion conditions, including maintaining combustion temperatures at

approximately 1000O C for a minimum of one second. This type of controlled

combustion is not feasible for small residential burning sources such as backyard burn

barrels or piles. 

2. National Emission Standards for Hazardous Air Pollutants

In the federal Clean Air Act Amendments of 1990, the U.S. EPA identified dioxins as

hazardous air pollutants (HAPs) because they were either known to have or may have

adverse effects on human health or the environment. Health and Safety Code

section 39658(b) requires the Board to designate federal HAPs as TACs, and the Board

did so in 1993 (ARB, 1993a). Therefore, dioxins are TACs both because they have

been identified by the Board through the Toxic Air Contaminant Identification and

Control Program and because they are HAPs.

3. SB 25 Children’s Environmental Health Protection Act Air Toxics Priorities List

The California Children’s Environmental Health Protection Act (SB 25, Escutia;

chaptered 1999), requires the California Environmental Protection Agency to specifically

consider children in developing criteria for evaluating TACs. The law requires OEHHA to

evaluate available information on TACs and develop a listing of up to five TACs that

“may cause infants and children to be especially susceptible to illness.” The initial listing

was made final in October 2001. Dioxins and PAHs are two of the top five compounds

initially listed. The listing will be updated periodically (OEHHA, 2001d).
II-1

II. PUBLIC OUTREACH AND REPORT PREPARATION

A. Outreach Efforts

Outreach and public participation are important components of ARB’s needs

assessment and report preparation process. For this assessment we developed an

extensive outreach program that involved State and local regulatory agencies, waste

management agencies and service providers, fire protection agencies, and other

interested parties. These entities participated in the development and review of the

necessary surveys and draft reports, conference calls, working group meetings,

workshops, and the proposed regulation. Outreach efforts also provided participants a

forum in which to address their concerns. ARB outreach activities included:

• establishing a Residential Burning working group which held 11 meetings and

conference calls between October 2000 and December 2001. The working group

consists of over 50 people;

• conducting six public workshops in December 2001 at the following locations and

times:

• Sacramento, Sacramento County – December 4, 2001

• Yreka, Siskiyou County – December 5, 2001

• Alturas, Modoc County – December 6 2001

• Susanville, Lassen County – December 7, 2001

• Hollister, San Benito County – December 10, 2001

• Alpine, San Diego County – December 17, 2001

• scheduled ten public workshops for January 2002 at the following locations:

• Nevada City, Nevada County – January 7, 2002

• Auburn, Placer County – January 7, 2002

• Jamestown, Tuolumne County – January 9, 2002

• Willows, Glenn County – January 10, 2002

• Oroville, Butte County – January 15, 2002

• Mariposa, Mariposa County – January 16, 2002

• Placerville, El Dorado County – January 17, 2002

• Eureka, Humboldt County – January 22, 2002

• Redding, Shasta County – January 23, 2002

• Yuba City, Yuba County – January 23, 2002

• mailing or faxing working group agendas, minutes, draft surveys, survey analyses,

draft and final reports to over 50 people;

• making newspaper display ads available for all workshop locations, as well as

providing local media advisories in advance of all workshops;
II-2

• developing and distributing two fact sheets;

• mailing workshop notices to over 4,000 people;

• meeting with waste management agencies and service providers on: 1) the

existing waste collection and disposal services available in those districts;

2) the ability to expand service; and 3) associated costs for expanded service;

• meetings with California fire protection organizations, including the Sacramento

Valley Fire Marshals Association, California Office of the State Fire Marshal, the

Placer County Residential Burning Committee, and the California Department of

Forestry and Fire Protection (CDF) to discuss fire safety issues;

• meetings with the Regional Council of Rural Counties on issues related to waste

disposal and environmental and economic impacts; and

• making information available through a residential burning web site.

1. Public Involvement

As described below, we worked with affected stakeholders and organizations interested

in minimizing exposure to dioxins and other toxic air pollutants emitted from residential

waste burning. These groups included the Regional Council of Rural Counties and the

County Supervisors Association of California, as well as the general public. To increase

the general public’s participation in this assessment, we have made information

available via the ARB’s Internet web site: 

http://www.arb.ca.gov/smp/resburn/resburn.htm

The web site provides background information on the ATCM development process,

including fact sheets, workshop dates and locations, and electronic links on residential

waste burning air toxic emissions and health effects.

2. Industry Involvement

Waste management agencies and service providers were consulted in the development

of this report and in evaluating the availability of alternative waste disposal options. 

Comments and suggestions were provided by these groups from across the State during

the development of surveys and subsequent analysis. Industry involvement in the

process has also included:

• approximately 200 telephone conversations and email exchanges;

• meetings with local waste management agencies in five of the six air

districts that currently allow the burning of household garbage; and
II-3

• completion of a waste management questionnaire on current and future

availability and cost of waste management services for the six air districts

in California that currently allow the burning of household garbage.

3. Government Agency Involvement

Other local, State, and federal agencies with an interest in dioxins emissions associated

with residential waste burning and use of burn barrels have been involved in the

assessment process to promote statewide consistency in addressing public health

concerns and providing a multi-media perspective. These agencies include: air districts,

the California Environmental Protection Agency’s (Cal/EPA’s) CIWMB and OEHHA,

CDF, the State Fire Marshal, and the U.S. EPA.

We have apprised the air districts of our activities through CAPCOA meetings, and have

also worked with them to gather information on how the air districts regulate residential

waste burning and burn barrel use. This work has included informational surveys and

telephone calls to the air districts, and participation by many air districts in the

Residential Burning Working Group.

B. Data Collection Tools to Assist in Report Preparation

Between October 2000 and October 2001, ARB staff conducted three surveys to gather

information associated with residential waste burning and the use of burn barrels to

support development of the ATCM. The three surveys were: 1) the Air District Rules

Survey (Rules Survey); 2) the ATCM Concept Survey (ATCM Survey); and 3) the Burn

Barrel Use Survey (Burn Barrel Survey). A fourth data collection tool utilized in

September 2001 was the Waste Management Services Questionnaire (Waste

Management Questionnaire).

1. Rules Survey

The Rules Survey was conducted in October 2000. This survey was sent to all air

districts in the State to assess air district rules and practices associated with residential

waste burning. The survey requested information on current rules regulating residential

burning, complaints and workload associated with residential burning, and suggestions

for State and local efforts to improve management of residential burning. All 35 air

districts in the State responded to the survey. The survey highlighted the variability in

how residential waste burning is regulated throughout the State. Many air districts also

reported that addressing complaints from residential waste burning represented a

significant workload.

2. ATCM Survey

The ATCM Survey was sent to members of the Residential Burning Working Group in

September 2001, with further input from CAPCOA in November 2001. The working

group is made up of representatives from the 27 air districts around the State that allow
II-4

some residential waste burning other than natural vegetation. The ATCM survey

gathered information about the air district's perspectives regarding how the ATCM

should be structured and implemented. Issues that were addressed included the types

of materials that should be included, the need for and the form of any exemptions, and

the implementation schedule. All 27 of the air districts responded to the survey and

provided input.

3. Burn Barrel Survey

The Burn Barrel Survey was sent to 21 air districts in the State that allow residential

waste burning but not residential garbage burning. It requested information on the

estimated number of burn barrels in each of the 21 air districts and the percentage of

barrels in each air district estimated to have illegal materials burned in them. Responses

were received from all 21 of the air districts surveyed.

4. Waste Management Questionnaire

The Waste Management Questionnaire was sent to agencies responsible for waste

management in the six air districts that allow the burning of household garbage in

September 2001. It gathered information on the availability of service in each area,

costs for service, and any obstacles that might be encountered to address the additional

waste that could no longer be burned under the proposed ATCM. Written or verbal

information was obtained from waste management agencies in all six air districts. 
III-1

III. PHYSICAL CHARACTERISTICS, SOURCES, AND AMBIENT

CONCENTRATIONS OF DIOXINS AND OTHER TOXIC AIR CONTAMINANTS

A. Dioxins

1. Background

"Dioxins" is a generic term used to denote any of a family of compounds that are

derived from dibenzo-p-dioxin, or a mixture of such compounds. The basic structure of

all dioxins consists of two benzene rings joined to each other by two oxygen atoms (see

Diagram below). A closely related family of compounds are the dibenzofurans. They

have structures and properties similar to dioxins and are often found in association with

them. These compounds are collectively referred to as dioxins. Dioxins are classified

into groups termed homologues on the basis of the number of chlorine atoms in the

molecule. Thus, tetrachloro-dibenzo-p-dioxins and dibenzofurans contain four chlorine

atoms, pentachloro-dibenzo-p-dioxins and dibenzofurans contain five chlorine atoms,

and so on. Within each homologue, individual isomers are characterized by the

location of the chlorine atoms on the rings.

2,3,7,8 Tetrachlorodibenzo-p-dioxin 2,3,7,8 Tetrachlorodibenzo furan

CHLORINATED DIOXINS/DIBENZOFURANS OF CONCERN

Dioxins Dibenzofurans

Tetrachloro 2,3,7,8 2,3,7,8 

Pentachloro 1,2,3,7,8 1,2,3,7,8 

2,3,4,7,8 

Hexachloro 1,2,3,4,7,8 

1,2,3,6,7,8 

1,2,3,7,8,9 

1,2,3,4,7,8 

1,2,3,6,7,8 

1,2,3,7,8,9 

2,3,4,6,7,8 

Heptachloro 1,2,3,4,6,7,8 1,2,3,4,6,7,8

1,2,3,4,7,8,9

NOTE: The numbers indicate the position of chlorine atoms on the dioxin or dibenzofuran molecule.
III-2

There are 75 different polychlorinated dibenzo-p-dioxins and 135 polychlorinated

dibenzofurans, differing from each other by the number and location of chlorine atoms

on the molecule. 

2. Physical Characteristics

The mixture of dioxins emitted from combustion sources are in both the gaseous and

particulate phase. The persistence of these substances may be a function of the phase

into which they are emitted. The gas/solid phase partition factor is influenced by flow

rate, temperature, and dimensions of the sampling. These substances do not appear

to degrade when sorbed to solids (ARB, 1986). It is believed that the hexa through

hepta chlorinated congeners are sorbed to particulates, whereas, the tetra and penta

congeners partition to the vapor phase (Bidleman, 1988).

Dioxins are highly persistent under normal environmental conditions, particularly when

adsorbed on soils or other substrates. The half-life of 2,3,7,8 Tetrachlorodibenzo-pdioxin has been reported to be approximately 25 to 100 years in subsurface soil and

9 to 15 years at the soil surface (Paustenbach et al., 1992). Several researchers have

reported global transport of dioxins in the atmosphere (Denison, 2000;

Commoner et al., 2000). Dioxins are degraded by sunlight in solution under laboratory

conditions, but the extent to which dioxins are degraded by sunlight in the atmosphere

is unknown (ARB, 1986). Gas-phase dioxins may be degraded by reaction with

hydroxyl (OH) radicals and direct photolysis. Particulate-associated dioxins are

removed from air by wet and dry deposition. The average half-life for particles in the

lower atmosphere is several days, whether particle-associated or gaseous

(Balkanski et al., 1993).

3. Sources and Emissions

Dioxins are formed as products of incomplete combustion when chlorine and complex

mixtures containing carbon are present. Conditions which have been associated with

formation of dioxins during combustion include: 1) poor gas-phase mixing; 2) low

combustion temperatures; 3) oxygen-starved conditions; 4) high particulate matter

loading; 5) particulate matter-bound copper; 6) presence of hydrogen chloride and/or

chlorine; and 7) significant gas-phase residence time in the 250-700o

C temperature

range. Dioxins are emitted from incinerators that burn residential waste, medical waste,

municipal solid waste, hazardous waste sewage sludge, tires, and metal smelting

operations when the feedstock contains dioxin precursors (Bumb et al., 1980;

U.S EPA, 1997a; U.S. EPA, 1997b; U.S. EPA, 2001a; U.S EPA, 2001b; ARB, 1990).

Dioxins are also formed in small quantities as unwanted combustion byproducts in

certain industrial processes associated with the manufacture of polychlorinated

biphenyls (PCBs). Other possible sources of dioxins are sawmills, wire and scrap metal

reclamation incinerators, black liquor boilers, cement kilns, cofiring wastes, transformer

fires, wood stoves/fireplaces, and agricultural burning. Dioxins can form in wood

through chlorination of phenolic compounds present in wood, paper pulp, or through the
III-3

combustion breakdown of pentachlorophenol, a pesticide used to inhibit mold growth in

lumber. 2,3,7,8-Tetrachlorodibenzo-p-dioxin is produced as an unwanted contaminant

during the manufacture of pesticides, such as chlorophenols, and their derivatives such

as 2,4,5-trichlorophenoxyacetic acid (ARB, 1997). Dioxins have also been detected in

fly ash and stack gas of various combustion processes (Tiernan, 1983).

Dioxins adsorbed on airborne particulate or in industrial effluent are deposited on the

soil and eventually bind to other organic substances and bottom sediment in lakes and

rivers. Although dioxins are encountered in both the vapor and particulate phases, it

has been suggested that ingestion results in 90 percent of human exposure 

(Gilman & Newhook, 1991). Atmospheric dioxins deposit on vegetation which farm

animals consume. Humans then ingest crops, fish, meat, and dairy products and thus

accrue a body burden of dioxin. Subsistence fisherman can have unusually high levels

of dioxin (U.S. EPA, 1989a; Hites, 1991). Secondary exposure, due to such soil and

water pollution, may be as significant as atmospheric exposure and could substantially

increase total risk (ARB 1986). Dioxins in very small concentrations are ubiquitous in

the environment and it is likely that some of the primary sources are not yet known. 

Dioxins have been found worldwide, even in remote areas (ARB, 1986).

The U.S. EPA 's national emissions inventory for dioxins in 1987 and 1995 is shown in

Table III-1 (U.S. EPA, 2001a). U.S. EPA’s best estimate of releases of dioxins to air,

water and land from reasonably quantifiable sources suggests an approximate

77 percent decrease between 1987 and 1995, due primarily to reductions in air

emissions from municipal and medical waste incinerators. In 1990, the ARB adopted a

control measure to reduce emissions of dioxins from medical waste incinerators by

99 percent. At that time, medical waste incinerators were one of the largest known

sources of dioxins in California. As a result of this regulation, the number of medical

waste incinerators in the State dropped sharply from about 150 to less than 15. In

1994, the U.S. EPA adopted a control measure to regulate municipal waste incinerators

by the year 2000 (Federal Register, 1994). Based upon the most recent source

emissions data, U.S. EPA estimates that uncontrolled combustion, such as burning of

residential waste, is expected to become the largest quantified source of dioxin

emissions to the environment in the United States (U.S. EPA, 2001b).
III-4

Table III-1. Inventory of Environmental Releases (grams/year TEQ*) of Dioxins

From Known Sources in the United States for 1987 and 1995

(U.S. EPA, 2001a)

 * Toxic Equivalent – a quantitative measure of the combined toxicity of a mixture of

dioxin-like chemicals
III-5

4. Ambient Concentrations

Limited data are currently available to characterize ambient concentrations of dioxins in

California. The ARB commissioned a study to assess the ambient concentrations of

dioxins in the South Coast Air Basin (Hunt et al. 1990). 2,3,7,8-Tetrachlorodibenzo-pdioxin levels were non-measurable at some sites and 0.0086 pg/m3

 at West Long

Beach (monitor near a petroleum refinery) and 0.034 pg/m3

 at the CalTrans site

(monitor near a highway intersection) (U.S. EPA, 1993a).

A study to assess ambient concentrations of dioxins was also conducted in Fresno,

California in 1991. The majority of the atmospheric burdens of dioxins are represented

by non 2,3,7,8-substituted species which are not of toxicological importance. However,

the reported range for 2,3,7,8-Tetrachlorodibenzo-p-dioxins was 0.012 to 0.027 pg/m3

and for 2,3,7,8-Tetrachlorodibenzo-p-furans was 0.041 to 0.134 pg/m3. It is thought

that combustion sources (including wood stoves as shown by high retene

concentrations) are responsible for these concentrations (ARB, 1993b).

The ARB is currently developing an air quality monitoring and testing program to collect

ambient data for dioxins, furans, and dioxin-like PCBs in California known as the

California Ambient Dioxin Air Monitoring Program (CADAMP). The CADAMP

monitoring will take place at a total of nine locations in the State (five in the San

Francisco Bay Area and four in the South Coast Air Basin). Monitoring will begin in

January 2002 and will continue for two years.

B. Benzene

Benzene is a clear, colorless, volatile, highly flammable liquid with a characteristic

sickly, sweet odor. It is chemically characterized by six carbon atoms linked in a planar

symmetrical hexagon (equal C-C bond lengths) with each carbon atom attached to a

hydrogen atom. The electronic structure of that geometry makes benzene unusually

stable. It does react with other compounds mainly by the substitution of a hydrogen

atom (U.S. EPA, 1993b). Benzene is soluble in water and miscible with alcohol,

chloroform, ether, carbon disulfide, carbon tetrachloride, glacial acetic acid, acetone,

and oils (Merck, 1989).

The predominant sources of total benzene emissions in the atmosphere are gasoline

fugitive emissions and gasoline motor vehicle exhaust. Mobile sources contribute

85 percent and industry related stationary sources 15 percent of the emissions. 

Approximately 70 percent of mobile source benzene emissions can be attributed to onroad motor vehicles, with the remainder attributed to non-road mobile sources 

(U.S. EPA, 1993b).

Although benzene is not present in household products except in small amounts in

some automotive and cleaning products, it is a widely used industrial chemical. In

1985, it was the 16th highest-volume chemical produced in the United States. It is used

in the manufacture of medicinal chemicals, shoes, dyes, detergents, explosives,
III-6

linoleum, oil cloth, and artificial leather. Benzene is a solvent for waxes, fats, resins,

paints, plastics, and fast drying inks. Other uses are as a raw material in the synthesis

of organic compounds such as cyclohexane, styrene, phenol, and rubber. Tobacco

smoke also contains benzene (ARB, 1997). Benzene emissions occur from residential

burning, agricultural burning, forest management burning, and wildfires. These

emissions can vary significantly from year to year (ARB, 1984). The primary stationary

sources that have reported emissions of benzene in California are crude petroleum and

natural gas mining, petroleum refining, and electric service (ARB, 1997).

C. 1,3-Butadiene

1,3-Butadiene is a flammable, colorless gas with a pungent, aromatic, gasoline-like

odor. It is insoluble in water, slightly soluble in methanol and ethanol, and soluble in

organic solvents such as benzene and ether (U.S. EPA, 1989b). 1,3-Butadiene is a gas

at most environmental temperatures and is very volatile even at lower temperatures

(ARB, 1997).

In California, the majority of 1,3-butadiene emissions are from incomplete combustion

of gasoline and diesel fuels. Mobile sources account for approximately 96 percent of

the total annual emissions statewide for quantified sources. Vehicles that are not

equipped with functioning exhaust catalysts emit greater amounts of 1,3-butadiene than

vehicles with functioning catalysts (ARB, 1992).

Other sources of 1,3-butadiene include petroleum refining, styrene-butadiene

copolymer production, and biomass burning, including residential wood combustion,

agricultural burning, and managed forest fires. The largest use of 1,3-butadiene in the

United States is in the production of synthetic elastomers, which include: styrenebutadiene copolymer, acrylonitrile butadiene-styrene resin, polybutadiene, neoprene,

and nitrile rubber. Products commonly made from the styrene-butadiene copolymers

include tires, mechanical rubber goods, and latex. Latex is commonly used in foam

products, paints, carpet and textile backing, paper coatings, and adhesives. The

second major national use of 1,3-butadiene is in the production of adiponitrile, the raw

material used in nylon 6,6 production (ARB, 1992). The primary stationary sources that

have reported emissions of 1,3-butadiene are petroleum refining, manufacturing of

synthetics and man-made materials, and oil and gas extraction (ARB, 1997).

D. Polycyclic Aromatic Hydrocarbons

Polycyclic organic matter (POM) consists of over 100 compounds and is defined by the

Federal Clean Air Act as organic compounds with more than one benzene ring that

have a boiling point greater than or equal to 100o

 C.

POM can be divided into the subgroups of polycyclic aromatic hydrocarbons (PAHs)

and PAH-derivatives. PAHs are organic compounds that include only carbon and

hydrogen with a fused ring structure containing at least two benzene (six-sided) rings. 

PAHs may also contain additional fused rings that are not six-sided. PAH-derivatives
III-7

also have at least two benzene rings and may contain additional fused rings that are not

six-sided rings. However, PAH-derivatives contain other elements in addition to carbon

and hydrogen (CAPCOA, 1993). 

In general, POM exists as a gas when its molecular weight is below 230 grams per

mole, and is a particle above this molecular weight. This means that compounds with

two rings (e.g., naphthalene) exist as a gas. Compounds with three to four rings 

(e.g., pyrene) exist either as a gas or particle depending on the temperature and

pressure. Compounds with five rings (e.g., dibenzo[a,h]anthracene, benzo[a]pyrene)

exist as particles in the atmosphere (ARB, 1997).

PAHs are primarily planar, nonpolar compounds that melt well above room temperature

(U.S. EPA, 1987). Generally, PAHs exist as colorless, white, or pale yellow-green

solids that are attached to particulate matter. PAHs may also exist as solids in soil or

sediment. Benzo[a]pyrene is a PAH and is soluble in benzene, toluene, and xylene, but

practically insoluble in water (ARB 1997). PAH-derivatives include nitro-PAHs, aminoPAHs, and oxygenated PAHs (phenols, quinones, and heterocyclic aromatic

compounds containing sulfur and oxygen (Finlayson-Pitts and Pitts, Jr., 1986).

POM is produced by the incomplete combustion of fossil fuels and vegetable matter. 

PAHs have been detected in motor vehicle exhaust, smoke from residential wood

combustion, and fly ash from coal-fired electric generating plants (Finlayson-Pitts and

Pitts, Jr., 1986). The primary stationary sources that have reported emissions of

benzo[a]pyrene in California are petroleum refineries, industrial machinery

manufacturers, and the wholesale trade in petroleum and petroleum products. The

primary stationary sources that have reported emissions of PAHs in California are

paper mills, manufacturers of miscellaneous wood products, and petroleum refining

(ARB, 1997).
III-8

E. Polychlorinated Biphenyls

There are 209 possible polychlorinated biphenyl (PCBs) isomers. PCBs vary in

appearance from mobile, oily liquids to white, crystalline solids to hard, non-crystalline

resins. They are thermally stable, resistant to oxidation, acids, bases, and other

chemical agents, and have excellent dielectric properties. PCBs are colorless crystals

in the pure form. The melting point is depressed when PCBs are mixed. PCBs are

practically insoluble in water, and soluble in oils and organic solvents. When heated to

decomposition, they emit toxic fumes of hydrochloric acid and other chlorinated

compounds (NTP, 1991).

Since 1974, all uses of PCBs in the United States have been confined to closed

systems such as electrical capacitors, electrical transformers, vacuum pumps, and gastransmission turbines. PCBs are no longer produced in the United States except for

limited research and development applications (NTP, 1991). Sources of PCBs are

landfills containing PCB waste materials and products, destruction of manufactured

articles containing PCBs in municipal and industrial waste disposal burners, and

gradual wear and weathering of PCB-containing products (ARB, 1997).

Other sources in California that have reported emissions of PCBs are adhesives and

sealants, fabricated rubber products, commercial prints and lithographs, and ground or

treated mineral facilities, electric services, and refuse systems. The primary stationary

sources that have reported emissions of PCBs in California are crude oil pipelines,

wholesale trade in miscellaneous durable goods, and hydraulic cement manufacturers

(ARB, 1997).
IV-1

IV. SUMMARY OF RESIDENTIAL WASTE BURNING PRACTICES AND

EMISSIONS

During the control measure development process, the practice of residential waste

burning, the use of burn barrels, and associated toxic air emissions were examined for

California. This chapter presents these findings, based on information collected from

the literature, surveys of air districts, waste management agencies, fire protection

agencies, and ARB analysis. 

A. Residential Waste Burning Practices

The types of materials that can be burned based on current air district rules are shown in

Table IV-1. Table IV-1 also lists prohibitions on the use of burn barrels. Eight air

districts restrict the materials that can be burned to natural vegetation. These eight air

districts represent approximately 79% of the statewide population. Current rules in 27

air districts allow the burning of some form of household wastes other than natural

vegetation in all or part of the air district. Non-vegetative waste materials may include,

but are not limited to, household garbage, plastics, paper, cardboard, cloth, and treated

wood products. 

Roughly 2.2 million people (722,400 households), about 7% of California's population,

live in the portions of the 27 air districts that allow the burning of such wastes. The

remaining 14% of the population live in the portions of these 27 air districts where only

the burning of vegetation is allowed. Six of the 27 air districts allow the burning of all

materials, including household garbage, in all or part of the district. The remaining 21 air

districts prohibit the burning of household garbage, but may allow the burning of various

materials such as paper, cardboard, cloth, and wood products. However, further

restrictions on allowable materials may occur due to local ordinances within cities in

some of these air districts. These additional prohibitions could be imposed by city

ordinance, through local fire agency regulations, or through adoption of certain portions

of the Uniform Fire Code which address the use of incinerators and allowable materials.

 In addition, six of the 21 air districts prohibit the use of burn barrels in all or part of the

air district. These local restrictions would further reduce the number of households that

are allowed to burn certain materials.

Due to the potentially overlapping nature of air district rules, local ordinances, and fire

agency prohibitions, it is difficult to estimate the true number of households burning their

residential waste in California. Information on waste disposal practices is also limited in

some areas, and the relationship between availability of service and an individual

household's decision to burn any or all of its waste is not always clear cut. For example,

even though some households have regular waste pickup for their household garbage,

they may still be burning their paper and cardboard in order to reduce waste disposal

costs. Also, some households that do not have waste pickup service dispose of their

waste by means other than burning. However, based on discussions with air district

staff and waste management agencies, we have developed our best estimate of the

number of households that could be burning their non-vegetative waste in California. 
IV-2

Table IV-1. Air District Rules on Residential Burning

Air District Garbage Burned Materials

Allowed to be

Burned*

Burn Barrels

Allowed

Great Basin ENTIRE AIR

DISTRICT

G V P C Yes

Modoc County ENTIRE AIR

DISTRICT

G V P C Yes

Monterey Bay Unified PART OF AIR

DISTRICT

G V P C Yes

Kern County PART OF AIR

DISTRICT

G V P C Yes

Sacramento Metro PART OF AIR

DISTRICT

G V P C Yes

San Diego County PART OF AIR

DISTRICT

G V P C Yes

Calaveras County NO V P C Yes

Mariposa County NO V P C Yes

Northern Sierra NO V P C Yes

Lassen County NO V P C Yes

Siskiyou County NO V P C Yes

Colusa County NO V P C Yes

Feather River NO V P C Yes

Tehama County NO V P C Yes

Imperial County NO V P C Yes

Lake County NO V P No

El Dorado County NO V P Yes

Amador County NO V P Yes

Tuolumne County NO V P Yes

North Coast Unified NO V P Yes

Mendocino County NO V P Yes

Northern Sonoma County NO V P Yes

Placer County NO V P Yes

San Luis Obispo County NO V P Portions Only

Butte County NO V P Yes

Glenn County NO V P Yes

Shasta County NO V P Yes

Bay Area NO V Yes

Antelope Valley NO V No

Mojave Desert NO V No

San Joaquin Valley NO V No

Santa Barbara County NO V No

South Coast NO V Yes

Ventura County NO V Yes

Yolo-Solano NO V Yes

* Materials Burned: G = Household Solid Waste (Garbage/Rubbish) 

V = Any kind of Vegetation 

P = Paper and Cardboard 

C = Cloth
IV-3

Approximately 82,000 households are located in the portions of the six air districts that

have no prohibitions on the materials that can be burned. In these six air districts, we

collected information on the availability of waste service, the prevalence of self-hauling

practices, as well as air district estimates of likely burners. Based on this information,

we estimate that about 15,000 households may be burning their residential waste,

including household garbage. This is shown in the third column of Table IV-2. However,

as discussed above, even some of the households with waste pickup service, or those

that self-haul, may still be burning some of their waste materials, such as paper and

cardboard.

An additional 641,000 households are present in the remaining portions of the 21 air

districts where burning of other waste materials is allowed. Because these households

are already required to dispose of their household garbage through non-burning

alternatives, we assumed that all of these households must either have waste pickup

service, or are self-hauling. Therefore, the decision to burn is based more on the

additional cost to dispose of additional materials such as paper and cardboard, as well

as the practical ease of doing so, rather than alternative disposal methods. 

The estimate of the number of households actually burning residential waste in these 

21 air districts (in third column) is based upon estimates provided by the air districts,

CDF, and local jurisdictions. Each agency may have used different methods to develop

its estimate. Some air districts used information on waste service availability and

judgement based on compliance inspections. In other air districts, the estimated number

of households burning is based upon the number of permits issued for residential

burning by CDF and other local fire agencies. In some cases, this may represent an

underestimate because not all households obtain permits outside of the summer

controlled burn season, and because a number of different agencies issue permits,

making tracking difficult. However, based upon the information provided by these

agencies, we estimate approximately 93,000 households may be burning materials such

as cardboard and paper in these 21 air districts. 

In total, approximately 108,000 households may be actually burning some or all of their

residential waste in the 27 air districts. A breakdown by county of the number of

households allowed to burn under air districts rules, as well as our best estimate of the

number of households actually burning is provided in Table IV-2. The first six air districts

in the table are allowed to burn all forms of waste in all or part of the air district. The

remaining 21 air districts do not allow the burning of household garbage, but do allow the

burning of other residential waste materials. The first column in the table gives the total

population in each of the 27 air districts, including areas prohibited from burning. The

second column shows the number of households that are allowed to burn residential

waste. The third column shows the number of households estimated to be actually

burning residential waste. 

However, many air districts also experience varying degrees of illegal garbage burning. 

Illegal garbage burning represents a substantial percentage of air quality complaints

from the public for many air districts (ARB, 2001). Some air districts report that as many
IV-4

as 100 percent of burn barrels inspected have illegal materials in them. It is difficult for

air districts to observe and cite illegal burning because they cannot see the materials in

the burn barrels from a distance.
IV-5

Table IV-2. Estimate of Households Burning by Air District

Air District Total

Population in

Air District

(2000

census)

ARB

Estimate of

Number of

Households

Allowed to

Burn Waste

Local estimate of 

Number of

Households

Actually Burning

Waste Outdoors

Great Basin 32,006 10,700 2,000

Kern County (east) 120,000 6,000 250

Modoc County 9,449 3,200 3,000

Monterey Bay Unified 710,598 39,000 3,600

Sacramento Metro 1,223,499 7,600 5,000

San Diego County 2,813,833 15,300 1,500

Amador County 35,100 11,700 1,800

Butte County 203,171 67,700 1,300

Calaveras County 40,554 13,500 2,500

Colusa County 18,804 6,300 2,000

El Dorado County 156,299 52,100 5,000

Feather River 139,149 46,400 3,600

Glenn County 26,453 8,800 2,800

Imperial County 142,361 47,500 5,000

Lake County 58,309 19,400 250

Lassen County 33,828 11,300 2,500

Mariposa County 17,130 5,700 2,000

Mendocino County 86,265 28,800 13,000

North Coast Unified 167,047 55,700 23,600

Northern Sierra 116,412 38,800 4,000

Northern Sonoma County 65,400 21,800 500

Placer County 248,399 82,800 2,000

San Luis Obispo County 246,681 16,200 500

Shasta County 163,256 54,400 2,000

Siskiyou County 44,301 14,800 6,500

Tehama County 56,039 18,700 6,000

Tuolumne County 54,501 18,200 6,000

TOTAL 7,028,844 722,400 108,200

B. Amount of Residential Waste Generated in California

On average, the typical household in California is comprised of approximately three

people and generates between 3 and 11 pounds of garbage per day. The range takes

into account factors such as the number of residents living in a household, physical

household size, family income, location within the State, recycling characteristics, and
IV-6

time of year. The best estimate of residential waste generation is 5.9 pounds per day

per household, based on the average waste disposal rates for each California county

and assuming three people per household. This amounts to 41 pounds per household

per week, and 2,137 pounds (970 kg) per household per year (CIWMB, 2000). Typical

California residential waste constituents and estimates of their relative proportions are

listed in Table IV-3 below. New York residential waste composition, the basis of the

U.S. EPA tests described below, is also shown for comparison.

Table IV-3. Typical California Residential Waste Constituents

Material Type California

Percentage*

New York

Percentage

Paper 44% 63%

Glass 7% 9%

Metals 8% 9%

Plastics 14% 12%

Food Waste 11% 7%

Other Materials (Wood, textiles, paint, etc.) 16% 0%

* Adjusted for removal of leaves, grass, and other organic materials

C. Emission Estimates for Residential Waste Burning

In order to assess the magnitude of emissions from residential waste burning, the

U.S. EPA conducted a number of tests to characterize the emissions of dioxins and

other TACs generated during the burning of household waste in burn barrels (EPA,

1997a). In an initial series of tests, four test burns were conducted to simulate the

typical waste generated by a recycling and non-recycling household. The waste

materials burned represented the typical percentages of materials disposed of by

residents in New York State. Waste materials included paper, plastics, food waste,

textiles, glass and ceramics, and metal and aluminum cans. A comparison of the

percentages of waste materials in the New York tests to California waste materials is

provided in Table IV-3. The California and New York waste compositions compare well,

with slightly more paper in the New York waste, and more plastics and other materials

such as wood and paint in the California mix. The materials were burned in a standard

55 gallon metal drum (sandblasted free of paint), with a series of air holes punched

near the bottom for ventilation. The tests took place in a burn hut that included

instrumentation to measure temperature and emissions.

These initial results showed significant emissions of dioxins and other TACs. However,

there was also significant variability in the dioxin emissions between tests. Therefore,

eighteen further tests were conducted to examine the factors influencing the emissions

of dioxins from residential waste burning in burn barrels (Lemieux, 2000). These further
IV-7

test results indicated that dioxin emissions from burn barrels were likely dependent

upon variations in the distribution of the waste materials which were actually burning at

a given time within the burn barrel, even when an identical waste mix was burned each

time. However, dioxin emissions were significant, across the range of measured

values.

We used these test results to estimate the yearly emissions of dioxins and other TACs

from residential garbage burning for a single household using a burn barrel. The

emission factors developed by U.S. EPA were combined with residential waste

generation rates and waste composition described above. Due to the variability in

emission rates, composite emission factors for dioxins were developed representing

each set of tests. The emission factors for the other pollutants are based on the

original tests. The residential waste combustion rate was 10.4 pounds per hour, and

the burn duration was 78 minutes, in accordance with the U.S. EPA test protocol.

The emission factors, and calculated emissions are provided in Table IV-4 for both

series of tests. The emission factors are reported in terms of milligrams of pollutant per

kilogram of trash burned, as well as grams per second, while emissions are reported in

terms of grams per household per year. The emissions represent total mass. In the

case of dioxins, the individual isomers of dioxins and furans were measured and

summed to the total. 

Table IV-4. Toxic and PM10 Emissions from Residential Waste Burning

Pollutant

Average

Emissions

Factor

(mg/kg burned)

Average

Emissions

(grams/second)

Average

Emissions

(grams/

household/year)

Dioxins

(Series 1 1997 Testing) 0.16 2.06E-07 0.15

Dioxins

(Series 2 2000 Testing) 0.005 6.10E-09 0.005

1,3-Butadiene 141.2 1.85E-05 137.0

Benzene 979.7 1.28E-03 950.0

PAHs 45.0 5.89E-05 43.5

PCBs 0.13 1.65E-07 0.12

PM10 1.23E+04 1.60E-02 1.12E+04
IV-8

As shown in the table, the average household burning residential waste could generate

between 0.005 and 0.15 grams of dioxins per year. These emissions are based on a

household that burned a complete mix of waste materials and likely represents the high

end of expected emissions. While these numbers appear small, it is important to

recognize that even small amounts of TACs can be hazardous to health. In addition,

there is no threshold below which exposure to dioxins has been deemed safe. In

addition, unlike medical and municipal waste incinerators, the temperatures at which

residential burning takes place (typically between 50o

 C and 600O C) do not achieve the

temperatures needed to minimize or eliminate the production of dioxins. 
V-1

V. POTENTIAL HEALTH IMPACTS OF DIOXINS AND OTHER TOXIC AIR

CONTAMINANTS FROM RESIDENTIAL WASTE BURNING

A. An Overview of Health Risk Assessment

A health risk assessment (HRA) is an evaluation or report that describes the potential a

person or population may have of developing adverse health effects from exposure to

an emission source. Some health effects that are evaluated could include cancer,

developmental effects, or respiratory illness. The exposure pathways that can be

included in an HRA depend on the toxic air pollutants that a person (receptor) may be

exposed to, and can include breathing, the ingestion of soil, water, crops, fish, meat,

cow’s milk, and eggs, and dermal exposure. The consumption of mother’s milk can be

evaluated for an infant receptor. When multiple exposure pathways are considered in

an HRA, the evaluation is called a multi-pathway assessment. 

For this HRA, we evaluated the potential multi-pathway health impacts for

polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (collectively

referred to as dioxins), benzene, 1,3-butadiene, PAHs, and PCBs. Multi-pathway

assessments are traditionally conducted when lipophilic (fat-loving), semi-volatile, or low

volatility compounds such as dioxins, PAHs, and PCBs are emitted.

To develop this HRA, we followed a four-step process. The four steps are Hazard

Identification, Dose-Response Assessment, Exposure Assessment, and Risk

Characterization.

1. Hazard Identification

In the first step, we identified the pollutant(s) of concern and the type of effect, such as

cancer or respiratory effects.

For this assessment, the pollutants of concern have been formally identified under the

AB 1807 Program as TACs. The ARB formally identified dioxins, benzene,

1,3-butadiene, PAHs, and PCBs as TACs under California’s Toxic Air Contaminant

Identification and Control Program (ARB, 1986; ARB, 1984; ARB, 1992; ARB, 1993a). 

This identification was done through an open public process as specified under Health

and Safety Code sections 39650 through 39662. In addition, dioxins, benzene, 

1,3-butadiene, PAHs, and PCBs are listed as hazardous air pollutants under the

Federal Clean Air Act (42 U.S.C. 7412).

The HRA was limited to these five substances (or groups of substances) after we

performed a screening HRA on over 260 substances that were detected in 

U.S. EPA-sponsored source tests on the emissions from residential waste burning 

(U.S. EPA, 1997a). Of these 260 substances or groups of substances, the 

Air Resources Board lists approximately fifty percent as TACs. We refined this HRA to

focus on these five substances or groups of substances because they were the main

risk drivers in a screening HRA performed by the ARB. These five substances or
V-2

groups constituted approximately seventy-three percent of the potential cancer risk

through breathing and approximately ninety-nine percent of the potential cancer risk

through ingestion routes (e.g., crop exposure). Other substances that were measured

that have also been identified as TACs included cadmium, chromium, and mercury.

2. Dose-Response Assessment

In this step of risk assessment, we characterized the relationship between a person’s

exposure to a pollutant and the incidence or occurrence of an adverse health effect.

OEHHA performs this step of the HRA for the ARB. OEHHA supplies these doseresponse relationships in the form of cancer potency factors or unit risk factors (URFs)

for carcinogenic effects and reference exposure levels (RELs) for non-carcinogenic

effects. The URFs and RELs that are used in California for the substances evaluated in

this HRA can be found in the following references:

(1) U.S. Environmental Protection Agency Integrated Risk Information System

(IRIS), 1996 (OEHHA, 1999c);

(2) The California Air Pollution Control Officer’s Association Air Toxics “Hot

Spots” Program, Revised 1992, Risk Assessment Guidelines, October 1993;

(3) The Office of Environmental Health and Hazard Assessment Air Toxics “Hot

Spots” Program Risk Assessment Guidelines, Part I, The Determination of

Acute RELs for Airborne Toxicants, March 1999;

(4) The Office of Environmental Health and Hazard Assessment Air Toxics “Hot

Spots” Program Risk Assessment Guidelines, Part II, Technical Support

Document for Describing Available Cancer Potency Factors, April 1999;

(5) The Office of Environmental Health and Hazard Assessment Air Toxics “Hot

Spots” Program Risk Assessment Guidelines, Part III, Technical Support

Document for the Determination of Noncancer Chronic Reference Exposure

Levels, April 2000; and

(6) The Office of Environmental Health and Hazard Assessment Air Toxics “Hot

Spots” Program Risk Assessment Guidelines, Part IV, Technical Support

Document for Exposure Assessment and Stochastic Analysis, September

2000.

3. Exposure Assessment

In this step of the risk assessment, we estimated the extent of public exposure by

looking at who is likely to be exposed, how exposure will occur (e.g., inhalation and

ingestion), and the magnitude of exposure.

Residential waste burning activities emit substances that can impact receptors

(residents) both in the near field and on a larger, regional scale. Avoiding the plume of
V-3

smoke is not necessarily sufficient to eliminate the potential health impacts. Waste

burning activities can still impact people who do not burn. Substances that are emitted

through incineration can travel long distances, depositing onto crops, soil, and water. 

Residents can be exposed to these substances when breathing or they can ingest the

substances in their diet or daily activities. Ingestion pathways can include soil ingestion,

breast milk ingestion, ingestion of crops, meat (e.g., chicken and cows), and cow’s milk.

Meat and milk products can be impacted because animals ingest the pollutants and

then these substances can be passed to people when animal products are ingested.

For this HRA, the receptors are assumed to be residents living near a single waste

burning emissions point (burn barrel). We used a multipathway assessment that

considers potential exposures through breathing, dermal absorption, and the ingestion

of soil, backyard garden crops, meat, eggs, cows milk, and breast milk.

For this HRA, we used emissions from the U.S. EPA source tests which were

conducted in 1997 and 2000 (U.S. EPA, 1997a; Lemieux, 2000). Emissions from the

2000 source tests were used for dioxins and PCBs because, according to U.S. EPA,

these emissions are more representative than the 1997 emissions. The emissions from

the 1997 source tests were used for benzene, 1,3-butadiene, and PAHs because these

compounds were not quantified in the 2000 tests. Note however, that the 1997 tests

showed higher dioxin and PCB emissions when compared to the 2000 tests. 

Computer air dispersion modeling was used to provide downwind ground-level

concentrations of the TACs at near-source locations (20 to 1,000 meters). The

dispersion modeling used both default meteorological conditions from SCREEN3 and

site-specific meteorological data from four locations across California (Alturas, Bishop,

San Benito, and Escondido). These locations were selected to represent a range of

meteorological conditions throughout the State where the burning of residential waste is

allowed.

4. Risk Characterization

This is the final step of risk assessment. In this step, we combined information derived

from the previous steps. Modeled concentrations, which are determined through

exposure assessment, are combined with the URFs (for cancer risk) and RELs (for noncancer effects) determined under the dose-response assessment. This step integrates

this information to quantify the potential cancer risk and non-cancer health impacts. 

B. The Tools Used For This Risk Assessment

The tools and information that are used to estimate the potential health impacts from a

source include an air dispersion model and pollutant-specific health risk values. 

Combining the output from the source tests, air dispersion model, and the

pollutant-specific health risk values provides an estimate of the potential cancer and

non-cancer health impacts from the emissions of a toxic air contaminant. A description
V-4

of the air dispersion modeling and pollutant-specific health effect values is provided

below.

1. Air Dispersion Modeling

Air dispersion models are used to estimate the downwind, ground-level concentrations

of a pollutant after it is emitted from a source. The downwind concentration is a

function of the quantity of emissions, release parameters at the source, and appropriate

meteorological conditions. We used the ISCST3 model for this assessment. The 

U.S. EPA recommends the ISCST3 model for refined air dispersion modeling 

(U.S. EPA, 1995a,b). This model is currently used by the ARB, air districts, and other

states. The dispersion modeling used both default meteorological conditions from

SCREEN3 and site-specific meteorological data from four locations across California

(Alturas, Bishop, San Benito, and Escondido). A detailed discussion of the air

dispersion modeling is presented in Appendix C. 

2. Pollutant-Specific Health Effects Values

Dose-response or pollutant-specific health effects values are developed to characterize

the relationship between a person's exposure to a pollutant and the incidence or

occurrence of an adverse health effect. A unit risk factor (URF), also known as a

cancer potency factor, with units of (micrograms per cubic meter)-1 or (μg/m3

)

-1, is used

when estimating potential cancer risks. A URF is defined as the estimated

upper-confidence limit (usually 95%) probability of a person contracting cancer as a

result of constant exposure to a concentration of one μg/m3

 of a pollutant over a

70-year lifetime.

Reference exposure levels (RELs) are used as an indicator to assess potential noncancer health impacts. A REL is defined as a concentration level at or below which no

adverse health effects are anticipated. RELs are designed to protect most of the

sensitive individuals in the population by including safety factors in their development

and can be created for both acute and chronic exposures. An acute exposure is

defined as one or a series of short-term exposures generally lasting less than 24 hours.

Chronic exposure is defined as repeated exposure usually lasting from one year to a

lifetime.

Exposure to dioxins, benzene, 1,3-butadiene, PAHs, and PCBs may result in both

cancer and non-cancer health effects. Table V-I presents the current health effects

values that were used in the HRA and the toxicological endpoints (organs or body

systems) that these substances may affect.
V-5

Table V-1. Pollutant-Specific Health Effects Values Used

For Determining Potential Health Impacts

Cancer Unit Risk Factors Non-Cancer Reference Exposure Levels Non-Cancer Toxicological

Endpoints

Compound

Inhalation1

(ug/m3)

-1

Oral 1,2

(mg/kg-d)-1

Acute 3

(inhalation)

(ug/m3

)

Chronic 4

(Inhalation)

(ug/m3

)

Chronic 2,4

(Oral)

(mg/kg/d)

Acute 3 Chronic 4

Benzene 2.9E-05 1.3E+03 6.0E+01

Developmental

Hematologic,

Immune,

Reproductive

Developmental

hematologic;

nervous

1,3-Butadiene 5 1.7E-04 2.0E+01 Reproductive

Polychlorinated Dibenzo-p-dioxins 6

2,3,7,8-TCDD 3.8E+01 1.3E+05 4.0E-05 1.0E-08

1,2,3,7,8-PeCDD 1.9E+01 6.5E+04 8.0E-05 2.0E-08

1,2,3,4,7,8-HxCDD 3.8E+00 1.3E+04 4.0E-04 1.0E-07

1,2,3,6,7,8-HxCDD 3.8E+00 1.3E+04 4.0E-04 1.0E-07

1,2,3,7,8,9-HxCDD 3.8E+00 1.3E+04 4.0E-04 1.0E-07

1,2,3,4,6,7,8-HpCDD 3.8E-01 1.3E+03 4.0E-03 1.0E-06

1,2,3,4,6,7,8,9-OCDD 3.8E-02 1.3E+02 4.0E-02 1.0E-05

Polychlorinated Dibenzofurans 7

2,3,7,8-TCDF 3.8E+00 1.3E+04 4.0E-04 1.0E-07

1,2,3,7,8-PeCDF 1.9E+00 6.5E+03 8.0E-04 2.0E-07

2,3,4,7,8-PeCDF 1.9E+01 6.5E+04 8.0E-05 2.0E-08

1,2,3,4,7,8-HxCDF 3.8E+00 1.3E+04 4.0E-04 1.0E-07

1,2,3,6,7,8-HxCDF 3.8E+00 1.3E+04 4.0E-04 1.0E-07

1,2,3,7,8,9-HxCDF 3.8E+00 1.3E+04 4.0E-04 1.0E-07

2,3,4,6,7,8-HxCDF 3.8E+00 1.3E+04 4.0E-04 1.0E-07

1,2,3,4,6,7,8-HpCDF 3.8E-01 1.3E+03 4.0E-03 1.0E-06

1,2,3,4,7,8,9-HpCDF 3.8E-01 1.3E+03 4.0E-03 1.0E-06

1,2,3,4,6,7,8,9-OCDF 3.8E-02 1.3E+02 4.0E-02 1.0E-05

Alimentary;

developmental;

endocrine;

hematologic;

reproductive;

respiratory
V-6

Table V-1 (continued). Pollutant-Specific Health Effects Values Used

For Determining Potential Health Impacts

Cancer Unit Risk Factors Non-Cancer Reference Exposure Levels Non-Cancer Toxicological

Endpoints

Compound Inhalation1

(ug/m3)

-1

Oral 1,2

(mg/kg-d)-1

Acute 3

(inhalation)

(ug/m3

)

Chronic 4

(Inhalation)

(ug/m3

)

Chronic 2,4

(Oral)

(mg/kg/d)

Acute 3 Chronic 4

Polycyclic Aromatic Hydrocarbons 8

Benzo[a]pyrene 1.1E-03 1.2E+01

Benz[a]anthracene 1.1E-04 1.2E+00

Benzo[b]fluoranthene 1.1E-04 1.2E+00

Benzo[k]floranthene 1.1E-04 1.2E+00

Chrysene 1.1E-05 1.2E-01

Dibenz[a,h]anthracene 1.2E-03 4.1E+00

Indeno[1,2,3-c,d]pyrene 1.1E-04 1.2E+00

Naphthalene 9.0E+00 Respiratory

Polychlorinated Biphenyls 5.7E-04 2.0E+00 1.2E+00 9 2.5E-05 10

Alimentary,

developmental,

immune,

reproductive

1. Office of Environmental Health Hazard Assessment, Air Toxics “Hot Spots” Program Risk Assessment Guidelines, Part II,

Technical Support Document for Describing Available Cancer Potency Factors, April 1999.

2. Office of Environmental Health Hazard Assessment, Air Toxics “Hot Spots” Program Risk Assessment Guidelines, Part IV,

Technical Support Document for Exposure Assessment and Stochastic Analysis, September 2000.

3. Office of Environmental Health Hazard Assessment, Air Toxics “Hot Spots” Program Risk Assessment Guidelines, Part I, The

Determination of Acute Reference Exposure Levels for Airborne Toxicants. Benzene has an REL based on a 6-hour averaging

period. 

4. Office of Environmental Health Hazard Assessment, Air Toxics “Hot Spots” Program Risk Assessment Guidelines, Part III,

Technical Support Document for the Determination of Noncancer Chronic Reference Exposure Levels, April 2000.

5. Office of Environmental Health Hazard Assessment, Adoption of Chronic Reference Exposure Levels For Airborne Toxicants,

Memorandum, January 2001.

6. Polychlorinated dibenzo-p-dioxin is listed here as a group heading. Individual congeners are listed below this heading with their

respective health factors. 

7. Polychlorinated dibenzofuran is listed here as a group heading. Individual congeners are listed below this heading with their

respective health factors. 

8. Polycyclic aromatic hydrocarbons (PAHs) are listed here as a group heading. Individual PAHs (and naphthalene) used in the

HRA are listed below this heading with their respective health factors. 

9. California Air Pollution Control Officer’s Association, Air Toxics Hot Spots Program, Revised 1992 Risk Assessment Guidelines,

October 1993.

10. United States Environmental Protection Agency, Integrated Risk Information System, 1996 (OEHHA, 1999c).
V-7

C. Potential Health Effects of Dioxins, Benzene, 1,3-Butadiene, PAHs, and

PCBs

This section summarizes the cancer and non-cancer impacts that can result from

exposure to dioxins, benzene, 1,3-butadiene, PAHs, and PCBs. The information

comes from ARB’s 1997 reference report, Toxic Air Contaminant Identification List –

Summaries unless otherwise noted (ARB, 1997). 

1. Dioxins

Exposure to dioxins may result in both cancer and non-cancer health effects. The

probable route of human exposure to dioxins is inhalation, ingestion, and dermal

absorption (ARB 1986). In addition, dioxins can be passed down to children through

mother’s milk. Once dioxin enters the human body, a small amount is metabolized and

eliminated, while the rest bioaccumulates in body fat. As fat is metabolized, stored

dioxins is released and excreted primarily in feces. The body's concentration is

dependent on the rates of ingestion, elimination, and storage capacity of dioxins. The

approximate half-life of dioxins in humans was estimated to range from 6 to 10 years

(ARB, 1997).

a. Cancer

The OEHHA staff has performed an extensive assessment of the potential health

effects of dioxins, reviewing available carcinogenicity data. OEHHA concluded that

dioxins are a potential human carcinogen with no identifiable threshold below which no

carcinogenic effects are likely to occur. The Board formally identified dibenzo-p-dioxins

and dibenzofurans (chlorinated in the 2,3,7 and 8 positions and containing 4,5,6, or

7 chlorine atoms) as a TAC in July 1986 (ARB, 1986). The State of California under

Proposition 65 listed polychlorinated dibenzo-p-dioxins and polychlorinated

dibenzofurans, and 2,3,7,8-Tetrachlorodibenzo-p-dioxin as carcinogens in April 1988

and January 1988, respectively (OEHHA, 2001b). 

In 1990, the U.S. EPA listed 2,3,7,8-Tetrachlorodibenzo-p-dioxin as a Hazardous Air

Pollutant (HAP) pursuant to subsection (b) of Section 112 of the Federal Clean Air Act

(42. U.S.C. 7412). The U.S. EPA is preparing a final Dioxin and Related Compounds

risk assessment document. The International Agency for Research on Cancer (IARC)

classified 2,3,7,8-tetrachlorodibenzo-p-dioxin as Group 1: Human carcinogen, based on

sufficient evidence in humans (ARB, 1997).

Human studies that have reported cancer increases are inconclusive because of

inadequate data. There is adequate evidence to support a conclusion that

2,3,7,8-Tetrachlorodibenzo-p-dioxin is carcinogenic in rodents and should be

considered a potential carcinogen to humans. Ingestion studies in rodents have shown

increases in tumors of the liver, lung, squamous cell, nasal turbinates, and hard palate

(ARB, 1997).
V-8

b. Non-cancer

Short-term (acute) and long-term (chronic) exposure to dioxins may also result in

non-cancer health effects. Acute exposure of humans to dioxins has caused chloracne,

liver toxicity, skin rashes, nausea, vomiting, and muscular aches and pains. A severe

weight loss in animals has been observed following acute exposure to dioxin as have

hyperkeratosis, facial alopecia, inflammation of the eyelids, and loss of fingernails and

eyelashes. The immune system appears to be very sensitive to dioxin toxicity. Thymic

atrophy is a prominent finding in exposed animals and has been observed in all

laboratory species examined. Other lymphoid tissues such as the spleen, lymph nodes,

and bone marrow are also affected. Symptoms of chronic exposure to dioxins include

splenic and testicular atrophy, elevated gamma-glutamyl transpeptidase levels,

elevated cholesterol levels, and abnormal neurological findings. Other effects may

include risk of enzyme induction, diabetes, and endocrine changes (ARB, 1997).

Human studies on the adverse reproductive and developmental effects of dioxins have

proven inconclusive. Animal studies have shown 2,3,7,8-Tetrachlorodibenzo-p-dioxin

to be both teratogenic and fetotoxic. Reproductive and teratogenic effects observed in

animals are cleft palate, kidney abnormalities, decreased fetal weight, and survival,

hydrocephalus, open eye, edema, resorptions, petechiae, and infertility (ARB, 1997). 

The State of California under Proposition 65 listed 2,3,7,8-Tetrachlorodibenzo-p-dioxin

as a chemical known to the State to cause developmental toxicity in April 1991 

(OEHHA, 2001b).

2. Benzene

Exposure to benzene may result in both cancer and non-cancer health effects. The

probable routes of human exposure to benzene are inhalation and ingestion of drinking

water (ARB, 1997).

a. Cancer

The OEHHA staff has performed an extensive assessment of the potential health

effects of benzene, reviewing available carcinogenicity data. The OEHHA staff agrees

with U.S. EPA and IARC that benzene is a human carcinogen with no identifiable

threshold below which no carcinogenic effects are likely to occur. The Board formally

identified benzene as a TAC in January 1985 (ARB, 1984). The State of California

under Proposition 65 listed benzene as a carcinogen in February 1987 (OEHHA

2001b). 

In 1990, the U.S. EPA listed benzene as a HAP pursuant to subsection (b) of Section

112 of the Federal Clean Air Act (42. U.S.C. 7412). The U.S. EPA has classified

benzene in Group A: Human carcinogen based on sufficient epidemiological evidence.

The IARC classified benzene in Group 1: Human carcinogen based on sufficient

evidence in humans (ARB, 1997). Increased incidences of leukemias, especially acute

myelogenous leukemia and its variants including erythroleukemia and myelomonocytic
V-9

leukemia, have been observed in humans occupationally exposed to benzene. A

retrospective mortality study in China in 1989 has provided supporting evidence that

benzene exposure is associated with cancers in humans. Animal cancer bioassays

show benzene causes leukemia and a variety of other cancers including cancers of the

lymphoid system, skin, ovary, oral cavity, lip, tongue, lung, mammary gland, and two

secretory organs unique to rodents, the Zymbal and preputial glands (ARB, 1997).

b. Non-cancer

Short-term (acute) and long-term (chronic) exposure to benzene may result in noncancer health effects. Brief inhalation exposure to high concentrations of benzene can

cause central nervous system depression. Acute effects include central nervous

system symptoms of nausea, tremors, drowsiness, dizziness, headache, intoxication,

and unconsciousness. Benzene vapors are mildly irritating to the eyes and respiratory

tract. Benzene can sensitize the myocardium to the arrythmogenic effects of

epinephrine. Chronic human inhalation exposure can cause hematopoietic system

decreases in erythrocytes, leukocytes, or platelets with progression to leukopenia,

thrombocytopenia, pancytopenia, and/or aplastic anemia. Occupational exposures to

low concentrations have been observed to have an initial stimulant effect on the bone

marrow, followed by aplasia and fatty degeneration. Workers chronically exposed to

benzene have shown alterations in serum levels of immunoglobulins (ARB, 1997).

Results from several studies conducted in rats and mice have indicated depressed

cellular proliferation in the bone marrow from short-term exposures to benzene. In

humans, there have been reports of menstrual disorders and possibly reduced fertility

associated with benzene exposure, but these reports are limited by factors such as

simultaneous exposure to several chemicals, or poor or no controls. In mice and rats,

following inhalation of benzene during pregnancy, reduced fetal weight and other

indications of growth retardation have been observed. Exposure of pregnant mice

resulted in alterations of hematopoiesis in the fetus or offspring, but no effects on red or

white blood cell count or hemoglobin analysis. The significance of the hematopoietic

alterations is unclear (ARB, 1997). The State of California under Proposition 65 listed

benzene as a chemical known to the State to cause developmental toxicity and male

toxicity in December 1997 (OEHHA, 2001b).

3. 1,3-Butadiene

Exposure to 1,3-butadiene may result in both cancer and non-cancer health effects. 

The probable route of human exposure to 1,3-butadiene is through inhalation 

(ARB, 1997).

a. Cancer

The OEHHA staff has performed an extensive assessment of the potential health

effects of 1,3-butadiene, reviewing available carcinogenicity data. The OEHHA staff

agrees with U.S. EPA and IARC that 1,3-butadiene is a probable human carcinogen
V-10

with no identifiable threshold below which no carcinogenic effects are likely to occur. 

The Board formally identified 1,3-butadiene as a TAC in July 1992 (ARB, 1992). The

State of California under Proposition 65 listed 1,3-butatiene as a carcinogen in

April 1988 (OEHHA, 2001b). 

In 1990, the U.S. EPA listed 1,3-butadiene as a HAP pursuant to subsection (b) of

Section 112 of the Federal Clean Air Act (42. U.S.C. 7412). The U.S. EPA has

classified 1,3-butadiene in Group B2: Probable human carcinogen. The International

Agency for Research on Cancer has classified 1,3-butadiene in Group 2A: Probable

human carcinogen based on limited evidence in humans and sufficient evidence in

animals. The United States Occupational Safety and Health Administration has

proposed that exposure to 1,3-butadiene is associated with an increased risk of death

from cancer of the lymphohematopoietic system, and has classified 1,3-butadiene as a

potential occupational carcinogen (ARB, 1997).

Epidemiological studies of production workers exposed to 1,3-butadiene provide limited

evidence of an increased risk of death from hematologic neoplasms, especially

leukemia and other lymphomas. Studies of mice exposed to concentrations of

1,3-butadiene indicate that 1,3-butadiene is taken up rapidly by the body and distributed

with metabolites to all tissues. This distribution can result in cancer in multiple sites,

including the heart, lung, mammary gland, ovaries, forestomach, liver, pancreas,

thyroid, testes, and hematopoietic system. Exposure to 1,3-butadiene at higher

concentrations is associated with tumors in the rat. It is important to note that

1,3-butadiene is 1 of only 2 chemicals (the other being the fungicide Captafol) known to

induce cancer in the heart of laboratory animals (ARB, 1997).

b. Non-cancer

Short-term (acute) and long-term (chronic) exposure to 1,3-butadiene may result in noncancer health effects. 1,3-butadiene vapors are mildly irritating to the eyes and mucous

membranes and cause neurological effects such as blurred vision, fatigue, headache,

and vertigo at very high levels. Epidemiological studies of workers in the rubber

industry have shown an increase in cardiovascular diseases such as rheumatic and

arteriosclerotic heart diseases and blood effects. Animal studies have shown

respiratory effects, blood effects and hyperplastic changes to the heart from prolonged

inhalation exposure to 1,3-butadiene.

No information is available on adverse reproductive or developmental effects of

exposure to 1,3-butadiene in humans. There is evidence of reproductive toxicity in

animal studies. Female mice exhibited ovarian atrophy from exposure to 1,3-butadiene

at 6.25 parts per million. In developmental toxicity studies, 1,3-butadiene has been

shown to be fetotoxic in the absence of producing maternal toxicity. At 40 parts per

million in mice, 1,3-butadiene resulted in reduced fetal weight of males, and at

200 parts per million, reduced ossification was reported in fetuses (ARB, 1997).
V-11

4. Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) is within the group of chemicals known as

particulate polycyclic organic matter (POM). POM was identified by the Board as a TAC

in April 1993 when it formally adopted the federal HAPs as TACs as required by

AB 2728 legislation (ARB, 1993a). Benzo[a]pyrene is in the PAH class of compounds. 

In April 1994, an exposure and health assessment for benzo[a]pyrene was prepared by

ARB and OEHHA and reviewed by the ARB’s Scientific Review Panel on TACs

(ARB, 1994).

Exposure to polycyclic aromatic hydrocarbons (PAHs) may result in cancer health

effects. The probable routes of human exposure to PAHs occurs through inhalation,

ingestion and dermal contact (ARB, 1997).

a. Cancer

The OEHHA staff has performed an extensive assessment of the potential health

effects of benzo[a]pyrene, reviewing available carcinogenicity data. The OEHHA staff

agrees with U.S. EPA and IARC that benzo[a]pyrene is a probable human carcinogen

with no identifiable threshold below which no carcinogenic effects are likely to occur

(ARB, 1994). The State of California under Proposition 65 listed 25 PAH compounds

(including benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene,

benzo[k]fluoranthene, chrysene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene) as

carcinogens between the years 1987 and 1990 (OEHHA, 2001b).

In 1990, the U.S. EPA listed POM as a HAP pursuant to subsection (b) of Section 112

of the Federal Clean Air Act (42. U.S.C. 7412). The U.S. EPA has classified

benzo[a]pyrene in Group B2: Probable human carcinogen. The International Agency

for Research on Cancer (IARC) has classified benzo[a]pyrene in Group 2A: Probable

human carcinogen based on sufficient evidence in animals and limited evidence in

humans. 

Results from epidemiologic studies have indicated an increase in lung cancer occurs in

humans exposed to coke oven emissions, roofing tar emissions, and cigarette smoke. 

Each of these mixtures contains a number of PAHs. Respiratory tract tumors have

been reported in animals exposed via inhalation to benzo[a]pyrene and forestomach

tumors, leukemia, esophageal and laryngeal tumors from oral exposure (ARB, 1997).

b. Non-cancer

No information is available on the acute effects of POM in humans. Enzyme alterations

in the mucosa of the gastrointestinal tract and increased liver weights have been

reported in animals exposed orally to several PAHs. Chronic exposure to

benzo[a]pyrene in humans has resulted in dermatitis, photosensitization in sunlight, eye

irritation and cataracts. Animal studies have reported effects on the blood and liver
V-12

from oral exposure to benzo[a]pyrene and effects on the immune system from dermal

exposure to benzo[a]pyrene (ARB, 1997)

No information is available on adverse reproductive or developmental effects of POM in

humans. Oral exposure to benzo[a]pyrene in animals has been reported to result in

adverse reproductive effects, including reduced incidence of pregnancy and decreased

fertility, and developmental effects such as reduced viability of litters and reduced mean

pup weight, and decreased fertility in offspring. Benzo[a]pyrene has been

demonstrated to cause transplacental carcinogenesis in animals (ARB, 1997).

5. Polychlorinated Biphenyls

Exposure to PCBs may result in both cancer and non-cancer health effects. The

probable routes of human exposure to PCBs occurs through inhalation, ingestion, and

dermal contact (ARB, 1997).

a. Cancer

The OEHHA staff has performed an extensive assessment of the potential health

effects of PCBs, reviewing available carcinogenicity data. The OEHHA staff agrees

with U.S. EPA and IARC that PCBs are a probable human carcinogen (OEHHA,

1999b). The Board identified polychlorinated biphenyls (PCBs) as a TAC in April 1993

when it formally adopted the federal HAPs as TACs as required by AB 2728 legislation

(ARB 1993a). The State of California under Proposition 65 listed polychlorinated

biphenyls and polychlorinated biphenyls (containing 60 or more percent chlorine by

molecular weight) as carcinogens in October 1989 and January 1988 respectively

(OEHHA, 2001b).

In 1990, the U.S. EPA listed PCBs as a HAP pursuant to subsection (b) of Section 112

of the Federal Clean Air Act (42. U.S.C. 7412). The U.S. EPA has classified PCBs as

Group B2: Probable human carcinogen. The IARC has classified PCBs as Group 2A:

Probable human carcinogen (ARB, 1997). 

Human studies were inconclusive but suggest an association between exposure to

PCBs and liver cancer. In studies in which rats and mice were orally exposed to some

PCB formulations, an increased incidence of liver tumors was observed (ARB, 1997).
V-13

b. Non-cancer

Short-term (acute) and long-term (chronic) exposure to PCBs may result in non-cancer

health effects. Exposure to PCBs may cause skin, eyes, nose, throat, and respiratory

tract irritation. Chronically overexposed workers may suffer from chloracne and mild

liver injury. Infrequently reported symptoms include anorexia, gastrointestinal upset,

and peripheral neuropathies. In animal studies, oral exposure to PCBs was reported to

cause possible liver, kidney, and central nervous system effects (ARB, 1997).

Mothers exposed to PCBs through fish consumption have given birth to infants with

adverse developmental effects including motor deficits, impaired psychomotor index,

impaired visual recognition memory, and deficits in short-term memory. Decreased

birth weights and lower gestational age at birth are reported among women

occupationally exposed to high levels of PCBs as compared to lower levels of PCBs. 

Animal studies have reported learning deficits, impaired immune function, cellular

alterations of the thyroid, and reproductive effects such as decreased fertility,

decreased conception, and disrupted ovarian cyclicity (ARB, 1997). The State of

California under Proposition 65 listed polychlorinated biphenyls as a chemical known to

the State to cause developmental toxicity in January 1991 (OEHHA, 2001b).

D. Summary of the Potential Health Impacts from Residential Waste Burning

This section presents the potential health impacts from the analysis that was performed

for residential waste burning. Potential health impacts are discussed both in terms of

individual risk, as well as community exposure.

1. Individual Health Impacts

Both carcinogenic and non-carcinogenic individual health risk impacts were estimated

at a variety of locations ranging from 20 to 1,000 meters downwind from a single burn

barrel. Depending upon property size, these distances could reflect impacts on both an

individual household, as well as neighboring households. 

Table V-2 provides an overview of the potential multipathway health impacts at

20 meters using both default meteorological conditions from SCREEN3 and sitespecific meteorological data from four locations across California (Alturas, Bishop, San

Benito, and Escondido). The purpose of presenting this data at a near-source location

of 20 meters is to illustrate what the potential health impacts may be if a resident is

located in close proximity to a burn barrel. ARB staff observed burn barrels well within

the 20 meter distance during tours provided by local air district personnel of residential

locations with burn barrels.

The table also provides estimates of potential cancer risk for each exposure pathway. 

Since an individual’s potential cancer risk will vary depending upon the routes they are

exposed to, the exposure pathways are presented separately to provide a feel for how

each pathway contributes to the total potential cancer risk. An individual's total
V-14

potential cancer risk can be determined by adding together the potential cancer risk for

each exposure route. The four basic pathways of inhalation, soil ingestion, skin

absorption, and mother’s (breast) milk are considered minimum pathways for this

assessment of residential waste burning (OEHHA, 2001c). However, the other

pathways (homegrown crops, meat, and cow’s milk) can be included or not, depending

upon individual lifestyles. For example, an individual who does not consume meat from

their own animals would not include the potential risk numbers from that exposure route

in their estimate of total potential cancer risk. If they have no homegrown crops, then

the crop pathway would not be included.

For more detailed information, tables B-1 to B-5 in Appendix B present the potential

multipathway health impacts at 20, 50, 100, 200, 500, and 1,000 meter distances for

each meteorological condition or site-specific meteorological data set.

Table V-2 shows a range of near-source potential multipathway cancer risk across all

meteorological conditions or data sets at approximately 6 to 2,300 chances per million. 

The lower end of this range includes the potential cancer risk from inhalation, soil

ingestion, dermal absorption, and breast milk pathways (OEHHA 2001c). The upper

end of the range estimates potential cancer risks across all included exposure

pathways (i.e., the four minimum pathways plus crop, meat, and milk ingestion). 

The highest non-cancer acute inhalation hazard index is 0.02. The highest non-cancer

chronic hazard index for the minimum the exposure pathways (inhalation, soil, dermal)

is 0.08 and the highest non-cancer chronic hazard index across all pathways is 2.0. 

Generally, hazard Indices less than 1.0 are not considered to be a concern to public

health. Hazard indices greater than 1.0 could be an indicator for potential non-cancer

health impacts. However for this assessment, hazard indices greater than 1.0 are only

present when all exposure pathways are included. As discussed above, if an

individual’s lifestyle does not include all exposure pathways then their potential health

risk would be reduced.
V-15

Table V-2. Overview of the Potential Health Impacts from

Residential Waste Burning at 20 Meters 1,2

Meteorological Data

Exposure Pathways SCREEN3 Alturas Bishop San Benito Escondido 3, 4

Cancer Risk (chances per million)

Inhalation 44 3.3 4.6 6.4 8.2

Soil Ingestion 16 1.2 1.6 2.2 2.9

Skin Exposure 14 1.0 1.4 2.0 2.6

Mothers Milk 5 8.9 0.7 1.0 1.3 1.7

Backyard Garden 56 4.2 5.8 8 10

Meat and Eggs 1010 75 105 145 187

Milk (cow) 1160 86 120 166 215

Total Cancer Risk 2309 172 239 331 428

Non-Cancer Hazard Indices

Acute Inhalation6 0.02 0.01 0.02 0.02 0.02

Chronic Multipathway 7 0.08 – 2.0 0.15 0.2 0.3 0.4

1. All results are rounded. Potential health impacts are calculated from air dispersion modeling results and risk at 20 meters. 

Emissions for dioxins and PCBs are from the U.S. EPA 2000 source tests. Emissions for benzene, 1,3-butadiene, and PAHs

are from the U.S. EPA 1997 source tests.

2. All risk assessment results are based on a 70-year exposure for all pathways except the mother’s (breast) milk pathway (44-

year). Results are based on the CAPCOA Risk Assessment Guidelines methodology, HRA 2.0e, and the updated OEHHA

cancer potencies and reference exposure levels as of January 2001.

3. All pathways of exposure are assumed to occur at the same distance (location) from the source.

4. Emissions are assumed to be uncontrolled (0.05 factor). Multipathway route assumptions include: 15% of produce in the

receptor’s diet is homegrown; 100% of dietary meat (beef, pork, and chicken), eggs, and cow’s milk is impacted; 50% of cattle’s

diet is from impacted grassland and other feed is not contaminated; Farm animal drinking water is from a 300 gallon trough,

measuring one square meter, and is consumed every 3.75 days byr one lactating cow.

5. PCB contribution calculated by ratio of PCB to PCDD body half-life (0.7) multiplied by the PCDD & PCDF mother’s milk to

inhalation ratio.

6. Benzene impacts were assessed using 6-hour average concentrations. Primary endpoints are cardiovascular or blood,

reproductive system, and immune system.

7. Dioxins, PAHs, and PCBs were assessed for chronic impacts. Includes both inhalation and non-inhalation exposure pathways. 

Primary endpoints are reproductive system, cardiovascular or blood, and nervous system. The lower end of the range includes

inhalation, soil, and dermal exposure pathways. The upper end of the range includes all exposure pathways, except mother’s

milk.

The potential cancer risk for the four minimum pathways at the near-source (20 meters)

residential receptor ranges from 6.2 chances per million at Alturas to approximately

83 chances per million under SCREEN3 meteorological conditions. Benzene, 

1,3-butadiene, and dioxins are the primary contributors to the potential health impacts

through inhalation exposure. Dioxins, PAHs, and PCBs are the primary contributors to

the potential cancer risk through ingestion pathways. Depending upon the

environmental setting of the emission’s source, additional pathways such as

consumption of produce from backyard gardens, home-raised meat, and cow’s milk

could be considered. If these additional pathways are considered, the range of total

potential cancer risk increases to approximately 170 chances in a million at Alturas and

approximately 2,300 chances per million under SCREEN3 meteorological conditions. 

These risk estimates assume that burning occurs twice per week for two hours

throughout the year. In some years, CDF may impose a ban on burning during the

summer fire season. Depending upon meteorological conditions, a reduction in the
V-16

period of burning would result in no reduction in potential health impacts up to a

20 percent reduction. 

2. Community Health Impacts

Dioxins are emitted from the burning of residential waste materials which can have near

source impacts on individuals in the household conducting the burning and on nearby

neighbors. However, there is also a broader community impact from the dioxins

generated from this source. Dioxins are widespread throughout the environment,

representing the cumulative emission impacts from many sources, including residential

waste burning. Although dioxins are formed from almost all combustion sources, the

most toxic forms are generated by burning manmade substances. The most toxic

forms existed only in trace amounts in the environment prior to the 1930’s.

Dioxins emitted from a source can travel long distances because they exist partially in

the vapor form and partially in the particulate form. They have a half-life in the

atmosphere of several days. Eventually, the dioxins in the air are deposited onto

vegetation, waterways and the soil.

Once deposited, dioxins are highly persistent, with the half-life in the soil surface

estimated at 9 to 15 years, and in the soil subsurface at 25 to 100 years. Dioxins can

also accumulate in the fat of fish and animals and are concentrated up the food chain. 

It is estimated that up to 90% of dioxin intake for a typical person comes from dietary

intake of animal fats (Gilman & Newhook, 1991). These various environmental sources

lead to widespread, low-level exposure of the general population to dioxins. Because

dioxins can be passed through mothers milk, young children are especially vulnerable. 

Children may also be more sensitive to dioxin exposure because of their rapid growth

and development (U.S. EPA, 2001a). 

Reducing emissions from the sources that emit dioxin into the atmosphere can

therefore reduce community exposure to dioxins. The typical person continues to

accumulate dioxins over a lifetime. Current average body burdens are close to levels at

which effects on the immune system occur. In addition, current average body burdens

pose an unacceptable cancer risk. Countries around the world, including the United

States have recognized the public health threat posed by dioxin emissions. They have

been taking steps to reduce dioxin emissions with measurable success. Further

reductions are dependent upon eliminating sources such as residential burning.
VI-1

VI. THE PROPOSED CONTROL MEASURE AND ALTERNATIVES

In the previous two chapters we assessed emissions and potential risk from residential

waste burning. This chapter contains a summary of the proposed control measure and

provides the basis for selecting the provisions being proposed and alternatives we

considered in developing this proposal. The proposed ATCM is set forth in Appendix A.

A. Summary of the Proposed Control Measure

1. General Provisions

The proposed control measure would minimize emissions of dioxins, as well as other

toxic air contaminants such as benzene, 1,3-butadiene, PAHs, and PCBs, and the

criteria pollutant, particulate matter, from residential waste burning by addressing both

the materials which can be burned, and the method of burning. The proposed ATCM

prohibits the burning of residential waste, other than natural vegetation, anywhere in the

State except for areas that qualify for a temporary exemption based upon specified

criteria. The use of burn barrels would also be prohibited statewide, except in the

exempt areas, as a means of ensuring that such barrels are not used for the burning of

prohibited residential waste. 

The ATCM would require the use of an ignition device approved by the Air Pollution

Control Officer. A variety of devices or materials can be used to ignite residential waste

fires, ranging from propane to diesel fuel. This provision will require the use of ignition

devices that ensure a fire that ignites quickly and that minimizes the production of

smoke, as appropriate to the conditions and materials burned in each air district.

It would also prohibit the burning of allowable combustibles, including natural

vegetation, as defined in the regulation, unless it is a permissive burn day in the air

district where the residential burning takes place. This requirement aligns the burning

of residential waste with the requirements for agricultural and prescribed burning. 

Burning only on permissive burn days will ensure optimal conditions for smoke

dispersion and minimize nuisance and health impacts. 

2. Applicability

The proposed ATCM applies to persons conducting outdoor burning of combustible or

flammable waste generated from inside residences, and from outdoor activities

associated with a residence, for the purpose of disposing of the waste. The proposed

ATCM also applies to persons lighting fires that burn combustible or flammable waste in

enclosed or partially enclosed vessels, such as incinerators or burn barrels, or in an

open outdoor fire, such as in pits or in piles on the ground. 
VI-2

3. Exemptions

With the concurrence of the ARB, air districts may specify geographic areas that will be

exempt from the prohibitions in the ATCM if they meet criteria including, but not limited

to, all of the following: 

1) no available waste pickup service, considering reasonable cost and

frequency of service; and

2) greater than a reasonable distance from an approved transfer station or

disposal facility or a communal or community dumpster, considering road

miles or time traveled, road conditions, terrain, weather conditions,

reasonable tipping fees, and hours of operation; and

3) low population density per census tract or other appropriate sub-unit of

the county area. 

Exemptions would only apply to residential waste materials that are allowed under air

district or local jurisdiction rules in effect as of the date of hearing notice for the Board

meeting to consider the proposed ATCM. The use of burn barrels would also be

allowed in these exemption areas.

In order to be considered for exemptions, air districts must submit documentation to the

ARB, which has been approved by the air district Board at a public hearing, by

March 1, 2003. The air district must provide mapped excluded geographic areas with a

detailed, written justification for the mapping based on the criteria listed above. The

justification must also include a demonstration that waste disposal alternatives are not

likely to become available within the next five years. 

ARB would have 60 days to review the documentation and approve or disapprove the

request. If the request is disapproved, the air district must resubmit the request within

30 days. However, it is ARB’s intention to work with the air districts requesting

exemptions in advance of request submittals in order to provide guidance on exemption

criteria and to facilitate the approval process. A determination of allowable exemption

areas would be revisited every five years. At that time, air districts must demonstrate to

the ARB that the criteria for the exemptions are still met, and that waste disposal

services for these areas were not expected within the next five-year time frame. 

Table VI-1 summarizes the requirements of the proposed ATCM. A further discussion

of the exemption criteria is provided in section B.3.

4. Schedule

The provisions of the regulation would be effective on July 1, 2003. As discussed

above, Requests for Exemptions would need to be submitted by March 1, 2003 to allow

time for ARB review and approval prior to the effective date of the regulation.
VI-3

Table VI-1. Requirements of the Proposed ATCM

Applicability Exemptions Requirements

Applies to all areas of the State. Allowed based upon air district

documentation of areas which

meet the criteria, and with ARB

concurrence: 1) availability and

cost of waste service, 2)

distance from and accessibility

of an approved transfer station

or landfilll, and 3) low population

density

Effective March 1, 2003:

By this date, air districts must

submit Requests for Exemption

with appropriate documentation

and justification.

Effective July 1, 2003:

The provisions of the ATCM

become effective.

Effective Every Five Years

after July 1, 2003:

Air districts may request

continuing exemptions. Air

districts must submit

documentation that the criteria

for the exemptions still exist.

B. Basis For The Proposed Regulation

California Health and Safety Code section 39665(b) requires the Board to address the

technological feasibility of proposed ATCMs. Health and Safety Code section 39665(b)

also requires the Board to address the “availability, suitability and relative efficacy” of

substitute products of a less hazardous nature when proposing an ATCM. In addition

to the issues to be addressed under Health and Safety Code section 39665(b), Health

and Safety Code section 39666 requires that any control measure for a TAC without a

Board-specified threshold level be designed to reduce emissions to the lowest level

achievable through the application of best available control technology (BACT) or a

more effective control method. 

To evaluate these factors, we reviewed existing literature on emissions from residential

waste burning, assessed control programs in other states, and held numerous

discussions with waste management agencies, waste service providers, the CIWMB,

fire protection agencies, and air districts about enforcement and the feasibility, cost,

and environmental impacts of alternative methods for disposing of prohibited residential

waste materials. We also reviewed existing air district rules governing residential waste

burning. 

1. Best Available Control Technology

Dioxins are a by-product of the combustion of residential waste materials containing

carbon and chlorine during low temperature, poor oxygen conditions. While the burning

of natural vegetation does produce some dioxins, the emissions are much lower than

the emissions from the burning of manmade materials. In addition, the burning of
VI-4

natural vegetation produce dioxin isomers which are less toxic. Dioxins are optimally

formed when combustion temperatures are within a window of 250o C and 700o C. The

formation of dioxins can be minimized or eliminated through careful control of

combustion conditions, including maintaining combustion temperatures at

approximately 1000oC for a minimum of 1 second. For major sources such as

municipal and hospital waste incinerators, combustion conditions can be carefully

controlled, and the required high temperature and residence time can be achieved. 

However, this type of controlled combustion is not feasible for small residential burning

sources such as backyard burn barrels or piles. No external control technologies, or

changes in burning practices, are available or achievable to reduce or eliminate dioxin

emissions from residential burning.

Testing performed by the U.S. EPA (U.S. EPA, 1997a; Lemieux, 2000) on a mixture of

residential waste materials including household food waste, plastics, glass, metal cans,

and paper demonstrated that dioxins are emitted during the burning of these materials.

As discussed in Chapter III, the burning of waste in burn barrels provides optimal

conditions for the formation of dioxins, including low combustion temperatures and low

oxygen availability. Typical combustion temperatures in burn barrels measured during

the U.S. EPA tests ranged from 50o

 C to 600o C, with temperatures within the optimal

250o C to 700o C window for a significant portion of the test duration (U.S. EPA, 1997a).

Individual tests are not available to quantify the dioxin emissions from separate material

types such as paper and cardboard. While the burning of plastics produces the

greatest amount of dioxins, both carbon and chlorine are present in all residential waste

materials, including paper and cardboard. Most paper and cardboard also contains

inks and dyes that can also release other toxic air contaminants when burned. 

Additionally, many modern paper products contain small amounts of plastics or have

plastic linings. Therefore, staff determined that best available control technology for

residential waste burning would be a prohibition on burning of all types of residential

waste materials other than natural vegetation. As noted in previous chapters, seven air

districts already prohibit the burning of non-vegetative materials, and six air districts

already prohibit the use of burn barrels.

2. Effectiveness

The proposed control measure would prohibit the burning of all residential waste

materials with the exception of natural vegetation except in areas with limited

exemptions. We estimate that approximately 108,000 households are burning some

form of non-vegetative waste and would be affected by the proposed regulation. In the

non-exempt areas, the proposed control measure would result in a complete elimination

of dioxins and other TACs generated from the burning of the prohibited residential

waste materials, although the potential for illegal burning of prohibited materials could

still exist. We recognize that in some areas, alternatives to burning residential waste

materials are not available at a reasonable cost. Therefore, the proposed ATCM allows

for limited exemption areas. However, exempted areas would need to meet stringent

criteria, with documentation provided by the air district, and with concurrence from the
VI-5

ARB. We estimated the number of households that might be exempt under the criteria

specified in the proposed regulation by assuming that only those households living

outside an incorporated community would be likely to meet the exemption criteria. 

Based upon the distribution of population in incorporated versus unincorporated areas

in the portion of each air district that allows burning of residential waste, we estimate

that up to 67,000 households could be exempt. This is approximately 62 percent of the

108,000 households that are estimated to be currently burning some form of residential

waste. 

3. Criteria for Exemptions

Pursuant to State law, control measures for TACs without a Board-specified threshold

exposure level such as dioxins must be based on best available control technology in

consideration of cost and risk. We developed a three-tiered exemption criteria

approach that is designed to minimize public health risk in consideration of cost and

feasibility in implementing best available control technology. These exemption criteria

were developed recognizing that there are some areas in the State where feasible and

cost-effective alternatives to burning of residential waste are not available. However,

exemptions must also address the need to minimize public exposure to dioxins and

other TACs generated from residential waste burning. 

In order request an exemption, an area must meet all three criteria: 1) no available

waste pickup service, considering reasonable cost and frequency of service; 2) greater

than a reasonable distance from an approved transfer station or disposal facility or a

communal or community dumpster, considering road miles or time traveled, road

conditions, terrain, weather conditions, reasonable tipping fees, and hours of operation;

and 3) low population density per census tract or other appropriate sub-unit of the

county area. 

Based upon discussions with air districts and waste management agencies, staff

determined that these exemption criteria must be flexible enough to address the unique

variability in waste disposal options and topography in each air district, while

maintaining an appropriate level of health protection. Thus "one-size-fits all" exemption

criteria were not appropriate. The following sections discuss the various factors that

influence how these exemption criteria may be met.

a. Availability of Waste Service

A number of different forms of curbside waste service exist throughout the State. Many

jurisdictions require mandatory garbage service. Mandatory service is defined as

service by a franchised waste provider where the household is required to pay for and

use the service. Voluntary service is defined as households that are served by a

franchised waste service provider, but where the household may elect to use or not use

the service. Finally, discretionary service represents households which are not served

by a selected franchise waste service, but which may contract for waste services on

their own. 
VI-6

Under the exemption criteria, areas with mandatory or voluntary waste service would be

considered to have available waste service. However, areas with discretionary service

may meet the first exemption criteria. In these areas, waste providers may not be

willing to serve all households due to access problems, or the cost of service may be

many times higher than contracted rates for the mandatory and voluntary service areas.

For example, in San Benito County, mandatory or voluntary service is provided to all

households in the northern portion of the county. However, households in the more

remote southern portions of the county have discretionary service only. In areas with

discretionary service, the feasibility and cost of the service will be considered in

determining whether an area meets this exemption criteria. Cost for service that

exceeds twice the median cost for currently served mandatory and voluntary areas in

the air district would be considered high.

b. Distance to Approved Disposal Facility

Many households that do not contract for regular curbside pickup elect to self-haul their

residential waste to approved landfills, transfer stations, or recycling facilities. The

number and location of these facilities in relation to the locations of households varies

throughout the State. Many counties have no landfills, and provide only transfer

stations. The waste from these transfer stations is then sent to landfills in other

counties or out of State. The distance an individual household would have to travel to

dispose of their waste therefore varies in each air district. In addition, reasonable travel

distances can vary depending upon road conditions, posted speed limits, terrain, and

weather conditions. A reasonable travel distance in a county with flat terrain, may be

unreasonable in another county with mountainous terrain and poor roads. For

example, current rules in the Kern County air district specify that households within

15 miles of an approved landfill or transfer station may not burn their residential waste. 

However, this criteria may not be appropriate in a more mountainous region. In

general, a half-hour travel time, or approximately 15 miles would be considered a

reasonable distance. 

The operating hours and tipping fees for a disposal facility may also be considered. For

example, in Modoc County, many of the transfer stations are only open a few days a

week, with limited operating hours. Therefore, the location of landfills and transfer

stations, their operating schedule, and reasonable travel distances in relation to the

locations of households all need to be considered in determining whether a specific

area would meet the second exemption criteria. 
VI-7

c. Population Density

The population density exemption criteria were developed to ensure that any allowable

burning would minimize public exposure to dioxins and other TACs. In addition, it is

recognized that it is more difficult to establish regular waste pickup service at a

reasonable cost in sparsely populated areas than in more densely populated areas.

Due to differences in topography and meteorological dispersion conditions that affect

exposure levels, staff determined that specifying a single population density value in the

proposed regulation was not appropriate. In addition, the distribution of the population

in a given area must be considered. For example, a more densely populated area may

exist within a broader region of very low population density. In this situation, the

average population density could be very low, however, protection of public health

would not be achieved by allowing burning in the more densely populated sub-area. 

Therefore, the criteria specify that population density exemptions must be made on a

sub-county basis such as a census tract or other unit of zoning.

4. Enforceability

Primary responsibility for enforcement of the proposed control measure, as with all

ATCMs, would be with the air districts. However, the ARB is also authorized to enforce

ATCMs (Health and Safety Code section 39669). Prohibitions on the burning of all

residential waste materials other than natural vegetation facilitates enforcement efforts

by creating a clear distinction between the types of materials which can and cannot be

burned. In addition, the enforceability of the proposed control measure is enhanced

through the elimination of burn barrels. Air districts report that many households burn

prohibited materials in burn barrels. 

In July 1997, the Lake County Air Quality Management District conducted a survey of

burn barrel contents from burn barrels randomly selected throughout the county. 

Inspectors found that greater than 90% of the 52 burn barrels evaluated had illegal

materials in them. Burn barrel contents included batteries, diapers, flashlights,

children’s toys, electronic devices, and other illegal materials (Lake County AQMD,

2001a, Lake County AQMD, 2001b). 

In September 2001, ARB surveyed the 21 air districts in California which allow

residential waste burning, but not garbage burning. The purpose of the survey was to

determine how many burn barrels there are in each of those air districts and what

percentage are found to contain illegal materials in them. All 21 air districts surveyed

responded. The initial survey found that there were about 113,000 burn barrels burning

residential waste. Some numbers were subsequently revised based on further

conversations with the air districts, resulting in our best estimate of 93,000 households

burning residential waste. Fifteen of the 21 air districts that responded to the survey

reported that greater than 50% of burn barrels in their air district have illegal materials

burned in them (ARB, 2001). 
VI-8

It is often difficult for air district enforcement staff to determine whether prohibited

materials have been burned in burn barrels. The use of open piles on the ground for

the burning of natural vegetation will therefore facilitate improved air district

enforcement efforts. A strong public education and outreach campaign to alert the

public to the health impacts of residential waste burning and the availability of

alternative waste disposal options will also assist with compliance efforts and minimize

the incidence of illegal burning.

5. Cost and Resource Requirements

The proposed control measure would have a limited fiscal impact on the State and air

districts, primarily in terms of enhanced public education and outreach, and

enforcement. It would also have a limited economic impact on consumers and local

waste management agencies where new service is established. These economic

impacts are discussed in Chapter VII.

6. Environmental Effects

The proposed control measure was evaluated for potential impacts on waste diversion

rates, landfill capacities, illegal dumping, illegal waste storage, increased vehicle traffic

due to expanded waste pickup service, and fire safety. Based on available information,

the ARB has determined that no significant adverse environmental impacts should

occur. Environmental impacts are discussed in Chapter VIII.

7. Alternative Waste Disposal Methods

The proposed control measure will require some households to use waste disposal

methods other than burning for some or all of the residential waste. The greatest

impact will be seen in the six air districts where there are no restrictions on the

materials that can be burned, and where some households therefore may not be using

any other alternative disposal mechanisms. Some of these waste materials, such as

food waste and other organic materials, can be composted, and probably already are in

many rural households. The remaining waste will need to be disposed of at a landfill,

transfer station, or recycling center, either through self-hauling or contracting for

curbside pickup. In areas where these disposal options are not available, considering

cost and feasibility, limited exemptions will allow for the continued burning of residential

waste. It should be noted however, that in some years, the CDF invokes a ban on all

residential burning during fire season, typically between July and October. During these

months, households may already be using some of the alternative disposal methods

discussed above. 

In the remaining 21 air districts which already prohibit the burning of household

garbage, households are already disposing of a portion of their waste through nonburning methods, presumably through curbside pickup or self-hauling. The proposed

control measure will require these households to dispose of additional materials,

primarily paper and cardboard, through the same non-burning disposal methods. 
VI-9

Other options to dispose of residential waste materials include the purchasing of

products that minimize the use of packaging and re-using materials, as well as

shredding and compacting of waste to reduce bulk.

8. Health Impacts

The proposed ATCM would result in a substantial reduction of dioxins and other TACs

from residential waste burning. As discussed in Chapter V, dioxins from residential

waste burning impact not only individuals located near the source of the burning, but

also the broader population due to their transport and deposition onto soil, water, and

vegetation. Dioxins can accumulate in the fatty tissues of animals that ingest the water

and vegetation. Further bioaccumulation occurs when the meat, milk, and eggs from

these animals are ingested by humans. Dioxin emissions from residential waste

burning contribute to this global accumulation of dioxins in the environment. Emissions

of dioxins from other large sources such as municipal and medical waste incinerators

have been controlled. The U.S. EPA estimates that emissions from residential waste

burning are one of the largest remaining sources of uncontrolled emissions of dioxins

(U.S. EPA, 2001b). Therefore, reductions in the emissions from residential waste

burning will reduce the environmental loading of dioxins and further reduce public

exposure to dioxins and resultant health impacts.

C. Alternatives to the Proposed Control Measure

Staff identified two alternatives to the proposed control measure. This section

discusses each of the two alternatives, and provides the reasons they were considered

to be less effective than the proposed regulation. The first alternative was to take no

action, to allow the continued burning of residential waste, and the use of burn barrels. 

The second alternative was to prohibit only the burning of household garbage. We

determined that these alternatives would not be as effective at reducing emissions of

and exposure to dioxins and other TACs from residential waste burning activities as the

proposed control measure. Furthermore, the two alternatives did not meet the HSC

section 39666 criterion to reduce emissions to the lowest level achievable through the

application of best available control technology, or a more effective control method, in

consideration of cost, risk, and environmental impacts.

1. Alternative One - No Action

The “no action” alternative would not address the potential risk posed by residential

waste burning activities. As evidenced by the potential health impacts discussed in

Chapter V, this alternative would not be protective of public health.

2. Alternative Two – Prohibition Only on Burning of Household Garbage

This alternative would prohibit only the burning of household garbage. Under this

alternative, households would still be allowed to burn their non-garbage wastes, such
VI-10

as paper, cardboard, wood products, and cloth. This would affect only six air districts,

or approximately 15,000 households that are likely to be burning residential waste in

these areas. However, this option would be less protective of public health and would

not promote the development and expansion of alternatives to burning in as many

areas. In addition, the alternative would do little to minimize the illegal burning of

garbage in burn barrels, or the burning of materials such as paper in more densely

populated areas.

D. Recommendation

As a result of the evaluation, with incorporation of recommended exemptions, we

consider the proposed ATCM to be environmentally, technically, and economically

feasible, resulting in a safe, effective, and less-hazardous alternative to burning. Based

on this evaluation, we believe that it is appropriate prohibit residential burning of all

materials with the exception of natural vegetation, as well as to eliminate the use of

burn barrels.
VII-1

VII. ECONOMIC IMPACTS OF THE PROPOSED AIRBORNE TOXIC CONTROL

MEASURE

This chapter discusses the impacts that the proposed ATCM may have on consumers

as well as costs to businesses and local, State, and federal agencies. 

A. Economic Impacts Analysis on California Businesses as Required by the

California Administrative Procedure Act (APA) and other State Law

1. Legal Requirements

Section 11346.3 of the Government Code requires State agencies to assess the

potential for adverse economic impacts on California business enterprises and

individuals when proposing to adopt or amend any administrative regulation. The

assessment shall include a consideration of the impact of the proposed regulation on

California jobs, business expansion, elimination or creation, and the ability of California

business to compete with businesses in other states.

Also, State agencies are required to estimate the costs or savings to any State or local

agency and school district in accordance with instructions adopted by the Department

of Finance. The estimate shall include any nondiscretionary costs or savings to local

agencies and the costs or savings in federal funding to the State.

Health and Safety Code section 57005 requires the ARB to perform an economic

impact analysis of submitted alternatives to a proposed regulation before adopting any

major regulation. A major regulation is defined as a regulation that will have a potential

cost to California business enterprises in an amount exceeding ten million dollars in any

single year. The proposed ATCM is not a major regulation.

2. Affected Businesses

Waste service providers in the 27 air districts that currently allow some form of

residential waste other than natural vegetation to be burned could be affected by the

proposed control measure. We estimate that there are more than 100 waste service

providers that serve these air districts. Private recycling centers and waste disposal

facilities could also be affected. 

3. Potential Impact on Consumers

Consumers who are currently burning their residential waste may have to pay more to

dispose of these materials. The proposed ATCM would require them to obtain waste

disposal services or to self-haul their waste to landfills or transfer stations. In some

areas, new waste service routes may need to be developed. In other areas, new

customers may be added to existing routes. The increased cost will vary depending

upon the costs associated with increasing waste management service in their area. 
VII-2

We surveyed a number of local waste management agencies to determine the costs

and availability of service. Based upon surveys conducted by ARB staff, and

information from the CIWMB, we identified several forms of service and cost structures

for service. Many jurisdictions require mandatory garbage service. Mandatory service

is defined as households that are served by a franchised waste provider selected by the

jurisdiction where the household is required to pay for and use the service. Voluntary

service is defined as households that are served by a franchised waste service provider

selected by the jurisdiction, but where the household may elect to use or not use the

service. Finally, discretionary service represents households which are not served by a

selected franchise waste service, but which may contract for waste services on their

own.

Within these forms of service, there are also a number of cost structures. In many

jurisdictions, a standard monthly fee covers the cost of pickup of one 32 gallon trash

container per week. Incremental fees often apply for additional or larger containers. In

other jurisdictions, the monthly fee is fixed regardless of the number or size of

container. Not all areas require the separation of natural vegetation (also known as

green waste) and recyclable materials in the waste containers. However, where this is

done, some include separate green waste and recyclable containers as part of the

overall monthly fee, while other jurisdictions may charge a small additional fee.

A number of different fee structures also exist for landfills and transfer stations. In most

jurisdictions, consumers pay what is known as a tipping fee. This tipping fee is based

upon the amount of material dropped off, and is often assessed by weight or volume. 

However, there are some jurisdictions, such as eastern Kern County, where all

households are assessed a flat annual fee for landfill services. This fee entitles each

household to drop off their waste materials at county landfills, and no "per use" tipping

fee is assessed. While some landfills and transfer stations do not separate the

materials that enter the landfill, many establish separate areas for recyclable materials.

Generally recyclable materials can be dropped off for no cost.

Based on surveys, we found that consumer costs for monthly curbside waste pickup

generally range from $8 to $25. This is typically 1 pickup per week for one or two 

32 gallon containers. In some jurisdictions, additional fees are charged for additional

cans, and/or for containers for recyclable materials. These additional fees can range

from $3 to $10 per month. We estimate that a consumer who did not previously

contract for waste service could therefore incur new yearly costs for waste pickup of

$96 to $420. This would apply primarily to consumers in the six air districts where there

are no restrictions on the materials that can be burned. In these air districts there may

be households where waste disposal options other than burning have not previously

been used. In the remaining 21 air districts where the burning of household garbage

has already been prohibited, it can be assumed that consumers are already using some

form of alternative waste disposal, whether it is curbside pickup or self-hauling. These

consumers however may have some additional waste that was previously burned. 

Assuming that these consumers live in jurisdictions where additional fees would apply
VII-3

for extra cans or recycling containers, they could incur additional yearly costs of $36 to

$120.

It is also possible that the expansion of existing routes could result in enhanced

economies of scale and some incremental reduction in costs to all consumers already

receiving service. Establishing service for a remote area not previously served

however, could necessitate service fees which are two to three times higher than the

typical fees described above. In this instance, the cost of service could be a

consideration in requesting an exemption for the specified area.

Alternatively, some consumers may elect to self-haul their waste to landfills and transfer

stations. Typical tipping fees for landfills and transfer stations generally range from

$25 to $85 per ton of compacted waste disposed or $3 to $20 per cubic yard of

uncompacted waste. Some landfills also charge on a per vehicle basis, regardless of

the amount of waste. However, as discussed above, some landfills and transfer

stations have established sorting areas for recyclable materials, and consumers are not

charged for the portion of their waste which is recyclable. 

Assuming that a household would make one trip per week to a landfill or transfer

station, with one half a cubic yard of waste in each trip, staff estimates that a consumer

who previously burned all of their waste could incur yearly costs of $78 to $520 to

self-haul their waste materials. These costs could be reduced in areas where

recyclable materials are separated. Consumers who had previously been self-hauling

only a portion of their waste, and burning the rest, would incur lower additional yearly

costs. Again, these costs could be reduced if the additional waste, which is often paper

and cardboard, was brought to a recycling facility. Households that self-haul could also

incur additional fuel costs to transport the material to the landfill or transfer station. 

Assuming a round trip distance to the landfill or transfer station of 20 miles, a fuel cost

of $1.50 per gallon, and a fuel efficiency of 20 miles per gallon, a household that

previously burned all their waste could incur additional costs of $1.50 per trip. At

52 trips per year, that additional fuel related costs would amount to $78 per year. This

cost would be less for households that previously transported some of their waste

materials, and only increase the frequency of trips as a result of the proposed

regulation. 

4. Potential Impact on Employment, Business Creation, Elimination or Expansion

The proposed ATCM is not expected to have a noticeable impact on the status of

California businesses. The primary businesses affected would be waste service

providers as well as operators of private recycling centers and waste disposal facilities. 

The proposed ATCM may actually create some business opportunities and employment

for California waste service providers in areas where either additional households opt

into service where service had been voluntary, or where service areas are expanded. 

New or expanded opportunities could also be created for recycling facilities.
VII-4

5. Potential Impact on Business Competitiveness

The proposed ATCM would have no impact on the ability of California waste service

providers to compete with similar businesses in other states. Waste service contracts

are determined on a local jurisdictional basis. The requirements of the proposed ATCM

would affect all waste service providers competing for a contract, regardless of where

they originate from.

B. Analysis of Potential Impacts to California State or Local Agencies

1. Costs to Air Districts

Although there are no specific mandates, the proposed ATCM could have some small,

but unquantifiable, economic impacts on the air districts. Health and Safety Code

section 39666 requires that after the adoption of the proposed ATCM by the Board, the

air districts must enforce the ATCM or adopt and enforce an equal or more stringent

regulation. Beginning in July 2003, the air districts, during their normal course of

business, will be responsible for enforcement activities and responding to complaints. 

The proposed regulation does not contain any specific requirements for enforcement or

inspection. In addition, because most air districts already have rules and regulations in

place that necessitate enforcement for currently prohibited materials, the enforcement

efforts required for the proposed regulation would build upon these existing efforts. Air

districts are also provided with State funding through the subvention process. Air

districts have discretion in using this funding for enforcement purposes, and can

apportion the funding based upon program needs.

The air districts may also need to carry out a public education and outreach campaign

to enhance compliance with the ATCM and to alert the public to available options for

waste disposal. However, ARB will develop public education and outreach materials

that can be provided to the air districts. Some air districts may also require resources to

determine exemption areas. We estimate that 1 to 2 person months would be needed

for this effort initially, with one half to one person month needed every five years to

renew exemptions. The ARB will provide technical assistance to the air districts in

preparing exemption requests. It should be noted that eight air districts already have

programs at least as stringent as the proposed ATCM and therefore would incur no

additional burden from the requirements of the regulation. 

2. Costs to Local Waste Management Agencies

The proposed ATCM could result in non-mandatory costs to local agencies responsible

for waste management services to the extent they choose to provide expanded waste

disposal services and to address waste diversion impacts. In many jurisdictions, waste

service is already available throughout the area, although in many cases it is not

mandatory. Additional households who might opt into service due to the proposed

ATCM would not have an impact on the local agency. The expansion of waste service

to areas which were previously unserved however, could result in increased costs to
VII-5

local agencies to develop new waste hauling contracts and for continued management

and oversight. However, the costs of additional waste service could be recovered

through waste collection service fees.

Local agencies could experience increased costs if they decide to expand the hours of

operation at a landfill or transfer station to meet consumer demand or need. Additional

costs could also be incurred if a waste agency needed to go through a permit

amendment process to expand the allowable capacity of a landfill. It is also possible

that a local jurisdiction could elect to build new transfer stations to address increased

demand or better serve outlying residents. Infrastructure costs to establish a small, 

unattended transfer station are approximately $10,000. Additional costs of

approximately $20,000 would be incurred for permitting, and costs would be higher for

larger, attended facilities. However, discussions with several waste management

agencies indicate that many factors would influence the decision to establish additional

transfer stations, therefore the potential for this impact cannot be quantified. 

Finally, local waste management agencies could develop new baseline waste disposal

levels to better address the addition of materials that were previously burned to the

waste stream and more accurately calculate diversion rates. Development of a new

baseline could cost approximately $50,000 for surveys at selected waste disposal

facilities. However, not all local waste management agencies may choose to develop

new baseline years.

3. Costs to State and Federal Land Management Agencies

Although there are no specific mandates, the proposed ATCM could have limited

economic impacts on State and federal land management agencies. The main impact

would be on public education, issuance or permits, and enforcement of complaints that

could arise from burning that occurred on State and federal responsibility area lands. 

As discussed above, ARB will provided the needed public education and outreach

materials. The number of permits is not expected to increase as a result of the

proposed regulation, and may decrease due to the decrease in the number of

households allowed to burn residential waste materials. In terms of enforcement, while

these fire agencies have primary responsibility for fire safety, they often are the first

ones to respond to complaints about burning, which often are not about fire safety, but

the burning of prohibited materials. Some jurisdictions have addressed this problem

through a memorandum of understanding between the local fire protection agencies

and the air district to allow the fire protection agency to recoup its costs for enforcement

through a pass-through of fines assessed by the air district. This has worked especially

well in Placer County. Similar efforts in other jurisdictions could minimize the economic

impact of enforcement efforts for these State and federal land management agencies. 
VIII-1

VIII. ENVIRONMENTAL IMPACTS OF THE PROPOSED AIRBORNE TOXIC

CONTROL MEASURE

The intent of the proposed ATCM is to improve air quality and protect the public health

by reducing the public’s exposure to potentially harmful emissions of dioxins, other

TACs, and particulate matter produced during the burning of residential waste

materials. An additional consideration is the impact that the proposed ATCM may have

on other areas of the environment. This chapter describes the potential impacts that

the proposed ATCM may have on waste diversion rates, landfill capacities, illegal

dumping, illegal waste storage, increased vehicle miles traveled due to expanded waste

pickup service, and fire safety. In evaluating the potential impacts, we considered the

role of exemptions in the proposed regulation. The goal of the exemptions would be to

allow burning to continue in those areas where feasible alternatives for waste disposal

do not exist, and where population density is low. These exemptions are expected to

mitigate the potential for adverse impacts in areas where they would be the most likely

to occur. Therefore, based on available information, the ARB has determined that no

significant adverse environmental impacts should occur.

A. Legal Requirements Applicable to the Analysis

The California Environmental Quality Act (CEQA) and ARB policy require an analysis to

determine the potential adverse environmental impacts of proposed regulations.4

 Since

the ARB’s program involving the adoption of regulations has been certified by the

Secretary of Resources (see Public Resources Code section 21080.5), the CEQA

environmental analysis is included in the Initial Statement of Reasons for a rulemaking

in lieu of preparing an environmental impact report or negative declaration. In addition,

prior to adopting the regulation, the ARB will respond in writing to all significant

environmental issues raised by the public during the public review period or at the

Board hearing. These responses will be contained in the Final Statement of Reasons

for the ATCM.

B. Waste Diversion Rates

The proposed ATCM will result in some increases in residential waste sent to municipal

waste disposal facilities. The increases would be greatest in the six air districts that

currently allow all types of materials to be burned. In the remaining 21 air districts, an

increase primarily in paper and cardboard could be seen at these facilities. This

additional waste would impact the 50 percent waste diversion requirements established

in State law by AB 939 (PRC 41780-41786). The goal of AB 939 is to decrease the

amount of materials disposed of at landfills through the development of source

reduction, recycling, and composting programs. The legislation established a

requirement of 25 percent diversion from landfills for all jurisdictions by

January 1, 1995, with a 50 percent diversion requirement by January 1, 2000. 

 

4 California Code of Regulations, title 17, sections 60005 through 60007.
VIII-2

Diversion rates are determined by measuring the amount of solid waste disposed of at

a permitted disposal and comparing that with the amount of estimated amount of waste

generated by that jurisdiction. Disposal is determined for the current year. Generation

is estimated for the current year by adjusting estimates for a base year (generally 1990)

based on changes in population, employment, and taxable sales corrected for inflation.

These base year generation rates however, would not have included waste that was

burned. 

Each local jurisdiction is responsible for developing local recycling and waste reduction

programs to meet the diversion requirements. Jurisdictions which cannot meet the

50 percent diversion requirement may request an extension, upon demonstration that

the jurisdiction is making a good faith effort to implement source reduction, recycling,

and composting programs, and that these programs represent the greatest diversion

amount that may reasonably and feasibly be achieved. 

The CIWMB is currently evaluating reports submitted by local jurisdictions to determine

whether they met the diversion requirements. Because the waste that is currently

burned was not included in the baseline generation values, the addition of this material

to landfills will impact waste diversion rates. However, efforts to promote recycling,

particularly for paper could help mitigate this impact. Jurisdictions may also elect to

develop new baseline levels to account for the waste that had previously been burned. 

In addition, as discussed above, CIWMB has a process to work with jurisdictions that

have not met the diversion requirements providing the jurisdiction is making a good faith

effort to meet the diversion goals.

C. Landfill Capacity

The addition of materials that were previously burned to existing landfills could cause

some landfills to reach capacity sooner than originally anticipated. Staff estimates that

the additional waste will not exceed 100,000 tons per year, which is less than one

percent of the existing waste disposed in California. This percentage may vary by air

district however, depending upon the amount of waste previously burned. As with the

waste diversion issue discussed above, efforts to promote recycling of materials can

help alleviate this potential impact.

D. Illegal Dumping

The proposed ATCM could result in some increases in illegal dumping near roadsides

and/or in remote wildland areas by households that refuse to either pay for curbside

service, or self-haul their waste to a transfer station or landfill. While illegal dumping is

a continuing concern for waste management officials, the proposed ATCM is not

expected to result in a significant increase in the small percent of the population that

contributes to this illegal activity. A strong public education and outreach campaign that

emphasizes the options that are available to consumers for disposing of their waste

legally can help mitigate this impact. In addition, the proposed regulation provides for
VIII-3

exemptions for those households that may not have alternative waste disposal options

other than burning. This should therefore minimize the possibility of illegal dumping.

E. Waste Storage

The proposed ATCM could result in some increases in illegal storage of residential

waste where inclement weather impacts residents’ ability to utilize available disposal

services, or where residents choose not to utilize available disposal services. This

could cause a public health impact associated with increases in disease transmitted by

vermin, as well as odor and nuisance problems. Again, a targeted public education and

outreach campaign can provide consumers with information about appropriate means

of disposing of their residential waste. In addition, as discussed above, the proposed

regulation provides for exemptions for those households that would have the greatest

difficulty in routinely disposing of their waste through non-burning alternatives, and

would therefore minimize the occurrence of extended waste storage. 

F. Potential Air Pollution Impacts

The proposed ATCM is designed to reduce the public health risks associated with

exposure to the emissions of dioxins and other toxic air contaminants. In addition, the

proposed ATCM will reduce the emissions of particulate matter. The proposed ATCM

will also result in reductions in oxides of nitrogen (NOx) and volatile organic compounds

(VOC). Oxides of nitrogen and volatile organic compounds contribute to the formation

of ozone, a key component of smog, and to particulate matter.

The proposed ATCM could result in some increases in vehicle miles traveled (VMT)

associated with increased garbage collection service and increased trips associated

with taking garbage to landfills and collection sites. As discussed in previous chapters,

as many as 108,000 households could be affected by the proposed ATCM. Many of

these households could potentially start receiving new curbside service, or start self

hauling their residential waste to a landfill of transfer station who were not previously

doing so. 

For many of these households where waste service has been voluntary, there are

existing waste service routes which already serve their neighborhood. In this situation,

the VMT from garbage trucks would not increase. However, in some cases, the

proposed ATCM could result in additional VMT for new waste service routes. Additional

VMT may also arise from increased trips by garbage trucks transporting additional

waste from transfer stations to a central landfill. Assuming that a garbage truck traveled

an additional 100 miles per week, or 5,200 miles per year, transporting additional

waste, and using ARB emission factors for refuse trucks in 2004, an additional

29 pounds of PM10, 641 pounds of NOx, and 102 pounds of VOC per year would be

generated. For comparison purposes, the additional PM10 emissions from the garbage

truck hauling waste for this scenario would nearly equal the PM10 emissions from one

burn barrel (approximately 25 pounds per year). The ARB also has an active program

to reduce particulate emissions from diesel vehicles through the diesel risk reduction
VIII-4

program. A comparison of NOx and VOCs cannot be made because these pollutants

were not measured in the U.S. EPA burn barrel tests.

Many households may also be self hauling a portion of their waste to the landfill. In

some cases, they may only increase the amount of material transported, but not the

frequency. However, in other cases, some households may increase the frequency

with which they transport their waste materials to the landfill or transfer station. 

Assuming two extra trips per month, at a distance of 20 miles per round trip, the extra

VMT would equal 520 miles per year. For a household that previously burned all of

their waste, and would therefore begin self-hauling their residential waste once per

week, the extra VMT would equal 1,040 miles per year. Using ARB emission factors for

light duty trucks (pick-ups) for 2004 of 0.021, 1.171, and 0.846 grams per mile

respectively for PM10, NOx, and VOC, the additional emissions would amount to

approximately 0.05 pounds of PM10, 2.7 pounds of NOx, and 2.0 pounds of ROG per

household per year. For comparison purposes, the additional PM10 emissions from

vehicle travel for one household is approximately 500 times smaller than the PM10

emissions from one burn barrel.

G. Fire Safety Issues

The proposed ATCM was evaluated to determine whether there could be any adverse

impacts on fire safety. Burn barrels are sometimes recommended by fire safety officials

for the burning of residential materials in order to provide a contained area for the fire. 

However, burn barrels are not typically used for the burning of vegetative material. 

Rather this material, because of its bulk, is typically burned in piles on the ground. In

areas that are not exempt under the proposed regulation, the burning of natural

vegetation will be the only material that can be burned under the proposed ATCM. 

However, areas that receive an exemption will be allowed to use burn barrels to burn

allowable waste materials. Therefore, the ATCM should not substantially impact fire

safety.

H. Combustion of Waste Materials Indoors

We received several comments that the proposed ATCM would result in the

inappropriate burning of residential waste material indoors, either through wood stoves

or fireplaces. We recognize that there is a possibility that some people might try this

alternative. As part of the public outreach materials that the ARB will prepare, we will

make it clear that this is an inappropriate activity and potentially extremely risky

because the pollutants can build up indoors. 

I. Environmental Justice

The ARB is committed to evaluating community impacts of proposed regulations,

including environmental justice concerns. Because some communities experience

higher exposures to toxic air pollutants, it is a priority of the ARB to ensure that full

protection is afforded to all Californians. The proposed ATCM is designed to reduce
VIII-5

emissions of dioxins and other TACs from residential waste burning, resulting in

reduced exposures to these emissions for all communities throughout the State, with

associated lower potential health risks.

J. Reasonably Foreseeable Alternatives to the ATCM

We have evaluated two alternatives to the proposed control measure: 1) no action, and

2) prohibition only on the burning of household garbage. Alternatives to the ATCM are

discussed in Chapter VI.
IX-1

IX. REFERENCES

ARB (1984). Report to the Scientific Review Panel on Benzene. Technical Support

Document. Air Resources Board, Stationary Source Division. Sacramento, California.

ARB (1986). Staff Report: Initial Statement of Reasons for Proposed Rulemaking. 

Public Hearing to Consider the Adoption of a Regulatory Amendment Identifying

Chlorinated Dioxins and Dibenzofurans as Toxic Air Contaminants. Agenda Item

No.: 86. Release Date: June 6, 1986. Scheduled for Consideration: July 24, 1986 

ARB (1990). Proposed Dioxins Control Measure for Medical Waste Incinerators. Air

Resources Board, Stationary Source Division. Sacramento, California.

ARB (1992). Proposed Identification of 1,3-Butadiene as a Toxic Air Contaminant. 

Staff Report, Executive Summary. Air Resources Board, Stationary Source Division. 

Sacramento, California.

ARB (1993a). The Identification of Federal Hazardous Air Pollutants as Toxic Air

Contaminants, California Air Resources Board, June 1993.

ARB (1993b). Measurements of Ambient Concentrations of Chlorinated Dioxins and

Furans, and Polycyclic Hydrocarbons. Contract No. A932-093. Final Report. Air

Resources Board, Research Division. Sacramento, California.

ARB (1994). Benzo[a]pyrene as a Toxic Air Contaminant. Technical Support

Document. Air Resources Board, Stationary Source Division. Sacramento, California.

ARB (1997). Toxic Air Contaminant Identification List – Summaries. Staff Report. Air

Resources Board, Stationary Source Division. Sacramento, California.

ARB (2001). ARB Burn Barrel Survey. Air Resources Board, Planning and Technical

Support Division. Sacramento, California. December 2001.

Balkanski et al. (1993). “Transport and residence times of tropospheric aerosols

inferred from a global three-dimensional simulation of 210Pb.” J. Geophys. Res. 

98:20573-20586.

Bidleman, T.F. (1988). "Atmospheric Processes. Wet and Dry Deposition of Organic

Compounds are Controlled by Their Vapor-Particle Partitioning." Environ. Sci. Technol.

22(4):361-367.

Bumb, et al. (1980). “Trace Chemistries of Fire: A Source of Chlorinated Dioxins.” 

Science. 210:385. 

CAPCOA, 1993. Air Toxics “Hot Spots” Program: Revised 1992 Risk Assessment

Guidelines. Prepared by the California Air Pollution Control Officers Association
IX-2

(CAPCOA), the Office of Environmental Health Hazard Assessment and the California

Air Resources Board. October, 1993.

CIWMB (2000). Residential Waste Disposal Rates. California Integrated Waste

Management Board, Sacramento, California. November 2, 2000.

URL: http://www.ciwmb.ca.gov/WasteChar/ResDisp.htm

Commoner, B. et al. (2000). Long-range Transport of Dioxin from North American

Sources to Ecologically Vulnerable Receptors in Nunavut, Arctic Canada. Final Report

to the North American Commission for Environmental Cooperation. Center for the

Biology of Natural Systems, Queens College, CUNY, USA, September 2000.

Denison, M.S. (2000). Organohalogen Compounds, Volume 45, Submitted Papers. 

20th International Symposium on Halogenated Environmental Pollutants and Persistent

Organic Pollutants (POPs). August 13-17, 2000. Editor and Publisher: Dr. Michael S.

Denison, University of California, Davis, California USA.

Finlayson-Pitts, B J., Pitts, J.N., Jr. 1986. Atmospheric Chemistry: Fundamentals and

Experimental Techniques. John Wiley and Sons, Publisher. New York, New York.

Federal Register (1994). United States Federal Register. September 20, 1994. 

40 CFR Part 60. FR 48198. Standards of Performance for New Stationary Sources: 

Municipal Waste Combustors (AD-FRL-5068-5). Emission Guidelines: Municipal

Waste Combustors (AD-FRL- 5068-6). Office of Air Quality Planning and Standards. 

United States Environmental Protection Agency. Washington, D.C

Gilman, A., and Newhook, R. (1991). "An Updated Assessment of the Exposure of

Canadians to Dioxins and Furans." Chemosphere. 23:1661-1667.

Hites, R.A. (1991). Atmospheric Transport and Deposition of Polychlorinated Dibenzop-dioxins and Dibenzofurans. Prepared for the U.S. Environmental Protection Agency. 

Methods Research Branch. Atmospheric Research and Assessment Laboratory. 

Office of Research and Development. Research Triangle Park, North Carolina. 

EPA/600/3-91/002.

Hunt, G. et al. (1990). Ambient Concentrations of PCDDs/PCDFs in the South Coast

Air Basin. California Air Resources Board. Contract No. A6-100-32. Document No.

1200-005-700.

Lake County AQMD (2001a). Mr. Bob Reynolds Presentation to the Mid-Spring Rural

California Air Pollution Control Officers Association Section Meeting: Burn Barrels and

Residential Burning. March 29-30, 2001.
IX-3

Lake County AQMD (2001b). “July 1997 Survey of Burn Barrel Contents in Lake

County.” Telephone Conversation between Mr. Bob Reynolds, Air Pollution Control

Officer, Lake County Air Quality Management District and Bruce Oulrey, ARB,

December 7, 2001.

Lemieux et al. (2000). "Emissions of Polychlorinated Dibenzo-p-dioxins and

Polychlorinated Dibenzofurans from the Open Burning of Household Waste in Barrels"

Environmental Science & Technology 34:377-384.

Marple, L., Brunk, R., Berridge, B., Throop, L. (1987). "Experimental and Calculated

Physical Constants for 2,3,7,8-tetrachlorodibenzo-p-dioxin." In: Solving Hazardous

Waste Problems. Exner, J.H., Editor. ACS Symposium Series 338. Developed from a

symposium sponsored by the Division of Environmental Chemistry at the 191st meeting

of the American Chemical Society, New York, New York. April 13-18. Page 105-113.

Merck (1989). The Merck Index. Edited by Susan Budavari. 11th edition. Merck & Co.,

Inc. Rahway, New Jersey.

NTP (1991). Sixth Annual Report on Carcinogens: 1991 Summary: . Pages 323-327.

National Toxicology Program, U.S. Department of Health and Human Services,

Research Triangle Park, North Carolina. 

OEHHA (1999a). Air Toxic Hot Spots Program Risk Assessment Guidelines, Part I,

The Determination of Acute Reference Exposure Levels for Airborne Toxicants, Office

of Environmental Health Hazard Assessment (OEHHA), March 1999.

OEHHA (1999b). Air Toxic Hot Spots Program Risk Assessment Guidelines, Part II,

Technical Support Document for Describing Available Cancer Potency Factors, Office

of Environmental Health Hazard Assessment (OEHHA), April 1999.

OEHHA (1999c). Facsimile From Office of Health and Environmental Assessment, 

U.S. EPA Chronic Reference Concentrations (RFC’s) Available on the U.S. EPA IRIS

Database (1996) as Referenced In Appendix F of the Emission Inventory Criteria and

Guidelines Report. June 14, 1999.

OEHHA (2000a). Air Toxic Hot Spots Program Risk Assessment Guidelines, Part III,

Technical Support Document for the Determination of Noncancer Chronic Reference

Exposure Levels, Office of Environmental Health Hazard Assessment (OEHHA),

April 2000.

OEHHA (2000b). Air Toxic Hot Spots Program Risk Assessment Guidelines, Part IV,

Technical Support Document for Exposure Assessment and Stochastic Analysis, Office

of Environmental Health Hazard Assessment (OEHHA), September 2000.

OEHHA (2001a). Memorandum “Adoption of Chronic Reference Exposure Levels For

Airborne Toxicants” to Winston H. Hickox, Agency Secretary, California Environmental

Protection Agency from Joan E. Denton, Director, OEHHA.
IX-4

OEHHA (2001b). State of California, Environmental Protection Agency, Office of

Environmental Health Hazard Assessment, Safe Drinking Water and Toxic

Enforcement Act of 1986, Chemical Known To The State To Cause Cancer And

Reproductive Toxicity, Office of Environmental Health Hazard Assessment,

November 16, 2001.

OEHHA (2001c). Telephone Conversation with Bob Blaisdell, Manager, Exposure

Modeling Unit, Office of Environmental Health Hazard Assessment and Greg Harris.

November 26, 2001.

OEHHA (2001d). Prioritization of Toxic Air Contaminants Under the Children’s

Environmental Health Protection Act. Office of Environmental Health Hazard

Assessment, Sacramento, California. Final Report, October 2001.

OEHHA (2001e). Personal communication with Bob Blaisdell, Manager, Exposure

Modeling Unit, Office of Environmental Health Hazard Assessment.

Paustenbach et al. (1992). "Recent Developments on the Hazards posed by 2,3,7,8-

Tetrachlorodibenzo-p-dioxin in soil: implications for setting risk-based cleanup levels at

residential and industrial sites." Journal of Toxicology and Environmental Health. 

36:103-149.

Pope III C.A. and D.W. Dockery (1999). “Epidemiology of Particle Effects.” Air

Pollution and Health, Academic Press, 675-705.

Samet, J.M., F. Dominici, S.L. Zeger, J. Schwartz, and D.W. Dockery (2000). National

Morbidirt, Mortality, and Air Pollution Study, HEI Research Report No. 94, Health

Effects Institute, Cambridge, MA.

Tiernan, T.O., Taylor, M.L., Garrett, J.H., VanNess, G.F., Solch, J.G., Deis, D.A.,

Wagel, D.J. (1983). "Chlorodibenzodioxins, Chlorodibenzofuran and Related

Compounds in Effluents from Combustion Processes." Chemosphere. 12(4/5):595-

606.

(U.S. EPA). Code of Federal Regulations, Part 60, subparts Eb and Cb-New Source

Performance Standards and Guidelines for Large Municipal Waste Combustors;

subparts AAAA and BBBB-New Source Performance Standards and Emission

Guidelines for Small Municipal Waste Combustion Units; subparts Ec and Cc-new

Source Performance Standards and Emission Guidelines for Hospital, Medical, and

Infectious Waste Incinerators; subparts CCCC and DDDD-New Source Performance

Standards and Emission Guidelines for Commercial and Industrial Solid Waste

Incineration Units.

U.S. EPA (1987). Locating and Estimating Air Emissions from Sources of Polycyclic

Organic Species. U.S. Environmental Protection Agency, EPA-450/4-84-007.
IX-5

U.S. EPA (1989a). Interim Procedures for Estimating Risks Associated with Exposures

to Mixtures of Chlorinated Dibenzo-p-dioxins and -dibenzofurans (CDDs and CDFs) and

1989 update. U.S. Environmental Protection Agency. Risk Assessment Forum. 

Washington, D.C. EPA/625/3-89/016.

U.S. EPA (1989b). Locating and Estimating Air Emissions from Sources of 1,3-

Butadiene. United States Environmental Protection Agency, EPA-450/2-89-021. 

December, 1989.

U.S. EPA (1993a). Ambient Concentration Summaries for Clean Air Act Title III

Hazardous Air Pollutants. Kelly, T.J., Ramamurthi, M., Pollack, A.J., Spicer, C.W. and

L.T. Cupitt. U.S. Environmental Protection Agency, U.S. EPA Contract No. 68-D80082.

U.S. EPA, (1995a). ISCST3 Model User’s Guide, Volume I, EPA-454/B-95-003a,

United States Environmental Protection Agency (U.S. EPA), Research Triangle Park,

North Carolina, September 1995.

U.S. EPA, (1995b). ISCST3 Model User’s Guide, Volume II, EPA-454/B-95-003b,

United States Environmental Protection Agency (U.S. EPA), Research Triangle Park,

North Carolina, September 1995.

U.S. EPA (1997a). “Evaluation of Emissions from the Open Burning of Household

Waste in Barrels, Volume 1. Technical Report. Prepared by: Paul M. Lemieux, U.S.

Environmental Protection Agency, National Risk Management Research Laboratory, Air

Pollution Prevention and Control Division, Research Triangle Park, NC 27711. 

EPA-600/R-97-134a, November 1997. 

U.S. EPA (1997b). Locating and Estimating Air Emissions from Sources of Dioxins and

Furans. U.S. Environmental Protection Agency, Research Triangle Park, NC: Office of

Air Quality Planning and Standards. DCN No. 95-298-130-54-01.

U.S. EPA (2001a). “Dioxin: Database of Sources. Database of Sources of

Environmental Releases of Dioxin-like Compounds in the United States (Version 3.0 for

reference year 1987 and 1995).” URL: http//cfpub.epa.gov/ncea/cfm/dioxindb.cfm. 

September 19, 2001. U.S. Environmental Protection Agency, Office of Research and

Development, Washington D.C., 20460.

U.S. EPA (2001b). “Dioxin: Summary of the Dioxin Reassessment Science --

Information Sheet 1”. U.S. Environmental Protection Agency, Office of Research and

Development, Washington D.C., 20460. May 25, 2001.
A-1

APPENDIX A

Proposed Regulation Order:

Airborne Toxic Control Measure to Reduce Emissions of

Toxic Air Contaminants from Outdoor Residential Waste Burning
A-2

Proposed Regulation Order

Airborne Toxic Control Measure to Reduce Emissions of

Toxic Air Contaminants from Outdoor Residential Waste Burning

Adopt new section 93113, title 17, California Code of Regulations, to read as

follows:

93113 Airborne Toxic Control Measure to Reduce Emissions of Toxic Air

Contaminants from Outdoor Residential Waste Burning.

(a) Applicability.

(1) Notwithstanding section 41806(a) of the Health and Safety Code, this

regulation shall apply to persons conducting outdoor burning of

combustible or flammable waste generated from inside residences and

from outdoor activities associated with a residence, for the purpose of

disposing of the waste.

(2) This regulation shall apply to persons lighting fires that burn combustible

or flammable waste, as defined, outdoors in enclosed or partially enclosed

vessels, such as incinerators or burn barrels, or in an open outdoor fire,

such as in pits or in piles on the ground. This regulation shall not apply to

persons lighting fires at the direction of a public officer in an emergency

situation for public health or fire safety reasons, in accordance with

section 41801 of the Health and Safety Code or other provisions of law.

(3) Except as provided in (a)(1) and (a)(2) above, nothing in this regulation

shall affect the applicability of the provisions of article 2 and article 3,

respectively, of chapter 3 of part 4 of division 26 of the Health and Safety

Code.

(b) Definitions.

Terms used shall have the same definitions as in Health and Safety Code

section 39010 et. seq., unless otherwise indicated. For purposes of this regulation, the

following additional definitions shall apply:

(1) “Air Pollution Control District” (APCD), “Air Quality Management District”

(AQMD), “air district,” or “district” means the Governing Board of an air

pollution control district or an air quality management district created or

continued in existence pursuant to Health and Safety Code section 40000

et seq.
A-3

(2) "APCO" means the Air Pollution Control Officer or the chief executive

officer of the respective local air pollution control district or local air quality

management district where the property is located, or a designated

representative.

(3) "ARB" means the State of California Air Resources Board.

(4) "Air Toxic" means toxic air contaminants as defined in section 39655 (a)

of the Health and Safety Code.

(5) "Allowable Combustibles" means dry natural vegetation waste originating

on the premises and reasonably free of dirt, soil and visible surface

moisture.

(6) "Approved transfer station or disposal facility" means a transfer station,

landfill, or municipal waste incinerator with a valid operating permit from

the solid waste authority with jurisdiction over its operation.

(7) "Approved ignition device" means an instrument or material that will ignite

open fires without the production of black smoke by the ignition device, as

approved by the APCO.

(8) "Available regular waste pickup service" means the availability of

mandatory or voluntary regular waste collection service, through a

licensed waste hauler, by virtue of the residence's location within an area

franchised by the local jurisdiction with authority to delineate and to

franchise geographic service areas, or through regular waste collection

service provided directly by the local jurisdiction.

(9) "Burn Barrel" means a metal container used to hold combustible or

flammable waste materials so that they can be ignited outdoors for the

purpose of disposal.

(10) "Combustible" means any substance capable of burning or any substance

that will readily burn.

(11) "Communal or Community Dumpster" means a dumpster or bin at a fixed

location and used by more than one household, under contract with a

licensed waste hauler, for disposal of residential waste.

(12) "Disallowed Combustibles" means any waste or manufactured material,

including but not limited to petroleum products and petroleum wastes;

construction and demolition debris; coated wire; putrescible wastes; tires;

tar; tarpaper; non-natural wood waste; processed or treated wood and

wood products; metals; motor vehicle bodies and parts; rubber;

synthetics; plastics, including plastic film, twine and pipe; fiberglass;
A-4

styrofoam; garbage; trash; refuse; rubbish; disposable diapers; ashes;

glass; industrial wastes; manufactured products; equipment; instruments;

utensils; appliances; furniture; cloth; rags; paper or paper products;

cardboard; boxes; crates; excelsior; offal; swill; carcass of a dead animal;

manure; human or animal parts or wastes, including blood; and fecal- and

food-contaminated material. For purposes of this regulation, dry, natural

vegetation waste from yard maintenance is not a disallowed combustible,

if reasonably free of dirt, soil and surface moisture.

(13) "Flammable" means capable of catching fire easily, or combustible.

(14) "Incinerator" means any device constructed of nonflammable materials,

including containers commonly known as burn barrels, for the purpose of

burning therein trash, debris, and other flammable materials for volume

reduction or destruction.

(15) "Mandatory regular waste pickup service" means regular waste collection

provided to residences by a local agency or an approved waste hauler,

where the local waste authority has designated a franchise or a permit,

and where each household is required to pay for and use the pickup

service.

(16) "Natural vegetation" means all plants, including but not limited to grasses,

forbs, trees, shrubs, flowers, or vines that grow in the wild or under

cultivation. Natural vegetation excludes vegetative materials that have

been processed, treated or preserved with chemicals for subsequent

human or animal use, including but not limited to chemically-treated

lumber, wood products or paper products.

(17) "Open outdoor fire" means the combustion of combustible material of any

type outdoors in the open, not in any enclosure, where the products of

combustion are not directed through a flue.

(18) "Permissive burn day" or "burn day" means any day on which agricultural

burning, including prescribed burning, is not prohibited by the ARB and

agricultural and prescribed burning is authorized by the air district

consistent with the Smoke Management Guidelines for Agricultural and

Prescribed Burning, set forth in sections 80100-80330 of title 17 of the

California Code of Regulations.

(19) "Processed or treated wood and wood products" means wood that has

been chemically treated to retard rot or decay or wood that has been

modified with glues, laminates, stains, finishes, paints or glosses for use

in furniture or for construction purposes, including but not limited to

plywood, particle board, fencing or railroad ties. For the purposes of this

regulation, dimensional lumber that has been air-dried or kiln-dried, with
A-5

no preservatives or finishes added, is not considered processed or treated

wood.

(20) "Residence" means a single- or two-family dwelling unit and the land and

ancillary structures surrounding it.

(21) “Residential waste burning” means the disposal of the combustible or

flammable waste from a single- or two-family dwelling unit or residence by

burning outdoors. Residential waste burning is not agricultural, including

prescribed, burning.

(22) "Voluntary regular waste pickup service" means regular waste collection

offered to residences by a local agency or an approved waste hauler,

where the local waste authority has designated a franchise or a permit,

but where each household has the option of not paying for and receiving

the pickup service that is available.

(23) "Waste" means all discarded putrescible and non-putrescible solid,

semisolid, and liquid materials, including but not limited to petroleum

products and petroleum wastes; construction and demolition debris;

coated wire; tires; tar; tarpaper; wood waste; processed or treated wood

and wood products; metals; motor vehicle bodies and parts; rubber;

synthetics; plastics, including plastic film, twine and pipe; fiberglass;

styrofoam; garbage; trash; refuse; rubbish; disposable diapers; ashes;

glass; industrial wastes; manufactured products; equipment; instruments;

utensils; appliances; furniture; cloth; rags; paper or paper products;

cardboard; boxes; crates; excelsior; offal; swill; carcass of a dead animal;

manure; human or animal parts or wastes, including blood; fecal- and

food-contaminated material; felled trees; tree stumps; brush; plant

cuttings and prunings; branches; garden waste; weeds; grass clippings,

pine needles, leaves and other natural vegetation waste.

(c) Prohibitions.

(1) No person shall burn disallowed combustibles from any property for the

purpose of disposing of waste material outdoors at a residence, except as

provided under subsection (e), “Exemptions”, below.

(2) No person shall dispose of allowable combustibles from any property by

burning them in a burn barrel or incinerator outdoors, except as provided

under subsection (e), “Exemptions”, below.

(3) No person shall ignite, or allow to become ignited, allowable combustibles

unless using an approved ignition device.
A-6

(4) No person shall ignite, or allow to become ignited, allowable combustibles

unless it is a permissive burn day in the air district where the residential

waste burning is to take place.

(d) Compliance Schedule.

(1) For the purposes of Section 39666(d) of the Health and Safety Code, the

date of adoption of this regulation shall be ____________ [insert the date

of filing with the Secretary of State].

(2) Unless an air district adopts an earlier effective date under section

39666(d) of the Health and Safety Code, or applies for exemptions under

subsection (e), below, the prohibitions set forth in subsection (c), above,

shall become effective on July 1, 2003.

(e) Exemptions.

(1) The prohibitions described in subsections (c)(1) and (c)(2), above, of this

regulation shall not apply to any exempted geographic area described

under subsection (e)(5), below.

(2) Any air district seeking an exemption from subsections (c)(1) and (c)(2),

above, shall file a Request for Exemption in writing to ARB before

March 1, 2003. The requirements for a Request for Exemption are

described in subsection (e)(4), below.

(3) No air district shall file a Request for Exemption to allow the burning of

any disallowed combustible prohibited by air district rules in effect on

January 4, 2002. An air district shall not apply for an exemption for a

geographic area with a more stringent local ordinance, in effect on

January 4, 2002, prohibiting the burning of a disallowed combustible,

otherwise allowed by the air district.

(4) A Request for Exemption shall include:

(A) a resolution from the air district's Governing Board adopted at a

public hearing approving the Request for Exemption; and

(B) a map of the exempted geographic areas within their jurisdiction,

which meet the criteria listed in subsection (e)(5), below, and

(C) a detailed, written justification for the mapping, including a

demonstration that alternatives for waste disposal, other than

residential waste burning, are not likely to become available within

the five-year exemption period, and

(D) an analysis showing that local ordinances existing on January 4,

2002 do not prohibit the outdoor burning of the materials requested
A-7

for exemption, in any part of the exempted geographic area.

(5) The exempted geographic areas must meet criteria including, but not

limited to, all of the following:

(A) no mandatory or voluntary regular waste pickup service,

considering reasonable cost and frequency of service; and

(B) greater than a reasonable distance from an approved transfer

station or disposal facility or a communal or community dumpster,

considering road miles or time travelled, road conditions, terrain,

weather conditions, reasonable tipping fees, and hours of

operation; and

(C) low population density per census tract or other appropriate subunit

of the county area, including but not limited to zoning designation

or parcel size.

(6) ARB shall review the air district's Request for Exemption and approve or

disapprove the Request for Exemption, in writing, within 60 days after

submittal. The approval shall state the exempted geographic areas in the

air district where the prohibitions of subsections (c)(1) and (c)(2), above,

apply.

(7) If the initial Request for Exemption is disapproved, the ARB shall return

the Request for Exemption to the air district for amendment. The

disapproval shall include reasons for the denial and the air district shall be

afforded an additional 30 days from the date of denial to submit a revised

Request for Exemption.

(8) Within 30 days of receipt of the revised Request for Exemption, the ARB

shall approve or reject the revised Request for Exemption, and shall

designate the geographic areas where the prohibitions of (c)(1) and (c)(2)

do not apply.

(9) Every five years after ARB has approved an air district’s Request for

Exemption, the air district, with the concurrence of ARB, shall determine

whether to renew the exemption for an additional five years and whether

the mapped exempted geographic area(s) should be modified. In

renewing the exemption or in modifying the exempted geographic area(s),

the Governing Board of the air district shall make a finding at a public

hearing that the exemption criteria in (e)(5) are still applicable to the

renewed or modified exempted geographic area.

(10) Consultation with, and concurrence from, the ARB on the renewal and/or

modification of the exempted geographic areas shall continue every five

years thereafter until the exemption criteria are no longer met, at which

time the exemptions shall terminate.
A-8

NOTE: Authority cited: Sections 39600, 39601, 39659 and 39666, Health and Safety

Code. Reference: Sections 39020, 39044, 39650 through 39669, 39701, 41700 and

41806, Health and Safety Code.
B-1

APPENDIX B

Risk Assessment Results Using SCEEN3 Meteorological Conditions

And Site-specific Meteorological Data
B-2

This appendix includes five tables that summarize the potential health impacts for

residential waste burning using default meteorological conditions from SCREEN3 and

site-specific meteorological data from four locations across California (Alturas, Bishop,

San Benito, and Escondido). Both carcinogenic and non-carcinogenic individual health

impacts are presented at locations ranging from 20 meters to 1,000 meters downwind

from a single burn barrel. The tables also provide estimates of potential cancer risk for

each exposure pathway.

Table B-1. Overview of the Potential Health Impacts from Residential Waste

Burning Using the Meteorological Conditions from SCREEN3. 1,2

Distance (meters)

20 50 100 200 500 1000 Exposure

Pathways 3, 4

Cancer Risk (chances per million)

Inhalation 44 17 6.4 2.0 0.4 0.1

Soil Ingestion 16 6.1 2.2 0.7 0.2 0.05

Skin Exposure 14 5.5 2.0 0.6 0.1 0.04

Mothers Milk 5 8.9 3.5 1.3 0.4 0.09 0.03

Backyard Garden 56 22 8.1 2.6 0.5 0.2

Meat and Eggs 1010 397 146 46 9.7 3.0

Milk (cow) 1160 456 168 53 11 3.4

Total Cancer Risk 2309 907 334 106 22 6.7

Non-Cancer Hazard Indices

Acute Inhalation 6 0.02 0.008 0.003 0.0009 0.0002 0.00006

Chronic

Multipathway 7

0.08 -

2.0

0.03 -

0.78

0.01 -

0.29

0.004 -

0.091

0.0008 -

0.019

0.0002 -

0.0058

1. All results are rounded. Potential health impacts listed at 50, 100, 200, 500, and 1,000 meters are extrapolated from air

dispersion modeling results and risk at 20 meters. Emissions for dioxins and PCBs are from the U.S. EPA 2000 source tests. 

Emissions for benzene, 1,3-butadiene, and PAHs are from the U.S. EPA 1997 source tests.

2. All risk assessment results are based on a 70-year exposure for all pathways except the mother’s (breast) milk pathway (44-

year). Results are based on the CAPCOA Risk Assessment Guidelines methodology, HRA 2.0e, and the updated OEHHA

cancer potencies and reference exposure levels as of January 2001.

3. All pathways of exposure are assumed to occur at the same distance (location) from the source.

4. Emissions are assumed to be uncontrolled (0.05 factor). Multipathway route assumptions include: 15% of produce in the

receptor’s diet is homegrown; 100% of dietary meat (beef, pork, and chicken), eggs, and cow’s milk is impacted; 50% of cattle’s

diet is from impacted grassland and other feed is not contaminated; Farm animal drinking water is from a 300 gallon trough,

measuring one square meter, and is consumed every 3.75 days by one lactating cow.

5. PCB contribution calculated by ratio of PCB to PCDD body half-life (0.7) multiplied by the PCDD & PCDF mother’s milk to

inhalation ratio.

6. Benzene impacts were assessed using 6-hour average concentrations. Primary endpoints are cardiovascular or blood,

reproductive system, and immune system. 7. 

Dioxins, PAHs, and PCBs were assessed for chronic impacts. Includes both inhalation and non-inhalation exposure pathways. 

Primary endpoints are reproductive system, cardiovascular or blood, and nervous system. The lower end of the range includes

inhalation, soil, and dermal exposure pathways. The upper end of the range includes all exposure pathways, except mother’s

milk.
B-3

Table B-2. Overview of the Potential Health Impacts from Residential Waste

Burning Using the Alturas Meteorological Data 1,2

Distance (meters)

20 50 100 200 500 1000 Exposure

Pathways 3, 4

Cancer Risk (chances per million)

Inhalation 3.3 0.9 0.3 0.07 0.01 0.003

Soil Ingestion 1.2 0.3 0.1 0.03 0.004 0.001

Skin Exposure 1.0 0.3 0.1 0.02 0.004 0.001

Mothers Milk 5 0.7 0.2 0.06 0.02 0.003 0.0007

Backyard Garden 4.2 1.1 0.3 0.09 0.02 0.004

Meat and Eggs 75 20 6.1 1.7 0.3 0.08

Milk (cow) 86 23 6.9 1.9 0.3 0.09

Total Cancer Risk 172 46 14 3.9 0.7 0.2

Non-Cancer Hazard Indices

Acute Inhalation 6 0.01 0.005 0.002 0.001 0.0002 0.00008

Chronic

Multipathway 7 0.15 0.04 0.01 0.003 0.0006 0.0001

1. All results are rounded. Potential health impacts listed at 50, 100, 200, 500, and 1,000 meters are extrapolated from air

dispersion modeling results and risk at 20 meters. Emissions for dioxins and PCBs are from the U.S. EPA 2000 source tests. 

Emissions for benzene, 1,3-butadiene, and PAHs are from the U.S. EPA 1997 source tests.

2. All risk assessment results are based on a 70-year exposure for all pathways except the mother’s (breast) milk pathway (44-

year). Results are based on the CAPCOA Risk Assessment Guidelines methodology, HRA 2.0e, and the updated OEHHA

cancer potencies and reference exposure levels as of January 2001.

3. All pathways of exposure are assumed to occur at the same distance (location) from the source.

4. Emissions are assumed to be uncontrolled (0.05 factor). Multipathway route assumptions include: 15% of produce in the

receptor’s diet is homegrown; 100% of dietary meat (beef, pork, and chicken), eggs, and cow’s milk is impacted; 50% of cattle’s

diet is from impacted grassland and other feed is not contaminated; Farm animal drinking water is from a 300 gallon trough,

measuring one square meter, and is consumed every 3.75 days by one lactating cow.

5. PCB contribution calculated by ratio of PCB to PCDD body half-life (0.7) multiplied by the PCDD & PCDF mother’s milk to

inhalation ratio.

6. Benzene impacts were assessed using 6-hour average concentrations. Primary endpoints are cardiovascular or blood,

reproductive system, and immune system.

7. Dioxins, PAHs, and PCBs were assessed for chronic impacts. Includes both inhalation and non-inhalation exposure pathways. 

Primary endpoints are reproductive system, cardiovascular or blood, and nervous system.
B-4

Table B-3. Overview of the Potential Health Impacts from Residential Waste

Burning Using the Bishop Meteorological Data 1,2

Distance (meters)

20 50 100 200 500 1000 Exposure

Pathways 3, 4

Cancer Risk (chances per million)

Inhalation 4.6 1.2 0.4 0.1 0.02 0.005

Soil Ingestion 1.6 0.4 0.1 0.04 0.007 0.002

Skin Exposure 1.4 0.4 0.1 0.03 0.006 0.002

Mothers Milk 5 1.0 0.3 0.08 0.02 0.004 0.001

Backyard Garden 5.8 1.5 0.5 0.1 0.02 0.007

Meat and Eggs 105 28 8.4 2.4 0.4 0.1

Milk (cow) 120 32 9.6 2.8 0.5 0.1

 

Total Cancer Risk 239 63 19 5.5 1.0 0.3

Non-Cancer Hazard Indices

Acute Inhalation 6 0.02 0.008 0.003 0.001 0.0002 0.00007

Chronic

Multipathway 7 0.2 0.05 0.02 0.005 0.0009 0.0002

1. All results are rounded. Potential health impacts listed at 50, 100, 200, 500, and 1,000 meters are extrapolated from air

dispersion modeling results and risk at 20 meters. Emissions for dioxins and PCBs are from the U.S. EPA 2000 source tests. 

Emissions for benzene, 1,3-butadiene, and PAHs are from the U.S. EPA 1997 source tests.

2. All risk assessment results are based on a 70-year exposure for all pathways except the mother’s (breast) milk pathway (44-

year). Results are based on the CAPCOA Risk Assessment Guidelines methodology, HRA 2.0e, and the updated OEHHA

cancer potencies and reference exposure levels as of January 2001.

3. All pathways of exposure are assumed to occur at the same distance (location) from the source.

4. Emissions are assumed to be uncontrolled (0.05 factor). Multipathway route assumptions include: 15% of produce in the

receptor’s diet is homegrown; 100% of dietary meat (beef, pork, and chicken), eggs, and cow’s milk is impacted; 50% of cattle’s

diet is from impacted grassland and other feed is not contaminated; Farm animal drinking water is from a 300 gallon trough,

measuring one square meter, and is consumed every 3.75 days by one lactating cow.

5. PCB contribution calculated by ratio of PCB to PCDD body half-life (0.7) multiplied by the PCDD & PCDF mother’s milk to

inhalation ratio.

6. Benzene impacts were assessed using 6-hour average concentrations. Primary endpoints are cardiovascular or blood,

reproductive system, and immune system.

7. Dioxins, PAHs, and PCBs were assessed for chronic impacts. Includes both inhalation and non-inhalation exposure pathways. 

Primary endpoints are reproductive system, cardiovascular or blood, and nervous system.
B-5

Table B-4. Overview of the Potential Health Impacts from Residential Waste

Burning Using the San Benito Meteorological Data 1,2

Distance (meters)

20 50 100 200 500 1000 Exposure

Pathways 3, 4

Cancer Risk (chances per million)

Inhalation 6.4 1.7 0.5 0.1 0.02 0.006

Soil Ingestion 2.2 0.6 0.2 0.05 0.008 0.002

Skin Exposure 2.0 0.5 0.2 0.04 0.008 0.002

Mothers Milk 5 1.3 0.3 0.1 0.03 0.005 0.001

Backyard Garden 8 2.1 0.6 0.2 0.03 0.008

Meat and Eggs 145 38 12 3.2 0.6 0.1

Milk (cow) 166 44 13 3.7 0.6 0.2

 

Total Cancer Risk 331 88 26 7.3 1.3 0.3

Non-Cancer Hazard Indices

Acute Inhalation 6 0.02 0.008 0.003 0.001 0.0002 0.00008

Chronic

Multipathway 7 0.3 0.08 0.02 0.006 0.001 0.0003

1. All results are rounded. Potential health impacts listed at 50, 100, 200, 500, and 1,000 meters are extrapolated from air

dispersion modeling results and risk at 20 meters. Emissions for dioxins and PCBs are from the U.S. EPA 2000 source tests. 

Emissions for benzene, 1,3-butadiene, and PAHs are from the U.S. EPA 1997 source tests.

2. All risk assessment results are based on a 70-year exposure for all pathways except the mother’s (breast) milk pathway (44-

year). Results are based on the CAPCOA Risk Assessment Guidelines methodology, HRA 2.0e, and the updated OEHHA

cancer potencies and reference exposure levels as of January 2001.

3. All pathways of exposure are assumed to occur at the same distance (location) from the source.

4. Emissions are assumed to be uncontrolled (0.05 factor). Multipathway route assumptions include: 15% of produce in the

receptor’s diet is homegrown; 100% of dietary meat (beef, pork, and chicken), eggs, and cow’s milk is impacted; 50% of cattle’s

diet is from impacted grassland and other feed is not contaminated; Farm animal drinking water is from a 300 gallon trough,

measuring one square meter, and is consumed every 3.75 days by one lactating cow.

5. PCB contribution calculated by ratio of PCB to PCDD body half-life (0.7) multiplied by the PCDD & PCDF mother’s milk to

inhalation ratio.

6. Benzene impacts were assessed using 6-hour average concentrations. Primary endpoints are cardiovascular or blood,

reproductive system, and immune system.

7. Dioxins, PAHs, and PCBs were assessed for chronic impacts. Includes both inhalation and non-inhalation exposure pathways. 

Primary endpoints are reproductive system, cardiovascular or blood, and nervous system.
B-6

Table B-5. Overview of the Potential Health Impacts from Residential Waste

Burning Using the Escondido Meteorological Data 1,2

Distance (meters)

20 50 100 200 500 1000 Exposure

Pathways 3, 4

Cancer Risk (chances per million)

Inhalation 8.2 2.2 0.7 0.2 0.03 0.009

Soil Ingestion 2.9 0.8 0.2 0.07 0.01 0.003

Skin Exposure 2.6 0.7 0.2 0.06 0.01 0.003

Mothers Milk 5 1.7 0.5 0.1 0.04 0.007 0.002

Backyard Garden 10 2.8 0.9 0.2 0.04 0.01

Meat and Eggs 187 51 15 4.3 0.8 0.2

Milk (cow) 215 58 18 4.9 0.9 0.2

 

Total Cancer Risk 428 116 35 9.8 1.7 0.5

Non-Cancer Hazard Indices

Acute Inhalation 6 0.02 0.008 0.003 0.0009 0.0002 0.00005

Chronic

Multipathway 7 0.4 0.1 0.03 0.008 0.001 0.0004

1. All results are rounded. Potential health impacts listed at 50, 100, 200, 500, and 1,000 meters are extrapolated from air

dispersion modeling results and risk at 20 meters. Emissions for dioxins and PCBs are from the U.S. EPA 2000 source tests. 

Emissions for benzene, 1,3-butadiene, and PAHs are from the U.S. EPA 1997 source tests.

2. All risk assessment results are based on a 70-year exposure for all pathways except the mother’s (breast) milk pathway (44-

year). Results are based on the CAPCOA Risk Assessment Guidelines methodology, HRA 2.0e, and the updated OEHHA

cancer potencies and reference exposure levels as of January 2001.

3. All pathways of exposure are assumed to occur at the same distance (location) from the source.

4. Emissions are assumed to be uncontrolled (0.05 factor). Multipathway route assumptions include: 15% of produce in the

receptor’s diet is homegrown; 100% of dietary meat (beef, pork, and chicken), eggs, and cow’s milk is impacted; 50% of cattle’s

diet is from impacted grassland and other feed is not contaminated; Farm animal drinking water is from a 300 gallon trough,

measuring one square meter, and is consumed every 3.75 days by one lactating cow.

5. PCB contribution calculated by ratio of PCB to PCDD body half-life (0.7) multiplied by the PCDD & PCDF mother’s milk to

inhalation ratio.

6. Benzene impacts were assessed using 6-hour average concentrations. Primary endpoints are cardiovascular or blood,

reproductive system, and immune system.

7. Dioxins, PAHs, and PCBs were assessed for chronic impacts. Includes both inhalation and non-inhalation exposure pathways. 

Primary endpoints are reproductive system, cardiovascular or blood, and nervous system.
C-1

APPENDIX C

Air Dispersion Modeling of Emissions

from Burn Barrels
C-2

Air Dispersion Modeling of Emissions

from Burning Barrels

Summary

The air dispersion of emissions from burning trash in domestic burning barrels is

evaluated to estimate downwind impacts. This analysis is based on an emission rate of

1 g/s input into the U.S. EPA air dispersion models, Industrial Source Complex – Short

Term 3 (ISCST3) and SCREEN3. As a result, the estimated short-term and long-term

average air concentrations may be directly scaled by the actual emission rate to

estimate downwind concentrations of actual pollutants. A summary of the results is

shown in Table C-1 below. A detailed description of the analysis with sensitivity studies

follow.

As an example, shown in Table C-1 below, the maximum annual average χ/q for

emissions from a burning barrel, based on meteorological data collected in Escondido,

is 1920 (μg/m3

)/(g/s) at the nearest receptor, 20 meters from the source. This is based

Table C-1

Maximum Annual Average Concentration (χ/q)

Above Ambient Conditions - Burning Barrel Emissions 

Met.

County

Modoc Inyo San Benito San Diego

Met. City Alturas Bishop San

Benito

Escondido SCREENING

Notes (a) (a) (a) (a) (b)

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3

)/(g/s)

20 773. 1070. 1490. 1920. 590.

50 206. 284. 395. 521. 232.

100 62.1 85.6 119. 158. 85.4

200 17.3 24.6 33.0 43.9 27.1

500 3.01 4.48 5.66 7.71 5.65

1000 0.78 1.22 1.47 2.03 1.73

Notes:(a) Annual χ/q for site specific meteorological data is based on

3,654 hours of emissions at 1 g/s.

(b) Annual χ/q for Screening analysis is based on 208 hours of

emissions at 1 g/s.

(c) χ/q is the concentration in μg/m3

 based on an hourly emission

rate of 1 g/s.

(d) Results are valid for two significant digits. Three significant

digits are reported to reduce round off error in subsequent calculations.

(e) Burning is permitted 12 months per year.
C-3

on uniformly distributing the emissions from burning over an assumed 3,654 daylight

hours in a year. Further description on how these values are derived is provided below.

Analysis

This analysis estimates the downwind concentration of emissions from burn barrels for

annual averages and six-hour averages. The following parameters are established for

the operating conditions of a domestic burning barrel based on discussions with various

air districts and at the committee meetings.

Burn Barrel Parameters

• Burning will occur during daylight hours.

• One family may burn twice per week.

• Each burn may last for two hours.

• Each burn can be at any time during a day.

• The final plume height is from 2 meters close to the barrel to a maximum of

4 meters further away from the barrel. Since maximum concentrations are

located close to the barrel, the final plume rise will be fixed at 2 meters.

• Perform a sensitivity study for periods for when burn bans are in effect

(i.e., June 15 to October 15 burn restrictions).

• Evaluate meteorological conditions for the following meteorological climates.

- Screening (Worst-Case Maximum)

- Modoc County

- Great Basin Air District Counties

- Monterey / San Benito Counties

- Eastern San Diego County

Based on the above parameters, we decided to simulate the release of emissions from

a burning barrel as a volume source in the ISCST3 and SCREEN3 air dispersion

models. The initial dispersion of the plume and the final plume rise of the plume will be

static regardless of atmospheric conditions. In this way, the calculations are consistent

with air district and committee recommendations on burn barrel plume conditions. The

following initial conditions are calculated for the above list of parameters.

Initial Conditions for Model Input

• σyo = σzo = L/4.3 = 1m / 4.3 = 0.23 meters

• Hfinal-plume-rise = 2 meters

• Hflagpole-receptor-height = 1 meter

• Minimum receptor distance to source = 20 meters

• Daylight hours defined as the following.

Winter 9am to 5pm (8 hours)

Spring 8am to 6pm (10 hours)

Summer 7am to 7pm (12 hours)

Fall 8am to 6pm (10 hours)

• Rural Dispersion Coefficients
C-4

Meteorological data are obtained from various California Irrigation Management

Information System (CIMIS) stations to represent the locations indicated above. CIMIS

stations are managed by the California Department of Water Resources. CIMIS data

are collected on two meter towers which is consistent with the plume height estimates

for the burn barrels. The atmospheric stability classes are based on the heat flux

method as described in U.S. EPA 8/95 and Pasquill 1983.

The nearby city for the CIMIS stations to represent the various county regions are

Alturas (Modoc County), Bishop (Great Basin District Counties), San Benito (San Benito

County), and Escondido (San Diego County). In all cases, we attempted to obtain the

latest consecutive five years of meteorological data as recommended by U.S. EPA

Guidelines. The data collected at Alturas, Bishop, and San Benito meets these

requirements for data from 1996 through 2000. The station located at Escondido

began collecting data in 1999. Therefore only the latest complete year, 2000, was

available for processing. Attachment B shows CIMIS information for the location of

each station in our analysis. 

Annual Average Concentration

The annual average concentration is assessed in a screening mode to estimate an

upper bound calculation as well as a refined mode to estimate a site specific

calculation. The refined modeling assessment is based on inputting meteorological

data from the four CIMIS stations, separately, into the ISCST3 air dispersion model. In

addition, the refined modeling assessment for estimating annual average

concentrations is based on uniformly distributing the emissions over all possible

operating hours on a daily basis. That is 8 hours, 10 hours, 12 hours, and 10 hours for

each of the fours seasons, respectively. As a result, the emissions are distributed over

3,654 hours in a year. This is critical for the health risk assessment which is based on

the annual average concentration. The emission rate on a gram per second basis for

estimating annual average concentrations from the refined χ/q the emissions should be

prorated over 3,654 hours.

The SCREEN3 air dispersion model is used to estimate the upper bound annual

average concentration. Initially, the SCREEN3 air dispersion model is used to estimate

the maximum one-hour concentration. The results from the SCREEN3 model show

that the maximum 1-hour concentration (χ/q) is 81,560 μg/m3

 at 20 meters for F stability

and 1 m/s wind speed. F stability is a stable condition that only occurs at night. 

Since one of the assumptions for the burn barrels is that emissions are for daylight

hours, the SCREEN3 model is used again for the next incremental stability class which

is a daytime neutral condition, D stability. The results from the SCREEN3 model show

the maximum 1-hour concentration (χ/q) is 49,550 μg/m3 at 20 meters for D stability. 
C-5

The standard procedure for estimating long-term (annual) averages from maximum 1-

hour averages is to apply the U.S. EPA scaling factor of 0.08. The screening factor of

0.08 is ideally used when the emissions are continuous over all hours of the year

(8760 hours/year). However, in the case for the burning barrels, it is assumed

emissions are for two hours per burn and two burns per week (208 hours/year).

Although not explicitly indicated in the U.S. EPA Guidance, the U.S. EPA screening

factor of 0.08 to estimate the annual average concentration from maximum 1-hour

concentration inevitably includes the effects of varying conditions of wind speed, wind

direction, and atmospheric stability over a year period.

Intermittent emissions, such as those from the burning barrels, could have the effect of

eliminating some of the annual variability of meteorological conditions. For example,

emissions only during the daytime could eliminate the variability of a drainage flow

pattern in mountainous terrain. Guidance for estimating long term averages for a

screening approach and intermittent emissions is not available. In the interim, we

recommend the following approach to estimate long term averages from a source with a

burning barrel schedule. Equation Box 1 shows an example that is described below.

Estimate the maximum one-hour concentration based on the SCREEN3 model

approach for possible meteorological conditions consistent with operating conditions. In

this case, the conditions are restricted to daytime neutral or unstable atmospheric

conditions. Estimate the concentration for the averaging period consistent with the

Equation Box 1

( )( ) 8 1 3 3 49,550 (0.5)(0.25) 6,194

8

2

0.5

m

g

m

g

hrs

hrs

period

burning

hr hr

μ μ χ χ  = 

 



 =















− = −

( )( )( )( ) ( )( )

hrs yr

year

non burn period hours

year

weeks

week

periods

period

hrs

hr

annual 8760 /

8 8 2 52 0 7928 − − −− + = χ

χ

( )( )( )

3 3 590

8760

8 2 52 6,194

m

g

m

g

annual

μ μ χ  =



 









 



 =





 





−

− 





 





  =



 









 











 











 









 











 





  =



 





lb s

g yr

yr

lbs Q

s

hr

wk

yr

days

wk

hrs

day

lb

g

yr

lbs Q

s

g qannual 748,800453.6

2 2 52 3600

453.6

( )( ) annual annual Concentration = χ q
C-6

operating conditions. In this case, emissions could occur during the daylight, an 8-hour

window during the winter and a 12-hour window during the summer. Therefore,

estimate the 8-hour concentration. Use the U.S. EPA screening factor of 0.7 ± 0.2 to

estimate the maximum 8-hour concentration. In addition, the emissions are prorated

over the 8 hours (i.e., 2hrs/8hrs).

The U.S. EPA Screening Guidance allows for deviation from the suggested

conversion factor on a case-by-case basis. We recommend the lower end of the

conversion factor (i.e., 0.5) because variability associated with seasonal differences in

wind speed, wind direction, and atmospheric stability would not be accounted for

otherwise.

The worst-case annual average screening concentration can be estimated by

assuming the worst-case 8-hour concentration occurs during each burn and no

emissions occur during all other hours in a year. Estimating the worst-case annual

average concentration is a matter of prorating the 8-hour concentration over an annual

average, as shown in the Equation Box 1.

The emission rate on a gram per second basis for estimating annual average

concentrations from the above χ/q now needs to be calculated based on the prorated

year (208 hours) instead of the full year (8760 hours). An example is shown in

Equation Box 1. This step is necessary for estimating risk with the Health Risk

Assessment Program.

Other Results

Table 1, above, shows the maximum annual average concentration (χ/q) for the burning

barrel emissions. Table 2, below, shows the maximum 6-hour average concentration

(χ/q) for the burning barrel emissions.

The six-hour average is based on the maximum two-hour average concentration

because of the assumption that the burns last for only two hours. The example

calculation in Equation Box 2 shows the method used to estimate the maximum sixhour concentration for Alturas. A similar method is used to estimate the six-hour

average in a screening mode from the maximum 1-hr concentration.

Equation Box 2

Example calculation for Alturas maximum 6-hour average at

20 meters from the source.

( )

( ) ( ) ( ) ( )( )

( )

( )( ) 



 



  =



 



 = + =





 



 =

−

−

−

3 3

2

6

2 3

16,290

6

48,871 2

6

2 0 4

48,871 ,( _ 3 _ )

m

g

m

g

hrs

hrs hrs

from ISCST output

m

g

HR

HR

HR

χ μ μ χ

μ χ
C-7

Attachment A shows sensitivity study results for evaluating the differences when

estimating concentrations in the non-predominant wind direction, as well as evaluating

the scenario of a burn ban for four months per year.

Table C-2

Maximum 6-hour Average Concentration (χ/q)

Above Ambient Conditions – Burning Barrel Emissions

Met.

County

Modoc Inyo San Benito San Diego

Met. City Alturas Bishop San Benito Escondido SCREENING

Notes (a) (a),(b) (a),(b) (a) (a)

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s)

20 16,300 17,800 18,800 15,400 16,500

50 7,170 7,370 7,880 5,940 6,490

100 3,570 2,860 3,120 2,160 2,390

200 1,400 945 1,040 678 758

500 334 202 227 139 158

1,000 110 63 71 42 48

Notes: (a) Six-hour maximum χ/q is based on 2 hours of emissions at 1 g/s and 4 hours of zero

emissions.

(b) χ/q for Inyo and San Benito is higher than for screening analysis. This is a result of slightly

stable conditions (E Stability) used for one of the two hours of emissions. This is a direct result of the

method used to distribute emissions over the seasons. The screening analysis assumes emissions are

for daytime (neutral or unstable) conditions.

(c) χ/q is the concentration in μg/m3

 based on an hourly emission rate of 1 g/s.

(d) Results are valid for two significant digits. Three significant digits are reported to reduce

round off error in subsequent calculations.
C-8

References for Appendix C

Marks’ Standard Handbook for Mechanical Engineers, 1987, McGraw-Hill, Inc.

Pasquill, Atmospheric Diffusion, 3rd Ed., 1983, Figure 6.10. 

U.S. EPA, Evaluation of Emissions From the Open Burning of Household Waste in

Barrels, Volume 1. Technical Report, November 1997, EPA-600/R-97-134a

U.S. EPA, Screening Procedures for Estimating the Air Quality Impact of Stationary

Sources, Revised, October 1992, EPA-454/R-92-019

U.S. EPA, User’s Guide for the Industrial Source Complex (ISC3) Dispersion Models,

September 1995, EPA-454/B-95-003a

U.S. EPA, Appendix W to Part 51 - Guideline on Air Quality Models, 2001

U.S. EPA, On-Site Meteorological Program Guidance For Regulatory Modeling

Applications, 8/95.
C-9

Attachment A

Sensitivity Study

Tables A-1 through A-6 show the results from sensitivity studies of various aspects of

the burning barrel evaluation. The primary focus of the sensitivity study are the effects

of burning restrictions during fire hazard seasons on downwind impacts. We note that

under certain years of high fire hazard, restrictions on burning may restrict the use of

burning barrels. In this sensitivity analysis, we assumed that a burning restriction is in

place from June 15 to October 15. Table CA-2 (w/burn restrictions) can be compared

to Table C-1 of the main text (w/o burn restrictions) to evaluate the differences caused

by the burn restrictions on the annual average concentration.

Another sensitivity study evaluates the maximum and minimum concentrations through

the evaluation of the predominant and non-predominant wind direction. Tables C-1 and

CA-1, C-2 and CA-4, and CA-2 & CA-3 show the minimum concentration in the nonpredominant wind direction for various averaging periods.

The final sensitivity study is to report the maximum two hour average concentration in

Tables A-5 and A-6 for both the predominant and non-predominant wind directions. 

The two hour concentrations are used to construct the six hour average concentrations

shown in Tables C-2 and CA-4.

The following list gives a brief description of each table.

Annual Average Concentrations Above Ambient Conditions

Table CA-1

Annual Average Concentration (χ/q)

Non-Predominant Wind Direction

Table CA-2

Maximum Annual Average Concentration (χ/q)

Predominant Wind Direction

(Burning is Restricted from 6/15 – 10/15)

Table CA-3

Annual Average Concentration (χ/q)

Non-Predominant Wind Direction

(Burning is Restricted from 6/15 – 10/15)
C-10

Six Hour Average Concentrations Above Ambient Conditions

Table CA-4

Six-Hour Average Concentration (χ/q)

Non-Predominant Wind Direction

Two Hour Average Concentration Above Ambient Conditions

Table CA-5

Two-Hour Maximum Average Concentration (χ/q)

Predominant Wind Direction

Table CA-6

Two-Hour Average Concentration (χ/q)

Non-Predominant Wind Direction

Table CA-1

Annual Average Concentration (χ/q)

Non-Predominant Wind Direction

Above Ambient Conditions - Burning Barrel Emissions

Met. City Alturas Bishop San Benito Escondido

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s)

20 145. 162. 70.9 41.0

50 42.5 39.2 21.6 11.0

100 13.5 11.2 6.96 3.28

200 3.85 2.99 2.00 0.88

500 0.69 0.47 0.36 0.15

1,000 0.19 0.11 0.10 0.04

Notes:(a) χ/q for site specific meteorological data is based on

3,654 hours of emissions at 1 g/s.

(b) Results are valid for two significant digits. Three

significant digits are reported to reduce round off error in

subsequent calculations.

(c) Burning is permitted 12 months per year.
C-11

Table CA-2

Maximum Annual Average Concentration (χ/q)

Above Ambient Conditions - Burning Barrel Emissions

(Burning is Restricted from 6/15 – 10/15)

Met. City Alturas Bishop San

Benito

Escondido SCREENI

NG

Notes (a) (a) (a) (a) (b)

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s)

20 571. 812. 1330. 1860. 393.

50 162. 277. 353. 514. 154.

100 50.3 88.3 106. 157. 56.9

200 14.5 25.4 29.4 44.4 18.1

500 2.72 4.61 5.05 7.83 3.76

1,000 0.77 1.26 1.30 2.06 1.15

Notes: (a) χ/q for site specific meteorological data is based on 2,280 hours of 

emissions at 1 g/s.

(b) χ/q for Screening analysis is based on 139 hours of emissions at 1 g/s.

(c) χ/q is the concentration in μg/m3

 based on an hourly emission rate of 1 g/s.

(d) Results are valid for two significant digits. Three significant digits are

reported to reduce round off error in subsequent calculations.

Table CA-3

Annual Average Concentration (χ/q)

Non-Predominant Wind Direction

Above Ambient Conditions – Burning Barrel Emissions

(Burning is Restricted from 6/15 – 10/15)

Met. City Alturas Bishop San

Benito

Escondido

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s)

20 157. 246. 87.1 40.8

50 45.4 35.4 27.5 10.6

100 14.4 10.2 8.79 3.16

200 4.12 2.72 2.51 0.86

500 0.74 0.44 0.46 0.14

1,000 0.20 0.10 0.12 0.04

Notes:(a) χ/q for site specific meteorological data is based on 2,280

hours of emissions at 1 g/s.

(b) χ/q is the concentration in μg/m3

 based on an hourly

emission rate of 1 g/s.

(c) Results are valid for two significant digits. Three significant

digits are reported to reduce round off error in subsequent calculations.
C-12

Table CA-4

Six-Hour Average Concentration (χ/q)

Non-Predominant Wind Direction

Above Ambient Conditions – Burning Barrel Emissions

Met. City Alturas Bishop San

Benito

Escondido

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s)

20 10,244 7,940 8,224 5,674

50 3,629 2,982 3,228 1,753

100 1,283 1,086 1,190 591

200 393 340 377 171

500 79 70 78 31

1,000 24 21 24 8

Notes: (a) χ/q for site specific meteorological data is based on 2

hours of burning and 4 hours of no burning with emissions at 1 g/s.

(b) χ/q is the concentration in μg/m3

 based on an hourly

emission rate of 1 g/s.

(c) Results are valid for two significant digits. Three

significant digits are reported to reduce round off error in subsequent

calculations.
C-13

Table CA-5

Two Hour Maximum Acute Average Concentration (χ/q)

Above Ambient Conditions – Burning Barrel Emissions

Met.

City

Alturas Bishop San

Benito

Escondid

o

SCREENIN

G

Avg. Two HR Two HR Two HR Two HR One HR

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s)

20 43,200 53,300 56,500 46,200 49,600

50 21,500 22,000 23,600 17,800 19,500

100 10,700 8,590 9,370 6,490 7,170

200 4,210 2,840 3,130 2,030 2,280

500 1,000 607 681 416 474

1,000 330 188 214 125 145

Notes: (a) χ/q is the concentration in μg/m3 based on an hourly emission rate of

1 g/s.

(b) Results are valid for two significant digits. Three significant digits are

reported to reduce round off error in subsequent calculations.

Table CA-6

Two-Hour Average Concentration (χ/q)

Non-Predominant Wind Direction

Above Ambient Conditions – Burning Barrel Emissions

Met.

City

Alturas Bishop San Benito Escondido

D (m) (μg/m3

)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s) (μg/m3)/(g/s)

20 30,700 23,800 24,700 17,000

50 10,900 8,940 9,690 5,260

100 3,850 3,260 3,570 1,770

200 1,180 1,020 1,130 512

500 236 209 235 93

1,000 72 63 72 25

Notes: (a) χ/q is the concentration in μg/m3 based on an hourly

emission rate of 1 g/s for two hours.

(b) Results are valid for two significant digits. Three

significant digits are reported to reduce round off error in subsequent

calculations.
C-14

Attachment B

CIMIS Details for Meteorological Stations

STATION NO. = 90 MAINT. BY = M-DWR

STATION NAME = Alturas ELEVATION = 4405 ft.

COUNTY = Modoc LATITUDE = 41D26'18"N (41.4383)

REGION = Northeast Plateau LONGITUDE = 120D28'45"W (120.4792)

NEARBY CITY = Alturas START DATE = 4/23/89

OWNER = University of California END DATE = ACTIVE

MAINT. PERSON = Northern District

STATION NO. = 126 MAINT. BY = M-OWN

STATION NAME = San Benito ELEVATION = 340 ft.

COUNTY = San Benito LATITUDE = 36D51'15"N

REGION = Monterey Bay LONGITUDE = 121D21'42"W

NEARBY CITY = Hollister START DATE = 6/ 9/94

OWNER = San Benito County Water Dist END DATE = ACTIVE

MAINT. PERSON = San Joaquin District

STATION NO. = 143 MAINT. BY =

STATION NAME = San Juan Valley ELEVATION = 245 ft.

COUNTY = San Benito LATITUDE = 36D49'23"

REGION = Monterey Bay LONGITUDE = 121D28'03"

NEARBY CITY = Hollister START DATE = 1/ 1/98

OWNER = Lisa Kemmer/San Benito WD END DATE = ACTIVE

MAINT. PERSON =

STATION NO. = 35 MAINT. BY = M-DWR

STATION NAME = Bishop ELEVATION = 4170 ft.

COUNTY = Inyo LATITUDE = 37D21'29"N

REGION = Bishop LONGITUDE = 118D24'14"W

NEARBY CITY = Bishop START DATE = 2/ 4/83

OWNER = DWR END DATE = ACTIVE

MAINT. PERSON = Southern District

STATION NO. = 153 MAINT. BY =

STATION NAME = Escondido SPV ELEVATION = 390 ft.

COUNTY = San Diego LATITUDE = 33D04'52"

REGION = South Coast/Valley LONGITUDE = 116D58'33"

NEARBY CITY = Escondido START DATE = 2/ 1/99

OWNER = END DATE = ACTIVE

MAINT. PERSON =
C-15

Attachment C

SCREEN3 Model Results

11/13/01

 15:11:28

 *** SCREEN3 MODEL RUN ***

 *** VERSION DATED 96043 ***

 Burn Barrel 

 SIMPLE TERRAIN INPUTS:

 SOURCE TYPE = VOLUME

 EMISSION RATE (G/S) = 1.00000 

 SOURCE HEIGHT (M) = 2.0000

 INIT. LATERAL DIMEN (M) = .2300

 INIT. VERTICAL DIMEN (M) = .2300

 RECEPTOR HEIGHT (M) = 1.0000

 URBAN/RURAL OPTION = RURAL

 THE REGULATORY (DEFAULT) MIXING HEIGHT OPTION WAS SELECTED.

 THE REGULATORY (DEFAULT) ANEMOMETER HEIGHT OF 10.0 METERS WAS ENTERED.

 BUOY. FLUX = .000 M**4/S**3; MOM. FLUX = .000 M**4/S**2.

 *** STABILITY CLASS 4 ONLY ***

 *** TERRAIN HEIGHT OF 0. M ABOVE STACK BASE USED FOR FOLLOWING DISTANCES ***

 DIST CONC U10M USTK MIX HT PLUME SIGMA SIGMA

 (M) (UG/M**3) STAB (M/S) (M/S) (M) HT (M) Y (M) Z (M) DWASH

 ------- ---------- ---- ----- ----- ------ ------ ------ ------ -----

 20. .4955E+05 4 1.0 1.0 320.0 2.00 2.01 1.30 NO

 50. .1946E+05 4 1.0 1.0 320.0 2.00 4.47 2.68 NO

 100. 7173. 4 1.0 1.0 320.0 2.00 8.36 4.78 NO

 200. 2275. 4 1.0 1.0 320.0 2.00 15.71 8.62 NO

 500. 474.2 4 1.0 1.0 320.0 2.00 36.28 18.36 NO

 1000. 144.9 4 1.0 1.0 320.0 2.00 68.25 32.10 NO

 DWASH= MEANS NO CALC MADE (CONC = 0.0)

 DWASH=NO MEANS NO BUILDING DOWNWASH USED

 DWASH=HS MEANS HUBER-SNYDER DOWNWASH USED

 DWASH=SS MEANS SCHULMAN-SCIRE DOWNWASH USED

 DWASH=NA MEANS DOWNWASH NOT APPLICABLE, X<3*LB

 ***************************************

 *** SUMMARY OF SCREEN MODEL RESULTS ***

 ***************************************

 CALCULATION MAX CONC DIST TO TERRAIN

 PROCEDURE (UG/M**3) MAX (M) HT (M)

 -------------- ----------- ------- -------

 SIMPLE TERRAIN .4955E+05 20. 0.

 ***************************************************

 ** REMEMBER TO INCLUDE BACKGROUND CONCENTRATIONS **

 ***************************************************
C-16

Attachment D

Example ISCST3 Input File / Output File

(Note: In the interest of brevity, only those pages deemed most prevalent from the

ISCST3 output have been reproduced here. The entire input/output files are available

on request.)

CO STARTING

 TITLEONE Burning Barrel Analysis

 TITLETWO Modoc County, Alturas Met. Data

 MODELOPT DFAULT RURAL CONC

 AVERTIME 1 2 6 PERIOD

 POLLUTID OTHER

 FLAGPOLE 1.0

 RUNORNOT RUN

 ERRORFIL ERRORS.OUT

CO FINISHED

SO STARTING

** LOCATION Srcid Srctyp Xs Ys (Zs)

 LOCATION VOL1 VOLUME 0. 0. 0.

** Volume Source QS HS Syo Szo

** Parameters: ---- ---- --- ---

 SRCPARAM VOL1 1. 2. 0.233 0.233

** Winter Spring

 EMISFACT VOL1 SEASHR 8*0. 8*1. 8*0. 7*0. 10*1. 7*0.

** Summer Fall

 EMISFACT VOL1 SEASHR 6*0. 12*1. 6*0. 7*0. 10*1. 7*0.

 SRCGROUP ALL

SO FINISHED

RE STARTING

 GRIDPOLR POLAR STA

 POLAR ORIG 0. 0.

 POLAR DIST 20. 50. 100. 200. 500. 1000.

 POLAR GDIR 36 10. 10.

 GRIDPOLR POLAR END

RE FINISHED

ME STARTING

 INPUTFIL alt96_00.txt

 ANEMHGHT 2 METERS

 SURFDATA 99090 1996 Alturas

 UAIRDATA 99090 1996 Holzworth

** DAYRANGE 1/1-6/15 10/16-12/31

ME FINISHED

OU STARTING

 RECTABLE ALLAVE FIRST

 MAXTABLE ALLAVE 20

 PLOTFILE PERIOD ALL plotann_alt_12m.dat

 PLOTFILE 6 ALL FIRST plotsix_alt_12m.dat

 PLOTFILE 2 ALL FIRST plottwo_alt_12m.dat

OU FINISHED1
C-17

*** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** MODEL SETUP OPTIONS SUMMARY *** - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  **Intermediate Terrain Processing is Selected **Model Is Setup For Calculation of Average CONCentration Values. -- SCAVENGING/DEPOSITION LOGIC -- **Model Uses NO DRY DEPLETION. DDPLETE = F **Model Uses NO WET DEPLETION. WDPLETE = F **NO WET SCAVENGING Data Provided. **NO GAS DRY DEPOSITION Data Provided. **Model Does NOT Use GRIDDED TERRAIN Data for Depletion Calculations **Model Uses RURAL Dispersion. **Model Uses Regulatory DEFAULT Options: 1. Final Plume Rise. 2. Stack-tip Downwash. 3. Buoyancy-induced Dispersion. 4. Use Calms Processing Routine. 5. Not Use Missing Data Processing Routine. 6. Default Wind Profile Exponents. 7. Default Vertical Potential Temperature Gradients. 8. "Upper Bound" Values for Supersquat Buildings. 9. No Exponential Decay for RURAL Mode **Model Assumes Receptors on FLAT Terrain. **Model Accepts FLAGPOLE Receptor Heights. **Model Calculates 3 Short Term Average(s) of: 1-HR 2-HR 6-HR and Calculates PERIOD Averages **This Run Includes: 1 Source(s); 1 Source Group(s); and 216 Receptor(s) **The Model Assumes A Pollutant Type of: OTHER  **Model Set To Continue RUNning After the Setup Testing. **Output Options Selected: Model Outputs Tables of PERIOD Averages by Receptor Model Outputs Tables of Highest Short Term Values by Receptor (RECTABLE Keyword) Model Outputs Tables of Overall Maximum Short Term Values (MAXTABLE Keyword) Model Outputs External File(s) of High Values for Plotting (PLOTFILE Keyword) **NOTE: The Following Flags May Appear Following CONC Values: c for Calm Hours m for Missing Hours b for Both Calm and Missing Hours
C-18

 **Misc. Inputs: Anem. Hgt. (m) = 2.00 ; Decay Coef. = 0.000 ; Rot. Angle = 0.0 Emission Units = GRAMS/SEC ; Emission Rate Unit Factor = 0.10 Output Units = MICROGRAMS/M**3  **Approximate Storage Requirements of Model = 1.2 MB of RAM. **Input Runstream File: quick_alt.in  **Output Print File: quick_alt_12m.out  **Detailed Error/Message File: ERRORS.OUT 1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** VOLUME SOURCE DATA *** NUMBER EMISSION RATE BASE RELEASE INIT. INIT. EMISSION RATE SOURCE PART. (GRAMS/SEC) X Y ELEV. HEIGHT SY SZ SCALAR VARY ID CATS. (METERS) (METERS) (METERS) (METERS) (METERS) (METERS) BY - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  VOL1 0 0.10000E+01 0.0 0.0 0.0 2.00 0.23 0.23 SEASHR
C-19

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  * SOURCE EMISSION RATE SCALARS WHICH VARY SEASONALLY AND DIURNALLY (SEASHR) * HOUR SCALAR HOUR SCALAR HOUR SCALAR HOUR SCALAR HOUR SCALAR HOUR  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  SOURCE ID = VOL1 ; SOURCE TYPE = VOLUME : SEASON = WINTER 1 .00000E+00 2 .00000E+00 3 .00000E+00 4 .00000E+00 5 .00000E+00 6 .0 7 .00000E+00 8 .00000E+00 9 .10000E+01 10 .10000E+01 11 .10000E+01 12 .1 13 .10000E+01 14 .10000E+01 15 .10000E+01 16 .10000E+01 17 .00000E+00 18 .0 19 .00000E+00 20 .00000E+00 21 .00000E+00 22 .00000E+00 23 .00000E+00 24 .0 SEASON = SPRING 1 .00000E+00 2 .00000E+00 3 .00000E+00 4 .00000E+00 5 .00000E+00 6 .0 7 .00000E+00 8 .10000E+01 9 .10000E+01 10 .10000E+01 11 .10000E+01 12 .1 13 .10000E+01 14 .10000E+01 15 .10000E+01 16 .10000E+01 17 .10000E+01 18 .0 19 .00000E+00 20 .00000E+00 21 .00000E+00 22 .00000E+00 23 .00000E+00 24 .0 SEASON = SUMMER 1 .00000E+00 2 .00000E+00 3 .00000E+00 4 .00000E+00 5 .00000E+00 6 .0 7 .10000E+01 8 .10000E+01 9 .10000E+01 10 .10000E+01 11 .10000E+01 12 .1 13 .10000E+01 14 .10000E+01 15 .10000E+01 16 .10000E+01 17 .10000E+01 18 .1 19 .00000E+00 20 .00000E+00 21 .00000E+00 22 .00000E+00 23 .00000E+00 24 .0 SEASON = FALL 1 .00000E+00 2 .00000E+00 3 .00000E+00 4 .00000E+00 5 .00000E+00 6 .0 7 .00000E+00 8 .10000E+01 9 .10000E+01 10 .10000E+01 11 .10000E+01 12 .1 13 .10000E+01 14 .10000E+01 15 .10000E+01 16 .10000E+01 17 .10000E+01 18 .0 19 .00000E+00 20 .00000E+00 21 .00000E+00 22 .00000E+00 23 .00000E+00 24 .0
C-20

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** GRIDDED RECEPTOR NETWORK SUMMARY *** *** NETWORK ID: POLAR ; NETWORK TYPE: GRIDPOLR *** *** ORIGIN FOR POLAR NETWORK *** X-ORIG = 0.00 ; Y-ORIG = 0.00 (METERS) *** DISTANCE RANGES OF NETWORK *** (METERS) 20.0, 50.0, 100.0, 200.0, 500.0, 1000.0, *** DIRECTION RADIALS OF NETWORK *** (DEGREES) 10.0, 20.0, 30.0, 40.0, 50.0, 60.0, 70.0, 80.0, 90.0, 100. 110.0, 120.0, 130.0, 140.0, 150.0, 160.0, 170.0, 180.0, 190.0, 200. 210.0, 220.0, 230.0, 240.0, 250.0, 260.0, 270.0, 280.0, 290.0, 300. 310.0, 320.0, 330.0, 340.0, 350.0, 360.0,
C-21

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** THE FIRST 24 HOURS OF METEOROLOGICAL DATA *** FILE: alt96_00.txt  FORMAT: (4I2,2F9.4,F6.1,I2,2F7.1,f9.4,f10.1,f8.4,i4,f7.2)  SURFACE STATION NO.: 99090 UPPER AIR STATION NO.: 99090 NAME: ALTURAS NAME: HOLZWORTH  YEAR: 1996 YEAR: 1996 FLOW SPEED TEMP STAB MIXING HEIGHT (M) USTAR M-O LENGTH Z-0 IPCODE PRATE YR MN DY HR VECTOR (M/S) (K) CLASS RURAL URBAN (M/S) (M) (M) (mm/HR) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  96 01 01 01 299.5 1.03 269.2 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 02 222.2 1.00 268.8 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 03 306.2 1.02 268.1 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 04 214.1 1.00 268.1 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 05 250.6 1.16 268.4 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 06 16.5 1.00 267.8 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 07 310.4 1.00 268.2 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 08 340.6 1.00 269.6 5 350.0 350.0 0.0000 0.0 0.0000 0 0.00 96 01 01 09 91.9 1.00 271.0 4 175.0 466.7 0.0000 0.0 0.0000 0 0.00 96 01 01 10 96.0 1.02 272.1 4 350.0 583.3 0.0000 0.0 0.0000 0 0.00 96 01 01 11 154.0 1.05 274.2 3 525.0 700.0 0.0000 0.0 0.0000 0 0.00 96 01 01 12 148.4 1.18 276.4 2 700.0 816.7 0.0000 0.0 0.0000 0 0.00 96 01 01 13 352.5 1.11 278.3 2 875.0 933.3 0.0000 0.0 0.0000 0 0.00 96 01 01 14 97.1 1.46 279.3 2 1050.0 1050.0 0.0000 0.0 0.0000 0 0.00 96 01 01 15 195.1 1.00 280.4 2 1050.0 1050.0 0.0000 0.0 0.0000 0 0.00 96 01 01 16 78.9 1.00 280.9 3 1050.0 1050.0 0.0000 0.0 0.0000 0 0.00 96 01 01 17 297.6 1.13 277.2 4 1050.0 1050.0 0.0000 0.0 0.0000 0 0.00 96 01 01 18 286.6 1.05 273.2 5 950.0 950.0 0.0000 0.0 0.0000 0 0.00 96 01 01 19 280.8 1.00 273.1 6 850.0 850.0 0.0000 0.0 0.0000 0 0.00 96 01 01 20 330.1 1.44 273.2 6 750.0 750.0 0.0000 0.0 0.0000 0 0.00 96 01 01 21 183.1 1.19 272.9 6 650.0 650.0 0.0000 0.0 0.0000 0 0.00 96 01 01 22 160.5 1.29 271.9 6 550.0 550.0 0.0000 0.0 0.0000 0 0.00 96 01 01 23 14.1 1.15 270.8 6 450.0 450.0 0.0000 0.0 0.0000 0 0.00 96 01 01 24 298.4 1.36 270.7 6 350.0 350.0 0.0000 0.0 0.0000 0 0.00 *** NOTES: STABILITY CLASS 1=A, 2=B, 3=C, 4=D, 5=E AND 6=F. FLOW VECTOR IS DIRECTION TOWARD WHICH WIND IS BLOWING.
C-22

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** THE PERIOD ( 43848 HRS) AVERAGE CONCENTRATION VALUES FOR SOURCE GROUP: ALL  INCLUDING SOURCE(S): VOL1 , *** NETWORK ID: POLAR ; NETWORK TYPE: GRIDPOLR *** ** CONC OF OTHER IN MICROGRAMS/M**3 ** DIRECTION | DISTANCE (METERS) (DEGREES) | 20.00 50.00 100.00 200.00 500.00 1000.00 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  10.00 | 359.28723 109.09495 35.23533 10.17595 1.86986 0.51552 20.00 | 322.79550 94.75423 30.04909 8.58382 1.55289 0.42200 30.00 | 303.82068 87.01556 27.26755 7.73402 1.38359 0.37210 40.00 | 310.64249 88.56834 27.80078 7.90533 1.41740 0.38177 50.00 | 343.76212 97.06303 30.28417 8.56304 1.52019 0.40539 60.00 | 415.36121 118.75463 37.26259 10.58086 1.89030 0.50684 70.00 | 483.38943 137.87877 43.25087 12.28842 2.19577 0.58894 80.00 | 551.75903 156.56862 48.91713 13.85778 2.47025 0.66145 90.00 | 625.56580 175.35014 54.31086 15.28538 2.69682 0.71475 100.00 | 701.34460 195.15503 60.22597 16.92513 2.97425 0.78414 110.00 | 743.75629 203.13817 62.05415 17.31683 3.00745 0.78362 120.00 | 764.23553 204.78236 61.90730 17.15272 2.93798 0.75377 130.00 | 772.67841 205.59232 62.08289 17.20626 2.93811 0.74987 140.00 | 745.85541 194.59494 58.10659 15.93469 2.66552 0.66503 150.00 | 723.08447 188.13655 56.23870 15.42978 2.57930 0.64322 160.00 | 697.60840 181.07933 54.17500 14.88348 2.49010 0.62121 170.00 | 675.42920 175.23468 52.36225 14.37422 2.39870 0.59566 180.00 | 658.65680 174.99783 52.97433 14.69991 2.50293 0.63527 190.00 | 579.61694 155.84921 47.50737 13.25050 2.28134 0.58686 200.00 | 437.30966 115.82762 34.90974 9.62612 1.63262 0.41498 210.00 | 317.55426 84.92886 25.80663 7.16093 1.23060 0.31777 220.00 | 232.50551 62.56200 19.06682 5.29708 0.91314 0.23672 230.00 | 186.68686 51.73637 16.08179 4.53995 0.80231 0.21303 240.00 | 159.59248 45.10520 14.17402 4.02594 0.71774 0.19218 250.00 | 148.55293 43.20642 13.82930 3.98011 0.72292 0.19682 260.00 | 151.88326 44.79121 14.40066 4.14873 0.75450 0.20557 270.00 | 175.13824 55.05038 18.46500 5.49965 1.04397 0.29501 280.00 | 157.86005 48.11384 15.69142 4.54722 0.83457 0.22946 290.00 | 154.47588 47.91508 15.80337 4.62305 0.86071 0.23978 300.00 | 155.87004 48.62551 16.12665 4.74183 0.88769 0.24817 310.00 | 146.41270 44.58778 14.54168 4.22844 0.78086 0.21581 320.00 | 144.94771 42.50871 13.51841 3.84975 0.69014 0.18579 330.00 | 179.44879 54.08427 17.46337 5.04325 0.92535 0.25465 340.00 | 233.74501 70.48315 22.71098 6.53114 1.19126 0.32634 350.00 | 324.58835 101.20020 33.15681 9.66215 1.79817 0.50140 360.00 | 379.02032 118.68980 38.97332 11.38465 2.12648 0.59483
C-23

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** THE MAXIMUM 20 1-HR AVERAGE CONCENTRATION VALUES FOR SOURCE GROUP: ALL  INCLUDING SOURCE(S): VOL1 , ** CONC OF OTHER IN MICROGRAMS/M**3 ** RANK CONC (YYMMDDHH) AT RECEPTOR (XR,YR) OF TYPE RANK CONC (YYMMDDHH) AT RECEPT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  1. 81534.78125 (98111108) AT ( -20.00, 0.00) GP 11. 62762.19531 (96111717) AT ( 3.47 2. 77099.78125 (97112708) AT ( 18.79, 6.84) GP 12. 62494.07812 (98110208) AT ( -20.00 3. 63778.89062 (96111108) AT ( -17.32, -10.00) GP 13. 62494.07422 (98111109) AT ( -6.84 4. 63717.26953 (97110408) AT ( -19.70, 3.47) GP 14. 62407.88281 (96013009) AT ( 0.00 5. 63717.26172 (00112308) AT ( -20.00, 0.00) GP 15. 62295.17188 (97120909) AT ( -18.79 6. 63617.28125 (97112808) AT ( -15.32, -12.86) GP 16. 62195.92578 (99011109) AT ( 18.79 7. 63525.13281 (98012209) AT ( 17.32, -10.00) GP 17. 62195.85938 (00111408) AT ( -19.70 8. 63206.09766 (00111208) AT ( 0.00, 20.00) GP 18. 61867.87500 (97120809) AT ( -3.47 9. 62999.52344 (00012309) AT ( -20.00, 0.00) GP 19. 61510.69922 (97122309) AT ( 17.32 10. 62999.52344 (00112608) AT ( -6.84, 18.79) GP 20. 61216.41016 (97030608) AT ( 15.32 *** RECEPTOR TYPES: GC = GRIDCART GP = GRIDPOLR DC = DISCCART DP = DISCPOLR BD = BOUNDARY
C-24

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** THE MAXIMUM 20 2-HR AVERAGE CONCENTRATION VALUES FOR SOURCE GROUP: ALL  INCLUDING SOURCE(S): VOL1 , ** CONC OF OTHER IN MICROGRAMS/M**3 ** RANK CONC (YYMMDDHH) AT RECEPTOR (XR,YR) OF TYPE RANK CONC (YYMMDDHH) AT RECEPT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  1. 48871.01172 (98120312) AT ( 20.00, 0.00) GP 11. 40026.98438 (99012910) AT ( -20.00 2. 47849.55469 (98011014) AT ( -6.84, -18.79) GP 12. 39146.01562 (97121716) AT ( 17.32 3. 43185.06250 (98111112) AT ( 3.47, -19.70) GP 13. 38723.82031 (97012414) AT ( 15.32 4. 41447.76172 (97122110) AT ( -17.32, 10.00) GP 14. 38549.89062 (97112708) AT ( 18.79 5. 41197.90625 (98011510) AT ( -3.47, -19.70) GP 15. 38313.87500 (00021810) AT ( 20.00 6. 40964.49219 (97062708) AT ( 15.32, -12.86) GP 16. 38282.94141 (00080108) AT ( 10.00 7. 40842.83594 (99011810) AT ( -15.32, -12.86) GP 17. 38258.22656 (96080108) AT ( -3.47 8. 40767.39062 (98111108) AT ( -20.00, 0.00) GP 18. 38173.92188 (00072508) AT ( 12.86 9. 40444.94141 (96122110) AT ( 3.47, 19.70) GP 19. 38112.43359 (96080708) AT ( 20.00 10. 40256.50000 (97011510) AT ( -20.00, 0.00) GP 20. 37763.02344 (97110210) AT ( 12.86 *** RECEPTOR TYPES: GC = GRIDCART GP = GRIDPOLR DC = DISCCART DP = DISCPOLR BD = BOUNDARY
C-25

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** THE MAXIMUM 20 6-HR AVERAGE CONCENTRATION VALUES FOR SOURCE GROUP: ALL  INCLUDING SOURCE(S): VOL1 , ** CONC OF OTHER IN MICROGRAMS/M**3 ** RANK CONC (YYMMDDHH) AT RECEPTOR (XR,YR) OF TYPE RANK CONC (YYMMDDHH) AT RECEPT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  1. 23044.16211 (98011012) AT ( 0.00, -20.00) GP 11. 16884.92969 (00072512) AT ( 12.86 2. 19217.70312 (97112712) AT ( 18.79, 6.84) GP 12. 16869.17578 (97062712) AT ( 15.32 3. 18968.23242 (98011018) AT ( -6.84, -18.79) GP 13. 16400.34961 (97120512) AT ( 6.84 4. 18637.32422 (97122112) AT ( -18.79, 6.84) GP 14. 16290.33789 (98120312) AT ( 20.00 5. 18598.71094 (98111112) AT ( 3.47, -19.70) GP 15. 16217.56641 (00021612) AT ( 19.70 6. 18119.53906 (98012218) AT ( -6.84, -18.79) GP 16. 16210.42773 (97080512) AT ( 12.86 7. 17679.75000 (00073012) AT ( 10.00, -17.32) GP 17. 15785.03711 (97110212) AT ( 12.86 8. 17354.37891 (00101112) AT ( -6.84, 18.79) GP 18. 15478.49512 (97122112) AT ( -17.32 9. 17291.69336 (98112712) AT ( -20.00, 0.00) GP 19. 15428.75195 (98071212) AT ( 19.70 10. 16999.28516 (96080112) AT ( -3.47, -19.70) GP 20. 15314.57812 (98011512) AT ( -3.47 *** RECEPTOR TYPES: GC = GRIDCART GP = GRIDPOLR DC = DISCCART DP = DISCPOLR BD = BOUNDARY
C-26

1 *** ISCST3 - VERSION 00259 *** *** Burning Barrel Analysis ***  *** Modoc County, Alturas Met. Data ***  **MODELOPTs:  CONC RURAL FLAT FLGPOL DFAULT  *** THE SUMMARY OF MAXIMUM PERIOD ( 43848 HRS) RESULTS *** ** CONC OF OTHER IN MICROGRAMS/M**3 ** NETWORK GROUP ID AVERAGE CONC RECEPTOR (XR, YR, ZELEV, ZFLAG) OF TYPE GRID-ID - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  ALL 1ST HIGHEST VALUE IS 772.67841 AT ( 15.32, -12.86, 0.00, 1.00) GP POLAR  2ND HIGHEST VALUE IS 764.23553 AT ( 17.32, -10.00, 0.00, 1.00) GP POLAR  3RD HIGHEST VALUE IS 745.85541 AT ( 12.86, -15.32, 0.00, 1.00) GP POLAR  4TH HIGHEST VALUE IS 743.75629 AT ( 18.79, -6.84, 0.00, 1.00) GP POLAR  5TH HIGHEST VALUE IS 723.08447 AT ( 10.00, -17.32, 0.00, 1.00) GP POLAR  6TH HIGHEST VALUE IS 701.34460 AT ( 19.70, -3.47, 0.00, 1.00) GP POLAR  7TH HIGHEST VALUE IS 697.60840 AT ( 6.84, -18.79, 0.00, 1.00) GP POLAR  8TH HIGHEST VALUE IS 675.42920 AT ( 3.47, -19.70, 0.00, 1.00) GP POLAR  9TH HIGHEST VALUE IS 658.65680 AT ( 0.00, -20.00, 0.00, 1.00) GP POLAR  10TH HIGHEST VALUE IS 625.56580 AT ( 20.00, 0.00, 0.00, 1.00) GP POLAR  *** RECEPTOR TYPES: GC = GRIDCART GP = GRIDPOLR DC = DISCCART DP = DISCPOLR BD = BOUNDARY
D-1

APPENDIX D

Glossary and Acronyms
D-2

Glossary and Acronymns

Glossary

Acute Exposure: One or a series of short-term exposures generally lasting less than

24 hours.

Air Dispersion A mathematical model or computer simulation used to estimate the

Model: concentration of toxic air pollutants at specific locations as a result

of mixing in the atmosphere.

Airborne Toxic Section 39655 of the Health and Safety Code, defines an “Airborne

Control Measure: Toxic Control Measure” means either of the following:

1) Recommended methods, and, where appropriate, a range of

methods, that reduce, avoid, or eliminate the emissions of a toxic

air contaminant. Airborne toxic control measures include, but are

not limited to, emission limitations, control technologies, the use of

operational and maintenance conditions, closed system

engineering, design equipment, or work practice standards, and the

reduction, avoidance, or elimination of emissions through process

changes, substitution of materials, or other modifications.

2) Emission standards adopted by the U.S. Environmental

Protection Agency pursuant to Section 112 of the federal act

(42 U.S.C. Sec. 7412).

Cancer Risk: The theoretical probability of contracting cancer when exposed for

a lifetime to a given concentration of a substance usually calculated

as an upper confidence limit. The maximum estimated risk may be

presented as the number of chances in a million of contracting

cancer.

Chronic Exposure: Long-term exposure usually lasting from one year to a lifetime.

Hazardous Air Means a substance that the U.S. Environmental Protection Agency

Pollutant or HAP: has listed in, or pursuant to, Section 112 subsection (b) of the

federal Clean Air Act Amendments of 1990 (42 U.S. Code, Section

7412(b)).

Hazard Index: The ratio of the concentration of a toxic pollutant with non-cancer

health effects and the reference exposure level for that pollutant.

Health Risk A comprehensive analysis of the dispersion of hazardous

Assessment (HRA): substances in the environment, the potential for human exposure,

and a quantitative assessment of both individual and

population-wide health impacts associated with the level of

exposure.
D-3

Near Source The location closest to an emission’s source where concentrations

Location: could be estimated through air dispersion modeling.

Non-cancer Risk: Refers to non-cancer health effects due to acute and/or chronic

exposure. This may be illustrated as an estimate of the hazard

index or total hazard index (by endpoint) resulting from exposure to

toxic air pollutants.

Reference These are used as indicators of potential non-cancer adverse

Exposure Level health effects. An REL is a concentration level at or below which

(REL): no adverse health effects are anticipated. RELs are designed to

protect most sensitive individuals in the population by including

safety factors in their development.

Risk: The possibility of injury or disease, which may result from exposure

to toxic air pollutants.

Scientific Review A nine-member panel appointed to advise the Air Resources Board

Panel on Toxic and the Department of Pesticide Regulation in their evaluation of

Air Contaminants the adverse health effects toxicity of substances being evaluated

(SRP): as Toxic Air Contaminants.

Toxic Air Section 39655 of the Health and Safety Code, defines a TAC as an

Contaminant air pollutant which may cause or contribute to an increase in

(TAC): mortality or an increase in serious illness, or which may pose a

present or potential hazard to human health. A substance that is

listed as a hazardous air pollutant pursuant to subsection (b) of

Section 112 of the federal act (42 U.S.C. Sec. 7412(b)) is a TAC. 

TACs that are pesticides are regulated in their pesticidal use by the

Department of Pesticide Regulation.

Total Hazard Index: The sum of hazard indices for pollutants with non-cancer health

effects that have the same or similar adverse health effects

(endpoints).

Unit Risk Factor: The estimated upper-confidence limit (usually 95%) probability of a

(URF): person contracting cancer as a result of a constant exposure to

1 μg/m3

 of a substance over a 70-year lifetime.
D-4

Acronyms

ARB Air Resources Board

APCD Air Pollution Control District

AQMD Air Quality Management District

ATCM Airborne Toxic Control Measure

Districts Local Air Pollution Control and Air Quality

Management Districts

HAP Hazardous Air Pollutant

HSC Health and Safety Code

IARC International Agency for Research on Cancer

OEHHA Office of Environmental Health Hazard Assessment

RfD Reference Dose

REL Reference Exposure Level

SB Senate Bill

SRP Scientific Review Panel on Toxic Air Contaminants

TAC Toxic Air Contaminant

URF Unit Risk Factor

U.S. EPA United States Environmental Protection Agency