Final Staff Report and 

Recommendations on Agricultural Burning 

Chapter 5 

Emissions from Agricultural Burning 

and Alternatives to Burning 

and Health Considerations 
Final Staff Report and 

Recommendations on Agricultural Burning 

This page intentionally blank. 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-1 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

Chapter 5: EMISSIONS FROM AGRICULTURAL BURNING AND 

ALTERNATIVES TO BURNING, AND HEALTH CONSIDERATIONS

Figure 5.1 Map illustrating PM2.5 Emissions in the Valley from Open Burning 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-2 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

5.1 DISTRIBUTION OF AGRICULTURAL OPEN BURNING EMISSIONS 

The map on the previous page illustrates the tons of PM2.5 emissions per square 

mile and existing and proposed biomass plants in the San Joaquin Valley air 

basin (Valley). The Sectional divisions of the map are the 103 burn allocation 

zones as developed by the District for use in the smoke management system 

(SMS). Each zone in the map is marked to illustrate the three-year average 

annual tons of PM 2.5 emissions per square mile generated from agricultural 

burning of all types for that zone between the years of 2007 and 2009. Most of 

the burn allocation zones with the highest emissions from agricultural burning 

have biomass facilities in or near them. 

5.2 CURRENT EMISSIONS INVENTORY FROM AGRICULTURAL BURNING 

For purposes of this report, the criteria pollutants analyzed include volatile 

organic compounds (VOC), oxides of nitrogen (NOx), and particulate matter 

(PM2.5). The 2007 Ozone Plan control measure for Open Burning (S-AGR-1) 

(Managed Burning and Disposal) pertains to the burning of any material including 

agricultural materials. The Plan identified the summer 2005 emissions inventory 

for open burning as 4.8 tons of NOx per day and 5.7 tons of VOC per day. In the 

winter, the 2008 PM2.5 Plan control measure for Open Burning (S-AGR-1) 

(Managed Burning and Disposal) identifies the 2005 emissions inventory for 

open burning as 8.16 tons of NOx per day, 10.70 tons of PM2.5 per day and 0.19 

tons of SO2 per day. As shown in Figure 5-2, agricultural burning is concentrated 

in winter months when PM2.5 is elevated and ozone values are relatively low. 

Figure 5-2

Average Monthly Agricultural Burning (2007-2009)

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

January 

February 

March

April

May

June

July

August

September

October

November

December

Burn Tons
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-3 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

Table 5-1 below presents the burn tons, burn acres, and tons of associated 

criteria pollutant emissions associated with agricultural burning averaged over a 

three year period for specific crop types and activities. The specific crop types 

and activities are the crops to be analyzed for the 2010 burn prohibitions 

resulting from state law. Because several crops are not a part of this analysis 

and do not pertain to this report, the data from those crops has been omitted 

from the table below. The data for this table is the best available information, 

and came from the District SMS emission database. 

Table 5-1 

Average Annual Tons, Acres, and Emissions 

from Open Burning of the Remaining CH&SC Crop Types (2007-2009) 

Emissions (Tons) 

Crop Name 

Burn 

Tons 

Burn 

Acres NOx PM 2.5 VOC PM 10 

Almond Pruning 51718 51718 152.57 173.26 134.47 181.01

Apple Pruning 900 391 2.34 1.66 1.03 1.75

Fig Pruning 1227 558 3.19 3.99 3.68 4.23

Pear Pruning 286 110 0.74 1.19 0.73 1.26

Pecan Pruning 501 295 1.30 1.83 1.58 1.96

Quince 47 28 0.12 0.17 0.15 0.18

Walnut Pruning 17083 14236 38.44 34.17 41.00 35.88

<20 Acre Orchard Removal 

(all crops) 70010 2334 182.03 255.54 220.53 273.04

Apple Orchard Removal 691 23 1.80 1.28 0.79 1.35

Citrus Orchard Removal 54035 1801 140.49 151.30 183.72 159.40

Fig Orchard Removal 2392 80 6.22 7.78 7.18 8.25

Pear Orchard Removal 490 16 1.27 2.03 1.25 2.16

Quince Orchard Removal 10 0 0.03 0.04 0.03 0.04

Brooder Paper <1 n/a 0.00 0.00 0.00 0.00

Diseased Beehives 90 41 0.20 0.68 0.48 0.71

Goat <1 n/a 0.00 0.00 0.00 0.003

Ponding/Levee Banks 302 139 0.68 2.29 1.62 2.40

Rice * 9049 3073 23.45 27.79 21.98 29.65

Raisin Trays 890 29683 1.90 0.33 1.94 0.35

Vineyard Removal 197140 13143 512.56 719.56 620.99 768.85

Totals: 406,861 117,668 1,069.3 1,384.9 1,243.2 1,472.5

* Note: no citrus pruning after 2005 

1. Rice category includes residual rice straw, rice straw, rice stubble, and rice field levees. 

Table 5-1 includes the Phase IV materials that were issued open burning 

permits. District staff calculated the burn acres and associated emissions from a 

list of the amounts of selected Phase IV materials that were issued open burning 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-4 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

permits, averaged from 2007-2009. The list includes almond pruning, walnut 

pruning, pecan pruning, vineyard removal, raisin trays, and rice stubble. The 

total acres burned from the three-year average of the crops previously mentioned 

are 109,128 acres. The emissions from such activities are presented below: 

Table 5-2 

Average Annual Emissions From 

Open Burning of Selected Phase IV Crops (2007-2009)

Emissions NOx PM 2.5 VOC PM 10 

Tons per Year 706.98 929.38 800.17 988.30 

5.3 EXPECTED EMISSIONS FROM ALTERNATIVES 

 (Criteria Pollutant – PM 2.5) 

Pruning Materials

The analysis in this report indicates that prunings from several crops will most 

likely be shredded on site, or already are shredded on site, as an alternative to 

open burning. The table below is a comprehensive comparison of the average 

annual PM 2.5 emissions from open burn versus shredding for the 

aforementioned crops. For purposes of this analysis, District staff assumed the 

average burn acres would remain constant and that all burn acres would be 

shredded on site. 

The information for this analysis was derived by inputting the burn acre data from 

the “Average Annual Tons, Acres, and Emissions from Open Burning of Crops 

(2007-2009) table presented in Section 5-1 of this report into the District 

Emissions Calculator. The District Emissions Calculator incorporates the 

emissions from various pieces of equipment, including tractors and excavators 

associated with the activity, emissions from transfer and delivery vehicles, and 

other processes such as chipping, as well as the emission factor for each crop 

type and activity. The data presented in the table below is a comprehensive 

emission inventory encompassing all aspects of the affected crops. 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-5 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

Table 5-3 

Comparison of the Average Annual PM 2.5 Emissions 

From Open Burning and Shredding (2007-2009) 

 PM 2.5 Emissions (Tons) 

Crop Name 

Burn 

Acres Open Burn Shred 

Almond Pruning 51718 203.0 4.8 

Apple Pruning 391 3.5 0.1 

Fig Pruning 558 4.8 0.1 

Pear Pruning 110 1.1 0.01 

Pecan Pruning 295 2.0 0.0 

Quince 28 0.2 0.003 

Walnut Pruning 14236 67.0 1.4 

Total: 67336 281.6 6.4 

Orchard Removal Materials

The analysis in this report also indicated that several crops are sent to the 

biomass facilities and will most likely continue to be sent to biomass facilities as 

biomass fuel as an alternative to open burning. The table below is a 

comprehensive comparison of the average annual PM 2.5 emissions from open 

burn versus biomass processing for the aforementioned crops. For purposes of 

this analysis, District staff assumed the average burn acres would remain 

constant and that all burn acres would be sent to the biomass plant as fuel. 

The information for this analysis was derived by inputting the burn acre data from 

the “Average Annual Tons, Acres, and Emissions from open burning of Crops 

(2007-2009) table presented in Section 5-1 of this report into the District 

Emission Calculator. The District Emission Calculator incorporates the 

emissions created from various pieces of equipment, including tractors and 

excavators associated with the activity, emissions from transfer and delivery 

vehicles, and other processes such as chipping, as well as the emission factor 

for each crop type and activity. The data presented in the next table is a 

comprehensive emission inventory encompassing all aspects of the affected 

crops. 

Table 5-4 

Comparison of the Average Annual PM 2.5 Emissions 

From Open Burning and Biomass Operations (2007-2009) 

 PM 2.5 Emissions (Tons) 

Crop Name 

Burn 

Acres Open Burn Biomass 

<20 Acre Orchard Removal 

(all crops) 2334 264.2 32.8 

Citrus Orchard Removal 1801 203.9 25.3 

Fig Orchard Removal 80 9.1 1.1 

Total: 4215 477.2 59.2 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-6 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

5.4 EMISSION REDUCTION ANALYSIS 

5.4.1 Introduction 

The recommendations as described elsewhere in this report will result in greater 

curtailment of agricultural open burning currently allowed under District Rule 

4103. The recommendations will result in the following additional prohibitions: 

 

Orchard Removals

 

• The prohibition of burning of all orchard removals from fig crops over 15 acres 

(District Rule 4103 currently allows burning at all acreage sizes). 

• The prohibition of burning of all orchard removals for all crops (with the 

exception of citrus, apples, pears, and quince) with acreages over 15 acres 

up to and including 20 acres (District Rule 4103 currently allows burning of 

acreages in this range). 

Prunings

• The prohibition of burning of all orchard pruning material from fig crops for all 

acreages (District Rule 4103 currently allows burning at all acreage sizes). 

• The prohibition of burning of prunings for each agricultural operation whose 

total nut acreage (i.e., almonds, walnuts, and pecans) at all agricultural 

operation sites is 3,500 acres or more. For each agricultural operation whose 

total nut acreage at all agricultural operation sites is less than 3,500 acres, 

burning of up to 20 acres of prunings per year is allowed plus additional 

acreage when a determination of economic hardship is made by the District 

(District Rule 4103 currently allows burning at all acreage sizes). 

The estimated emission reductions to be achieved by the new prohibitions listed 

above are presented in Table 5-5. Details of the emission reduction analysis are 

discussed in the next section (Methodology and Calculations). 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-7 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

Table 5-5 

Total Annual Emission Reductions from All New Open Burning 

Prohibitions 

Category Crop Nox 

(ton/year) 

PM2.5 

(ton/year) 

VOC 

(ton/year) 

Figs 2.8 6.7 6.1 

Orchard 

Removals All Orchards 

Less Than 

20 Acres* 

25.8 61.7 56.4 

Figs 0.4 2.1 1.7 

Almond 9.5 48.8 38.0 

Pecan 0.0 0.1 0.1 

Orchard 

Prunings 

Walnut 0.7 3.7 2.9 

Total 39.2 123.1 105.2 

* except citrus, apples, pears and quince 

5.4.2 Methodology and Calculations 

Step 1: Determine the reduction in acreage which will be burned as a result of 

the new prohibitions

District staff analyzed information collected during 2007-2009 from the District’s 

Smoke Management System (SMS) in order to estimate the reduction in acreage 

of burning resulting from the new prohibitions. The SMS manages agricultural 

open burning in the San Joaquin Valley Air Basin (SJVAB) and collects and 

maintains information pertinent to the amount and type of material burned in the 

SJVAB. For each permitted open burning operation during the time period, the 

SMS identifies the specific item burned and the associated acreage. 

In order to estimate the reductions in acreage of orchard burning resulting from 

each of the new orchard prohibitions listed, it was assumed that average annual 

acreage of permitted burns in the SMS for the period 2007-2009 is representative 

of the expected burning reduction for each category. 

Extraction and analysis of data from the SMS for orchard removals yielded the 

following annual reductions in acres burned: 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-8 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

Table 5-6 Data from the SMS for Orchard Removal and Pruning 

New Prohibition

Annual 

Reduction in 

Acreage Burned

Orchard removals from fig crops over 15 acres 61 

Orchard pruning material from fig crops for all acreages 557 

Orchard removals for all crops (with the exception of citrus, apples, 

pears, and quince) 560 

Almond pruning material 12,670 

Pecan pruning material 22 

Walnut pruning material 969 

Step 2: Establish Applicable Emission Factors on a Per Acre Basis

Differential emission reduction factors for orchard removals and for orchard 

prunings, along with the basis for their development, are presented in Tables 5-7 

and 5-8 respectively of the cost and emissions section of this staff report 

(Chapter 5). 

Differential emission reduction factors for orchard removals (assuming 30 tons 

dry biomass per acre) are based on chipping and conversion of the removed 

trees to biomass fuel rather than burning: 

Differential 

Emission 

Factor 

(tons/acre) 

=

Burning 

Emission 

Factor 

(tons/acre)

- 

Chipping/Biomass 

Emission Factor 

(tons/acre) 

From Table 5-4 of the cost and emissions section the differential emission factors 

for orchard removals between 15 and 20 acres are: 

NOx 0.0460 tons per acre 

PM2.5 0.1101 tons per acre

VOC 0.1007 tons per acre 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-9 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning 

Differential factors for prunings (assuming 1 ton of dry prunings per acre) are 

based on chipping and land incorporation of prunings in lieu of burning: 

Differential 

Emission 

Factor 

(lb/acre) 

=

Burning 

Emission 

Factor 

(lb/acre) 

- 

Land 

Incorporation 

Emission Factor 

(lb/acre) 

From Table 5-8 of the cost and emissions section the differential emission factors 

for orchard prunings are: 

NOx 1.5 lb per acre 

PM2.5 7.7 lb per acre

VOC 6.0 lb per acre 

Step 3: Apply Applicable Emission Factor to Acreage Data Extracted from the 

SMS 

 

Tables 5-11 and 5-12 present the results for orchard removals and prunings 

respectively. 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

Revised July 21, 2010 

5-10 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

Table 5-7

Emission Reductions from New Orchard Removal Prohibitions 

Prohibition NOx PM2.5 VOC 

Crop 

Current 

Permitted 

Open 

Burning 

New 

Prohibition 

Acres 

Reduced 

per SMS

Differential 

Emission 

Factor 

(ton/acre) 

Annual 

Emission 

Reduction 

(tons) 

Differential 

Emission 

Factor 

(ton/acre) 

Annual 

Emission 

Reduction 

tons) 

Differential 

Emission 

Factor 

(ton/acre) 

Annual 

Emission 

Reduction 

tons) 

Figs 

Permitted 

at all 

acreages 

Prohibited 

for acreage 

greater than 

15 acres 

61 0.046 2.8 0.1101 6.7 0.1007 6.1 

All other crops 

(with the 

exception of 

citrus, apples, 

pears, and 

quince) 

Permitted 

for 20 

acres or 

Less 

Prohibited 

for acreage 

greater than 

15 acres 

560 0.046 25.8 0.1101 61.7 0.1007 56.4 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

Revised July 21, 2010 

5-11 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

Table 5-8 

Emission Reductions from New Orchard Pruning Prohibitions 

Prohibition NOx PM2.5 VOC 

Crop 

Current 

Permitted 

Open 

Burning 

New 

Prohibition 

Acres 

Reduced 

per SMS

Differential 

Emission 

Factor 

(lb/acre) 

Annual 

Emission 

Reduction 

(ton) 

Differential 

Emission 

Factor 

(lb/acre) 

Annual 

Emission 

Reduction 

(ton) 

Differential 

Emission 

Factor 

(lb/acre) 

Annual 

Emission 

Reduction 

(ton) 

Figs 

Permitted 

at all 

acreages 

Prohibited for 

all acreages 557 1.5 0.4 7.7 2.1 6.0 1.7 

Almond (surface 

harvested crop) 

Permitted 

at all 

acreages 

Prohibited for 

acreage 

greater than 

20 acres 

12,670 1.5 9.5 7.7 48.8 6.0 38.0 

Pecan (surface 

harvested crop) 

Permitted 

at all 

acreages 

Prohibited for 

acreage 

greater than 

20 acres 

22 1.5 0.0 7.7 0.1 6.0 0.1 

Walnut (surface 

harvested crop) 

Permitted 

at all 

acreages 

Prohibited for 

acreage 

greater than 

20 acres 

969 1.5 0.7 7.7 3.7 6.0 2.9 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-12 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

5.5 HEALTH BENEFITS OF REDUCED OPEN BURNING 

Given the minimal impact of open burning on ozone levels in the Valley 

mentioned above, this discussion emphasizes the health benefits of reduced 

open burning and associated PM 2.5 emissions. Prior scientific studies as well 

as District experience have shown the importance of steadily reducing population 

exposure to PM 2.5 through controls on residential wood burning and open 

burning. The San Joaquin Valley experiences some of the highest annual 

average concentrations of PM 2.5 in the nation. Well-defined epidemiological 

relationships have been established between exposure to elevated PM 2.5 and a 

range of health endpoints, including ischemic heart disease, asthma, chronic 

bronchitis, premature mortality, and others. The region can experience multi-day 

periods of atmospheric stagnation during which very little air mass is transferred 

in and out of the Valley. The net result can be a daily buildup of PM 2.5 levels, 

sometimes beyond the 24 hour federal standard of 35 μg/m3

. 

Unlike areas such as Southern California where PM 2.5 levels are more 

distributed throughout the year, fine particulates are seasonally concentrated in 

the Valley. Because of this seasonal concentration effect, District controls 

currently imposed on open burning and residential wood burning have had a 

disproportionate effect in reducing wintertime PM 2.5 concentrations. In the case 

of residential wood burning, an external scientific evaluation was conducted by 

California State University (CSU) Fresno of Rule 4901’s periodic curtailments 

(see www.cvhpi.org). This assessment found that as of the winter 2007-08 

season (prior to the October 2008 amending of Rule 4901), daily curtailments 

coupled with reduced household wood burning overall had resulted in a 12.9% 

and 13.6% reduction in annual PM 2.5 concentrations for Bakersfield and 

Fresno, respectively. Using the US EPA’s BenMAP model for calculating health 

benefits of reduced PM2.5 exposure, these reductions translated into significant 

public health benefits, including significantly reduced cardiovascular disease, 

pulmonary disease, and pre-mature deaths. 

A key element in this success has been the imposition of restrictions in 

residential wood burning on days when meteorological conditions create the risk 

of health standard violations. Initially, as of November 1, 2003, that threshold 

was established at the 1997 24 hr. PM 2.5 standard of 65 μg/m3. As amended in 

October 2008 for the 2008-09 winter season, that daily curtailment threshold was 

substantially reduced to 30 μg/m3

. That reduced curtailment threshold has 

benefited public health in three ways: First, it has resulted in an absolute 

reduction in the total seasonal tonnage of residential wood burned. Second, it 

has insured that on days when wood burning is allowed, each ton of emissions is 

more thoroughly diluted and dispersed, with attendant reductions in harmful peak 

exposures. And third, by restricting burning to days with reasonably good 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-13 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

atmospheric dispersion, the formation of secondary aerosols such as ammonium 

nitrate during multi-day stagnation events is minimized. 

By restricting the analysis to the Bakersfield and Fresno/Clovis metro areas, the 

health evaluation of Rule 4901 (Wood Burning Fireplaces and Wood Burning 

Heaters) was made possible by a well-defined pre-and post-Rule 4901 

population exposure estimate for PM2.5. However, in the case of health benefits 

from reduced burning under Rule 4103, it is not possible to replicate this analysis 

for several reasons. First, ambient monitors are generally not found in rural 

areas. In addition, the population density is considerably lower. As a result, 

estimating accurate population exposure reductions resulting from current or 

estimated reductions on agricultural burning is very difficult and not attempted 

here. 

However, it is possible to draw on the experience of the District evaluation of 

Rule 4901 to draw some reasonable conclusions that provide a public health 

justification for past and prospective reductions in open burning under Rule 4103. 

First, the basin-wide emissions inventory for open burning and residential wood 

combustion are comparable. According to the 2008 CARB emissions inventory, 

estimated tons per day (tpd) of PM2.5 from wood burned by households was 9.5 

and 14.8 for agricultural material. Second, it is important to note at that as of 

December 2009, daily county-level curtailments of open burning are based on 

the same predicted 24 hr. 30 μg/m3

 concentration threshold used in Rule 4901. 

This means that a predominant source of rural and urban open burn emissions 

has been eliminated on low dispersion days, with corresponding reductions in 

overall exposure to individuals in areas where open burning is occurring, as well 

as minimizing exposure to secondary PM2.5. 

Reduced emissions from Rule 4103 are presented below in Table 5-9. In a 

historical sense, reductions achieved to date represent a very rapid rate of 

emission decline in a given economic sector, with attendant health benefits to a 

more dispersed, rural population. 

Table 5-9 

Reductions in Criteria Pollutants Under Rule 4103 Since 2004 

 NOx PM10 PM2.5 VOC CO 

Total Tonnage Reduction 

Since 2004 1,217 1,981 1,860 1,516 15,273

% Reduction Since 2004 48.9% 52.7% 52.6% 50.4% 48.5%

TPD Reduction Since 2004 3.3 5.4 5.1 4.2 41.8

Additional reductions anticipated under the amended Rule 4103 are shown 

above. The more modest reductions arising from the recommendations reflect 

the current balance of commodity profitability and costs for processing at 

biomass plants, as defined by the CH&SC. Past experience has shown that the 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-14 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

per unit costs of alternative disposal options with less environmental impacts 

tend to decline over time due to, in this case, new biomass plant capacity and the 

emergence of alternative disposal technologies. The District supports legislation 

that will encourage, promote and facilitate alternative uses for agricultural 

material as well as policies and initiatives that encourage renewable energy and 

energy efficiency including supporting legislation that provides additional biomass 

capacity utilizing agricultural materials. It is likely that the current constraints on 

open burning emission reductions imposed by the CH&SC will be reduced over 

time, with proportional health benefits. 

5.6 HEALTH RISK ASSESSMENT OF OPEN BURNING AND 

ALTERNATIVES 

Often under the requirements of CEQA-mandated risk assessments, the District 

routinely employs several health risk assessment (HRA) models in order to 

estimate health risks posed by exposure to air pollutants from existing or 

hypothetical sources. These HRA models are based on the following elements: 

(1) knowledge from prior scientific studies about the relative toxicity of pollutants, 

(2) similar knowledge about the relative effects of increased concentrations of a 

given pollutant, (3) the hourly rate of emissions by mass or parts per volume, i.e. 

emission factor, from a given source and the duration of those emissions, (4) 

specification of meteorological conditions, (5) how the pollutants are dispersed 

and/or transformed in the atmosphere, (6) a gradient or exposure surface that 

specifies various concentration levels at a given distance from a source and time, 

(7) (in some cases) the spatial distribution and characteristics of the exposed 

population, and (8) (in some cases) whether and how different sub-populations 

may be differentially affected such as children to a given level and duration of 

exposure. 

To evaluate the acute (short-term) and chronic (long-term) health impact of open 

burning of agricultural material and alternative disposal methods, the following 

scenarios were analyzed (modeled): 

Scenario 1: Open burning of prunings from 20 acres of nut trees. Emission 

sources included diesel exhaust from equipment used to form the 

burn piles, and emissions from combustion of the organic material. 

Scenario 2: Land incorporation of prunings from 20 acres of nut trees. Emission 

source included diesel exhaust from equipment used to shred and 

incorporate prunings into the soil. 

Scenario 3: Transfer of prunings from 20 acres of nut trees to a biomass facility. 

Emission sources included diesel exhaust from equipment used to 

collect and chip/shred prunings, diesel exhaust from trucks used to 

transport the chipped material to the biomass plant, diesel exhaust 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-15 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

from equipment used to unload and process the chipped material at 

the biomass plant, and emissions from the biomass combustor. 

Scenario 4: Open burning of 20 acres of nut trees (orchard removal). Emission 

sources included diesel exhaust from equipment used to form the 

burn piles and emissions from the combustion the organic material. 

Scenario 5: Transfer of 20 acres of nut trees (orchard removal) to a biomass 

facility. Emission sources included diesel exhaust from equipment 

used to collect and chip/shred the orchard material, diesel exhaust 

from a truck used to transport the chipped material to the biomass 

plant, diesel exhaust from equipment used to unload and process 

the chipped material at the biomass plant, and emissions from the 

biomass combustor. 

5.6.1 Methodology and Calculations 

Emissions for each scenario evaluated were calculated using District-developed 

spreadsheets and the parameters listed below: 

Table 5-10 

Variables used to estimate scenario emissions 

Variables Prunings Orchard 

Removal 

Crop type Orchard Orchard 

Ag material (acres) 20 20 

Material removed (tons/acre) 1 30 

Roots removed (tons/acre) 0 1 

Field equipment activity (hours/acre) 1 1 

Power plant equipment activity (hours/acre) 2 2 

Ag material delivered to power plant 

(tons/truck) 

24 24 

Round trip distance to power plant (miles) 100 100 

Off-road diesel equipment was used to process crop material in the field and at 

the biomass facility. Off road equipment activity was modeled as an area source 

over the entire surface of the orchard or that portion of the biomass facility used 

to receive and process wood chips. All particulate matter from off-road diesel 

equipment exhaust was modeled as diesel particulate matter (DPM). Relative 

risks generated by air contaminants from the open burning of agricultural material 

were calculated using the California Air Resources Board (CARB) particulate 

matter speciation profile 450 for particulates, and emission factors from Lemieux, 

Lutes and Santoianni (2002) for volatile organic compounds. Emissions from 

open burn piles were modeled as point sources to allow for thermal loft from the 

heat of combustion. The open burning of orchard prunings was assumed to 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-16 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

occur in four separate piles located at the southern border of the orchard. The 

open burning of the orchard removal material was assumed to occur in twenty 

piles evenly distributed within the orchard over a 24 hr. period. All particulate 

matter from on-road diesel truck exhaust was modeled as DPM. On-road truck 

travel was modeled as a line source consisting of a one mile series of volume 

sources. 

To calculate pollutant dispersion and the resulting exposure gradient, the 

AERMOD model was used. Meteorological data for 2004-2008 from Bakersfield 

was employed to determine the dispersion factors (i.e., the predicted 

concentration or Χ divided by the normalized source strength or Q) for a receptor 

(human population) grid. These dispersion factors were input into the Hot Spots 

Analysis and Reporting Program (HARP) risk assessment module to calculate 

the chronic and acute hazard indices as well as the carcinogenic risk for five 

scenarios outlined above. No actual locations and nearby populations were used 

in the model analysis. 

5.6.2 Health Risk Assessment Results 

Worst case health risks for the open burning of agricultural material and their 

alternatives are presented in Table 5-11 (pruning scenario) and Table 5-12 

(orchard removal scenario). The model results for open burning of prunings 

show that the cancer risk and chronic hazard indices are very low and not of 

concern for all disposal options. The acute hazard index in this case pertains to 

risk of an acute respiratory response over the short-term (24 hour) exposure 

generated by the burning of the prunings for a person standing within 25 meters 

of the burn piles. In this air pollutant modeling scenario, any acute hazard index 

score of over 1.0 indicates the potential for a negative impact on respiratory 

health. As shown, this threshold is not exceeded for a maximum 24 hour. 

exposure scenario. 

In the case of a worst-case health risk assessment for orchard removal options 

are shown in Table 5-11. As in the case of prunings, cancer and chronic hazard 

indices for all options are very low values that do not indicate excessive risk. As 

shown in Figure 5-3, the open burning exposure scenario is based on the 

assumption that removed trees are put into 20 piles, one per acre, and burned 

simultaneously. In this case, the acute hazard index score for 24 hr. exposure in 

the zone nearest the burn piles is excessive (10.70). As one moves further from 

the burn zone this relative hazard to short-term respiratory health drops relatively 

quickly, falling by approximately 50% after 500 meters and to an acceptable level 

of less than 1.0 after 1,000 meters. 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-17 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

Table 5-11 

Comparative Pruning Risk (20 Acres): Open Burning vs. Chipping/Shredding and 

Incorporation vs. Biomass Facility

Health Risk 

Source 

Maximum 

Individual Cancer 

Risk2

 

(x 10-6) 

Acute Hazard 

Index 

Chronic Hazard 

Index 

Orchard Burning 3.32 0.83 0.07 

Land Incorporation 7.59 nc1 nc 

Biomass Facility – Off Site 

 Orchard 9.69 nc nc 

 Transit 0.00 nc nc 

 Off Site Total 9.69 nc nc 

Biomass Facility – On Site 

 Facility 0.10 0.00 0.00 

 Transit 0.00 nc nc 

 On Site Total 0.10 0.00 0.00 

1

 Acute and Chronic Hazard Indices were not calculated since there is no risk factor or the risk factor is so low that it has 

been determined to be insignificant for this type of unit. 

2 70 year exposure used.

 

Table 5-12 

Comparative Orchard Burning Risk (20 Acres): Open Burning vs. Chipping/Shredding, 

On-Site Biomass Facility vs. Off-Site Biomass Facility 

Health Risk 

Source 

Maximum 

Individual Cancer 

Risk2

(x 10-6) 

Acute Hazard 

Index 

Chronic Hazard 

Index 

Orchard Burning 2.69 10.70 0.58 

Biomass Facility – Off Site 

 Orchard 1.84 nc1 nc 

 Transit 0.09 nc nc 

 Off Site Total 1.93 nc nc 

Biomass Facility – On Site 

 Facility 0.55 0.00 0.00 

 Transit 0.09 nc nc 

 On Site Total 0.65 0.00 0.00 

1

 Acute and Chronic Hazard Indices were not calculated since there is no risk factor or the risk factor is so low that it has 

been determined to be insignificant for this type of unit. 

2 9 year exposure used.
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

Revised July 21, 2010 

5-18 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

Figure 5-3 

Acute Respiratory Risk Isopleths for Open Burning of Prunings (24 hr exposure) 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

Revised July 21, 2010 

5-19 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

Figure 5-4 

Acute Respiratory Risk Isopleths for Open Burning of Orchard Removal (24 hr exposure) 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-20 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

There are a number of practices currently employed by District Compliance staff 

under the policy for Rule 4103 that are designed to minimize the potential health 

hazard of orchard removal burnings of this scale. The Appendix A (p. 7) from the 

Rule 4103 District Policy identifies the conditions that must be satisfied when 

District Compliance staff conduct their mandatory field site inspections prior to 

granting approval to proceed with burning: 

Burn permits issued in rural residential areas, or in other areas 

where smoke may affect smoke sensitive areas, must include sitespecific instructions and permit conditions. The instructions and/or 

conditions must limit the possible smoke impact on nearby 

neighbors and/or smoke sensitive areas. 

1. The permit applicant must be advised that only those materials 

produced along with the crop and listed on the burn permit may 

be permitted to burn. 

2. Additional permit conditions may stipulate any or all of the 

following: 

a. The wind direction required at the time of ignition 

b. The burn site location on the property 

c. The day(s) of the week the burning may occur 

d. The time of day a burn may be ignited 

e. The time of day to cease burning or cease adding material to 

the fire 

f. The size of the burn pile permitted to be burned at one time 

g. The permit will be issued for the duration of need only. 

Compliance Appendix A (p. 35) from the Rule 4103 District Policy also makes 

explicit limits on burning in smoke sensitive areas with greater population 

densities or facilities with sensitive individuals:

SMOKE SENSITIVE AREAS: Smoke sensitive areas are populated 

areas or other areas where smoke and air pollutants can adversely 

affect public health or welfare. These areas can include cities, 

towns, communities, campgrounds, trails, recreational areas, 

hospitals, nursing homes, medical clinics, schools, day-care 

centers, roads and highways, airports, public events, and shopping 

centers. 

A District on-site inspection is required near dense populations or 

smoke sensitive areas. If the District determines there is a reason 

to believe smoke produced from a proposed burn may cause 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-21 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

complaints or create a nuisance, the burning may only be permitted 

under the following conditions: 

A. The District must determine there is no other reasonable 

method of disposal. 

B. The quantities of materials to be burned shall be limited as 

needed. 

C. The days burning may be authorized may be limited. For 

example, a burn site upwind from a school may have to limit 

burning to when school is not in session, such as on weekends 

or during school vacation provided that no other special events 

or school functions are occurring during these off times. 

D. Permittee must establish and provide an at-ready means to 

extinguish the fire if directed to do so by the District or any 

public officer. 

E. Additional permit conditions may stipulate: 

1. The wind direction required at the time of ignition. 

2. The burn site location on the property. 

3. The day(s) of the week the burning may occur. 

4. The time of day a burn may be ignited. 

5. The time of day to cease burning or cease adding material 

to the fire. 

6. The size of the burn pile and/or the number of burn piles 

authorized to burn at one time. 

7. The permit will be issued for the duration of need only. 

F. If any of the conditions provided above cannot be met, such 

burning shall not be permitted. 

Because of these limitations, excess acute health risks from orchard removals 

are minimized. As noted above, the overall trajectory of health risks from 

agricultural open burning has been following a steep downward path since 2004. 

The results of this health risk assessment underscore the logic of (1) the current 

balance stuck under the current CH&SC between the economic costs of 

alternatives to burning on the one hand and the potential health impacts of open 

burning on the other, as well as (2) the ongoing importance of finding new 

incentives and technologies for the long-term elimination of open burning of 

agricultural materials. 
San Joaquin Valley Unified Air Pollution Control District May 20, 2010 

 Revised July 21, 2010 

5-22 Chapter 5: Emissions from Agricultural Burning and 

Alternatives to Burning and Health Considerations 

 Final Staff Report and 

Recommendations on Agricultural Burning

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