2020 National Emissions Inventory Technical Support Document: Waste Disposal Open Burning Yard Waste


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2020 National Emissions Inventory Technical
Support Document: Waste Disposal - Open
Burning - Yard Waste

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EP A-454/R-23 -00 ljj
March 2023

2020 National Emissions Inventory Technical Support Document: Waste Disposal - Open

Burning - Yard Waste

U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Air Quality Assessment Division
Research Triangle Park, NC

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Contents

List of Tables	i

36	Waste Disposal - Open Burning - Yard Waste	36-1

36.1	Sector Descriptions and Overview	36-1

36.2	EPA-developed estimates	36-1

36.2.1	Activity data	36-1

36.2.2	Allocation procedure	36-3

36.2.3	Emission factors	36-3

36.2.4	Controls	36-3

36.2.5	Emissions	36-4

36.2.6	Example calculations	36-4

36.2.7	Improvements/Changes in the 2020 NEI	36-5

36.2.8	Puerto Rico and U.S. Virgin Islands	36-5

36.2.9	References	36-5

List of Tables

Table 36-1: Adjustment for Percentage of Forested Acres	36-3

Table 36-2: Sample calculations for CO emissions from open burning	36-4

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36 Waste Disposal - Open Burning-Yard Waste

36.1 Sector Descriptions and Overview

This source category covers intentional burning for waste disposal purposes of leaf and brush species in
outdoor areas, and emission estimates for leaf and brush waste burning are a function of the amount of
waste burned per year. Section 34 covers open burning for municipal solid waste. Section 35 covers
open burning for municipal solid waste.

Table 36-1 shows, for open burning -yard waste, the nonpoint SCCs in the 2020 NEI, whether generated
by EPA, or provided by SLTs. The SCC level 3 and 4 descriptions are also provided. The SCC level 1 and 2
descriptions are "Waste Disposal, Treatment, and Recovery; Open Burning" for all SCCs.

Table 36-1: Open burning SCCs in the 2017 NEI

SCC

Description

EPA

S/L/T

2610000100

All Categories; Yard Waste - Leaf Species Unspecified

2610000300

All Categories; Yard Waste - Weed Species Unspecified (incl Grass)

2610000400

All Categories; Yard Waste - Brush Species Unspecified

A list of agencies that submitted open burning, yard waste emissions is provided in Section 6.2.3.

36.2 EPA-developed estimates

The calculations for estimating the emissions from the burning of yard waste involve first estimating the
amount of leaf and brush waste generated in each county. The amount of county-level yard waste
burned is estimated by calculating the per capita amount of leaf and brush waste generated and
multiplying that by the number of people likely to burn waste in each county. The number of people
likely to burn waste is based on the rural population in each county. The total amount of yard waste
burned is multiplied by emissions factors for criteria air pollutants (CAPs) and hazardous air pollutants
(HAPs) to estimate emissions of these pollutants from yard waste burning.

36.2.1 Activity data

The activity data for this source category is the amount of leaf and brush waste generated, which is
estimated using data the EPA report Advancing Sustainable Materials Management: 2018 Fact Sheet
[ref 1], The report presents the total mass of waste generated from the residential and commercial
sectors in the United States by type of waste for the calendar year 2018.

The per capita value of yard waste subject to burning was developed based on EPA's total amount of
waste generated [Table 1 in ref 1], According to the 2010 version of the same EPA report, residential
waste generation accounts for 55-65% of the total waste from the residential and commercial sectors
[ref 2]; for the per capita calculation, the median value of 60% of total waste generated is assumed. This
number is multiplied by the amount of yard waste generated and divided by the U.S. population in 2018
[ref 3] to determine the per capita amount of yard waste generated in the United States.

36-1

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YW X 0.60

(1)

PC,

¦yw

Where:

PCyw = Per capita value of yard waste in the US, in tons per person

YW = Annual yard waste generated, in million tons

Py,us = Population of the US for year of inventory, in million people

As open burning is generally not practiced in urbanized areas, only the rural population in each county is
assumed to practice open burning. The rural and urban populations are taken from 2020 U.S. Census
data [ref 4], It is assumed that 24% of the rural population burns yard waste [ref 5],

PBurric = Population likely to burn in county c
RPopc = Rural population in county c in 2020

The number of people likely to burn waste in each county (from equation 2) is then used with the value
of per capita yard waste generated (from equation 1) and two assumptions to determine the amount of
leaf and brush waste burned. The first assumption concerns the composition of yard waste; of the total
amount of yard waste generated, yard waste composition is assumed to be 25 percent leaves, 25
percent brush, and 50 percent grass by weight [ref 6], However, open burning of grass clippings is not
typically practiced by homeowners, and as such only estimates for leaf burning and brush burning are
developed.

The second assumption adjusts for variations in vegetation; the percentage of forested acres (including
rural forest and urban forest) is determined using Version 2 of the Biogenic Emission Landuse Database
(BELD2) within the Biogenic Emissions Inventory System (BEIS) [ref 7], Based on this percentage, county-
level yard waste values are adjusted according to the values in Table 36-2. To better account for the
native vegetation that likely occurs in residential yards of farming states, agricultural land acreage is
subtracted before calculating the percentage of forested acres. All municipios in Puerto Rico and
counties in the U.S. Virgin Islands, Hawaii, and Alaska were assumed to have greater than 50 percent
forested acres.

PBurnc = RPopc x 0.24

(2)

Where:

LWC = PBurnc x PCyw x YWFrt x AFfa c

(3)

(4)

BWC = PBurnc x PCyw x YWFrt x AFfa c

Where:

LWC = Annual leaf waste burned in county c, in tons
BWC = Annual brush waste burned in county c, in tons

36-2

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Population likely to burn in county c, from equation 2

Per capita value of yard waste in the US, in tons per person, from equation 1
Fraction of total yard waste for waste type t (leaf or brush)

Adjustment factor based on percent of forested acres in county c, from Table 36-2

Table 36-2: Adjustment for Percentage of Forested Acres

Percent Forested Acres per
County

Adjustment for Yard Waste
Generated

< 10%

0% generated

> 10% & < 50%

50% generated

>50%

100% generated

36.2.2	Allocation procedure

National values for the amount of waste generated are distributed to the counties based on rural
population, as described in Section 36.2.1.

36.2.3	Emission factors

Emissions factors for open burning of yard are provided in the "Wagon Wheel Emission Factor
Compendium" on the 2020 NEI Supporting Data and Summaries site. The emissions factors for CAPs are
from AP-42 [ref 8], the emissions inventory improvement program [ref 9], and an ERTAC workgroup [ref
10]. For burning of leaves, emissions factors for PM25 are calculated by multiplying the PM10 emissions
factor by a ratio of 0.7709. Emission factors for NH3 were derived from the 2002 NEI crop residue
emission estimates using the ratio of NH3/NOx for pasture grass from Pouliot et al. (2017) [ref 11] and
the NOx emission factor from AP-42. Emissions factors for HAPs are from an EPA Control Technology
Center report [ref 12] and can be found online under EIS Augmentation Datasets in the zipped data set
"HAPAugmentation_Nonpoint."

36.2.4	Controls

Controls for residential yard waste burning are generally in the form of a ban on open burning of waste
in a given municipality or county. However, literature suggests that burn bans are not 100% effective. It
is therefore assumed that approximately 25% of the residents that may burn yard waste would burn do
so even if a ban is in place. For counties that have burn bans, the assumption is applied by multiplying
0.25 by the annual waste burned. Currently no counties are assumed to have burn bans in place.

If county c has a burn ban	(5)

ThenLWc = LWC x 0.25

If county c has a burn ban	(6)

Then BWC = BWC x 0.25

Where:

LWC = Annual leaf waste burned in county c, in tons
BWC = Annual brush waste burned in county c, in tons

PBurric	=

PCyW	=

YWFrt	=

AFfa,c	=

36-3

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36.2.5 Emissions

The annual amount of leaf and brush waste burned in each county is multiplied by the emissions factors
provided in the "Wagon Wheel Emission Factor Compendium" on the 2020 NEI Supporting Data and
Summaries site to estimate emissions. Emissions for leaves and residential brush are calculated
separately since emission factors vary by yard waste type.

Ep c = LWC X EFp

Ep,c = EWC x EFp

(7)

(8)

Where:

<-P,C

LWC
BWC
EFd

=	Annual emissions of pollutant p in county c

=	Annual leaf waste burned in county c, in tons

=	Annual brush waste burned in county c, in tons

=	Emission factor for pollutant p, in lbs. of pollution per ton of waste burned

36.2.6 Example calculations

Table 36-3 lists sample calculations to determine the CO emissions from open burning of yard waste.
The values in these equations are demonstrating program logic and are not representative of any
specific NEI year or county.

Table 36-3: Sample calculations for CO emissions from open burning

Eq.#

Equation

Values

Result

1

YW X 0.60

34.5 million tons x 0.60

0.065 tons yard
waste per person
per year

1 uyw n

"y,us

318.85 million people

2

PBurnc = RPopc x 0.24

22,921 people x 0.24

5,501 people likely
to burn

3

LWC = PBurnc x PCyw x YWFrt

5,501 people x 0.065 tons
x 0.25 x 1

89.39 tons of leaf
waste burned

4

BWC = PBurnc x PCyw x YWFrt

5,501 people x 0.065 tons
x 0.25 x 1

89.39 tons of brush
waste burned

5

If county c has a burn ban
Then LWC = LWC x 0.25

N/A

does not have a
burn ban

6

If county c has a burn ban
ThenBWc = BWC x 0.25

N/A

does not have a
burn ban

7

Ep c = LWC X EFp

89.39 tons of leaf waste
x 112 lbs. per ton

5.01 tons CO
emissions from
burning of leaf
waste

36-4

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Eq.#

Equation

Values

Result

Epc = BWC X EFV

89.39 tons of brush waste x
140 lbs. per ton

6.26 tons CO
emissions from
burning of brush
waste

36.2.7 Improvements/Changes in the 2020 NEI

For the 2020 NEI, ammonia emissions factors were developed for leaf waste and brush waste so that
ammonia emissions are estimated for these sources. The ammonia emissions factors are developed by
applying the ratio of NH3 to NOx emissions from pasture grass, using emissions data from Table 1 in
Pouliot et al. (2011) [ref 11], to the NOx emissions factors used for these sources, from AP-42 [ref 8],

36.2.8 Puerto Rico and U.S. Virgin Islands

Emissions from Puerto Rico are calculated using the same method described above. For the U.S. Virgin
Islands, emissions are calculated using 2010 population data, since 2020 Census Data does not exist for
the U.S. Virgin Islands.

36.2.9 References

1. U.S. Environmental Protection Agency. 2018. Advancing Sustainable Materials: 2015 Fact Sheet.
Table 1. Generation, Recovery and Discards of Materials in MSW, 2015 (in millions of tons and
percent of generation of each material).

2. U.S. Environmental Protection Agency. 2011. Municipal Solid Waste Generation, Recycling, and
Disposal in the United States: Facts and Figures for 2010—Fact Sheet, p. 4.

3. U.S. Census Bureau. Total Population, American Community Survey.

4. U.S. Census Bureau, Decennial Censuses, 2010 Census: Summary File 1.

5. Environment Canada. 2001. "Household Garbage Disposal and Burning." Prepared by Environics
Research Group.

6. Two Rivers Regional Council of Public Officials and Patrick Engineering, Inc. 1994. "Emission
Characteristics of Burn Barrels," prepared for the U.S. Environmental Protection Agency, Region
V.

7. U.S. Environmental Protection Agency. 2023. Biogenic Emission Inventory System (BEISi

8. U.S. Environmental Protection Agency. 1992. AP-42, Fifth Edition, Volume 1, Chapter 2: Solid
Waste Disposal. Section 2.5: Open Burning.

9. Eastern Research Group, Inc. Emissions Inventory Improvement Program. Volume III: Chapter

16, Open Burning. 2001.

10. Huntley, Roy, 2009. Spreadsheet "state comparison ERTAC SS version? 4 Nov 23 2009.xls".

11. G. Pouliot, V. Rao, J.L. McCarty, and A. Soja. 2017. Development of the crop residue and
rangeland burning in the 2014 National Emissions Inventory using information from multiple
sources. Journal of the Air & Waste Management Association, 67(5), 613-622.
https://doi.org/10.1080/10962247.2Q16.1268982.

12. U.S. Environmental Protection Agency, Control Technology Center. 1997. Evaluation of
Emissions from the Open Burning of Household Waste in Barrels. EPA-600/R-97-134a.

36-5

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United States	Office of Air Quality Planning and Standards	Publication No. EPA-454/R-23-001jj

Environmental Protection	Air Quality Assessment Division	March 2023

Agency	Research Triangle Park, NC

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