13.6 Emissions Summaries

13.6.1 Wildland Fires

This section shows several graphics and tables that describe emissions of wild and prescribed fires in the 2023 NEI based on the methods discussed above. Table 13.14 provides national totals of acres burned and CAPs emissions for wildfires, prescribed burns and pile burns. Pile burns are part of the prescribed burn category but are show separately here since it is a new method for the 2023 NEI.

Table 13.14: National wildland fire acres burned and emissions for the 2023 NEI
Pollutant 2023NEI Wildfires 2023NEI Prescribed burns (no pile burns) 2023NEI Pile burns Total Wildland
ACRES BURNED 2,911,888 13,181,343 16,093,231
PM2.5 (tons) 884,537 1,126,551 29,123 2,040,211
VOC (tons) 2,371,088 1,810,376 3,433 4,184,897
NOX (tons) 68,017 121,462 7,690 197,169
CO (tons) 6,789,077 7,804,179 224,516 14,817,773
SO2 (tons) 49,961 78,207 381 128,549
NH3 (tons) 65,260 68,369 1,532 135,161

Table 13.15 provides national totals for burned acres and CAPs for each forest/ecoregion and fire type. The newly added SCCs allow for further analyses like this table. As mentioned earlier in the year 2023 was a very quiet wildfire season. It is unusual for the prescribed burns PM2.5 emissions to be higher than wildfire emissions but this case can occur during very quiet wildfire seasons. Most of the Boreal Forest emissions occurred in Alaska. Note grassland acres burned make up a good portion of the acres burned for the US but grasses have a lower PM2.5 emissions factor. Figure 13.5 provides an illustration of just the PM2.5 emissions nationally and by forest/ecoregion for year 2023.

Table 13.15: Wildland fire acres burned and emissions for the 2023 NEI by forest/ecoregion.
SCC Ecoregion Acres PM2.5 VOC CO NOx SO2 NH3
Eastem Forest Prescribed Burning 5,492,380 600,639 764,156 4,024,217 74,348 36,862 25,461
Western Forest Wildfires 960,708 366,068 862,274 2,713,692 25,629 26,709 27,555
Boreal Forest Wildfires 295,253 335,318 1,202,892 2,812,756 22,159 10,736 26,215
Grassland Prescribed Burning 4,785,192 290,207 536,545 2,114,821 23,004 26,356 26,468
Western Forest Prescribed Burning 1,518,351 162,316 316,485 1,152,784 13,733 10,910 10,549
Eastern Forest Wildfires 530,066 114,006 151,673 766,339 14,253 7,181 4,922
Grassland Wildfires 757,901 45,053 82,867 321,715 3,544 3,850 3,943
Boreal Forest Prescribed Burning 105,746 39,394 128,338 318,077 2,703 1,210 3,037
Shrubland Wildfires 367,960 24,093 71,382 174,576 2,432 1,485 2,624
Flint Hills Prescribed Burning 1,114,770 22,828 38,932 115,655 6,355 2,268 1,638
Shrubland Prescribed Burning 164,903 11,168 25,920 78,625 1,319 601 1,216
This figure shows 2023 NEI PM~2.5~ emissions by forest/ecoregion and fire type category

Figure 13.5: 2023 NEI PM2.5 emissions by forest/ecoregion and fire type category

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Figures 13.6 and 13.7 show acres burned and PM2.5 emissions for all fires by month in 2023. The total emissions that result from month-to-month result from a combination of different fuels that burn in different fires. It is seen that wildfires (WF) are more prevalent in the hotter months, and prescribed fires (RX) occur more often in the cooler months of 2023. Flint Hills prescribed burns are show separately to mark when those occurred over eastern Kansas and Oklahoma. Pile burns (PB) emissions are also shown but are very minor in most months.

This figure shows Monthly acres burned by fire type for 2023 NEI CONUS Wildland Fires

Figure 13.6: Monthly acres burned by fire type for 2023 NEI CONUS Wildland Fires

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This figure shows Monthly PM~2.5~ by fire type for 2023 NEI CONUS Wildland Fires

Figure 13.7: Monthly PM2.5 by fire type for 2023 NEI CONUS Wildland Fires

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Next, Table 13.16 shows a summary of acres burned and PM2.5 by state, fire type and combustion phase. In terms of total WLF acres burned, several states are shown to have more than one million acres burned in 2023, with FL, GA, KS and TX being the highest acres burned states. However, due to the nature of fuels burned and the type of fire that occurs in the various States, AK and OR are highest for estimated PM2.5 emissions.

Table 13.16: Summary of acres burned and PM2.5 emissions by state and fire type
State Prescribed burns acres burned Prescribed burns PM2.5 (tons) Wildfires acres burned Wildfires PM2.5 (tons) Total Wildland fire acres burned Total Wildland fire PM2.5 (tons)
AL 806,372 64,127 4,980 871 811,352 64,998
AK 17,223 14,615 296,751 336,654 313,974 351,269
AZ 237,971 17,056 214,436 14,455 452,407 31,511
AR 520,289 74,454 15,748 3,607 536,037 78,061
CA 150,734 25,702 376,952 116,250 527,686 141,953
CO 53,893 4,955 47,194 8,429 101,086 13,384
CT 1,118 158 321 80 1,438 238
DE 1,909 218 1,909 218
DC 8 3 8 3
FL 1,565,478 137,813 102,035 10,052 1,667,513 147,865
GA 1,241,104 96,029 17,236 2,382 1,258,339 98,411
HI 580 54 13,297 1,322 13,877 1,376
ID 72,627 12,009 104,523 25,278 177,150 37,287
IL 185,894 13,585 108 12 186,002 13,597
IN 65,815 6,899 597 102 66,411 7,001
IA 213,009 12,656 23,161 1,654 236,170 14,311
KS 1,481,127 43,261 6,035 260 1,487,162 43,521
KY 151,625 18,780 43,915 14,199 195,540 32,979
LA 698,543 73,607 172,194 18,922 870,737 92,530
ME 2,090 345 307 62 2,397 407
MD 24,920 2,367 1,460 207 26,380 2,574
MA 3,375 434 1,038 268 4,414 702
MI 24,926 2,454 4,071 924 28,997 3,378
MN 150,995 14,687 7,214 2,395 158,209 17,082
MS 413,569 32,426 27,694 2,888 441,263 35,313
MO 658,573 79,396 20,846 5,020 679,420 84,416
MT 86,362 9,919 112,404 29,025 198,765 38,944
NE 187,934 10,079 59,876 5,290 247,810 15,369
NV 12,625 256 4,844 72 17,469 328
NH 950 128 43 11 994 139
NJ 26,758 6,377 17,657 11,739 44,414 18,116
NM 172,902 9,808 200,081 20,181 372,984 29,988
NY 21,304 2,942 1,166 318 22,470 3,260
NC 189,832 17,901 90,035 17,994 279,867 35,895
ND 62,047 2,113 7,956 261 70,003 2,374
OH 49,263 5,029 770 185 50,034 5,214
OK 731,471 53,451 133,808 17,355 865,279 70,806
OR 53,051 24,004 224,305 129,372 277,356 153,376
PA 60,280 7,187 9,914 2,675 70,194 9,862
RI 663 101 465 99 1,128 200
SC 411,521 32,656 6,339 854 417,860 33,511
SD 65,773 3,073 1,662 33 67,435 3,106
TN 251,609 33,795 18,346 5,563 269,955 39,358
TX 1,647,666 109,636 223,948 14,414 1,871,614 124,050
UT 41,367 4,437 27,601 3,985 68,968 8,422
VT 1,950 246 12 4 1,963 250
VA 153,265 17,141 31,558 8,989 184,823 26,130
WA 10,964 680 167,917 32,574 178,881 33,254
WV 59,695 10,621 49,188 16,011 108,884 26,632
WI 87,971 11,919 4,352 769 92,324 12,689
WY 50,358 4,965 15,518 465 65,876 5,431
National Total 13,181,343 1,126,551 2,911,888 884,537 16,093,231 2,011,088

Figures 13.8 and 13.9 show 2023 county total area (acres) burned and PM2.5 emissions for wildfires, respectively. Even though 2023 was a quiet wildfire season the western portion of the country had the higher emitting counties. Figures 13.10 and 13.11 show 2023 county total area (acres) burned and PM2.5 emissions for prescribed burns, respectively. The Southeast states are seen to be dominated by prescribed fires. This is a typical pattern we see from NEI-to-NEI.

This figure shows 2023 NEI wildland fires county area burned density map

Figure 13.8: 2023 NEI wildland fires county area burned density map

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This figure shows 2PM~2.5~ county emissions for wildfires for 2023 NEI

Figure 13.9: PM2.5 county emissions for wildfires for 2023 NEI

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This figure shows 2023 NEI prescribed burns acres burned density map

Figure 13.10: 2023 NEI prescribed burns acres burned density map

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This figure shows PM~2.5~ county emissions for prescribed burns for 2023 NEI

Figure 13.11: PM2.5 county emissions for prescribed burns for 2023 NEI

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The amount of fire activity acquired by EPA for the NEI effort continues to increase with each NEI. When Smartfire2 doesn’t have any national or S/L/T activity to reconcile with it, it is then labeled as a satellite-only detected fire or HMS-only detected fire. Due to the location and months of these HMS-only detected fires they are assigned the prescribed burn fire type. If the HMS-only detect occurs on agricultural lands it is assigned an agricultural burn SCC. Table 13.17 provides a summary of the total acres and emissions from these HMS-only detected fires by fire type. Note that about 40% of the acres burned and emissions for prescribed burns (RX) are from HMS-only detected fires. In previous NEIs, this percentage approached or exceeded 50%. In future NEIs, if even more prescribed fire activity data is provided this percentage should continue to be reduced. The wildfire activity is much more complete thanks to national attention and detailed datasets. The HMS-only detects in summer months in western states are assumed to be wildfires and this only adds up to about 7% of the total wildfire acres burned and about 3% of the total emissions.

Table 13.17: Summary of acres burned and emissions by fire type for satellite-detected (HMS) only fires versus all fires totals
Fire Type Description Acres Burned PM2.5 VOC CO NOx SO2 NH3
Total RX 13,181,343 1,126,551 1,810,376 7,804,179 121,462 78,207 68,369
HMS only RX 5,582,767 463,476 742,355 3,204,575 46,615 33,167 29,847
HMS % of Total RX 42.4% 41.1% 41.0% 41.1% 38.4% 42.4% 43.7%
Total WF 2,911,888 884,537 2,371,088 6,789,077 68,017 49,961 65,260
HMS only WF 219,343 22,591 53,190 155,985 1,981 1,478 1,753
HMS % of Total WF 7.5% 2.6% 2.2% 2.3% 2.9% 3.0% 2.7%

Figure 13.12 provides a county map of the total HMS-only acres burned for prescribed burns in the 2023 NEI. The map shows that most of the HMS-only acres burned are in the southern central parts of the US. These are areas where there is a lack of prescribed burn activity available for use in the NEI. Table 13.18 provides state totals of HMS-only acres burned versus total acres burned for prescribed burns. There are numerous states in the southern central part of the country that have HMS-only acres burned about 80+% of their total acres burned by prescribed burns.

Satellite-only (HMS) detected county acres burned for prescribed burns

Figure 13.12: Satellite-only (HMS) detected county acres burned for prescribed burns

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Table 13.18: Summary of acres burned by state for satellite-detected (HMS) only fires
State HMS detect only acres Total prescribed acres % not reconciled with activity
Texas 1,461,453 1,647,099 88.7%
Louisiana 727,379 907,641 80.1%
Oklahoma 671,152 759,581 88.4%
Missouri 620,100 693,623 89.4%
Kansas 415,477 1,488,957 27.9%
Arkansas 250,372 583,223 42.9%
Tennessee 227,511 268,918 84.6%
Iowa 188,047 215,154 87.4%
Nebraska 178,847 187,300 95.5%
Illinois 167,466 185,836 90.1%
Total 4,907,803 6,937,332 70.7%

13.6.2 Agricultural field burning

The NEI uses numerous SCC to classify agricultural burns. Table 13.19 provides a national summary by SCC for the EPA default 2023 NEI emissions. A total of about 54,500 tons of PM2.5 are estimated to be emitted by this sector. Figure 13.13 provides a county map of agricultural burn PM2.5 emissions for year 2023 using the EPA methodology. Note higher emissions are estimated for portions of southern Florida and parts of California and Washington. Figure 13.14 provides monthly PM2.5 emissions for agricultural field burning in tons. Note emissions are smaller during the summer months with peaks in April, August and October. Table 13.20 lists the top ten states for PM2.5 emissions with Florida being the state with highest emissions. Shown in Table 13.21: are comparisons of PM2.5 emissions for those states that submitted PM2.5 vs EPA estimates. Only a few S/L/Ts submitted emissions.

Table 13.19: National Agricultural burning PM2.5 emissions by SCC for 2023 EPA default emissions
SCC SCC Description 2023 EPA-default PM2.5 emissions (tons)
2801500000 Agricultural Field Burning; Unspecified crop type 14,738
2801500141 Agricultural Field Burning; Field Crop is Bean (red) 6,392
2801500150 Agricultural Field Burning; Field Crop is Corn 8,803
2801500151 Agricultural Field Burning; Double Crop Winter Wheat and Corn 46
2801500160 Agricultural Field Burning; Field Crop is Cotton 1,236
2801500171 Agricultural Field Burning; Fallow 2,891
2801500220 Agricultural Field Burning; Field Crop is Rice 2,250
2801500250 Agricultural Field Burning; Field Crop is Sugar Cane 1,882
2801500262 Agricultural Field Burning; Field Crop is Wheat 5,533
2801500263 Agricultural Field Burning; Double Crop Winter Wheat and Cotton 10
2801500264 Agricultural Field Burning; Double Crop Winter Wheat and Soybeans 1,345
2801540000 Agricultural Field Burning - Ditch Burning 1,508
2811020002 Rangeland Burning 7,928
TOTAL 54,562
2023 NEI annual, county PM~2.5~ emissions for crop residue burns

Figure 13.13: 2023 NEI annual, county PM2.5 emissions for crop residue burns

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2023 NEI monthly PM~2.5~ emissions (tons) for crop residue burns

Figure 13.14: 2023 NEI monthly PM2.5 emissions (tons) for crop residue burns

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Table 13.20: Top ten states: 2023 EPA-default agricultural burning PM2.5 emissions
State Name PM2.5 (tons)
Florida 7,139
California 4,929
Washington 4,094
Arkansas 4,080
Louisiana 4,051
North Dakota 2,920
Nebraska 2,588
Texas 2,523
Georgia 2,251
Kansas 2,170
Table 13.21: Comparison of State vs EPA 2023 PM2.5 emissions (tons) for agencies that submitted.
State/Tribe S/L/T-submitted EPA-default
Maricopa County, AZ 0 44
Idaho 1,038 907
New Jersey 50 20
Washington 3,056 4,094
Nez Perce 524 Not available