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Statewide Emission T

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

IntroductionEmission Trends and ForecastsThe most current emissions data available are for 2012. Included are the latest point source estimates provided by districts as well as inventory improvements from recent SIPs. Any data prior to this year are derived from historical emissions data where available, and backcasted emissions based on historical socioeconomic growth and control information. Future year estimates are forecasted from the 2012 base year and control measures reported through June 2013. Forecasts take into account emissions data, projected growth rates, and future adopted control measures to estimate emissions in future years.On a statewide basis, emissions of NOx are forecasted to decline 

between 2000 and 2035. Emissions of VOC are forecasted to decrease through 2025 with a slight increase after 2025. In addition to being ozone precursors, both NOx and VOC contribute to secondary PM10

and PM2.5. Direct PM10 and PM2.5 emissions show a decrease from 

2000 to 2015, and are predicted to increase slightly after 2015.Emissions of DPM are forecasted to decline through 2020, remaining relatively constant thereafter.Statewide SOx emissions decreased overall from 2000 through 2035. 

Statewide NH3 emissions are expected to slowly increase from 2000 

to 2035.SIP and transportation conformity inventory forecasts may differ from the forecasts presented in this almanac. For more information on these forecasts, please see the ARB SIP web page at www.arb.ca.gov/planning/sip/sip.htm.

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

Statewide Population and VMTAirborne pollutants result in large part from human activities, and growth generally has a negative impact on air quality. California is fortunate in that it boasts the world’s most progressive emission controls. These controls have resulted in significant air quality improvements, despite substantial growth.During 1992 through 2011, statewide maximum 8-hour ozone values decreased 38 percent. This air quality improvement occurred at the same time the State’s population increased 21 percent and the average daily VMT increased 41 percent. Ambient annual average PM2.5

values in the non-desert areas also show improvement: a 32 percent decrease from 1999 to 2011. While the air quality improvements are impressive, additional emission controls will be needed to offset future growth.

Table 3-2 

Statewide Populatio

Parameter 1990 1995 2000 2005 

Population 29828496 31711849 34000835 35985582 3Avg. Daily VMT/1000 655348 726101 813292 892024 

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

Emission Trends and Forecasts - NOxNOx emission standards for on-road motor vehicles were introduced 

in 1971, followed in later years by the implementation of increasingly more stringent standards and the introduction of three-way catalysts. NOx emissions from on-road motor vehicles have declined 

by 42 percent from 2000 to 2010. NOx emissions are projected to 

further decrease by 73 percent between 2010 and 2035. This occurs as vehicles meeting more stringent emission standards enter the fleet, and all vehicles use cleaner burning gasoline and diesel fuel or alternative fuels.NOx emissions from other mobile categories on the whole are projected to decrease from 2000 to 2035. The two largest NOx contributors in the other mobile category are off-road equipment and ships. 

Stationary source NOx emissions are estimated to drop by 51 percent 

between 2000 and 2015. This decrease has been largely due to a switch from fuel oil to natural gas and the implementation of combustion controls such as low-NOx burners for boilers and catalytic converters for both external and internal combustion stationary sources. 

For additional information on these forecasts, please refer to the ARB SIP web page at www.arb.ca.gov/planning/sip/sip.htm.

NOX Emission Trends (tons/day, annual average)

Emission Source 2000 2005 2010 2015 2020 2025 2030 2035All Sources 3782 3214 2324 1887 1553 1312 1224 1200

Stationary Sources 584 402 313 288 291 297 303 310Area-wide Sources 96 85 75 74 74 73 75 75On-Road Mobile 2097 1769 1210 808 545 389 345 328

Gasoline Vehicles 1098 681 489 313 211 153 119 94Diesel Vehicles 999 1088 721 496 333 235 226 235

Other Mobile 1006 958 725 717 643 553 502 487

Gasoline Fuel 62 62 47 42 40 39 39 40Diesel Fuel 867 826 613 608 532 441 389 372Other Fuel 77 70 65 66 72 73 73 74

Table 3-3 

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

Emission Trends and Forecasts - VOCs

VOC emissions in California are projected to decrease by about 46 percent between 2000 and 2035, largely as a result of the State’s onroad motor vehicle emission control program. This includes the use of improved evaporative emission control systems, computerized fuel injection, engine management systems to meet increasingly stringent California emission standards, cleaner gasoline, and the Smog Check program. VOC emissions from other mobile sources are projected to decline between 2000 and 2035 as more stringent emission standards are adopted and implemented. Substantial reductions have also been obtained for area-wide sources through the vapor recovery program for service stations, bulk plants, and other fuel distribution operations. There are also on-going programs to reduce overall solvent VOC emissions from coatings, consumer products, cleaning and degreasing solvents, and other substances used within California. For additional information on these forecasts, please refer to the ARB SIP web page at www.arb.ca.gov/planning/sip/sip.htm. 

VOC Emission Trends (tons/day, annual average)

Emission Source 2000 2005 2010 2015 2020 2025 2030 2035All Sources 2902 2261 1943 1624 1561 1554 1568 1574

Stationary Sources 564 416 417 401 425 445 465 481Area-wide Sources 783 713 655 611 630 647 665 673On-Road Mobile 1056 675 505 299 220 188 168 145 Gasoline Vehicles 1005 621 468 276 199 167 145 120 Diesel Vehicles 51 54 37 23 21 21 23 25Other Mobile 500 458 366 314 286 273 270 275

 Gasoline Fuel 388 352 282 234 207 193 187 187 Diesel Fuel 84 79 56 50 45 45 47 52 Other Fuel 27 27 28 30 34 35 36 36

Table 3-4 

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

Emission Trends and Forecasts - Directly Emitted PM

PM2.5 emissions are projected to decrease from 2000 to 2035 as a 

result of reduced stationary source and area-wide source emissions. PM2.5 emissions are dominated by area-wide sources. Emissions from paved road dust and unpaved road dust emissions remain fairly constant through the forecast period. Other area-wide source emissions, which include managed burning, residential wood combustion, and fugitive windblown dust, decrease from 2000 to 2035. Exhaust emissions from diesel mobile sources dropped from 2000 to 2035 due to more stringent emissions standards and the introduction of cleaner burning diesel fuel. PM2.5 emissions from stationary sources and 

area-wide sources are expected to increase slightly after 2015.

Table 3-5 

Directly Emitted PM2.5 Emission Trends (tons/day, annual average)

Emission Source 2000 2005 2010 2015 2020 2025 2030 2035All Sources 661 524 447 410 414 419 434 441

Stationary Sources 92 91 82 65 69 72 75 78Area-wide Sources 445 309 275 277 281 284 294 295 Paved Road Dust 24 24 26 25 25 26 26 26 Unpaved Road Dust 28 28 26 27 27 27 27 27 Other Area-wide Sources 394 257 223 225 229 231 241 242

On-Road Mobile 61 59 47 33 31 33 34 36 Gasoline Vehicles 27 23 21 21 21 22 23 24 Diesel Vehicles 34 36 26 12 10 11 11 12Other Mobile 62 65 43 36 33 31 31 32

 Gasoline Fuel 9 10 9 8 8 7 7 7 Diesel Fuel 45 47 26 19 16 14 14 15 Other Fuel 88889999

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

Emission Trends and Forecasts - Directly Emitted PM

PM10 emissions are projected to decrease from 2000 to 2035 as a 

result of reduced area-wide source emissions. PM10 emissions are 

dominated by other area-wide sources, primarily managed burning, residential wood combustion, and fugitive windblown dust. Emissions from paved road dust and unpaved road dust emissions remain fairly constant through the forecast period. Other area-wide source emissions decrease by 52 percent from 2000 to 2010 and increase after 2010. Exhaust emissions from diesel mobile sources dropped by 32 percent from 2000 to 2010 due to more stringent emissions standards and the introduction of cleaner burning diesel fuel. PM10 emissions from stationary sources and area-wide sources 

are expected to increase slightly after 2015.

Table 3-6 

Directly Emitted PM10 Emission Trends (tons/day, annual average)

Emission Source 2000 2005 2010 2015 2020 2025 2030 2035

All Sources 2436 1700 1549 1491 1525 1544 1572 1590Stationary Sources 153 170 184 130 140 147 154 162Area-wide Sources 2122 1366 1236 1254 1282 1292 1310 1314 Paved Road Dust 160 162 179 166 170 171 172 173 Unpaved Road Dust 278 276 255 271 271 271 271 271 Other Area-wide Sources 1685 928 802 817 841 850 866 871

On-Road Mobile 92 92 82 67 68 71 75 79 Gasoline Vehicles 50 48 48 49 50 52 55 57 Diesel Vehicles 42 44 33 19 18 18 20 22Other Mobile 69 70 47 39 36 34 33 34 Gasoline Fuel 12 12 11 10 9 8 8 8 Diesel Fuel 48 50 28 21 17 15 15 16 Other Fuel 8 8 8 9 10 10 10 10

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

Emission Trends and Forecasts - Diesel PMDiesel PM emissions decreased 37 percent from 2000 to 2010 primarily as a result of more stringent emissions standards and the introduction of cleaner burning diesel fuel. Emissions from diesel mobile sources are projected to continue to decrease after 2010. Overall, statewide emissions are forecasted to decline by 71 percent between 2000 and 2035.

Diesel PM Emission Trends (tons/day, annual average)

Emission Source 2000 2005 2010 2015 2020 2025 2030 2035All Sources 86 88 54 31 25 23 23 25

Stationary Sources 33211111Area-wide Sources 00000000On-Road Mobile 34 35 24 9 6 6 7 7

Gasoline Vehicles 00000000Diesel Vehicles 34 35 24 9 6 6 7 7

Other Mobile 48 50 28 21 17 15 15 16

Gasoline Fuel 00000000Diesel Fuel 48 50 28 20 17 15 15 16Other Fuel 00000000

Table 3-7 

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

SOX Emission Trends (tons/day, annual average)

Emission Source 2000 2005 2010 2015 2020 2025 2030 2035All Sources 289 287 123 78 82 88 94 101

Stationary Sources 132 97 64 54 55 58 60 63Area-wide Sources 97766677On-Road Mobile 13 13 5 6 6 5 5 6

Gasoline Vehicles 54454444Diesel Vehicles 79111112

Other Mobile 136 169 46 13 15 18 21 26

Gasoline Fuel 00000000Diesel Fuel 133 166 43 9 11 14 17 21Other Fuel 33444455

Emission Trends and Forecasts - Oxides of SulfurEmissions of SOx declined about 57 percent in California between 

2000 and 2010. Sulfur dioxide emissions from stationary sources decreased between 2000 and 2010 due to improved industrial source controls and switching from fuel oil to natural gas for electric generation and industrial boilers. The SOx emissions from land-based 

on- and off-road gasoline and diesel-fueled engines and vehicles have also decreased due to lower sulfur content in the fuel and recent regulations adopted by the ARB. The “Fuel Sulfur and Other Operation Requirements for Ocean-Going Vessels within California Waters and 24 Nautical Miles of the California Baseline” adopted in 2008 requires the use of cleaner marine distillate fuels in ocean-going vessels that visit California seaports. The SOx reductions seen in the 

“Other Mobile” category can be attributed to this effort.Despite major reductions overall since 2000, SOx emissions from 

the “other mobile” categories are expected to increase slightly in the future due to the significant growth in shipping activities expected for California.

Table 3-8 

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ARB Almanac 2013 – Chapter 3: Statewide Emission Trends and Forecasts 

Emission Trends and Forecasts - AmmoniaAmmonia emissions are projected to increase slightly from 2000 to 2035 by about seven percent. Most of the ammonia emissions are from area-wide sources. The major area-wide source of ammonia is livestock waste. Area-wide source emissions are projected to remain relatively flat from 2000 to 2035. Ammonia emissions from on-road vehicles are produced by three-way catalyst equipped gasoline vehicles. On-road mobile ammonia emissions are forecasted to decrease by 40 percent between 2000 and 2035. Ammonia emissions from stationary sources are primarily related to NOx emission controls, the 

manufacture of a variety of products, and waste disposal. Their emissions are expected to double by 2035. However, because area-wide dominate, the overall trend is flat.

NH3 Emission Trends (tons/day, annual average)

Emission Source 2000 2005 2010 2015 2020 2025 2030 2035

All Sources 730 741 752 719 742 770 776 779Stationary Sources 53 61 66 89 95 100 104 107Area Wide 614 622 637 588 610 634 634 633On-Road Mobile 63 58 48 41 37 36 37 38 Gasoline Vehicles 62 57 47 39 35 34 35 36 Diesel Vehicles 11112222Other Mobile 00001111 Gasoline Fuel 00000000 Diesel Fuel 00001111 Other Fuel 00000000

Table 3-9 

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