Chap

Current Emission

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

This chapter provides statewide information on current emissions and air quality, relative to the national ambient air quality standards. The first section of this chapter includes a summary table of the statewide emission inventory and the air quality information can be found in the second section.It should be noted that emission inventories are developed for many purposes, including SIPs, and for other planning and regulatory needs. For this edition of the Almanac, the current emissions data represent a calendar year 2012 snapshot with updated mobile source estimates from the EMFAC2011 and various off-road models. Also included are the latest point source estimates provided by districts as well as inventory improvements from recent SIPs.Emissions DataThe summary table shows emission data by three major source categories: stationary, area-wide, and mobile sources. Emission data for natural sources are provided in Appendix D. The remaining sections of this Chapter provide information on emissions and air quality on a statewide basis. Emissions are presented for NOx, VOC, PM10, PM2.5, 

DPM, SOx, and NH3.

Emissions are reported as annual averages in tons per day (tpd). For most sources and pollutants that are not seasonal, this describes emissions very well. However, for some pollutants such as PM10 and 

PM2.5, annual averages do not give an accurate indication of the 

seasonal nature of emissions. Many sources of PM10 and PM2.5 are 

seasonal, including wildfires, agricultural processes, and residential wood combustion. Additionally, many sources of PM10 and PM2.5 can 

also be very localized, and basinwide annual averages do not give any information about these sources.

Introduction

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

NOx is a group of gaseous compounds of nitrogen and oxygen, many 

of which contribute to the formation of ozone, PM10, and PM2.5. 

Most NOx emissions are produced by the combustion of fuels. 

Industrial sources report NOx emissions to local air districts and the 

ARB. Other sources of NOx emissions are estimated by the local air 

districts and the ARB. Mobile sources (including on-road and other mobile) make up about 83 percent of the total statewide NOx emissions. Area-wide sources, which include residential fuel combustion 

and managed burning and disposal, contribute only a small portion of the total NOx emissions.

NOx Sources - Statewide 

Table 2-1 

NOx Emissions (annual average)

Emissions Source tons/day Percent

Stationary Sources 284 13%

Area-wide Sources 75 4%

On-Road Mobile 1024 49%

 Gasoline Vehicles 395 19%

 Diesel Vehicles 629 30%

Other Mobile 723 34%

 Gasoline Fuel 45 2%

 Diesel Fuel 613 29%

 Other Fuel 65 3%

Total Statewide 2106 100%

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

Directly Emitted Particulate Matter (PM10 and PMPM is a mixture of substances that includes elements such as carbon and metals; compounds such as nitrates, sulfates, and organic compounds; and complex mixtures such as diesel exhaust and soil. PM2.5

includes fine particles with a diameter of 2.5 microns or smaller and is a subset of PM10. These particles come in many sizes and shapes 

and can be made up of hundreds of different chemicals. Some particles, known as primary particles are emitted directly from a source, such as construction sites, unpaved roads, fields, smokestacks or fires. Others form in complicated reactions in the atmosphere of chemicals such as sulfur dioxides and nitrogen oxides that are emitted from power plants, industries and automobiles. These particles, known as secondary particles, make up most of the fine particle pollution in the country. 

Table 2-3 

PM2.5 Emissions (annual average)

Emissions Source tons/day PercentStationary Sources 62 15%

Area-wide Sources 271 65%

On-Road Mobile 43 10%

 Gasoline Vehicles 21 5%

 Diesel Vehicles 22 5%

Other Mobile 42 10%

 Gasoline Fuel 9 2

%

 Diesel Fuel 25 6%

 Other Fuel 8 2

%

Total Statewide 418 100%

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

Oxides of Sulfur (SOx) are a group of compounds of sulfur and oxygen. Stationary sources account for 49 percent of the emissions of 

SOx. Emissions from stationary sources are related to diesel fuel combustion. Other mobile sources, primarily ocean-going vessels, generate about 40 percent of the statewide SOx emissions. 

SOx Sources - Statewide

Table 2-5 

SO

X Emissions (annual average)

Emissions Source tons/day Percent

Stationary Sources 52 49%

Area-wide Sources

6 6%

On-Road Mobile

5 5%

 Gasoline Vehicles 4 4

%

 Diesel Vehicles 1 1

%

Other Mobile 42 40%

 Gasoline Fuel 0 0

%

 Diesel Fuel 38 36%

 Other Fuel 4 3

%

Total Statewide 105 100%

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

Table 2-7 Diesel engines at ports, including ships, cargo handling equipment, locomotives, and trucks, emit a complex mixture of air pollutants, composed of gaseous and solid material. The solid particles in diesel exhaust, which at times may be visible, are known as particulate matter, which includes carbon particles or “soot.” In 1998, ARB identified DPM as a toxic air contaminant based on its potential to cause cancer and other health problems.Health risks from DPM are highest in areas of concentrated emissions, such as near ports, rail yards, freeways, or warehouse distribution centers. Exposure to DPM is a health hazard, particularly to children whose lungs are still developing, and the elderly who may have other serious health problems. DPM is also a large component of PM pollution in many cities. Table 2-7 shows the source categories for DPM.Diesel PM Sources - Statewide

Diesel PM Emissions (annual average)

Emissions Source tons/day PercentStationary Sources

2 3%

Area-wide Sources

0 0%

On-Road Mobile 20 42%

 Gasoline Vehicles 0 0

%

 Diesel Vehicles 20 42%

Other Mobile 27 55% Gasoline Fuel 0 0

%

 Diesel Fuel 27 55%

 Other Fuel 0 0

%

Total Statewide 49 100%

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

2012 Statewide Emission InventorySummary

Table 2-8 

* Includes directly emitted particulate matter only.

** Natural sources are provided in Appendix D. These summaries do not include emission estimates of wind blown  23 tons/day of PM10.

Division  Major Category VOC Stationary Sources 384  Fuel Combustion 26  Waste Disposal 38 

 Cleaning and Surface Coatings 139  Petroleum Production and Marketing 131  Industrial Processes 49 Area-Wide Sources 609 

 Solvent Evaporation 354  Miscellaneous Processes 255 

Mobile Sources 746  Light Duty Passenger Vehicles 139  Light and Medium Duty Trucks 157 

 Heavy Duty Trucks 64 

 Other On-Road 44 

 Aircraft and Trains 37 

 Ships, Ocean Going Vessels & C Harbor Craft 14  Pleasure Crafts 98 

 Recreational Vehicles 34  Off-Road Equipment 123 

 Other Off-Road 36 

Total Statewide - All Sources** 1739 

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

2012 Statewide Emission Inventoryby Sub-Category

Table 2-9 

* Includes directly emitted particulate matter only.

Division  Major Category Sub-Category VOC Stationary Sources (division total) 384  Fuel Combustion (major category total) 26  - Electric Utilities 2 

 - Cogeneration 2  - Oil And Gas Production (Combustion) 2 

 - Petroleum Refining (Combustion) 3  - Manufacturing And Industrial 7 

 - Food And Agricultural Processing 3 

 - Service And Commercial 5 

 - Other (Fuel Combustion) 1 

 Waste Disposal (major category total) 38  - Sewage Treatment 1 - Landfills 12

 - Incinerators 1 - Soil Remediation 0 - Other (Waste Disposal) 24 

 Cleaning And Surface Coatings (major category total) 139 

 - Laundering 2 - Degreasing 34 

 - Coatings And Related Process Solvents (sub-category total) 58  - Auto Marine, & Aircraft 21 

 - Paper & Fabric 1 - Metal, Wood, & Plastic 21 

 - Other 15

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2012 Statewide Emission Inventoryby Sub-Category 

Table 2-9 (continued)* Includes directly emitted particulate matter only.

Division  Major Category Sub-Category VOC Stationary Sources (division total) (continued) Cleaning And Surface Coatings (major category) (continued) - Printing 18  - Adhesives And Sealants 20  - Other (Cleaning And Surface Coatings) 8 Petroleum Production And Marketing (major category total) 131  - Oil And Gas Production 36  - Petroleum Refining 12  - Petroleum Marketing (sub-category total) 83  - Fuel Distribution Losses 15  - Fuel Storage Losses 2 - Vehicle Refueling 38  - Other 28  - Other (Petroleum Production And Marketing) 0 Industrial Processes (major category total) 49  - Chemical 15  - Food And Agriculture 18  - Mineral Processes 4  - Metal Processes 0 - Wood And Paper 2  - Glass And Related Products 0 - Electronics 0 - Other (Industrial Processes) 9

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

2012 Statewide Emission Inventoryby Sub-Category 

Table 2-9 (continued)

* Includes directly emitted particulate matter only..

Division  Major Category Sub-Category VOC Area-Wide Sources (division total) 609 

 Solvent Evaporation (major category total) 354  - Consumer Products 205  - Architectural Coatings And Related Process Solvent (sub-category total) 78  - Architectural Coating 66 

 - Thinning & Cleanup Solvents 12  - Pesticides/Fertilizers (sub-category total) 42 

 - Farm Use 39  - Commercial Use 2 - Asphalt Paving / Roofing 29 

 - Other (Solvent Evaporation) - Miscellaneous Processes (major category total) 255 

 - Residential Fuel Combustion (sub-category total) 57 

 - Wood Combustion 54 

 - Cooking And Space Heating 3 

 - Other 0 

 - Farming Operations (sub-category total) 146 

 - Tilling,Harvesting, & Growing 0 

 - Livestock 146 

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2012 Statewide Emission Inventoryby Sub-Category

Division  Major Category Sub-Category VOC Area-Wide Sources (division total) (continued) Miscellaneous Processes (major category) (continued) - Construction And Demolition (sub-category total) 0  - Building 0  - Road Construction Dust 0  - Paved Road Dust 0  - Unpaved Road Dust 0  - Fugitive Windblown Dust (sub-category total) 0  - Farm Lands 0  - Pasture Lands 0  - Unpaved Roads 0  - Fires 1 - Managed Burning And Disposal (sub-category total) 43  - Agricultural Burning** 11  - Non-Agricultural Burning** 32  - Other 0 - Cooking 7  - Other (Miscellaneous Processes) 2 

Table 2-9 (continued)* Includes directly emitted particulate matter only.** Agricultural burning includes the prescribed burning of prunings and fi eld crops. Non-agricultural burning includes 

abatement.

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

2012 Statewide Emission Inventoryby Sub-Category 

Table 2-9 (continued)* Includes directly emitted particulate matter only.

Division  Major Category Sub-Category VOC Mobile Sources (division total) 746  On-Road Motor Vehicles (major category total) 403  - Light Duty Passenger (sub-category total) 139  - Non-Evaporative 65 

 - Evaporative 74 

 - Diesel 0 - Light Duty Trucks(<3750 lbs.) (sub-category total) 42 

 - Non-Evaporative 19 

 - Evaporative 23 

 - Diesel 0 - Light Duty Trucks (>3750 lbs) (sub-category total) 59 

 - Non-Evaporative 27 

 - Evaporative 32 

 - Diesel 0 - Medium Duty Trucks (sub-category total) 56 

 - Non-Evaporative 31 

 - Evaporative 25 

 - Diesel 0 - Light Heavy Duty Gas Trucks (<10000 lbs) (sub-category total) 25 

 - Non-Evaporative 16 

 - Evaporative 9 - Light Heavy Duty Gas Trucks (>10000 lbs) (sub-category total) 2 - Non-Evaporative 1 - Evaporative 1 - Medium Heavy Duty Gas Trucks (sub-category total) 6 - Non-Evaporative 4 - Evaporative 2

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

2012 Statewide Emission Inventoryby Sub-Category 

Table 2-9 (continued)* Includes directly emitted particulate matter only.

Division  Major Category Sub-Category VOC Mobile Sources (division total) (continued) On-Road Motor Vehicles (major category) (continued) - Heavy Heavy Duty Gas Trucks (sub-category total) 1 - Non-Evaporative 1 - Evaporative 0 - Light Heavy Duty Diesel Trucks (<10000 lbs) 4 

 - Light Heavy Duty Diesel Trucks (>10000 lbs) 1 

 - Medium Heavy Duty Diesel Trucks 5 

 - Heavy Heavy Duty Diesel Trucks 21 

 - Motorcycles (sub-category total) 36 

 - Non-Evaporative 26 

 - Evaporative 11 

 - Heavy Duty Diesel Urban Buses 1 

 - Heavy Duty Gas Urban Buses (sub-category total) 1 - Non-Evaporative 1 - Evaporative 0 - School Buses (sub-category total) 1 - Non-Evaporative 1 - Evaporative 0 - Diesel 0 - Other Gas Buses (sub-category total) 1 - Non-Evaporative 1 - Evaporative 0 - Motor Coach Diesel Buses 0 - All Other Diesel Buses 0 - Motor Homes (sub-category total) 2 - Non-Evaporative 1 - Evaporative 1 - Diesel 0

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Division  Major Category Sub-Category VOC Mobile Sources (division total) (continued) Other Mobile Sources (major category total) 342  - Aircraft 29  - Trains 8  - Ships and Commercial Boats 0 - Ocean Going Vessels (sub-category total) 9  - Residual Oil 0 - Diesel 9  - Commercial Harbor Craft 5  - Pleasure Craft (sub-category total) 98  - Non-Evaporative 75  - Evaporative 22  - Diesel 1 - Off-Road Recreational Vehicles (sub-category total) 34  - All-Terrain Vehicles 12  - Motorcycles 17  - Snowmobiles 3 - Golf Carts, Specialty Carts & Minibikes 2 - Off-Road Equipment (sub-category total) 123  - Lawn And Garden Equipment 81  - Non-Evaporative 45  - Evaporative 35  - Diesel 1 - Commercial & Industrial Equipment 42  - Non-Evaporative 18  - Evaporative 9 - Diesel 16  - Natural Gas 0  - Farm Equipment (sub-category total) 18  - Non-Evaporative 2 - Evaporative 2 - Diesel 14  - Fuel Storage and Handling 18 Total Statewide - All Sources** 1739 

2012 Statewide Emission Inventoryby Sub-Category

Table 2-9 (continued)

* Includes directly emitted particulate matter only.** Natural sources are provided in Appendix D. These summaries do not include emission estimates of wind blown  23 tons/day of PM10.

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Ozone concentrations in California have improved greatly over the last several decades as a result of the implementation of comprehensive control programs for mobile and stationary sources. Compared with 1990, ozone concentrations are about 10 to 50 percent lower throughout California, with some of the largest decreases occurring in areas with the worst ozone air quality. Additionally, the number of days people are exposed to unhealthy ozone levels has dropped by an average of over 65 percent among the air basins. A number of areas in the State have been below the federal ozone standards for many years, and seven areas that were originally designated as nonattainment for the 1997 federal 8-hour ozone standard of 0.08 ppm now meet this standard. In addition, many of these areas also meet, or are very close to meeting the more health-protective 2008 8-hour ozone standard of 0.075 ppm. Progress continues in all areas of the State, with the greatest remaining challenge in the South Coast and San Joaquin Valley.The 2011 data from California’s ozone network are summarized in Table 2-10 and 2-11. Table 2-10 summarizes design values and the number of days exceeding the 0.075 ppm 8-hour ozone standard in each of California’s 15 air basins. Air basins represent relatively large 

areas of the State with similar meteorology and are often geographically linked. Although nine air basins have at least one site with con- ave at least one site with concentrations above the standard, there can be a great deal of variability centrations above the standard, there can be a great deal of variability 

in ozone levels within an air basin. The in ozone levels within an air basin. Therefore, Table 2-11 provides a summary for the individual regions within these air basins that have been designated as nonattainment. Nonattainment areas are portions of an air basin(s) with unique air pollution characteristics and in some cases can share boundaries with air basins. Of the nonattainment areas 7 of the 16 had concentrations in 2011 which were within 

Statewide Ozone - 2011 Air Quality

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National 8-Hour Nonattainment Areas: Design Values and 8-Hour Exc

Ozone - 2011 Air Quality Tables8-Hour Design Values and Exceedance Days by Air BasinTable 2-10 

Table 2-11 

AIR BASIN 2011 8-Hour Desig

Great Basin Valleys 0.071 

Lake County 0.057Lake Tahoe N/A Mojave Desert 0.097 

Mountain Counties 0.084 

North Central Coast 0.070North Coast 0.047Northeast Plateau 0.058Sacramento Valley 0.095 

Salton Sea 0.093 

San Diego 0.082 

San Francisco Bay Area 0.076 

San Joaquin Valley 0.099 

South Central Coast 0.083 

South Coast 0.107 

Area Design Values 

Butte County 0.077 Calaveras County 0.077 

Coachella Valley 0.093 

Eastern Kern 0.080 Imperial County 0.080 Mariposa County 0.077 

Nevada County (Western part) 0.079 

Sacramento Metropolitan Area 0.095 San Diego County 0.082 

San Francisco Bay Area 0.076 

San Joaquin Valley 0.099 San Luis Obispo County (Eastern San Luis Obispo) 0.078 

South Coast Air Basin 0.107 Tuscan Buttes 0.076 Ventura County 0.083 

West Mojave Desert 0.097 

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

Due to California’s comprehensive emission control program, PM2.5

concentrations in California have improved greatly since monitoring began in 1999. Compared with 1999, 24-hour PM2.5 concentrations 

are about 40 to 50 percent lower throughout California, with some of the largest decreases occurring in areas with the worst PM2.5 air 

quality. A number of areas in the State have been below the federal PM2.5

standard for many years, and four areas that were originally designated as nonattainment for the 2006 federal 24-hour PM2.5 standard 

of 35 

μg/m3 now meet this standard. Progress continues in all areas of 

the State, with the greatest remaining challenge in the South Coast and San Joaquin Valley.The 2011 data from California’s PM2.5 network are summarized in 

Tables 2-12 and 2-13. Table 2-12 summarizes annual and 24-hour PM2.5 design values in each of California’s 15 air basins. Air basins 

represent relatively large areas of the State with similar meteorology and are often geographically linked. Although three air basins have at least one site with concentrations above the standard, there can be a great deal of variability in PM2.5 levels within an air basin. 

Therefore, Table 2-13 provides a summary for the individual regions within these air basins that have been designated as nonattainment for the 24-hour standard. Nonattainment areas are portions of an air basin(s) with unique air pollution characteristics and in some cases can share boundaries with air basins. Five of the seven nonattainment areas had 2011 concentrations meeting the standard. Only the South Coast and San Joaquin Valley had 2011 concentrations above the standard.As mentioned above, the highest PM2.5 levels are found in the South 

Coast and San Joaquin Valley, with the highest 24-hour design value 

Statewide PM2.5 - 2011 Air Quality

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Table 2-12 

* These statistics and determination of their validity are calculated according to the methods specified in 40 CFR Part 50, Apleteness. Both the 98th percentile concentration and the average of quarters concentration relate to the national PM2.5 sta

** Calexico-Ethel design value is based on incomplete data24-hour data - The table may include data from extreme, exceptional, or unusual concentration events: however, thAnnual average data - Extreme, exceptional, or unusual concentration events do not generally significantly influenc

PM2.5 - 2011 Air Quality Tables24-Hour and Annual Average Design Values by Air Basin

National PM2.5 Nonattainment Areas: 24-Hour Design Values by Area

Table 2-13 

AIR BASIN 2011 24-Hour Desig

in micrograms/cubic 

Great Basin Valleys 36.0 

Lake County 7.0 Mojave Desert * Mountain Counties 33.0 

North Central Coast 15.0 North Coast 23.0 Northeast Plateau * 

Sacramento Valley 35.0 

Salton Sea 35.0** San Diego 24.0 

San Francisco Bay Area 31.0 

San Joaquin Valley 62.0 

South Central Coast 22.0 

South Coast 39.0 

Area Design Value

Imperial 35* 

Butte County 35 Sacramento Metro Area 35 San Francisco Bay Area Air Basin 31 San Joaquin Valley Air Basin 62 South Coast Air Basin 39 Yuba City/Marysville 27 

* Calexico-Ethel design value is based on incomplete dataAreas with clean data findings: Butte County, Sacramento, San Francisco Bay Area, and Yuba City/Marysville

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Statewide Carbon Monoxide, Nitrogen Dioxide, Sulfu2011 Air QualityThe national CO standard is now attained statewide in California. The requirements for cleaner vehicles and fuels have been primarily responsible for the reductions in CO, despite significant increases in population and the number of vehicle miles traveled each day. 8-hour CO design values range from 0.90 to 7.52 ppm, all well below the federal 8-hour CO standard of 9 ppm.California has attained the annual average NO2 standard since 1998, 

with current annual average NO2 concentrations ranging from 1 to 

18 ppb, well below the federal annual average standard of 53 ppb. In the early 1980s, 1-hour NO2 concentrations in California were as high as 300 ppb, three times the level of the new 1-hour standard. Today, 1-hour NO2 design values range from 23 to 75 ppb, with 

all values meeting the level of the federal 1-hour NO2 standard of 

100 ppb. The current monitoring network provides a robust indicator of regional exposure to NO2. U.S. EPA has also established new 

monitoring requirements to measure NO2 concentrations near major 

roadways in urban areas. Air districts in California are in the process of developing this new network, which will be phased in between 2014 and 2017.

Nitrogen DioxideCarbon Monoxide 

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ARB Almanac 2013 – Chapter 2: Current Emissions and Air Quality 

Carbon Monoxide, Nitrogen Dioxide, Sulfur Dioxide Peak Indicator and Design Values by Air Basin

Table 2-14 

AIR BASIN 2011 Carbon Monoxide 8-Hour Design Value (ppm) 

Great Basin Valleys No Data 

Lake County No Data 

Lake Tahoe No Data Mojave Desert 4.25 Mountain Counties No Data 

North Central Coast 0.90 North Coast 1.61 Northeast Plateau No Data Sacramento Valley 2.42 Salton Sea 7.52 San Diego 2.31 San Francisco Bay Area 2.61 

San Joaquin Valley 2.23 South Central Coast 1.81 South Coast 3.83 

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