2013 Almanac Quick Facts

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General StatewideAir Quality InformationSouth Coast
San Joaquin ValleyEmissions Information
Population and VMT

Over the last 20 years, California's population increased 22 percent and the number of vehicle miles traveled each year increased more than 45 percent.

VOC and NOx

At the same time statewide emissions of VOC and NOx, key contributors to ozone and particulate matter, decreased 50 and 60 percent, respectively, since 1990.

Vehicle Standards

Today’s car is 98 percent cleaner than a similar mid-1970s model, and new diesel engines are 95 percent cleaner than those manufactured during the 1980s.

Statewide Progress

As a result, more areas in California continue to come into compliance with the ozone and PM standards.

Population Exposure

Although California has made great strides in improving air quality, ozone, and PM2.5 still present significant challenges. Nonetheless, nearly 63 percent of Californians now live in areas that meet the current federal standard for ozone, compared with only 24 percent in 1990. Progress toward attainment continues to occur throughout the State.

Ozone concentrations

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.

Areas Meeting the Current Ozone Standard

As a result, ozone air quality in 23 countries and 10 additional partial county areas now meet the current 8-hour ozone standard of 0.075 ppm.

Areas Attaining the Previous Ozone Standard

Seven areas, originally designated as nonattainment, now attain the previous 8-hour ozone standard of 0.08 parts per million (ppm). In addition, although U.S. EPA revoked the federal 1-hour ozone standard, Sacramento recently attained this milestone.

PM2.5 Exceedance Days

The number of days exceeding the 24-hour PM2.5 standard statewide has declined dramatically since 2001, from 299 day to 128 days, and the annual average concentrations have declined approximately 35 percent in most California air basins.

About South Coast

California’s largest urban area includes most of Los Angeles County, all of Orange County, and the western urbanized portions of Riverside and San Bernardino counties. More than 16 million people, representing 42 percent of the State’s population, live in the South Coast and generate 24 percent of the State’s NOx emissions and 16 percent of the State’s PM2.5 emissions.

Although South Coast ozone and PM2.5 levels are still among the highest in the nation, the region’s long history of emission control programs has resulted in continued progress over the years. Since 1990, air quality has improved throughout the South Coast, despite significant economic growth and increases in population.

VMT and Population

VMT increased 42 percent from 1990 to 2010, and population increased 20 percent, yet on-road NOx emissions decreased 62 percent and PM2.5 emissions decreased 53 percent.

Ozone Exposure

Today, approximately 55 percent of the South Coast population lives in areas that meet the current federal 8-hour ozone standard. Contrast this with 1990, when air quality throughout the South Coast region violated the standard.

Ozone Exceedance Days

In 1990, ozone concentrations exceeded the 8-hour standard on 181 days with concentrations as high as 0.186 ppm. The 2011 design value was 0.107 ppm, with 106 days exceeding the standard.

PM2.5 Concentrations

The South Coast has experienced dramatic improvements in PM2.5. Both annual and 24-hour concentrations decreased almost 50 percent since 2001, and concentrations are nearing the levels of the federal standards with compliance of both standards expected by 2014.

About San Joaquin Valley

The San Joaquin Valley (Valley) also faces significant challenges in terms of ozone and PM2.5 air quality. The Valley encompasses a large area that includes eight counties, bordered by the San Francisco Bay and Sacramento Valley areas of northern California and the South Coast region of southern California. Although the Valley is the State’s largest agricultural area, urban and industrial development has increased substantially over the last several decades. About 10 percent of the State’s population now lives in the Valley, generating about 15 percent of the State’s NOx emissions and 20 percent of the State’s PM2.5 emissions.

Over the next decade, population and VMT are expected to grow more rapidly in the Valley than in other parts of the State. The wide distribution of emission sources, along with weather and terrain that provide optimum conditions for the formation of high ozone and PM2.5 concentrations, further complicates the challenge of improving air quality. However, despite these challenges and as a result of ongoing emission control programs, ozone and PM2.5 air quality in the San Joaquin Valley has improved since the 1990s.

VMT and Population

Between 1990 and 2010, VMT increased 87 percent and population increased 45 percent, yet on-road NOx emissions decreased 33 percent and PM2.5 emissions decreased 56 percent.

Ozone Exposure

Today, about 17 percent of San Joaquin Valley residents live in areas that meet the current federal 8-hour ozone standard. In 1992, ozone concentrations exceeded the standard throughout the Valley.

Ozone Attainment Progress

While progress toward attainment has been more gradual in the Valley than in other parts of the State, the federal 8-hour ozone design value has decreased 12 percent since 1990, and the number of days exceeding the standard has decreased 29 percent (from 153 to 109).

PM2.5 Concentrations

Annual and 24-hour PM2.5 design values decreased 26 and 40 percent, respectively, during the last decade. Compliance with the annual standard of 15 µg/m3 is expected in 2014, and with the 24-hour standard in 2019.

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