Air Quality

California Air Quality

California’s poor air quality has posed a serious public health problem since the 1950s. Over the past several decades, public agencies have taken action to try to address the issue and California has seen progress in pollution remediation and subsequent air quality.

The City of Los Angeles covered in smog. The link between fracking and air quality is most pronounced in urban areas

The City of Los Angeles obscured by air pollution in the 1980s. (Source: Shutterstock)

Even with significant reductions in air pollution, however, California is still home to some of the most polluted air in the United States, with 89% of residents living in counties with unhealthy air.1  The most polluted air can be found in the San Joaquin Valley and Los Angeles basin, where residents are subject to unhealthy air for several months out of the year. In fact, 1/3 of Californians live in areas that do not meet US federal standards for air quality. Currently, out of the state’s 5 largest urban areas, only San Francisco meets all standards for ozone and particular matter. In the San Joaquin Valley, only 25% of residents enjoy air that meets federal standards for ozone.. With the EPA proposing to improve federal standards for ozone because the current standards are too weak to ensure respiratory health, it is likely that even more Californians are subject to substandard air than the data suggests.

While there are many substances that can contaminate air, the most widespread contaminants are ozone – or smog – and particulate matter. Public health experts consider ozone and particulate matter to be among the most dangerous contaminants to the health and lives of millions of Americans causing a host of health issues,2 3 including:

  • Breathing and heart problems;
  • Aggravation of asthma, bronchitis and emphysema;
  • Decreased lung growth in children;
  • Higher chance of developing respiratory illness such as pneumonia or bronchitis; and
  • Lung cancer.

California is still struggling with poor air quality and its negative health consequences. The links between oil production, enhanced well stimulation, and air quality run from the toxic chemicals used in various oil production processes to the frequent trucking to and from well sites, these processes threaten to further pollute our air.

Fracking and Air Quality

Increased truck traffic associated with unconventional oil and gas extraction is a major contributor to elevated ozone and particulate matter levels. Although the number of truck trips per well varies, estimates range from 1,600 truckloads per well to nearly 4,000.4 5


Graphic showing the 3,940 truck trips per well. Transportation is one of the many broad-picture factors that show a link between fracking and air quality.

(Data source: The Pacific Institute)

In 2013, California’s oil wells produced approximately 3.1 million barrels of water, much of which is transported to injection wells by truck.  The combination of increased emissions for heavy truck traffic and the refining of additional carbon-intensive oil has a devastating effect on local air quality. This effect is most pronounced in areas that are already overstressed such as Kern County and the Los Angeles basin. With enhanced drilling methods, the drilling process itself is energy intensive and results in the release of particulates and other chemicals that when exposed to sunlight form ozone and smog.

In addition to ozone and particulate matter, the chemicals used in oil and gas extraction also pose a serious risk to California’s air quality. A recent study found that 37% of the chemicals used in drilling operations are volatile and could become airborne.6 Of those chemicals, more than 89% can cause damage to the eyes, skin, sensory, organs, respiratory and gastrointestinal tracts, or the liver, and 81% can cause harm to the brain and nervous system. Because these chemicals can vaporize, they can enter the body not only through inhalation, but also absorption through the skin. Learn more about potential health impacts.

Another major concern resulting from fracking and other advanced well stimulation techniques is gas leakage. Studies have shown that the amount of methane leaking from wells can approach levels that not only produce the harmful health effects that result from the chemical on the ground level, but contribute to global warming as well.

Refining California’s Dirty Oil

Fracked oil has limited uses in its crude form. The oil must be transported from the well site by pipeline, rail and truck to refineries, where it is  separated, converted, and refined into useful products such as gasoline, heating oil, jet fuel, and petrochemical feedstock. 7

California's refineries produce many harm pollutants. Pollutants are the main link between fracking and air quality.

Refineries produce many harmful air pollutants. (Source: Communities for a Better Environment)

California’s 20 refineries are clustered primarily in the San Francisco Bay area, the Los Angeles area, and the Central Valley near Bakersfield. Each day, these refineries process approximately two million barrels of petroleum. California’s oil refineries emit local toxic air pollution, regional smog-forming pollutants and global greenhouse gases. People living in close proximity to these oil refineries have been shown to have an increase risk of leukemia,8 9 and\\ non-Hodgkin lymphoma,10 and asthma.11

In response to a lawsuit alleging that the EPA was using grossly outdated and insufficient methods to monitor air pollution surrounding oil refineries in California and two other states, new regulations of oil refineries were proposed in April 2014 and will be finalized in April 2015. The new regulations will require that refineries decrease emissions of toxic gases and volatile organic compounds, includes restrictions for “flaring” and other escaped gasses, and require that refineries monitor benzene (a known carcinogen) levels around their sites. Whether the new regulations will effectively reduce the health risk of living near oil refineries is a question for further study.


  1.  American Lung Association’s 2013 State of the Air Report
  2.  American Lung Association’s Health Effects of Ozone and Particulate Pollution
  3.  CDC’s website pages on Air Quality
  4.  Potential Development of the Marcellus
  5.  Hydraulic Fracturing 101
  6.  Natural Gas Operations from a Public Health Perspective
  7. California Energy Commission’s Energy Almanac
  8.  Leukemia Incidence in People Living Close to an Oil Refinery
  9.  Leukemia Risk Associated with Low-Level Benzene Exposure
  10.  Racial Differences in Chronic Lymphocytic Leukemia
  11.  Risk of Asthmatic Episodes of Children
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