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Cough, Cough! LA’s Ozone Levels Among Worst In The Nation

An overhead view of the 405 freeway with neighborhoods nearby.
An aerial view of Interstate Highway 405 in Los Angeles.
(Joe Klamar
AFP via Getty Images)
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San Bernardino, Riverside and Los Angeles have the worst ozone pollution in the nation, according to an annual report by the American Lung Association.

The large metropolitan statistical areas also include Long Beach and Anaheim. The areas also received failing grades for high particulate matter.

Ozone is a gas found in the earth’s atmosphere. High above us, it is beneficial, but ozone pollution — which happens when emissions react under heat and sunlight — is very harmful to humans. Ozone can damage the respiratory tract and lungs, resulting in symptoms such as coughing, chest tightness and worsening of asthma symptoms.

The "State of the Air” report showed the number of days of “very unhealthy” or “hazardous” air in the Los Angeles-Long Beach metropolitan area actually improved compared to last year’s report. However, Los Angeles-Long Beach still ranks as the most ozone-polluted metro area in the U.S.

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More than 15 million people live in the combined statistical areas, but some people are more vulnerable to illness and death from their exposure.

In San Bernardino, the air quality was “unhealthy for sensitive groups” or worse for almost half the year.

“Even one poor air quality day is one too many for children, older adults, people with chronic illness, lower-income residents and people of color. Policymakers at the local, state and federal levels must act to ensure that everyone has clean air to breathe, and no community is left behind,” said Mariela Ruacho, the clean air advocacy manager for the American Lung Association.

The report measured air quality between 2019 and 2021, which it noted were among the seven hottest years on record globally.

A flow chart showing how emissions from fossil fuel burning engines react under heat and sunlight to create ground level ozone, which is harmful.
Emissions from fossil fuel burning engines react under heat and sunlight to create ground-level ozone, which is harmful to human health.
American Lung Association)

Heat is a major contributor to ozone pollution. Natural disasters like wildfires have also released hazardous fine particles into the air in California and other western states. The particles in smoke, known as PM 2.5, are tiny enough to enter the bloodstream and cause a number of health challenges. Particle pollution causes breathing problems of varying severity, including asthma attacks and COPD exacerbations — even lung cancer, according to Ruacho.

The American Lung Association found that counties in California and several western states received failing grades for air quality: Transportation, including diesel trucks, trains and planes coupled with cars, refineries and power plants were the main culprits.

“California must shift to zero-emission technologies and invest public funds only in transportation projects that support healthy air,” Ruacho said.

Statewide, more than 98% of Californians live in a community earning a failing grade for unhealthy ozone pollution days, unhealthy particle pollution days and unhealthy annual particle pollution levels. More than 4 in 10 Californians live in an area with failing grades for each pollutant.

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The report said nationwide ozone smog generally improved because of the Clean Air Act, but fine particle pollution worsened. It adds that more than 1 in 3 people in the U.S. live in counties that had unhealthy levels of ozone or particle pollution. The American Lung Association is now calling on lawmakers to urgently take action.

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