The Most Polluted Cities in California

California has amazing mountain resorts, deserts, a fine climate, and great beaches, but it has a bad reputation when it comes to air pollution. This state is home to some of the most polluted cities in the United States.

 According to the State of the Air report by the American Lung Association, multiple cities in California have low air quality. These cities appear on the lists for annual particle pollution levels, unhealthy spikes in particle pollution, and unhealthy ozone days.

Smoke coming out a factory representing some of the most polluted cities

Particle pollution refers to microscopic remnants from diesel engines, coal-fired power plants, wood-burning stoves, and wildfires, among other sources. Research has stated that these particles can get stuck in your lungs and even your bloodstream, and trigger heart attacks, asthma attacks, strokes, and in extreme cases lung cancer.  

Among the most polluted cities by year-long particle pollution are:

  • Bakersfield,
  • Fresno-Madera-Hanford,
  • Visalia,
  • Los Angeles-Long Beach,
  • San Jose-San Francisco-Oakland,
  • El Centro,
  • Sacramento-Roseville, and
  • Redding-Red Bluff.

On the other hand, the report also grades short-term particle pollution, which was deadly spikes mainly driven by smoke from major wildfires.

Some of the most polluted cities by short-term particle pollution include:

  • Fresno-Madera-Hanford,
  • Bakersfield,
  • San Jose-San Francisco-Oakland,
  • Los-Angeles-Long Beach,
  • Redding-Red Bluff,
  • Sacramento-Roseville,
  • Visalia, Chico, and
  • El Centro.

Lastly, ozone pollution, also referred to as smog, is an air pollutant that harms people and the environment. Inhaling ozone can cause coughing, wheezing, and chest tightness. Children who play outdoors in polluted environments are especially susceptible.

Ozone levels rise when pollutants emitted by chemical plants, refineries, industrial boilers, power plants, and cars chemically react in the presence of sunlight.

According to the state of the air report, the most polluted cities in California by ozone pollution are:

  • Los Angeles-Long Beach,
  • Bakersfield,
  • Visalia,
  • Fresno-Madera-Hanford,
  • San Diego-Chula Vista-Carlsbad,
  • San Jose-San Francisco-Oakland,
  • El Centro, and
  • Redding-Red Bluff.

The CEO and President of the American Lung Association, Harold Wimmer, stated that the nation needs stronger limits on particle and ozone pollution to safeguard health, especially for people with lung disease and children.  


Do you want to know the quality of the air you breathe? Download AirCare – our free mobile app that tracks air pollution from your pocket, and check out the AirCare blog!

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