New report: 28 Million Californians Experienced Over 100 Days of Dirty Air in 2020

Media Contacts
Ben Grundy

Former Conservation Campaign Associate, Environment California

California – Over 28 million Californians —about 70% of the state’s population— experienced over 100 days of unhealthy air quality in 2020, according to a new report from Environment California Research & Policy Center, Frontier Group and CALPIRG Education Fund. Air pollution increases the risk of premature death, asthma attacks, cancer and other adverse health impacts, and causes 34,000 deaths every year in California.

“Even one day of breathing in polluted air has negative consequences for our health,” said Ben Grundy, Associate with Environment California Research & Policy Center. “This is unacceptable, and we need to do more to deliver cleaner air for our communities.” 

Eight California areas mentioned in the report experienced over 200 days with elevated ozone and/or particulate pollution. The Hanford-Corcoran area in the Central Valley experienced the most days of polluted air (254 days). It is followed by the San Diego-Chula Vista-Carlsbad metro area (232 days), Madera (223 days), Fresno (218 days), and the Los Angeles-Long Beach-Anaheim metro area (209 days). Overall, around 38.6 million Californians— approximately 98% of the state’s population— experienced more than 30 days with elevated ozone and/or particulate pollution. [See chart with city by city data below.]

In the report, Trouble in the Air: Millions of Americans Breathed Polluted Air in 2020, researchers reviewed Environmental Protection Agency air pollution records from across the country. The analysis, which looks at the most recent data available, focuses on ground-level ozone and fine particulate pollution, which are harmful pollutants that come primarily from burning fossil fuels such as coal, diesel, gasoline and methane gas, and from wildfires. 

Researchers also produced a digital map of bad air days across the country in 2020. With the COVID pandemic in full swing, last year included periods in which people spent more time at home and drove their gas-powered vehicles less — yet bad air quality persisted. 

“One of the top sources of air pollution is transportation,” said Sander Kushen, Advocate with CALPIRG Education Fund. “As our driving has picked up in 2021, you can be sure our vehicle pollution has kept pace. If we want to make a dent in these terrible numbers and save lives, we have got to wean ourselves off of burning fossil fuels to get around.”

The report notes that pollutants from the transportation sector made up 71% of California’s pollution from nitrogen oxides in 2017.

Compounding the existing air quality problems are extreme drought and extended wildfire seasons, which add fine particulate pollution that we can’t easily prevent as our climate continues to heat up. Wildfires are becoming more severe, and that means more smoke filling our air.

While the report finds that air pollution problems persist, the solutions for cleaning our air are readily achievable. The report recommends that policymakers electrify our buildings, equipment and transportation; transition to clean renewable energy; and strengthen federal air quality standards. Congress is considering a bipartisan infrastructure bill that would jumpstart cleaner transportation projects, including $7.5 billion for electric vehicle charging stations. Congress is also considering the Build Back Better Act, which could create even larger investments in climate solutions that can also clean our air.  

The California state legislature is also investing in clean air, with record infusions of almost $4 billion in funding for clean car incentive programs and charging infrastructure. Senator Nancy Skinner, Budget Chair for the California state senate, said California should be doing even more: “As much progress as California has made, we still have many low income communities that suffer from high rates of asthma and other health problems because of dirty air. And several of our large metro areas remain among the worst in the nation for dangerous particulate and ozone pollution,” Skinner said.

“When the health of a family member is threatened, we do what it takes to save them,”  Kushen said. “Every child, grandparent and American should be able to breathe clean air. Our leaders need to act swiftly to zero out pollution from all aspects of our lives. When they do, we’ll all breathe easier.”


  • Senator Nancy Skinner, D-Berkeley

    • “As much progress as California has made, we still have many low income communities that suffer from high rates of asthma and other health problems because of dirty air. And several of our large metro areas remain among the worst in the nation for dangerous particulate and ozone pollution. But the good news is the best actions we can take to clean the air also combat the climate crisis.”

  • Dr. John Balmes, Physician Member at CARB and UCSF/UCB Professor

    • “The terrible air quality from wildfire smoke that we experience should be a wake-up call to the climate emergency. We need to double down on our efforts to develop clean transportation and clean energy solutions.”

  • Councilmember John J. Bauters, City of Emeryville: 

    • “No Californian should have to experience one day of polluted air. Air quality will only get worse as our climate warms, so we have no time to lose. We must make progress toward clean air.”

  • Nurse Alexis Duran, CA Alliance of Nurses for Healthy Environments:

    •  “As a healthcare professional, it is standard practice to address any cause that would affect a patient’s airway, breathing or circulation (ABC’s) as a potential threat to their survival. Poor air quality negatively impacts all three. Air pollution is a public health emergency that requires our immediate attention and action.”

  • Supervisor John Gioia, Contra Costa (Bay Area Air Quality Management District board member): 

    • “Everyone has a right to breathe clean air.  Too many communities in California have unhealthy air, especially lower income communities of color.  We need to quicken our transition to a zero emission transportation system and take bolder steps to reduce pollution from both stationary and mobile sources.   This is the equity issue of our time.”



Environment California Research & Policy Center is a 501(c)(3) organization dedicated to protecting our air, water and open spaces. We work to protect the places we love, advance the environmental values we share, and win real results for our environment.

CALPIRG Education Fund is an independent, non-partisan group that works for consumers and the public interest. Through research, public education and outreach, we serve as counterweights to the influence of powerful special interests that threaten our health, safety or well-being. 

Frontier Group is a nonpartisan research and policy development center, providing information and ideas to help build a cleaner, healthier and more democratic America.