Last Updated on April 29, 2025 by BVN
Overview: San Bernardino and Riverside Counties in California have been ranked as the most polluted counties to live in due to ozone and particle pollution, according to the American Lung Association’s annual “State of the Air” Report. The Inland Empire region is considered America’s most ozone-impacted region, which increases risks of asthma, allergic responses, and chronic obstructive pulmonary disease (COPD). Local environmental activists and politicians are working to improve the air quality through warehouse regulations and clean air legislation. Assemblymember Robert Garcia has introduced Assembly Bill 914, the Pollution Hotspots Solution Act, to provide new tools to clean up polluted air by creating a statewide program.
Breanna Reeves
San Bernardino and Riverside Counties have once again been ranked as the top two most polluted counties to live in when measured by ozone and particle pollution by the American Lung Association (ALA).
San Bernardino County received an “F” grade across all categories used to monitor air quality in the ALA’s annual “State of the Air” Report. According to the report, San Bernardino County experienced 152 days — the equivalent of five months — of ozone days. Ozone pollution, also known as smog, can come from gases that come out of tailpipes, factories and many other sources. It is toxic to people.
The report noted that Southern California is America’s most ozone-impacted region, which increases risks of asthma, allergic responses and chronic obstructive pulmonary disease (COPD).
“About 88% of Californians live in communities impacted by unhealthy levels of ozone and/or particle pollution,” explained Will Barrett, senior director of Clean Air Advocacy at the ALA. “The Inland Empire is basically the region of the country that has the highest number of unhealthy ozone pollution days, or smoggiest days.”
It is widely known that San Bernardino and Riverside Counties are recognized as having the largest warehouse industry in the state, with Amazon’s largest air hub, known as KSBD, located at the San Bernardino International Airport (SBC).
As of February 2025, 2,534 warehouses are scattered across San Bernardino County and comprise 369,000 daily truck trips, according to data provided by Warehouse CITY, a dashboard created by Pitzer College in collaboration with Radical Research. The daily diesel particulate matter released from these trips is estimated to be 510.4 pounds per day. While there is no documented “safe” daily diesel particulate matter, increased and long-term exposure to diesel PM has significant negative impacts on human health and the environment.
“The air pollutants covered in this report are widespread and can impact anyone’s health. Both ozone and particle pollution can cause premature death and other serious health effects such as asthma attacks, heart attacks and strokes, preterm births, and impaired cognitive functioning later in life. Particle pollution can also cause lung cancer,” Mariela Ruacho, senior manager for Clean Air Advocacy with the ALA stated in a press release.
The California Air Resources Board (CARB) noted that diesel exhaust is responsible for about 70% of the total cancer risk from air pollution.
“One of the things that we know a lot of the time talking about air quality, is people with lower incomes, people of color, are often more likely to be impacted by multiple sources of local air pollution,” Barrett explained. In San Bernardino County, 56% of the population identifies as Hispanic.
“A person of color in the United States is twice as likely as a white person to live in a community that has the worst air quality — failing grades on every category in the report,” Barrett continued. “We know air pollution does discriminate. It does have a heavier toll on many communities, often communities of color and often communities of lower incomes.”
However, local environmental activists and local politicians are working to improve the air quality through warehouse regulations and clean air legislation.
In March, Assemblymember Robert Garcia (D-Rancho Cucamonga), who represents cities like Bloomington, Colton and Fontana, introduced Assembly Bill 914, the Pollution Hotspots Solution Act that will provide California with new tools to clean up its polluted air by creating a statewide program called the Indirect Source Rule.
The bill is supported by the ALA and about 20 other health and medical organizations and additional health experts, all of whom submitted a joint letter of support to Isaac G. Bryan, chair of the Assembly Natural Resources Committee. According to the letter, transportation sources and diesel engines drawn to indirect sources of pollution like warehouses “deliver heavy doses of carcinogenic diesel exhaust to residents on a daily basis.” To address these impacts, several local Industrial Special Risks (ISR) policies were developed.
“The bill would also prioritize controls for indirect sources that contribute to high-level, localized concentrations of pollutants in disadvantaged, low-income, and high-poverty communities,” the letter reads. “We strongly urge you to support for AB 914 (R. Garcia) and vote “yes” because California needs all the tools available to reduce pollution and deliver cleaner air to breathe.”
In March, under the Trump administration’s directive, the Environmental Protection Agency (EPA) announced 31 deregulatory actions and stated that “the agency is committed to fulfilling President Trump’s promise to unleash American energy, lower[ing] cost of living for Americans.”
Regulations being reconsidered under the EPA’s action include the reconsideration of Particulate Matter National Ambient Air Quality Standards, multiple National Emission Standards for Hazardous Air Pollutants and terminating Biden’s Environmental Justice and DEI arms of the agency, among others.
“We’re urging everyone to get involved in petitioning Congress to save the EPA public health mission, and that’s at a federal level,” Barrett shared.
“At the local level, people can get involved in their own community, and whether they’re interested in warehouse issues or other freight related issues, there are plenty of avenues to get involved with the local Air Quality Management District or local government to advocate for cleaner air.”
