San Bernardino County ranks worst in the nation for ozone pollution

Despite progress since the 90s, the number of unhealthy smog days in San Bernardino County worsens

San Bernardino County ranks worst in the nation for ozone pollution
 buzbuzzer from Getty Images Signature

Exposure to unhealthy air continues to make breathing difficult and put sensitive populations at risk in San Bernardino County.  

Once again, San Bernardino County has been labeled worst in the nation for ozone pollution, receiving an F grade across multiple air quality categories, according to the latest findings from the American Lung Association's 2024 "State of the Air" report.

San Bernardino experienced nearly six months of unhealthy smog days per year, far more than any other county during the study's three-year period from 2020 to 2022.

Why it matters: Ozone gas is a powerful lung irritant that reacts with the delicate lining of the small airways, causing inflammation and other damage. Exposure to ozone gas can impact multiple body systems, increasing the risk of premature birth and asthma in children, causing or worsening lung and heart disease, and shortening lives. Children, pregnant people, and the elderly are especially at risk. 

Despite hopes for improved air quality during the COVID-19 pandemic due to reduced human activity, the report indicates that poor air quality persisted, impacting millions of people. The report points to increased freight and goods movement and escalating wildfire incidents contributed to sustained pollution levels during this period. 

Details: This year's report includes the most recent air quality data from 2020-2022 and is updated to reflect the new annual particle pollution standard that the U.S. Environmental Protection Agency (EPA) finalized in February 2024.

The report grades exposure to unhealthy levels of ground-level ozone air pollution and exposure to particle pollution over three years. 

Ozone pollution: The report found that ozone pollution has generally improved nationwide partly due to the Clean Air Act's effectiveness. Still, more than 100 million people nationwide live with unhealthy ozone pollution, including 18 million in Southern California.

San Bernardino, Riverside, and Los Angeles counties once again top the list for the most ozone pollution nationwide.

San Bernardino County, a hub for warehouses and semi-trucks moving goods around the region, experienced an average of 175 unhealthy air days, about 50 more than Riverside County and 60 more than Los Angeles County. 

Of these unhealthy days, 20% of the days in San Bernardino County were "very unhealthy" days, compared to 8% in Riverside County and 14% in Los Angeles County. 

"A major increase in the approval of warehouses and the growth in the logistics industry has essentially invited tens of thousands of new daily truck trips to the region," said Will Barrett, a senior director for the American Lung Assn. told the LA Times

From the mid-90s until 2014, San Bernardino saw a steady decline in ozone pollution - with a reduction of 88 days. However, in recent years, San Bernardino County has seen 55.3 fewer days of unhealthy air compared to 1996. The report warns that climate change-driven warmer temperatures pose challenges to further progress.

High Ozone Days in San Bernardino County. (Source: American Lung Association.)

On the same day the report was released, the Biden administration announced $1.5B to support the goal to transition to zero-emissions heavy-duty trucks that burn fossil fuel and release particle pollution. 

Particle pollution: The report also examined short—and long-term exposure to particle pollution, also known as soot. 

The study outlines the staggering health impacts of particle pollution. Short-term spikes in exposure can trigger illness, hospitalization, and premature death. Day-in and day-out exposure can also be deadly, with studies showing long-term exposure to particle pollution can worsen existing cardiovascular and respiratory diseases and heighten the likelihood of developing diabetes and lung cancer. Studies have also found a link between long-term exposure to particle pollution and an increased risk of Parkinson’s disease, Alzheimer’s disease, and clinical depression and anxiety.

The report found a nationwide increase in the days when particle pollution reached "very unhealthy" and "hazardous" levels, marking the highest figures in the 25 years of reporting.

The top four counties most polluted by short-term particle pollution are in California. 

Similarly, year-round particle pollution levels have reached alarming heights, with more than 90.7 million people living in counties exceeding the new national air quality limit. 

San Bernardino County is ranked 10th worst for year-round particle pollution, behind seven other counties in California and two in Oregon. 

Unequal impact of pollution: The report highlights the disproportionate impact of air pollution on communities of color, who are not only more likely to be exposed to unhealthy air but also more susceptible to adverse health effects, including asthma, diabetes, and heart disease. 

The data shows that individuals of color are 2.3 times more likely than their white counterparts to live in areas with failing grades on all three air pollution measures. 

The takeaway: Harold Wimmer, President and CEO of the American Lung Association, expressed both concern and disappointment at the findings.

"We have seen impressive progress in cleaning up air pollution over the last 25 years, thanks in large part to the Clean Air Act. However, when we started this report, our team never imagined that 25 years in the future, more than 130 million people would still be breathing unhealthy air," Wimmer stated. 

He emphasized the urgent need for action to combat the escalating threat of climate change, which exacerbates air pollution and poses significant health risks to individuals of all ages.

Moving Forward: The full report results and a petition for stronger air quality regulations can be found here.

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