Nearly half of all Americans are now living in regions with unhealthy grades of air pollution, according to the 2022 American Lung Association (ALA) State of the Air Report.

Findings from the 23rd iteration of the annual national report on particulate matter and ozone-related climate health showed that more than 137 million Americans are living in areas with unhealthy levels of particle pollution or ozone—a 2.1 million increase from the 2021 report. An additional 9 million more Americans were affected by daily spikes in potentially deadly particle pollution than observed last year, and the rate of “very unhealthy” and “hazardous” air quality days in the past 3 years reached an all-time high for the two-decade report.

The ALA accumulates and publishes comprehensive national climate data annually to provide local-level insights into the change of air quality over time. Ozone and particle pollution data are derived from the US Environmental Protection Agency’s (EPA) Air Quality System (AQS), with a third party providing characterized hourly averaged ozone concentration information and the 24-hour averaged particulate matter concentration information for each monitoring site from 2018 – 2020.

Grades of ozone-related and short-term particulate matter air quality were defined by the 6-item National Ambient Air Quality Standard, which characterizes air quality from “Good” to “Hazardous.” ALA experts sought to identify number of days that 8-hour daily maximum concentrations occurred in each observed US county. Weighted averages for severity of each pollutant in each county were calculated to define A-F grades on air quality health.

More than 63 million Americans lived in counties that received an “F,” or failing, grade for spikes in daily particle pollution. By far, the most impacted region in the US during this time period was the West; all but 1 of the 25 worst cities for short-term particle pollution was in the western half of the country. The Fresno-Madera-Hanford region of California was the lone area to surpass 50 weighted average days of poor particulate matter. Another 11 California cities were in the top 25, as were 9 Pacific Northwest cities.

“This continues a shifting geographic trend driven in large part by the increasing number and size of wildfires resulting from climate change-induced health and drought,” the report read.

What’s more, the rate of “hazardous” daily particle pollution days in the US are increasing exponentially—from 10 days in the prior report to 74 this year. These days occurred in counties that are home to approximately 4.5 million Americans.

Rates of annual particulate matter are similarly most severely impacting California, per the new report: 7 of the 10 most polluted cities are in California. However, the remainder of the most impacted cities are more evenly spread throughout the US. Investigators observed the following cities new to the top 25 list:

• Chico, CA
• Bend-Prineville, OR
• Yakima, WA
• Augusta, GA

Cities to leave the top 25 list from the prior report included:

• Cleveland, OH
• Missoula, MT
• New York, NY

“For the year-round average levels of fine particles, all cities but the ten most polluted meet the current national air quality standards and get a passing grade in ‘State of the Air,’” the report read. “However, evidence shows that no threshold exists for harmful effects from particle pollution, even below the official standard.”

Los Angeles-Long Beach was by far the most impacted city by ozone pollution, being the only city to exceed 100 weighted average days of pollution. In fact, the major California city exceeded 160 days. However, the 25 most ozone-polluted US cities reported fewer bad air days on average from 2018-2020 than did those in last year’s report of 2017-2019.

While there are regional and even local improvements observable in this year’s report, certain populations remain at greater exposure and severity risk; the ALA observed the following high-risk subpopulations are present throughout counties with at least 1 failing air quality grade:

• People of color (72 million)
• People living in poverty (15.9 million)
• Children (31 million)
• Adults ≥65 years old (21 million)
• Patients with asthma (12.3 million)
• Patients with COPD (6.1 million)
• Patients with lung cancer (66,000)
• Patients with cardiovascular disease (8 million)
• Pregnant women (1.5 million)

In fact, people of color were 3.6 times more likely to live in a county with a failing grade for all 3 pollutants than White people.

On a positive note, the ALA report did observe 64 US cities with monitoring data that reported no high ozone days and 80 with no high short-term particle days—the latter of which was a 32-day decrease from last year’s report. The cleanest cities per particle pollution and ozone pollution day rates included the following:

• Bangor, ME
• Burlington-South Burlington-Barre, VT
• Charlottesville, VA
• Elmira-Corning, NY
• Harrisonburg-Staunton, VA
• Lincoln-Beatrice, NE
• Roanoke, VA
• Urban Honolulu, HI
• Virginia Beach-Norfolk, VA-NC
• Wilmington, NC

Acknowledging the rate of cleanest cities appearing in the eastern region of the country, the report stated that a “combination of policy-driven reductions in emissions on the one hand and climate changed-fueled increases in pollution on the other hand” has driven the disparity of air quality in eastern and western regions of the country.

In fact, it was only 15 years ago that the annual report showed only 22.7% and 19.4% of the counties and states, respectively, to get failing grades in particle pollution were west of the Rocky Mountains. This year, 89.5% and 73.3% of such counties and states to report such failing grades were from that region.

“Historically urban, industrialized eastern and midwestern states like New Jersey, New York and Ohio, which in 2007 had 21 counties on the list between them, are now getting passing grades,” the report read. “A similar story can be told for annual particle pollution.”

The 2022 State of the Air Report is available on the American Lung Association website.