SLO County got an F for air quality on American Lung Association report card. This is why

How bad is the air quality in San Luis Obispo County?

The San Luis Obispo area was one of the 25 most polluted metropolitan areas in the United States in terms of ozone, according to the American Lung Association’s 2024 State of the Air report.

Each year, the association issues report cards for all U.S. cities and counties where air quality data is collected on ozone and particle pollution. Metro areas are ranked from cleanest to most polluted in terms of pollution and each county is given a grade ranging from A to F.

The Los Angeles-Long Beach metro area topped the list of the spots with the most high ozone days.

Bakersfield, meanwhile, led the nation in terms of year-round and short-term particle pollution.

“Particle pollution and ozone are a threat to human health at every stage of life,” the American Lung Association said on its website, noting that “some groups of people are more at risk of illness and death than others.”

These include children, pregnant people, people 65 and older and those with asthma and other lung diseases.

What’s the air quality in SLO County?

The 2024 State of the Air report grouped San Luis Obispo and Paso Robles together in a single metropolitan area.

The San Luis Obispo-Paso Robles area was No. 23 on a list of the 25 worst metro areas in the nation for high ozone days, according to the State of the Air report.

On average, the area had 10.7 high ozone days per year for the period between 2020 and 2021.

The area landed at No. 26 on the list of metro areas with the worst 24-hour particle pollution, with an annual average of seven high particle days.

In terms of metro areas with the worst annual particle pollution, the San Luis Obispo-Paso Robles area was No. 84. It had an annual average concentration of 8.7 micrograms per cubic meter of air.

Overall, San Luis Obispo County scored an F for ozone and another failing grade for short-term particle pollution on its air quality report card.

It scored a passing grade for long-term particle pollution.

Which US cities have the worst ozone pollution?

Here are the top 10 most polluted metropolitan areas in the United States in terms of ozone, according to the American Lung Association:

1. Los Angeles-Long Beach

2. Visalia

3. Bakersfield

4. Fresno-Madera-Hanford

5. Phoenix-Mesa, Arizona

6. Denver-Aurora, Colorado

7. Sacramento-Roseville

8. San Diego-Chula Vista-Carlsbad

9. Salt Lake City-Provo-Orem, Utah

10. Houston-The Woodlands, Texas

What are the top 10 worst cities for particle pollution?

These 10 metro areas had the worst year-round particle pollution, the State of the Air report said:

1. Bakersfield

2. Visalia

3. Fresno-Madera-Hanford

4. Eugene-Springfield, Oregon

5. San Jose-San Francisco-Oakland

6. Los Angeles-Long Beach

7. Sacramento-Roseville

8. Medford-Grants Pass, Oregon

9. Phoenix-Mesa, Arizona

10. Fairbanks, Alaska

These 10 metro areas topped the list for the worst short-term particle pollution:

1. Bakersfield

2. Fresno-Madera-Hanford

3. Fairbanks, Alaska

4. Eugene-Springfield, Oregon

5. Visalia

6. Reno-Carson City-Fernley, Nevada

7. San Jose-San Francisco-Oakland

8. Redding-Red Bluff

9. Sacramento-Roseville

10. Chico

How does American Lung Association come up with rankings?

The American Lung Association’s State of the Air report for 2024 ranked U.S. cities and graded counties based on ozone and particle pollution during 2020, 2021 and 2022, according to its website.

Data on ozone and short-term particle pollution at locations across the country came from the U.S. Environmental Protection Agency’s Air Quality System, as did data on year-round particle pollution by county.

The American Lung Association said it was assisted by members of the National Association of Clean Air Agencies and the Association of Air Pollution Control Agencies.