The 10 cities with the worst (& best) air quality in the U.S.



Myles Ma

Myles Ma

Senior Managing Editor

Myles Ma is a health care expert & personal finance writer for Policygenius. He edits the Easy Money newsletter.

Published August 13, 2018|2 min read

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Updated September 8, 2020: Hilo, Hawaii, is, by acclamation, one of the most beautiful places on earth. It's got waterfalls. It's got jungles. It's got rainbows.

It it also happens to be located in the vicinity of a handful of active volcanoes, including Mauna Loa, the largest active volcano on the planet. Regular eruptions give Hilo the worst air quality of any city in the country, according to data from the Environmental Protection Agency. The EPA measures how polluted the air is using a metric called the Air Quality Index, which scales from zero to 500, with higher numbers indicating dirtier air.

Hilo had the highest median AQI in 2017, at 146. For all but 64 days, the air in Hilo was considered unhealthy, or worse, for sensitive groups. The smog that issues forth from the volcano is so regular that locals have a word for it: vog. (Hint: living in area with unhealthy air quality can affect your insurance rates. Learn more here.)

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If you're planning a trip or a move to a new place, make sure you can breathe easy. Check out the 10 areas with the worst air quality in the U.S., plus the 10 with the best. We based our rankings on 2017 data from the EPA, which tracks air pollutants like carbon monoxide, nitrogen dioxide, ozone, sulfur dioxide and particle pollution. (If you're traveling to a dangerous country, here's how you can protect yourself.)

The 10 places with the worst air quality

1. Hilo, Hawaii

Population: 200,381 Median AQI: 146 Top pollutant: Sulfur dioxide

2. Riverside-San Bernardino-Ontario, California

Population: 4.6 million Median AQI: 99 Top pollutant: Ozone

3. Phoenix-Mesa-Scottsdale, Arizona

Population: 4.7 million Median AQI: 84 Top pollutant: Particulate matter

4. Bakersfield, California

Population: 893,119 Median AQI: 84 Top pollutant: Ozone

5. Payson, Arizona

Population: 53,501 Median AQI: 84 Top pollutant: Sulfur dioxide

6. Visalia-Porterville, California

Population: 464,493 Median AQI: 80 Top pollutant: Ozone

7. Los Angeles-Long Beach-Anaheim, California

Population: 13.4 million Median AQI: 79 Top pollutant: Ozone

8. Fresno, California

Population: 989,255 Median AQI: 74 Top pollutant: Ozone

9. Hanford-Corcoran, California

Population: 150,101 Median AQI: 70 Top pollutant: Ozone

10. San Diego-Carlsbad, California

Population: 3.3 million Median AQI: 65 Top pollutant: Ozone

Want more city guides? Check out these best (and worst) cities for renters.

The 10 places with the best air quality

1. College Station-Bryan, Texas

Population: 258,044 Median AQI: 0 Top pollutant: Sulfur dioxide

2. Enid, Oklahoma

Population: 61,581 Median AQI: 0 Top pollutant: Sulfur dioxide

3. Malone, New York

Population: 51,116 Median AQI: 0 Top pollutant: Sulfur dioxide

4. Seneca Falls, New York

Population: 34,498 Median AQI: 0 Top pollutant: Sulfur dioxide

5. Monroe, Michigan

Population: 149,649 Median AQI: 1 Top pollutant: Sulfur dioxide

6. Ottawa-Peru, Illinois

Population: 149,037 Median AQI: 1 Top pollutant: Sulfur dioxide

7. Washington, North Carolina

Population: 47,088 Median AQI: 1 Top pollutant: Sulfur dioxide

8. Mount Pleasant, Texas

Population: 32,904 Median AQI: 1 Top pollutant: Sulfur dioxide

9. Salem, Ohio

Population: 103,077 Median AQI: 3 Top pollutant: Sulfur dioxide

10. Jasper, Indiana

Population: 54,923 Median AQI: 4 Top pollutant: Sulfur dioxide

Consider protecting yourself while you're traveling. Here's how travel insurance can help.

Image: Nastia Kobzarenko