Health Insurance
A Breath of Fresh(er) Air: Average Concentration of Air Pollutants in the US Fell Between 2012 and 2022
There may be a silver lining amid the haze: The average concentration of air pollutants in the U.S. fell over the past 10 years. However, some metros have better air quality than others. As climate change contributes to more frequent and severe wildfires, some places may be particularly prone to unhealthy air.
The newest ValuePenguin study will highlight which metros have the most air pollution and explain how air quality plays a role in health insurance.
On this page
- Key findings
- The concentration of air pollutants in the U.S. fell over 10 years
- California metros dominated places with the most air pollution
- 38.3% of measured days in Riverside, Calif., in 2022 had unhealthy air
- As wildfires spread through Canada, New York City experienced several days of unhealthy air in a short period
- Air quality and health insurance: What to know
- Methodology
Key findings
- The average concentration of air pollutants in the U.S. fell between 2012 and 2022. In this period, fine particulate matter (PM2.5) — tiny, inhalable air particles that can be detrimental to human health — decreased by 15.2%, while ozone levels — the main ingredient in smog — decreased by 12.5%.
- Eight of the 10 metros with the most air pollution in 2022 were in California. Visalia, Calif., ranked first with an average annual PM2.5 concentration of 20.7 µg/m3. The California metro was followed by Bakersfield, Calif. (16.0 µg/m3), and Eugene, Ore. (15.7 µg/m3). The metros with the lowest concentration were Kahului, Hawaii (2.5 µg/m3), Honolulu (3.7 µg/m3) and Duluth, Minn. (3.8 µg/m3).
- Riverside, Calif., had the highest percentage of measured days with unhealthy air in 2022. 38.3% of the days measured in Riverside had unhealthy air, followed by Phoenix (27.4%) and Visalia (21.7%). 248 metros had no unhealthy days for sensitive groups in 2022.
- Between June 13 and July 12, 2023, New York City experienced eight days of unhealthy air, resulting in an average AQI of 74. This means more than 1 in 4 days in New York had unhealthy air.
What’s considered poor air quality?
To determine the metros with the highest number of days with poor air quality in 2022, researchers analyzed Environmental Protection Agency (EPA) Air Quality Index (AQI) data. The AQI values considered "poor" are:
- Hazardous (301 or higher)
- Very unhealthy (201 to 300)
- Unhealthy (151 to 200)
- Unhealthy for sensitive groups (101 to 150)
Researchers only analyzed metros with at least 100 recorded days of AQI values in 2022.
The concentration of air pollutants in the U.S. fell over 10 years
Generally speaking, air pollution in the U.S. has fallen. This applies to two major types of air pollution: fine particulate matter (PM2.5) — tiny inhalable air particles — and ozone — the main ingredient in smog. Between 2012 and 2022, PM2.5 levels decreased by 15.2%, while ozone levels decreased by 12.5%.
Average air pollution concentration in the U.S. by year
Year | Average PM2.5 concentrations (µg/m3) | Ozone (ppm) |
---|---|---|
2012 | 9.2 | 0.076152 |
2013 | 9.0 | 0.066652 |
2014 | 8.9 | 0.066975 |
2015 | 8.6 | 0.067650 |
2016 | 7.8 | 0.068765 |
2017 | 8.1 | 0.067792 |
2018 | 8.3 | 0.069159 |
2019 | 7.7 | 0.065223 |
2020 | 8.1 | 0.065408 |
2021 | 8.5 | 0.066694 |
2022 | 7.8 | 0.066652 |
Source: ValuePenguin analysis of Environmental Protection Agency (EPA) data.
According to ValuePenguin health insurance expert Divya Sangameshwar, this is a direct result of the U.S. government’s commitment to clean air, which began in 1970 with the Clean Air Act. In fact, since the Clean Air Act was enacted, outdoor air pollutants have decreased by 78%, according to the EPA.
Why is air quality important? According to the American Lung Association (ALA), several health risks are associated with breathing polluted air. These include premature deaths, asthma attacks, lung cancer and cardiovascular disease.
California metros dominated places with the most air pollution
While air pollutants have fallen overall, that doesn’t mean the country is pollutant-free. In fact, those who live in California are particularly less likely to enjoy clean air. Of the 10 metros with the most air pollution in 2022, eight were in California.
According to Sangameshwar, that’s likely due to the high number of wildfires in the state.
"California and other parts of the West Coast have been suffering under the burden of increasingly worsening wildfires over the past decade," she says. "The intensification of wildfires, fueled by climate change, has led to poorer air quality in the areas most impacted. The level of commitment that America displayed toward reducing emissions needs to be shown toward reversing the impact of climate change."
Visalia, Calif., led here with an average annual PM2.5 concentration of 20.7 µg/m3. While Visalia didn’t experience any wildfires in 2022, there were 10 wildfires in the surrounding areas, burning at least 3,104 acres combined. Smoke from wildfires can travel hundreds or thousands of miles, according to the EPA — making it likely that each wildfire impacted the air quality in Visalia. Additionally, the EPA states Visalia’s surrounding mountain ranges in the San Joaquin Valley trap air pollutants and pollution sources from heavy traffic on nearby roadways.
10 metros with the most air pollution in 2022
Rank | Metro | Average PM2.5 concentration (µg/m3) |
---|---|---|
1 | Visalia, CA | 20.7 |
2 | Bakersfield, CA | 16.0 |
3 | Eugene, OR | 15.7 |
4 | Hanford, CA | 14.7 |
5 | Modesto, CA | 13.4 |
6 | Stockton, CA | 12.1 |
7 | Fresno, CA | 12.0 |
8 | Indianapolis, IN | 10.7 |
8 | Yuba City, CA | 10.7 |
10 | Merced, CA | 10.5 |
Source: ValuePenguin analysis of EPA Air Quality System (AQS) data.
Following that, Bakersfield, Calif. (16.0 µg/m3), and Eugene, Ore. (15.7 µg/m3), had the next highest levels of air pollution. In 2022, there were six wildfires surrounding the Bakersfield area, burning 4,264 acres.
On the other hand, the metros with the lowest average PM2.5 concentration were Kahului, Hawaii (2.5 µg/m3), and Honolulu (3.7 µg/m3). That may be due to the trade winds in the area. In an interview with Hawaii Public Radio, ALA Hawaii executive director Pedro Haro attributed the high rankings among several Hawaii metros to the Pacific trade winds pushing out pollution to the middle of the ocean.
Rounding out the bottom three was Duluth, Minn., at 3.8 µg/m3.
Full rankings
Metros with the most/least air pollution in 2022
Rank | Metro | Average PM2.5 concentration (µg/m3) |
---|---|---|
1 | Visalia, CA | 20.7 |
2 | Bakersfield, CA | 16.0 |
3 | Eugene, OR | 15.7 |
4 | Hanford, CA | 14.7 |
5 | Modesto, CA | 13.4 |
6 | Stockton, CA | 12.1 |
7 | Fresno, CA | 12.0 |
8 | Indianapolis, IN | 10.7 |
8 | Yuba City, CA | 10.7 |
10 | Merced, CA | 10.5 |
11 | Houston, TX | 10.4 |
12 | Kalamazoo, MI | 10.3 |
Source: ValuePenguin analysis of EPA AQS data. Note: Includes metros with available data.
38.3% of measured days in Riverside, Calif., in 2022 had unhealthy air
PM2.5 and ozone are just two factors of poor air quality. Using the EPA’s Air Quality Index (AQI), which measures particle pollution, ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide, we also looked at which metros had the most unhealthy air in 2022.
Riverside, Calif., ranked highest here: 38.3% of the days measured in Riverside in 2022 had unhealthy air, meaning 93 days had an AQI level of 101 or higher. While Riverside had two major fires in 2022 (burning a combined 170 acres), this metro was particularly exposed to pollutants carried from Los Angeles over air currents.
Phoenix (27.4%) followed. The Arizona metro has more sunlight and less cloud cover than others, making it more prone to ozone pollution. Additionally, high temperatures raise ozone layers, and the temperatures in Phoenix regularly exceeded 100 degrees Fahrenheit during summer 2022.
Finally, Visalia rounded out the top three at 21.7%.
5 metros with the highest percentage of days with unhealthy air in 2022
Rank | Metro | Number of days with unhealthy air | Average AQI | Number of days measured | % of days with unhealthy air |
---|---|---|---|---|---|
1 | Riverside, CA | 93 | 84 | 243 | 38.3% |
2 | Phoenix, AZ | 83 | 77 | 303 | 27.4% |
3 | Visalia, CA | 46 | 67 | 212 | 21.7% |
4 | Los Angeles, CA | 33 | 70 | 182 | 18.1% |
5 | Eugene, OR | 31 | 43 | 181 | 17.1% |
Source: ValuePenguin analysis of EPA AQS data. Note: Metros with less than 100 recorded days of AQI values were excluded.
Overall, there were 25 metros where average AQI levels were 51 or higher, meaning the air quality was moderate or worse. Of these, Riverside again made the top of the list, with an average AQI level of 84. Phoenix (77) and Los Angeles (70) followed.
There’s some good news, though, as 248 metros had no days of unhealthy air quality in 2022.
In 2021, Phoenix had the highest percentage of days with unhealthy air
Looking only at metros with 365 days of recorded data, we also determined which metros had the highest percentage of days with unhealthy air the previous year in 2021. Phoenix ranked first here, with 237 days of unhealthy air. At 64.9%, that’s almost two-thirds of the year. Phoenix also had the highest average AQI levels at 123.
While the rankings shifted in 2022, we're avoiding comparisons to 2022 because our 2021 data only included metros with 365 days of recorded data. Meanwhile, the number of recorded days in 2022 varied by metro.
Following Phoenix, Riverside had 166 days of unhealthy air quality (or 45.5% of the year), while Visalia experienced 134 days (or 36.7%). Riverside also had the second-highest average AQI, at 97. Bakersfield, Calif., had the next-highest average AQI at 84.
Meanwhile, 61 metros with full data had no unhealthy air quality days in 2021.
Full rankings
Metros with the highest percentage of days with unhealthy air in 2022
Rank | Metro | Number of days with unhealthy air | Average AQI | Number of days measured | % of days with unhealthy air |
---|---|---|---|---|---|
1 | Riverside, CA | 93 | 84 | 243 | 38.3% |
2 | Phoenix, AZ | 83 | 77 | 303 | 27.4% |
3 | Visalia, CA | 46 | 67 | 212 | 21.7% |
4 | Los Angeles, CA | 33 | 70 | 182 | 18.1% |
5 | Eugene, OR | 31 | 43 | 181 | 17.1% |
6 | Dallas, TX | 32 | 51 | 213 | 15.0% |
7 | El Centro, CA | 34 | 57 | 238 | 14.3% |
8 | Fresno, CA | 32 | 64 | 243 | 13.2% |
9 | Denver, CO | 35 | 61 | 282 | 12.4% |
10 | Bakersfield, CA | 23 | 57 | 210 | 11.0% |
11 | Las Cruces, NM | 28 | 54 | 273 | 10.3% |
12 | Hanford, CA | 31 | 67 | 304 | 10.2% |
Source: ValuePenguin analysis of EPA AQS data. Notes: Rankings are restricted to the top 100 metros. Metros with less than 100 recorded days of AQI values were excluded.
Metros with the highest percentage of days with unhealthy air in 2021
Rank | Metro | Number of days with unhealthy air | Average AQI | % of days with unhealthy air |
---|---|---|---|---|
1 | Phoenix, AZ | 237 | 123 | 64.9% |
2 | Riverside CA | 166 | 97 | 45.5% |
3 | Visalia, CA | 134 | 80 | 36.7% |
4 | Bakersfield, CA | 128 | 84 | 35.1% |
5 | Los Angeles, CA | 98 | 77 | 26.8% |
6 | Fresno, CA | 82 | 67 | 22.5% |
7 | Denver, CO | 67 | 61 | 18.4% |
8 | Sacramento, CA | 58 | 62 | 15.9% |
9 | Truckee, CA | 53 | 45 | 14.5% |
10 | Hanford, CA | 51 | 61 | 14.0% |
11 | Klamath Falls, OR | 50 | 45 | 13.7% |
12 | Salt Lake City, UT | 48 | 52 | 13.2% |
Source: ValuePenguin analysis of EPA AQS data. Notes: Rankings are restricted to the top 100 metros. Only metros with 365 days of AQI values were included.
As wildfires spread through Canada, New York City experienced several days of unhealthy air in a short period
While air quality has improved overall, climate change may make further progress difficult. New York offers a recent example of that: As smoke from wildfires in Canada billowed over New York City, air quality dropped significantly.
Between June 13 and July 12, 2023 — the latest 30 days at the time of our research — New York City recorded an average AQI of 74, reaching a high of 158 on June 30. In total, there were eight days of unhealthy air — meaning more than 1 in 4 days in New York had unhealthy air.
New York City air quality, June 13 to July 12
Date | AQI |
---|---|
June 13 | 71 |
June 14 | 47 |
June 15 | 44 |
June 16 | 74 |
June 17 | 91 |
June 18 | 70 |
June 19 | 44 |
June 20 | 44 |
June 21 | 32 |
June 22 | 31 |
June 23 | 33 |
June 24 | 43 |
Source: ValuePenguin analysis of EPA AQS data. Note: Though the air quality started to fluctuate more frequently in the week before our analysis period started, city-level data was only available for the previous 30 days at the time of our research.
As climate change worsens, wildfires will likely continue to contribute to poor air quality — particularly because wildfires contribute to higher ozone levels and more particulate matter. In 2022, there were 66,255 wildfires in the U.S., burning 7,534,403 acres. As of Aug. 17, 2023, there have been 35,382 wildfires across the U.S., which have burned 1,679,776 acres.
Air quality and health insurance: What to know
From reducing lung function to causing cancer, poor air quality can harm our health. But what does that mean for our health insurance? According to Sangameshwar, it likely means increased health care costs.
"Thanks to poor air quality, Americans may need to spend a lot more money on medication use, emergency department visits, hospitalizations and testing," she says. "For the nearly 56% of Americans enrolled in high-deductible health plans, these potential expenses may not even be fully covered by their insurance plans or savings in their health savings accounts (HSAs)."
While insurers can’t raise your rates or deny you coverage for a preexisting condition, Sangameshwar says unhealthy air quality could also have a longer-term impact on insurance premiums in your area. Even if you remain unaffected by poor air, it could lead to others in your area getting sick — which could cause insurers to raise rates, citing an increase in their costs.
Methodology
ValuePenguin researchers analyzed Environmental Protection Agency (EPA) data to determine U.S. air pollution levels since 2000. Specifically, researchers analyzed fine particulate matter (PM2.5) and ozone levels in metropolitan statistical areas (MSAs).
To determine the metros with the highest number of days with poor air quality in 2022, researchers analyzed EPA Air Quality Index (AQI) data. The AQI values are:
- Hazardous (301 or higher)
- Very unhealthy (201 to 300)
- Unhealthy (151 to 200)
- Unhealthy for sensitive groups (101 to 150)
Researchers only analyzed metros with at least 100 recorded days of AQI values in 2022.
To analyze the early impact of the Canadian wildfires, researchers compiled AQI data from New York City between June 13 and July 12, 2023.