A non-profit called Environment America recently released a report regarding how many days various American cities experienced elevated ozone levels or elevated levels of particulates high enough to bring air quality to an AQI score over 50 (moderate), which can be hazardous to some. While several places in Colorado experienced more than 100 days last year where air quality was at this level, Boulder was the only city to break 150 days.
According to the report, ozone levels were elevated 106 days in Boulder in 2020, with elevated levels of particulates present 82 days. There's some overlapping on those days, with 151 total days having air quality worse than 50 on the AQI scale due to ozone, particulates, or both.
It's important to note that Boulder was in the area of several wildfires last year, which can be detrimental to air quality.
Other spots in Colorado also had air above the AQI score of 50 more than 100 times last year, including Greeley (147 total days), the Denver-Aurora-Lakewood area (129 total days), Fort Collins (114 total days), and Colorado Springs (111 total days).
The non-profit that released the report, Environment Colorado, is headquartered in Denver with their stated mission on the website being: "to transform the power of our imaginations and our ideas into change that makes our world a greener and healthier place for all."
Side Note: According to AirNow.gov, an AQI score in the range of 51 to 100 is considered moderate – acceptable, but with possible risk for some people who are unusually sensitive to air pollution. Technically, ozone AQI was reported 351 days in 2020 in Boulder and particulate AQI was reported 365 days, though not enough to pass the threshold where air becomes hazardous to some.
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