# of days air quality in Vermont posed a moderate or greater risk to sensitive populations
Story Behind the Curve
Vermont experienced relatively clean air quality in 2022. There were zero days that either ozone or particulate matter exceeded the national ambient air quality standards, and therefore zero days categorized as "Unhealthy for Sensitive Groups." All 56 days counted for this metric with some level of poor air quality were in the "Moderate" category of the Air Quality Index for 2022. Usual sources of air pollution that contribute to the worst air quality days in Vermont include transport from upwind states in summer (ozone) or local woodsmoke in winter (particulate matter), as well as wildfire smoke. Wildfire smoke events seen in Vermont in 2023 will be included in next year's report. Air quality impacts from wildfire smoke in Vermont are sporadic and do not usually occur every year. While the target number of days with poor air quality is zero, in reality this is unrealistic because air quality is affected by natural phenomenon (such as wildfire smoke) and emissions from upwind of Vermont's borders. These factors, in addition to changes in meteorology from year to year, result in great year-to-year variability, but there is a significant improvement in the long term air quality trend.
Notes on Methodology
This metric counts the number of days per year that the “air quality index” (AQI) was categorized as “Moderate” or “Unhealthy for Sensitive Groups” (USG) for at least one pollutant at one monitoring site based on the National Ambient Air Quality Standards (NAAQS) for ozone and fine particulate matter (PM2.5). Air quality in the USG range exceeds the federal air quality standards (i.e., is worse than the standard); Moderate air quality still poses some risk to those with respiratory illnesses and can have additional environmental and visibility impacts. Ozone is monitored in Bennington, Rutland, and Underhill; PM2.5 is monitored in these locations, as well as in Burlington.