A2: Air Quality Index

Metrics

Air Quality Index (AQI)

The Air Quality Index is a national tool from the Environmental Protection Agency used to communicate outdoor air quality as it relates to human health. Calculated using the average pollutant concentration over 24 hours compared with federal standards, when Air Quality Index values surpass 100, it is generally considered unsafe for sensitive groups. Measuring the number of “bad air days” exceeding an Air Quality Index of 100 is a common strategy for understanding the air quality of an area. Shown here are the number of “bad air days” in each county monitored.

A.2.1 Days of AQI>100 by indicator pollutant

This chart compiles data from the Environmental Protection Agency counting the number of days with an Air Quality Index over 100. Bars are colorized with the indicator pollutant, or pollutant causing potential health hazard that day. The y-axis is measuring days with AQI greater than 100, with the scale going from 0 to 350 days. The x-axis is years, going from 2000 to 2023. A standout year is 2013, with a huge level of Ozone and PM2.5 pollutants.

On This Page

County History

A.2.2 County history of AQI>100 days

Year Box Elder Cache Carbon Davis Duchesne Garfield Iron Salt Lake San Juan Tooele Uintah Utah Washington
2000 1 12 - 27 - - - 52 11 - - 27 -
2001 24 16 - 22 - - - 54 1 2 - 41 -
2002 34 15 - 31 - - - 66 7 5 - 39 -
2003 16 10 - 17 - - - 39 8 1 - 30 -
2004 7 39 - 9 - - - 55 6 0 - 28 12
2005 20 38 - 31 - - - 60 4 12 - 22 21
2006 16 9 - 16 - - - 54 2 12 - 34 7
2007 19 18 - 19 - - - 63 6 12 - 36 4
2008 12 15 - 17 - - - 33 4 5 - 23 7
2009 5 28 - 15 - - - 37 2 10 2 22 3
2010 11 20 - 10 - - - 23 2 10 47 14 8
2011 8 10 1 4 23 - - 30 3 7 32 9 5
2012 14 7 12 0 9 2 - 17 5 7 16 12 12
2013 22 44 13 11 44 2 - 5 0 15 64 41 2
2014 6 13 0 11 2 0 - 22 0 1 8 12 1
2015 5 4 2 7 3 2 - 27 1 4 2 13 3
2016 4 8 0 14 8 0 - 27 0 7 11 19 0
2017 11 17 0 28 9 2 - 44 0 17 11 14 1
2018 9 7 5 13 11 2 - 41 7 10 11 32 1
2019 2 14 1 6 11 0 - 16 0 2 17 1 0
2020 3 9 12 14 5 0 - 20 2 5 3 5 3
2021 4 10 0 26 8 2 4 47 2 16 8 17 3
2022 0 7 0 10 4 0 0 22 0 6 0 5 0
2023 0 8 0 13 34 0 1 16 0 0 9 0 0

References

  1. US Environmental Protection Agency. (2024). Air Quality Index Daily Values Report. (# Days Unhealthy, # Days Very Unhealthy, # Days Hazardous). [Data set]. AirNow. https://www.epa.gov/outdoor-air-qualitydata/air-quality-index-daily-values-report