Community Life
Days with Good Air Quality


Days with Good Air Quality

What does this measure?

The percentage of days for which air quality was monitored and found to be good, indicating healthy air both for sensitive groups, such as people with asthma, and for the population as a whole. The Air Quality Index (AQI) summarizes levels of ground-level ozone, particulate matter (soot and other particles), carbon monoxide, sulfur dioxide, and nitrogen dioxide into one measure.

Why is this important?

Exposure to these pollutants can cause short-term health effects such as irritation to the eyes, nose and throat, coughing, sneezing, runny nose, and shortness of breath. Continued exposure can also worsen medical conditions such as asthma and heart disease.

How is our county doing?

In 2021, 89% of days with air quality measurements in Essex County were good air days, down from the rate in 2020, and a 21 percentage point increase from 2000.

How do we compare to similar counties?

Lake County, IL had the lowest percentage of good air days in 2021, at 74%. Middlesex County, MA had the highest at 93% and Westchester County, NY was similar to Essex County. Since 2000, most counties have had an increase in the number of good air days.

Notes about the data

Comparable national and state data is not available due to the quantity and location of EPA monitoring stations. Data for this indicator are expected to be released annually in July.

Days with Good Air Quality
2000200120022003200420052006200720082009201020112012201320142015201620172018201920202021
Essex County, MA68%74%73%80%75%65%70%63%67%76%72%68%74%76%83%82%88%88%86%90%90%89%
Middlesex County, MA75%76%80%93%92%86%83%83%88%90%87%92%90%94%95%95%94%96%91%93%93%93%
Lake County, IL80%77%74%84%87%76%86%79%84%87%82%88%82%87%89%92%88%88%86%86%83%74%
Westchester County, NY81%71%75%81%85%75%79%66%71%77%74%73%80%82%82%79%82%90%87%90%90%89%

Source: U.S. Environmental Protection Agency
Notes: Data were not available for the state or for some counties because they do not have air quality monitoring stations.




Number of Days with Good Air Quality
2000200120022003200420052006200720082009201020112012201320142015201620172018201920202021
Essex County, MA250270265293274239254229247276262248270276304299321321314329330324
Middlesex County, MA275278292338337313304302321330318334328335338345341341333337340338
Lake County, IL291280270308318278313287309308299316296305317332306316304210199180
Westchester County, NY287257261291298272274239260280271263292300299290300327316330327325

Source: U.S. Environmental Protection Agency
Notes: Data were not available for the state or for some counties because they do not have air quality monitoring stations.




INDICATORS TREND | ESSEX COUNTY