In the previous post, I reported on the percentage of days during which air quality was in the good range in 20 Missouri counties. It is one thing to ask whether a county’s air quality is good, and another to ask if it is so bad that it is unhealthy. This post focuses on the percentage of days with unhealthy air quality.
I looked at data from the EPA’s Air Quality System Data Mart for 20 Missouri counties. The data covered the years 2003-2016, plus the years 1983 and 1993 for a longer term perspective. For a fuller discussion of air quality and the data used for this post, and a map of the 20 counties, see my post Air Quality Update, 2016.
The EPA data distinguishes 4 levels of unhealthy air: Unhealthy for Sensitive Individuals, Unhealthy, Very Unhealthy, and Hazardous. No Missouri county was reported to have Very Unhealthy or Hazardous air quality for any of the years I studied. Figure 1 shows the percentage of monitored days for which air quality was either Unhealthy for Sensitive Individuals, or Unhealthy. The top chart shows a group of counties along the Mississippi River north or south of St. Louis. The middle chart shows a group of counties in the Kansas City-St. Joseph region. The bottom chart shows a group of widely dispersed counties outside of the other two areas.
(Click on chart for larger view).
The percentage of unhealthy air days was 3% or below for all Missouri counties . There were no unhealthy air days at all in 12 of the 20 counties. Compared to 2014, two counties in the Mississippi region and one in the Kansas City region showed very small increases (St. Charles, Jefferson, and Stoddard Counties). Jackson County showed a significant decrease and the City of St. Louis showed a very small decrease. The other counties all stayed the same.
It is heartening, and good for the lungs too, that no county in Missouri had a significant fraction of days on which the air quality was unhealthy. The state clearly has improved its air quality.
Environmental Protection Agency. Air Quality Index Report. This is a data portal operated by the EPA. Data downloaded on 3/23/2017 from http://www.epa.gov/airdata/ad_rep_aqi.html.