By Karyn Loughrin, CEDIK GIS Associate
Good air quality, while extremely important to people’s health, can be hard to measure. The air we walk through and breathe is full of millions of different particles, some of which are harmful. The Environmental Protection Agency (EPA) has placed regulations on several specific pollutants to protect people’s health and the environment. Particulate matter is one such pollutant. There are two categories for particulate matter: inhalable coarse particles (PM10) and fine particle matter (PM2.5). Fine particle matter can be easily inhaled and lead to aggravated asthma, nonfatal heart attacks, and premature death in people with heart or lung disease.
We looked at the fine particulate matter levels in Kentucky using the 2011 CDC Wonder data and mapped the annual average levels by county. These data are a combination of levels reported at the ground by monitors and information from a satellite that measures particles in the atmosphere. Using both sets of data and an algorithm, the data were compiled into one continuous map. In 2011, the EPA regulation on PM2.5 was 15.0 µg/m. We found that while all counties were compliant, there were higher particulate matter levels in the southwestern part of the state—Christian, Caldwell, and Trigg counties had the three highest levels of particulate matter (Map 1).
Particulate matter has several sources; major ones include agriculture, fire, dust, and fuel combustion. Fuel combustion includes electrical generation, industrial boilers, residential, and commercial/industrial uses of fossil fuels. In 2011, agriculture was the main source of particulate matter in Kentucky counties with high levels (See Figure 1).Agricultural sources of particulate matter are crop and livestock dust, fertilizer application, and livestock waste. In Southwestern Kentucky, the source is almost exclusively crop and livestock dust. Through tillage, dust particles are aerated and released into the air. Map 2 shows that, compared to other regions, the southwestern part of the state’s primary land use is agriculture. While certain tillage practices can reduce soil erosion from air and wind, it is unclear how much either no-till or conservation tillage are practiced in this region. Additionally, Map 2 shows that southwestern Kentucky has fewer trees, which are able to help stabilize soil and trap practical pollutants. Both agricultural activity and fewer trees seem to be likely causes of higher levels of particulate matter in Southwestern Kentucky.
However, across the border in Tennessee, there are a group of counties with similar levels of particulate matter, yet the main source in Tennessee for 2011 was fuel combustion. When both Tennessee and Kentucky counties are combined, fuel combustion is the largest documented source for fine particulate matter in the two-state area. Perhaps it is no surprise then that the EPA cited the Tennessee Valley Authority (TVA) in 2011 for violating the Clean Air Act at several of their fossil fuel plants. Many of these plants fall in areas with high levels of particulate matter and may have contributed to these levels (See Map 3).
In subsequent years, the TVA has updated or scaled back production in some of their older plants. While overall emissions are being reduced, particulate levels due to fuel combustion may change little in southwestern Kentucky. The two busiest TVA power plants—which each process 20,000 tons of coal a day—are within 100 miles of each other. The Cumberland Fossil Plant in Cumberland City, Tennessee resides close to the Kentucky/Tennessee border and the Paradise Fossil Plant is housed in Muhlenberg County, Kentucky.
Along with these observations, it must be noted that air quality is tricky to measure. However, it seems like the higher levels of particulate matter in the southwestern part of Kentucky are most likely a combination of the fossil fuel power plants and agricultural activities. In order to improve air quality, sources of pollution must be reduced and particle entrapment or absorption must be increased. This issue affects the health and well-being of residents in southwestern Kentucky and beyond as air pollutants can easily travel from one area to another.