8. Calcasieu Parish, LA
> Number of facilities contributing to toxic air: 11
> Avg daily PM2.5 concentration: 7.6 micrograms per cubic meter– #1,723 highest out of all counties
> Population: 202,858 — #331 largest out of all counties
> Population density: 198.13 people per square mile — #528 highest out of all counties
Known as a center of petrochemical refining, Lake Charles is the seat of Calcasieu Parish and home to numerous chemical manufacturers, most of which lie just west of the Calcasieu River. Multiple recent explosions at a Westlake Chemical plant have brought scrutiny on the Houston-based company, which has a long record of chemical spills and air quality violations. Unfortunately, Westlake is just one of many companies in the parish that have released harmful emissions after hurricanes and explosions in the area.
7. Jefferson County, AL
> Number of facilities contributing to toxic air: 12
> Avg daily PM2.5 concentration: 10.8 micrograms per cubic meter– #34 highest out of all counties
> Population: 658,615 — #101 largest out of all counties
> Population density: 600.21 people per square mile — #204 highest out of all counties
Centered around Birmingham, Jefferson County has long been a hub of iron and steel production because of its proximity to large deposits of coal, iron ore, and limestone, which are needed to make iron. Industry hotspots in the area include Southland Tube Inc., which makes carbon steel pipes, and ABC Coke, a coal processing plant northeast of Birmingham that is the leading merchant producer of foundry coke in the U.S.
6. Hartford County, CT
> Number of facilities contributing to toxic air: 13
> Avg daily PM2.5 concentration: 7.4 micrograms per cubic meter– #1,850 highest out of all counties
> Population: 892,153 — #62 largest out of all counties
> Population density: 1,198.34 people per square mile — #105 highest out of all counties
Connecticut is a hub of aerospace manufacturing, and Hartford County has multiple aircraft component manufacturing plants, including Pratt & Whitney in East Hartford, Paradigm in Manchester, and Collins Aerospace (formerly Hamilton Sundstrand) in Windsor Locks. According to the American Lung Association’s 2020 State of the Air Report, the Hartford metro area has the 25th worst ozone pollution in the nation.
5. Brazoria County, TX
> Number of facilities contributing to toxic air: 13
> Avg daily PM2.5 concentration: 9.7 micrograms per cubic meter– #201 highest out of all counties
> Population: 368,062 — #191 largest out of all counties
> Population density: 231.27 people per square mile — #473 highest out of all counties
Just south of Houston, Brazoria County is home to multiple industrial zones including a Chevron Phillips chemical plant in Sweeny that was part of a recent EPA settlement for violating the Clean Air Act and state pollution laws. Multiple chemical companies are also headquartered in Freeport, including Dow Chemicals, who also recently settled with the EPA for pollution violations.
4. Los Angeles County, CA
> Number of facilities contributing to toxic air: 16
> Avg daily PM2.5 concentration: 12.0 micrograms per cubic meter– #20 highest out of all counties
> Population: 10,040,682 — #01 largest out of all counties
> Population density: 2,108.46 people per square mile — #54 highest out of all counties
The most populous county in the U.S., Los Angeles County is known for its smog and automobile exhaust pollution. It is also home to five major oil refineries as well as several chemical manufacturers. Industrial centers are concentrated in the southern end of the county, nearest to the neighborhoods of West Long Beach, Wilmington, and Carson.
