ST. LOUIS – Large tracts of the St. Louis metro area are awash in air pollutants 30 times smaller in diameter than a single human hair, according to analysis from The Guardian newspaper.

Researchers from the University of Washington and Virginia Tech took modeling and data from the Center for Air, Climate and Energy Solutions, and applied that to metropolitan areas across the contiguous United States.

According to the analysis, neighborhoods or regions with a higher population of persons of color suffer greater air pollution.

Illustration courtesy of the Environmental Protection Agency

The analysis uses publicly available data from 2011 to 2015 on the levels of “fine particulate matter,” also known as PM 2.5.

The Guardian says those years are the most recent on record that can be applied to a national model. Racial demographic data was used from the same time period for the sake of consistency.

What is PM 2.5? The Environmental Protection Agency defines it as “fine, inhalable particles, with diameters that are generally 2.5 micrometers and smaller.”

For comparative purposes, fine beach sand and a human hair are 90 micrometers and 50 to 70 micrometers in diameter, respectively.

These types of particles come from automobiles and factories, construction sites, wildfires, and other chemicals.

PM 2.5 particles are so small they can get deep into your lungs and bloodstream, and lead to a litany of health problems over time, such as “respiratory disease, heart attacks, and strokes,” according to The Guardian.

The St. Louis area ranks seventh on The Guardian’s analysis, saying the air quality is affected by nearby power plants and factories. The areas with the worst pollution are north of Delmar Boulevard, as well as Ferguson, and Granite City, East St. Louis, and Belleville in the Illinois Metro East.

The worst location? Bakersfield, California. Although it isn’t a major metropolitan area, the agricultural town is surrounded by mountains, which trap all kinds of pollutants, including farming chemicals, dust, and truck exhaust.

You can see the full Top 10 list by visiting The Guardian.