The Why Axis website, a frequent source of information for editorials on this page, is spending the entire month of May producing information about air quality in America.
Take a deep breath: The site uses Environmental Protection Agency information to show that air quality in large areas of the country is less clean and healthy than it should be, and this is very likely a long-term cause of illness and death.
In an effort to answer a basic question — “which places in the U.S. have the dirtiest air?” — the site is reporting on measurements of something called “average annual fine particle pollution.” This somehow got the abbreviation PM2.5, and The Why Axis says it is important “because it’s small enough to get inhaled deep into the lungs, where it can enter the blood stream and even the brain. All manner of health problems ensue.”
The EPA says average annual levels of PM2.5 in a specific location should not surpass 12 micrograms per cubic meter of air. But the World Health Organization recently lowered its PM2.5 limit down to 5 micrograms, or less than half of the EPA’s, based on recent research that says this stuff is a lot more damaging than previously believed.
The WHO also says that nobody should have to breathe air with PM2.5 levels above 15 micrograms for more than 24 hours.
The bad news is that even with tremendous gains in American air quality over the past 50 years, there are still places in the country whose average PM2.5 levels exceed that 15-microgram warning all year round.
In 2018, the most recent information available, the nation’s worst air quality by far was in the Central Valley of California, which is surrounded by mountain ranges that limit the spread of air. It also has a lot of agriculture, oil refining and heavy vehicle use, all of which tend to affect air quality.
Which leads to the question: What about Mississippi and Louisiana?
You would think that mostly rural Mississippi would have wonderful air quality, but no: EPA surveys of average annual PM2.5 levels put most of both states slightly higher than average on a range of zero to 18 micrograms.
Southwest Mississippi and the Delta have less PM2.5 pollution, in a range from 9 to 11 micrograms. Jackson and most of the rest of the state are higher (a national map is included with this editorial on the newspaper website).
As for Louisiana, most of the state appeared to measure between 11 and 15 micrograms. A small area along the Gulf of Mexico is among the healthiest in the South, thanks to offshore breezes.
The map says much of the nation has decent air. But the air in a band of seven Southern states, along with large parts of Illinois, Indiana and Ohio, is more polluted by fine particles.
If you use EPA standards (12 micrograms), Mississippi and Louisiana are doing OK. But we are nowhere close to meeting the WHO’s recommendations (5 micrograms) for air quality.
Jack Ryan, Enterprise-Journal
