The United States' network of 3,900 air monitoring devices across the country routinely miss "major toxic releases and day-to-day pollution dangers," Reuters reports after examining data from the Environmental Protection Agency.
The air monitoring system failed to detect any risk from 10 of the biggest oil refinery explosions from the past decade, despite thousands of people requiring hospitalization and the refineries themselves reporting toxic emissions to regulators, Reuters notes.
In one example from a refinery explosion in Philadelphia last year, the refinery owner told regulators the blast released nearly 700,000 of hazardous chemicals and 3,200 pounds of hydrofluoric acid. Yet, the city's Air Quality Index showed the day was one of the cleanest of 2019, a statistic Johns Hopkins University environmental engineering professor Peter DeCarlo called "crazy."
In some cases, dangerous air quality levels are missed because there are no monitors for small particle pollution present in the first place, Reuters reports. An oil refinery in Superior, Wisconsin, experienced a leak of 17,000 barrels of asphalt in 2018, covering the city in black smoke. But Superior's population of 27,000 is considered too small to require permanent government air pollution monitors nearby despite the presence of the refinery, a spokeswoman for the Wisconsin Department of Natural Resources told Reuters. Read more about the system's failures at Reuters.