Key pieces of environmental monitoring equipment in the US often fail to provide accurate air quality measurements, even when toxic clouds are spewing out of an exploded oil refinery, according to a jaw-dropping new report from Reuters. 

“The government network of 3,900 monitoring devices nationwide has routinely missed major toxic releases and day-to-day pollution dangers,” the report says.

Air monitors are essential tools for determining the air quality of a particular area. An accurate air quality index (AQI) is important: hazardous particulates in the air can cause or worsen serious heart and lung problems. The article highlights myriad problems with the Environmental Protection Agency’s air quality monitoring system, using data from both the EPA and independent monitoring organizations.

One of the most egregious examples happened in 2019, when a refinery explosion released nearly 700,000 pounds of hazardous chemicals into the air in south Philadelphia. The monitors for the area reported that day’s air quality as one of the cleanest of the year. This discrepancy is due to the fact that the nearest air monitor was programmed to only run once every six days, meaning it completely missed the explosion.

Even air monitors that are operating every day of the week can be inaccurate for other reasons, Reuters found, including caps on the levels they’ll record. A monitor for Imperial County, California recorded nothing above a certain number of particulates, when in reality the levels in the air were more than twice that amount.

There also just aren’t that many EPA monitors in the country, meaning it’s impossible to get a truly accurate picture of the quality of the air around us. AQI can be drastically different from one block to the next, granular changes that are often overlooked in the big picture. The EPA has even redrawn maps of specific areas, essentially gerrymandering the air to ensure industrial sites can be built in areas that already have high levels of pollution.

Where the official EPA monitors have fallen short, community-led air monitoring programs have stepped up. Citizen scientists are using their own monitors to track AQI and put pressure on local governments to regulate air quality. In Imperial County, environmental officials adjusted the cap on their air monitors after community monitors showed the severity of the true pollution levels.

To fully grasp the troubling inconsistencies in AQI recording, read Reuters’ full report here.