As we recently reported, a satellite study from NASA scientists revealed that there were at least 39 unreported sources of man-made sulfur dioxide pollution leaking into the air. A well-known health hazard, sulfur dioxide poses significant risks to human health when inhaled and is one of the six air pollutions tightly regulated by the United States Environmental Protection Agency.

The major method used to calculate emissions of dangerous chemicals like sulfur dioxide involves measuring fuel usage and other factors on the ground. These figures help regulators make crucial policy decisions about the permissible amount of these chemicals that can be emitted into the air we breathe. The survey reveals that investigators numbers were more than a little off.

According to Chris McLinden, atmospheric scientists with Environment and Climate Change Canada in Toronto and the study’s lead author, “We now have an independent measurement of these emission sources that does not rely on what was known or thought known. When you look at a satellite picture of sulfur dioxide, you end up with it appearing as hotspots – bulls’ eyes, in effect – which makes the estimates of emissions easier.”

The NASA satellite used in the study gathered data from 2005 to 2014 and identified clusters of coal-fueled power plants, smelters, and oil and gas production found in the Middle East, Latin America, and parts of Russia. Scientists quickly realized that the amounts reported to authorities were significantly lower than what the satellite measurements found.

“Quantifying the sulfur dioxide bulls’-eyes is a two-step process that would not have been possible without two innovations in working with the satellite data,” said study co-author Nickolay Krotov.

Sulfur dioxide causes serious harm if ingested in dangerous concentrations. According to the EPA, side effects of exposure can include bronchoconstriction, exacerbating the symptoms of asthma and a long list of other respiratory illnesses.

A NASA press release describing the details of the survey can be found here.