Scientists at NASA have used a satellite to locate 39 large sources of human-made pollution that have never been reported.

The human-made sources of toxic sulfur dioxide (SO2) emissions are known to be a major health hazard, contribute greatly to acid rain and is heavily regulated by the U.S. Environmental Protection Agency because of this.

Lead study author, Chris McLinden who is an atmospheric scientist with Environment and Climate Change Canada in Toronto, stated that the amount they discovered makes up around 12 percent of all SO2 man-made emissions – an alarming figure that could impact greatly on air quality. The team used new data analysis methods to study images taken by the satellite from 2005 to 2014 and used wind methods such as strength and direction as well as how the sulfer dioxide is dispersed and diluted by wind activity.

“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 sulphur dioxide, you end up with it appearing as hotspots – bull’s-eyes, in effect – which makes the estimates of emissions easier,” he said.

Overall, 114 unreported sources of sulfer dioxide were detected but among the countries where the 39 man-made sources were found included Mexico, Middle East and many areas in Russia who have power plants that use coal as well as oil and gas.

“Generally, these previously unreported sources tended to pop up in more developing types of nations,” Dr. McLinden stated, “where perhaps their legal requirements for reporting are not as rigorous as what we might be used to in the U.S and Canada, for example.”

The team hope that the new findings and techniques will help detect future sulfer emissions and allow environmental agencies to act on tackling the issue.

“The conventional, bottom-up emissions inventories used to assess impacts … are often incomplete or outdated, particularly for developing nations that lack comprehensive emission reporting requirements and infrastructure,” state the authors. “We anticipate that our inventory will help eliminate gaps in bottom-up inventories, independent of geopolitical borders and source types.”

The findings were published in the journal Nature Geoscience.