Pollution knows no border, so keeping an eye on the sources of toxic air requires a global perspective. To do so, NASA has been using Aura, a sophisticated spacecraft that studies the distribution and density of sulfur dioxide in the atmosphere.
Using data from Aura, researchers from Environment and Climate Change Canada, NASA and two universities have discovered 39 previously unreported sources of sulfur dioxide that are responsible for 6.3 to 12.7 million tonnes (7 to 14 million tons) of the dangerous chemical every year – about 6 to 12 percent of all man-made emissions worldwide.
One-third of these sources – usually coal plants, smelters and refineries – are located around the Persian Gulf, as well as Mexico, Russia and other areas in the developing world. The discrepancy of what has been reported and what has now been measured might have an impact on both a regional and global level.
"We now have an independent measurement of these emission sources that does not rely on what was known or thought known," said Chris McLinden, lead author of the study, in a statement.
The scientists also pinpointed 75 natural sources of sulfur dioxide – non-erupting volcanos that are slowly leaking sulfur dioxide into the atmosphere. Using Aura to monitor volcanoes is very advantageous. Most of them are in remote locations and cannot easily be monitored regularly on land. The research is published this week in Nature Geoscience.
Sulfur dioxide is an incredibly dangerous pollutant. When released into the atmosphere, it reacts with water and oxygen to form sulfuric acid, and with other substances to form atmospheric particulate. These substances can lead to dire consequences for human health, the environment, and the economy.
Thanks to newly developed software, the team were able to track how the pollutant is spread and diluted by the wind. This data can be used not just for tracking, but also for better constructing our climate models.
"The unique advantage of satellite data is spatial coverage," said Bryan Duncan, an atmospheric scientist at NASA’s Goddard. "This paper is the perfect demonstration of how new and improved satellite datasets, coupled with new and improved data analysis techniques, allow us to identify even smaller pollutant sources and to quantify these emissions over the globe."