Scientists discover dozens of new sources of dangerous air pollution, pumping millions of tonnes of sulfur dioxide into air

Scientists may have significantly underestimated a dangerous source of pollution in the atmosphere, new research suggests.

A satellite study, published Monday in the journal Nature Geoscience, has revealed nearly 40 previously unreported major sources of sulfur dioxide emissions - a pollutant that can cause multiple harmful health and environmental impacts and even exacerbate global warming.

Sulfur dioxide pollution can come from a variety of sources, both natural and industrial, including volcanoes, oil refineries and the burning of fossil fuels. Although it has a relatively short lifespan in the atmosphere - a few hours to a few days - it’s important for scientists to keep track of its presence to help inform air quality and climate models and create pollution-cutting policies.

Until now, scientists have mostly relied on emissions inventories drawing on national reports to identify the world’s sulfur dioxide sources and the amount of pollution they’re putting out. Satellite information has been able to help scientists further quantify sulfur dioxide emissions - but this method has mostly been useful when the scientists already know where the emissions are coming from. That’s because winds can help obscure sulfur dioxide hotspots, making it difficult to pick them out if their location isn’t already known.

But in the new study, researchers from Canada’s environment and climate change department and other institutions in the Unite States and Canada have described a new method that allows them to identify and map sulfur dioxide sources all over the world - including sources that may not have been previously identified or reported. And they’ve found that anywhere from 7 to 14 million tonnes of sulfur dioxide may be missing from global inventories each year.

The new method combines satellite data with wind information to more accurately pinpoint pollution sources.

“For each satellite measurement, we would know wind speed and direction and thus, using both pieces of information together, we can actually detect the location of where the sulfur dioxide is coming from,” said Chris McLinden, a research scientist with Environment and Climate Change Canada and the new study’s lead author. “And so we were able to essentially do a global search for these sources.”