Air pollution shines from this alarming map

Traces of engraving draw a map of settlements and industry in a haunting graphic published by data analysis startup Descartes Labs.

The stains and silver locks represent emissions of nitrogen dioxide, a gas produced by combustion that contributes to the problems of acid rain, haze and lungs. Although there are natural sources of nitrogen dioxide, people are major emitters, according to the Environmental Protection Agency.

Cars, trucks, power plants, factories and even lawnmowers and construction site machines can draw nitrogen dioxide into the atmosphere. Forest fires and agricultural fires can also. "You look at a map showing where the objects are burned," says Laura Mazzaro, atmospheric scientist and environmental engineer at Descartes.

Image: Labels Descartes

The data comes from the Sentinel 5P satellite – a satellite launched in October 2017 to monitor the atmosphere. It is part of a family of satellites launched by the European Space Agency and designed to observe our planet. Other satellites in the series are looking at vegetation, temperature and even cracks in the Antarctic ice.

This particular map is a version of a series of images that Descartes Labs published earlier in February and reported for the first time by Axios. To achieve them, Descartes researchers created a composite from individual images captured by the Sentinel-5P satellite in August and September 2018, according to Tim Wallace, head of graphic design at Descartes. Cloudy days and poor quality images were filtered to generate a map of the average amount of nitrogen dioxide in the lowest part of the Earth's atmosphere "on a given day in those two months," said Wallace.

Nitrogen dioxide does not survive long enough in the atmosphere to move far from the place where it is produced. So you expect to see nitrogen dioxide emissions focus on cities, where more people drive cars. But there are also unexpected sources, says Wallace. "There are traces of ships and industrial cities in the middle of nowhere," he says.

Combined with the nitrogen dioxide that floats over the cities, these tracks along the dark parts of the map provide a clear picture of how we, humans, contaminate the air we breathe, almost everywhere we go.