NOAA’s Polar-Orbiting Satellites See Drop in U.S. Air Pollution

NOAA’s new generation polar-orbiting satellites are seeing a dramatic reduction in the amount of air pollution in the U.S., as the COVID-19 pandemic creates an economic and societal slowdown.

“The unintended drop in air pollution levels have become evident,” said Mitch Goldberg, chief program scientist of NOAA’s Joint Polar Satellite System (JPSS). “Observations collected from JPSS and partner satellites are giving NOAA scientists the ability to see how urban and industrial locations contribute to a region’s air pollution through the emissions of gasoline-based gases and fine particles.”

Nitrogen Dioxide (NO₂) is a key component of urban air pollution. As gasoline-based vehicular traffic drops, so do NO₂ emissions and airborne particulate pollution. NOAA scientists looked for the signals of decreased NO₂ emissions by using instruments on the NOAA/NASA Suomi-NPP satellite and on the European Space Agency’s (ESA) Sentinel-5P satellite.

Because the COVID-related slowdown in most parts of the U.S. began in mid-March, scientists looked at both NO₂ and airborne particulates for March 2019 (pre COVID-19) and March 2020 (during COVID-19). They also compared the differences between weekdays versus weekends during the same time period.

The air pollution data showed that the U.S. economic slowdown has reduced vehicular traffic, especially when considering the class of vehicle. While truck traffic has only decreased by about 20 percent since February 16, 2020, according to the Ozone Transport Commission, car traffic nationwide has dropped by about 50 percent or more. The results even show an additional reduction of all vehicle traffic on weekends.

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