As people in Los Angeles went through the day on January 6, 2025, NASA’s TEMPO (Tropospheric Emissions: Monitoring of Pollution) sensor performed hourly east-to-west scans of North America.
As people in Los Angeles went through the day on January 6, 2025, NASA’s TEMPO (Tropospheric Emissions: Monitoring of Pollution) sensor performed hourly east-to-west scans of North America. From its geostationary orbit 22,000 miles (35,000 kilometers) away, the pollution-measuring satellite observed the city's normal daily signature—a plume of nitrogen dioxide (NO2) emerging during the morning commute and lingering over the city for the rest of the day.
“On the day before the fire, NO2 built up hour by hour, and, like clockwork, drifted east in afternoon sea breezes, as we’ve observed it most days,” said Laura Judd, an atmospheric scientist at NASA’s Langley Research Center. Motor vehicles are major sources of the gas in Los Angeles, though other main sources include power plants, port facilities, and industrial sites.
Air quality experts consider the reddish-brown gas, primarily a byproduct of fossil fuel combustion, to be hazardous to human health. It also contributes to the formation of ground-level ozone and particulate matter, also health hazards. The image above (upper left) shows NO2 over the city at 1:50 p.m. Pacific Time on January 6. It is one of nine images of the Los Angeles area captured by TEMPO over the course of the day and dozens more in the days that followed, some of which are shown above.
Read more at NASA Earth Observatory
Image: NASA Earth Observatory image by Michala Garrison, using TEMPO data from NASA Earthdata.
