Particulates tracked by satellite

American scientists have been using satellites to help gauge the levels of airborne particulate matter in an effort to build up a broader picture than might be possible with widely-scattered monitoring stations.

Although the monitoring stations give more accurate results, their limited range means that their coverage is localised and, in some smaller urban centres and rural areas, often non-existent.

Researchers from Harvard University are now using NASA-owned satellites to help the Environmental Protection Agency (EPA) track fine particulate matter which can be inhaled deep into the lungs causing serious damage to the respiratory system.

Particulate matter comes from a wide range of sources but most come from burning fossil fuels.

The work at Harvard is focusing on ultrafine particles smaller than 2.5 microns in diameter, or PM2.5, which pose the greatest threat to human health.

"We want to be able to expand on the EPA monitoring network," said Harvard research fellow Yang Liu, who led the study.

"The challenge is that a satellite measures something different than the EPA's ground stations. A satellite looks down and sees the whole air column from top to bottom.

"Our goal is to be able to convert these observations into a measure of aerosol concentrations at the surface."

The project used two satellites, one giving a broad overview of vast areas while the other provided more detailed data from a more tightly-focused area.

Part of the challenge will be to mesh the results from both satellites together.

"The two instruments don't make daily observations of the same region," said Mr Liu,

"But they give a good snapshot of what's happening. There are other instruments, on weather satellites for example, that have daily and even more frequent coverage.

"If all goes well, this could become a new data source for studying the health effects of PM 2.5."

Sam Bond


air quality


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