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particulate map_randall_martin_atmospheric science_outline

It's been exciting for us to start developing linkages between atmospheric science and the health community.

Satellite mapping of fine atmospheric particles


Air pollution has been a hot topic for years, and it’s only getting hotter. But for a long time, no one really knew the long-term global levels of fine particular matter, also known as aerosols. Now, Dr. Randall Martin, from Dalhousie’s Department of Physics and Atmospheric Science, and Dr. Aaron van Donkelaar, a PhD graduate of the department, have produced a map showing just that.

“We are looking at parts of the world we just haven’t seen before and the levels we are seeing are surprisingly high in some areas,” says Dr. van Donkelaar. “The impacts of that are potentially quite high for the quality of human life for a lot of people.”

Some of the results are quite shocking. For example: 50 percent of the population in Eastern China was affected by high concentrations of pollutants. In Northern India, that number was 38 percent. Both far exceed even the weakest of World Health Organization (WHO) standards.  

Health researchers see this map as a valuable contribution because of the size of the particles studied: they’re small enough to be easily absorbed by the body. Aerosols measure less than 2.5 microns in diameter—about a third of the size of a red blood cell.

“They are the particles that are most likely to penetrate deep into our lungs where they can then cause more damage than larger particles,” says Dr. Martin. Despite their size, fine particulates can be seen from space. “That’s also important,” he continues. “Other pollutants, like ozone, are much harder to see down at the surface from space.”

But it was a long road to completing the map. Between 2001 and 2006, Dr. Martin and Dr. van Donkelaar analyzed the data gathered from NASA Terra satellite readings. Then with input from NASA scientists (listed as co-authors on the paper), they merged the satellite data with a global 3D model of the atmosphere and compared it against available ground data.

Dr. van Donkelaar believes the sheer volume of data adds a huge benefit to the project. “One the reasons we did the long-term average is because of the errors and so taking that much data together, we have more confidence in it.”

The researchers will continue working on the map, investigating trends on how concentrations of these pollutants change over time, where they rise, and how they fall in the Earth’s atmosphere.

“It’s been exciting for us to start developing linkages between atmospheric science and the health community,” says Dr. Martin.

Read more and see the full map in Dal News.