Dust in the wind

They’re tiny, tiny, tiny—no bigger than 2.5 microns or about 20 times smaller than the diameter of an average human hair—and yet they have the potential to change the way clouds form and to affect rain and snowfall patterns. They heat or cool parts of the atmosphere. And they get sucked deep into our lungs.

They’re called aerosols, miniscule particles and droplets that float in the global atmosphere. And they’re the focus of a new national research network that includes Dalhousie University researchers.

The Canadian Aerosol Research Network (CARN) has been started with $15 million in funding from the Canada Foundation for Innovation, governmental agencies and industrial partners. The money will include creating infrastructure for the Atlantic Aerosol Research Centre, to be based at Dalhousie University on the east coast, the University of British Columbia Centre for Aerosol Research on the west coast, and the Southern Ontario Centre for Aerosol Research at the University of Toronto.

“We’re interested in what’s in those particles ... They could be metal oxides, combustion byproducts, dust, soil, sea salt spray, oil droplets. We’re interested in how they behave in the air, their chemical reactions, and how they behave once we breathe them in.” — Judy Guernsey, lead investigator

“We’re interested in what’s in those particles,” says Judy Guernsey, one of the lead investigators with CARN and associate professor in the Department of Community Health and Epidemiology, Faculty of Medicine. “They could be metal oxides, combustion byproducts, dust, soil, sea salt spray, oil droplets… We’re interested in how they behave in the air, their chemical reactions, and how they behave once we breathe them in.”

Aerosols, both solids and liquids, are generated both naturally and as a result of human activities. Volcanic activity, forest fires, wind blown soil, mold, and marine-derived particles such as sea spray and gaseous emissions from phytoplankton and sea weed are the most common natural sources of aerosols.

Human-produced aerosols come primarily from smoke, such as coal-burning power plants and the internal combustion engines of cars, trucks and ships. Pollutant gases such as volatile organic compounds, oxides of sulfur and nitrogen emitted by fossil fuel combustion react with other gases, such as ammonia from agricultural activity, to generate secondary aerosols and ground-level ozone as a result of complex chemical reactions in the atmosphere.

Because of their small size, aerosols can penetrate the deepest part of the lungs and lead to such health problems as asthma, lung cancer and cardiovascular disease. Indeed, there is strong evidence now that aerosols emitted by vehicles actually exacerbate  asthma.

One of the main themes of the Atlantic Aerosol Research Centre and CARN is to disentangle which aerosols are natural and which are the result of human activity. “We want to know how they behave in the atmosphere over time and ultimately how these different aerosols impact health and the environment,” says Mark Gibson, senior research scientist with CARN and an environmental health chemist.

The funding ($4.2 million for Dalhousie) will go to setting up a permanent laboratory for the research within the Faculty of Medicine, acquiring some high-powered equipment that will process air pollution data acquired by satellites, and modeling the spatial variability of air pollution locally, nationally and even globally. A new environmental health faculty member will be recruited to help direct the work of the network. The centre is truly cross-disciplinary, drawing expertise from the Departments of Community Health and Epidemiology, Physics and Atmospheric Science, Chemistry, Oceanography, Civil Engineering and the College of Sustainability.

“It’s very exciting for us—we’ll have the first fully equipped research laboratory dedicated to studying environmental health in Atlantic Canada,” says Dr. Guernsey.

Dr. Guernsey and her colleague Dr. Gibson have laid the groundwork for aerosol research through their work with the Atlantic RURAL Centre. They’re currently engaged in studies for Health Canada examining the residential indoor air quality of 50 Halifax homes, wood smoke exposure in the Annapolis Valley and “fugitive dust,” airborne particles from contaminated sites such as former gold mines. 

“Once the lab is set up, there will be spin offs. We’ll be able to look at any toxic agent(s) found in water, food, soil or the air,” says Dr. Gibson.

“And not just here in Atlantic Canada,” adds Dr. Guernsey. “One of our colleagues is now examining personal exposure to poor air quality in rural Kenya and we are planning similar research in India.”