Researchers explore secret life of indoor air particles, cancer, water treatment

Forty-four U of T projects have been awarded a total of $12.1 million from the Canada Foundation for Innovation (CFI) for infrastructure that will advance research in everything from water treatment to cancer.

One of them is led by Jeffrey Siegel of civil engineering. “Exploring the Secret Life of Indoor Air Particles” investigates a little-known threat to human health.

Siegel says there are between 100 and 10,000 microscopic particles in every cubic centimetre of air.

“We can’t see them, but they’re all around us. We’re breathing them all the time. Even if we’re very conservative in our estimates, the average Canadian eats about seven kilograms of dust over a lifetime. And that’s just ingestion. We inhale a lot more.”

Indoor particles can be outdoor pollutants that migrated inside, or they can originate from indoor activities such as cooking and vacuuming. Some particles are benign, but others cause serious long-term health problems ranging from heart disease to lung cancer. Though we know they’re a threat — Siegel says they’re widely acknowledged as the number one environmental health risk — they don’t get as much press as their outdoor cousins.

“Research on outdoor particles has been going on for decades and decades,” says Siegel. “But the average Canadian spends 90 per cent of his or her time indoors. Compared to what we know about outdoor particles, we know nothing about indoor ones.”

Siegel has been working to understand the physical, chemical and biological characteristics of indoor particles — they’re all made up of chemicals that can be analyzed and microbes that can be identified using DNA sequencing. His CFI funding will purchase equipment that will allow him to study the physical characteristics of particles, too. This is important because the size of a particle is directly related to how dangerous it is to human health.

“A particle that is a tenth of a micron long [a micron is one-millionth of a metre] will go very deep into your lung and has the potential to do a lot of damage,” he says. “A particle that is much larger, perhaps a few microns long, will settle in your upper respiratory tract. It might have health effects, but they’re going to be less severe.”

Siegel plans to conduct what he calls “filter forensics,” examining used filters from residential forced air heating and cooling systems. The CFI-funded equipment will allow him to extract filter dust, which can be invisible to the naked eye, and study it. The data collected can be combined with more easily generated chemical and biological data to make more realistic predictions about people’s long-term exposure to indoor particles.

The funding for Siegel’s project, and those of the other researchers, comes from CFI’s John R. Evans Leaders Fund, previously called the Leaders Opportunity Fund. The agency recently renamed the fund in honour of former U of T president Evans, who was also CFI’s first board chair.

“Congratulations to all the winners,” said Professor Paul Young, U of T’s vice-president of research and innovation. “CFI funding has been essential to our ability to attract the world’s best researchers, and has, in turn, allowed those researchers to make progress on some of the most pressing problems of our time.”

(Read a list of U of T’s CFI-funded projects.)

Jenny Hall is a writer with the Office of the Vice-President, Research & Innovation at the University of Toronto