Whenever investigating an aerosol—any particle suspended in a gas—scientists must consider its size, concentration, and chemical composition, Biswas notes. Aerosol scientists and engineers, including members of CAST, have access to a wide range of instruments such as aerosol mass spectrometers that enable them to accurately determine what is circulating in the ambient atmosphere.

“These particles are very small, and their size is in a range where if you inhale it. It might penetrate into your lungs,” he says. “That much we know, though their exact size varies. Also, the concentration [how much] is important, and the third thing is the chemical composition.”

The smoke from Canada’s fires contains a dangerous mixture of gaseous and particle pollutants, according to Cassandra Gaston, an associate professor of atmospheric sciences at the Rosenstiel School of Marine, Atmospheric, and Earth Science.

“Recent studies have pointed out that smoke particles from fires contain quite a bit of material that’s toxic when inhaled, so this is very concerning,” says Gaston, who along with Kumar, is also a member of CAST. “The EPA monitors, regulates, and issues warnings based on concentrations of particles in the atmosphere, and a lot of those regulations come down to the size [of the particles]. The smaller particles are more hazardous to health, and smoke particles do tend to be in the smaller particle size range.”

Gaston, who directs an atmospheric chemistry observatory on the Caribbean island of Barbados that monitors Saharan dust particles across the Atlantic Ocean, points out that not all small particles are the same.

“They’re made up of different chemical components, depending on where they come from,” she explains. “Smoke particles tend to have quite a few toxins associated with them. It is very worrisome that we’re seeing such high levels. When we think about wildfires or dust or pollution, it’s easy to say: ‘Well, that’s happening in another part of the world, so it’s not our problem.’ But as we’ve observed from wildfires and from Saharan dust, atmospheric transport is great at bringing air pollution from one part of the world to another very, very quickly.”

Read the full article about wildfire smoke by Robert C. Jones Jr. at Futurity.