Air pollutants under scrutiny



Each year, some three billion tonnes of aerosols are released into the atmosphere. The particles are emitted by automobiles, factories and natural sources such as volcanic eruptions and soil erosion. Aerosols play a role in cloud formation, transport other toxic particles and absorb and diffuse part of the sun's ray. They are also responsible for air quality, especially in major cities. Even so, owing to their complex chemical composition, aerosols remain climatic agents that science does not yet fully understand. Andreas Zuend, professor and researcher in the Department of Atmospheric and Oceanic Sciences at McGill University, has set his sights on demystifying the pollutants. 

Aerosols play a role in cloud formation, transport other toxic particles and absorb and diffuse part of the sun's ray. 

Until recently, experts believed that aerosols came in one of two forms: solid or liquid. However, the latest research has shown that they also come in in-between states. They can be viscous—a bit like honey—or glassy at cold temperatures. These changes impact the particles' transport and properties and therefore air pollution and climatic conditions. 

Andreas Zuend and his team are focused on developing a model to predict the degree of viscosity of the aerosols in the air. To train the model, they used viscosity data on a range of chemical substances from laboratories in Canada and abroad. Mathematical formulas make it possible to assess the viscosity of aerosols according to their composition and at different temperatures. The researchers ultimately aim to integrate their model into atmospheric chemical transport models to improve, among other things, air quality forecasts.