Physicochemical studies of aerosols at Montreal Trudeau Airport: The importance of airborne nanoparticles containing metal contaminants.

Airborne particles, specifically nanoparticles, are identified health hazards and a key research domain in air pollution and climate change. We performed a systematic airport study to characterize real-time size and number density distribution, chemical composition and morphology of the aerosols (∼10 nm-10 μm) using complementary cutting-edge and novel techniques, namely optical aerosol analyzers, triple quad ICP-MS/MS and high-resolution STEM imaging. The total number density of aerosols, predominantly composed of nanoparticles, reached a maximum of 2 × 106 cm-3 and is higher than reported values from any other international airport. We also provide evidence for a wide range of metal in aerosols, and emerging metals in nanoparticles (e.g., Zn and Ni). The geometric mean, median and 99th and 1st percentile values of observed nanoparticle number densities at the apron were 1.0 × 105, 9.0 × 104, 1.2 × 106 and 9.3 × 103 cm-3, respectively. These observations were statistically higher than corresponding measurements in downtown Montreal and at major highways during rush hour. This airport is thus a hotspot for nanoparticles containing emerging contaminants. The diurnal trends in concentrations exhibit peaks during flight and rush hours, showing correlations with pollutants such as CO. The HR-TEM-EDS provided evidence for nano-sized particles produced in combustion engines. Implications of our results for air pollution and health are discussed.