Air pollution data at high temporal and spatial resolution across Canada: Emission and wildfire adjusted Community Multiscale Air Quality (CMAQ)

The Air Quality Health index (AQHI) is a communication tool, which sums adverse health risks associated with three major air pollutants, ground-level ozone (O3), nitrogen dioxide (NO2) and fine particulate matter (PM2.5), to provide guidance on daily outdoor activities to the public to protect their health from outdoor air pollution. The AQHI is therefore based on mainly two databases: public health data and outdoor air pollution data. The main source of outdoor air pollutant concentrations is the National Air Pollution Surveillance (NAPS) program, which provides accurate and long-term air quality data across Canada. NAPS was established in 1969 to monitor and assess the quality of ambient air in the populated regions (i.e. urban areas) of Canada. Starting with 36 monitoring sites for Canada-wide database, today 286 sites in 203 communities are located in every province and territory. Even if the number of NAPS ground-monitoring stations has increased and its spatial coverage has extended, there is still a concern that Canadians living in rural areas are not covered by NAPS stations and therefore have been underrepresented in the air pollution related programs including the AQHI. To improve the current AQHI, this project has three main focuses: (1) to extend spatial coverage (in particular, rural areas), (2) to include more recent years, and (3) to consider the influence of climate changes (e.g., extreme PM2.5 from wildfires). Including rural areas is essential for the AQHI to be a national program, being not limited to urban areas. Since rural areas do not have NAPS stations, we need estimated concentrations from satellite, land use regression models, emission sources and/or other resources. This is the main purpose of this project. Currently Health Canada (HC) has CMAQ data on O3, NO2, PM2.5 and SO2 for 2000-2020. However, wildfire-adjusted CMAQ data are for 2015-2020, not earlier years. HC thus needs the wildfire-adjusted CMAQ data for more recent years (2021-2023) and earlier years (2001-2014)

The project has three objectives to address the concerns related to the estimated concentrations of air pollution across Canada: (1) improved models (e.g., emission and wildfire adjusted CMAQ) to better estimate the four air pollutants (O3, NO2, SO2 and PM2.5); (2) extended spatial coverage to include rural areas (high spatial coverage); and (3) extended temporal coverage with hourly air pollution concentrations in addition to daily and yearly averaged air pollution for the years 2021-2023 and 2001-2014. Note: Multiple rural areas are combined into a census division, which has at least 40,000 population but no NAPS monitoring station.