A baseline characterization of fine particulate matter (PM2.5) concentration and releases in Nova Scotia, Canada

Abstract

Three industrial facilities (a kraft pulp mill, a tire manufacturing, and a coal-fired power generation plant), have operated in Pictou County, Nova Scotia, Canada for more than 50 years. The local population, including an Indigenous community, has raised concerns for several decades about the environmental and human health impacts of local air and effluent pollution. Numerous studies have reported negative air, water, sediment, and ecological and human health impacts in the region. However, previous studies mainly focused on wastewater effluent discharge from the kraft pulp mill, with only a few studies focused on air pollution. These limited air pollution studies pointed out the pulp mill as the primarily responsible for local emissions of fine particulate matter (PM2.5), but with high levels of uncertainty. This study analyzed hourly and daily PM2.5 concentrations measured at an air quality monitoring station in Pictou (part of the National Air Pollution Surveillance [NAPS] network) between 2004 and 2021. For events of high PM2.5 concentrations (which occurred predominantly in April and May in 2014 and 2015), air masses were tracked using the HYSPLIT model to evaluate if long-range transboundary pollution could have contributed to PM2.5 concentration. Results suggest that the pulp mill was likely the primary source of high PM2.5 concentrations recorded at the Pictou NAPS station. Measured PM2.5 concentrations only met the desirable air quality management concentrations after the pulp mill installed a recovery boiler electrostatic precipitator in October 2015 to reduce PM2.5 emissions.