After a summer of Canadians feeling the impact of climate change from repeated air quality warnings due to smoke from forest fires, researchers at Saint Mary’s University have some good news to share. According to a recent peer-reviewed paper, surface-level ozone levels have decreased over the past two decades in Nova Scotia, an important finding for a province dealing with long-range pollution transport due to its positioning relative to the earth’s wind currents. These pollutants can harm humans, animals, and farm crops—affecting air quality in a similar way to the more visible impact of smoke from forest fires.
Morgan Mitchell (BSc ’19, MSc ’21), a research associate in the Department of Environmental Science, recently published the peer-reviewed paper in the journal Atmospheric Environment. The paper, titled “Surface ozone in the North American pollution outflow region of Nova Scotia: Long-term analysis of surface concentrations, precursor emissions and long-range transport influence,” is the first analysis of long-term (2000-2018) hourly ozone monitoring data at three locations in Nova Scotia: urban Halifax, suburban Halifax at Lake Major and a regional background site at Aylesford Mountain. Hourly ozone concentrations were analyzed by year, season, and time of day at each station over the entire study period.
The study showed that Nova Scotia experiences elevated surface ozone pollution episodes regularly, and while overall pollution has decreased, more research is needed to find out why the decrease has flattened out in the past five years.
In addition to examining ozone pollution, the study also covers transboundary pollution episodes, looking at the frequency of their occurrence and quantifying them. Nova Scotia regularly feels the impact of transboundary pollution episodes when air pollution from other areas such as the Eastern United States comes to the province via wind currents. Using a new, innovative method relying on spatial correlation of ozone between Halifax and otherwise clean ‘background’ stations (Kejimkujik and Aylesford), the findings in the paper show that the proportion of transboundary pollution has increased by 15% over the study period, with transported pollution accounting for 45-63% of elevated ozone days in Halifax.
Morgan says by driving less, considering the source of items we purchase, and acting locally, individuals can make a positive impact on pollution levels.
About the researchers
After completing her Bachelor of Science in Environmental Science in 2019, Morgan earned a Master of Science in Applied Science in 2021. She now works full-time as an air quality specialist with Environment and Climate Change Canada.
Working with supervisor Dr. Aldona Wiacek, a professor in the departments of Environmental Science as well as Astronomy and Physics, Morgan contributed to research focusing on human
impacts on the atmospheric environment. Dr. Wiacek’s long-term work focuses on measuring and tracking trace gases and aerosols (suspended solids and liquids) in the atmosphere as related to air pollution and climate change. Using both field work and the newly-established SMU Atmospheric Observatory (SAO) on the roof of the Student Centre, Dr. Wiacek and her team take long term measurements of trace gases and aerosols, which are necessary to inform policy related to air pollution formation and green house gas emissions controls.
Looking for more?
Morgan recently spoke to reporter Paul Withers at CBC about the research and paper.