Event Details

2023 wildfire smoke exposure and public health in Ontario: Triangulation of evidence

During the 2023 wildfire season, millions of people in Canada and the U.S. experienced unprecedented exposure to wildfire smoke originating from South Central Canada, encompassing Ontario and Quebec. This exposure was notably pronounced during the large fires that erupted in early June (referred to as the wildfire event). While the health impact of this event was assessed in certain U.S. regions, the impact on Ontario's population remains unknown. Furthermore, there is limited understanding of the specific health effects resulting from this wildfire smoke exposure. To address these gaps, we leveraged this wildfire event as a natural experiment to quantify the effect of wildfire smoke exposure on selected respiratory and cardiovascular outcomes across Ontario’s 22 largest health regions (~80% of total population) and will present the results in this PHO Rounds. Health data for this period were collected from two complementary sources: the Acute Care Enhanced Surveillance Application (ACES) in Ontario for real-time syndromes of public health concern and the Canadian Institute for Health Information’s National Ambulatory Care Reporting System (NACRS) for emergency department visits. Triangulating evidence from both data sources and multiple epidemiological methodologies, our analysis revealed that the wildfire event was responsible with heightened adverse effects in Ontario, particularly impacting respiratory outcomes, with effects persisting for up to five days.

Presenter(s): Hong Chen

Hong Chen is a Research Scientist with Population Studies Division, Health Canada. He also holds a scientist position at Public Health Ontario and an affiliation with ICES as a senior adjunct scientist. He is an assistant professor with Dalla Lana School of Public Health at the University of Toronto and an adjunct professor with the University of Ottawa. Hong's current research is focused on assessing the health impacts of ambient air pollution and evaluating the health benefits of policies and programs using causal inference methodologies.


The opinions expressed by speakers and moderators do not necessarily reflect the official policies or views of Public Health Ontario, nor does the mention of trade names, commercial practices, or organizations imply endorsement by Public Health Ontario.


Public Health Ontario Rounds are a self-approved group learning activity (Section 1) as defined by the Maintenance of Certification Program of the Royal College of Physicians and Surgeons of Canada (RCPSC). In order to receive written documentation for Continuing Medical Education (CME) credits, please check “Yes” beside the question “Do you require CME credits?” on the registration form.

College of Family Physicians of Canada (CFPC) Affiliate Members may count RCPSC credits toward their Mainpro+ credit requirements. All other CFPC members may claim up to 50 Certified credits per cycle for participation in RCPSC MOC Section 1 accredited activities.

PHO Rounds are also approved by the Council of Professional Experience for professional development hours (PDHs) for members of the Canadian Institute of Public Health Inspectors (CIPHI).

For more information or for a record of registration for other Continuing Education purposes, please contact capacitybuilding@oahpp.ca.


Public Health Ontario is committed to complying with the Accessibility for Ontarians with Disabilities Act (AODA). If you require accommodations to participate in this event, please contact 647-260-7100 or capacitybuilding@oahpp.ca.

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Updated 17 July 2024