Toward an Improved Air Pollution Warning System in Quebec.

Area of Science:

• Environmental Health
• Public Health
• Atmospheric Science

Background:

• Air pollution varies by city, impacting local health, especially for those with pre-existing conditions.
• Existing air quality standards may not fully address city-specific health impacts.
• Local air pollution warning systems are crucial for public health protection.

Purpose of the Study:

• To propose specific air pollution indicators and thresholds for local warning systems in Montreal and Quebec City.
• To develop a system that considers local health impacts from short-term pollution episodes.
• To optimize the detection of excess mortality linked to air quality.

Main Methods:

• Utilized historical health data to identify extreme excess mortality episodes.
• Selected fine particulate matter (PM2.5) and combined oxidant capacity (Ox) as key environmental exposures.
• Determined optimal indicators and thresholds by analyzing their effectiveness in detecting mortality events.

Main Results:

• Established summer thresholds: Montreal (31 μg/m³ PM2.5, 43 ppb Ox), Quebec City (32 μg/m³ PM2.5, 23 ppb Ox).
• Established winter thresholds: Montreal (25 μg/m³ PM2.5, 26 ppb Ox), Quebec City (33 μg/m³ PM2.5, 21 ppb Ox).
• Sensitivity analysis indicated that Ox is a more significant determinant of excess mortality than PM2.5.

Conclusions:

• The proposed thresholds are adapted to Montreal and Quebec City's specific air quality and health contexts.
• The developed warning system provides locally relevant guidance for air pollution events.
• Oxidant capacity (Ox) should be prioritized in local air quality monitoring and warning systems.