On February 5, 2026, Environment Canada issued an Air Quality Health Index bulletin that raised Edmundston’s AQHI to Moderate (4) after elevated levels of fine particulate matter (PM2.5) were recorded. The AQHI bulletin, produced by Environment Canada in partnership with New Brunswick provincial departments, advises people with heart or lung conditions to monitor symptoms and consider reducing or rescheduling strenuous outdoor activities.
Meteorologists say the deterioration was driven by a temperature inversion over the Saint John River Valley: cold winter air trapped near the surface prevented vertical dispersion of local emissions, allowing wood smoke and industrial exhaust to accumulate and raise PM2.5 levels. This pattern commonly affects people with asthma, chronic obstructive pulmonary disease (COPD) and other respiratory illnesses.
Twin Rivers Paper Company Inc., the city’s largest pulp-and-paper facility, is a known local source of SO2 and PM2.5 emissions and has been identified in regional studies as contributing to air pollution in the Edmundston–Madawaska area. The mill operates under a provincial Class 1 air approval and generally meets regulatory requirements, though residents and regulators have reported periodic emissions upsets. The advisory targets the roughly 30% of the local population who fall into ‘at-risk’ categories (people with cardiovascular or respiratory conditions, the elderly and young children) who are most likely to be affected by a Moderate AQHI.
Healthy residents generally do not need to change their usual outdoor routines unless they experience symptoms such as coughing or throat irritation, but at-risk individuals are advised to avoid heavy outdoor exertion until conditions improve. Environment Canada and provincial monitoring networks continue to track air quality in real time; separately, Twin Rivers Paper Company Inc. was fined in 2024 under the Fisheries Act for a pipeline failure that released process water to the Madawaska River (that enforcement action concerned water pollution, not the AQHI advisory).
