As smoke from Canadian wildfires blankets the US, can wearing a mask help?

Key Points:

• Over 800 active wildfires in Canada have caused smoke to spread into parts of the U.S., leading to air quality alerts in states such as Minnesota, Illinois, Pennsylvania, and New York.
• Experts recommend wearing N95 masks outdoors to protect against fine particulate matter (PM2.5) in wildfire smoke, as these masks filter at least 95% of airborne particles and create a tight seal around the face.
• PM2.5 particles are extremely small and can penetrate deep into the lungs and bloodstream, causing both short-term symptoms like irritation and coughing, and long-term health issues such as worsening asthma and heart disease.
• Surgical masks, cloth masks, paper dust masks, and bandanas are ineffective against PM2.5, and N95 masks must be properly fitted and certified by the National Institute of Occupational Safety and Health to provide adequate protection.
• Indoor air quality can be improved by closing windows and using HEPA filters, which help reduce fine particulate matter when masks cannot be worn continuously; New York City is distributing free KN95 masks to residents at multiple locations.