Wildfire smoke from Canada is causing poor air quality in the Northeast and Midwest regions of the United States. People are being advised to stay indoors, wear masks, and use air purifiers to protect themselves. The United States Environmental Protection Agency (EPA) has established an Air Quality Index (AQI) to measure air pollutants, with higher AQI levels indicating a greater health concern. Particulate matter, especially PM2.5, which consists of tiny particles that can penetrate deep into the lungs and bloodstream, poses a significant risk to health, particularly for individuals with heart or lung disease, older adults, infants, children, and pregnant women. Exposure to PM2.5 has been linked to respiratory problems, cardiovascular issues, lung cancer, stroke, and cognitive decline.

Children are more susceptible to air pollutants due to their smaller airways and higher inhalation rate. While the AQI provides recommendations on outdoor activities, the risk to individuals in good health from poor air quality is not clearly defined. Wearing a well-fitted N95 or P100 respirator mask is recommended for protection against wildfire smoke. Staying indoors and using air conditioning with closed windows is generally advised, but it's important to be aware that pollutants can still be present indoors, particularly from cooking, smoking, and burning candles. Using a portable air purifier with a HEPA filter can help improve indoor air quality. In severe cases, seeking emergency shelter may be necessary if smoke is negatively affecting health.