• Particulate Matter (PM) is a mixture of solid and liquid particles that are suspended in the air. These are categorized into coarse, fine and ultrafine. PM2.5 are fine particles that have a diameter less than 2.5 micrometers (more than 100 times thinner than a human hair) and remain suspended in the air for longer durations. The health risk with PM2.5 is that they can travel deep into the respiratory tract, reaching the lungs and entering the blood stream.
  • PM2.5 is used when describing pollutant levels both outdoor and indoor, where health impact from exposure considers amount of PM2.5 over a 24-hour period. Most studies indicate PM2.5 at or below 12 μg/m3 is considered healthy with little to no risk from exposure. If the level goes to or above 35 μg/m3 during a 24-hour period, the air is considered unhealthy and can cause issues for people with existing breathing issues such as asthma. Prolonged exposure to levels above 50 μg/m3 can lead to serious health issues and premature mortality.
  • Exposure to fine particles can also affect lung function and worsen medical conditions such as asthma and heart disease. Scientific studies have linked increases in daily PM2.5 exposure with increased respiratory and cardiovascular hospital admissions, emergency department visits and deaths.
  • Studies also suggest that long-term exposure to fine particulate matter may be associated with increased rates of chronic bronchitis, reduced lung function and increased mortality from lung cancer and heart disease. People with breathing and heart problems, children and the elderly may be particularly sensitive to PM2.5.
  • The Indoor Air Hygiene Institute requires a PM2.5 level of 12 μg/m3 or less, with infrequent or no spikes of 35 μg/m3 or higher.
  • The most common way to manage PM2.5 in indoor air is using HEPA-grade filters in the air management system and/or air purifiers. In areas with high outdoor pollution (above 35 μg/m3 in the outdoor air), windows to the building should be closed and outdoor air brought inside using HEPA filtration.    
poor indoor air quality can trigger asthma

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