As California residents, we are all too familiar with the orange skies that plagued the East Coast last week from Canadian wildfires and just hit the Midwest. And we have faced the plague of poor outdoor air quality many times while doing extensive public health work in cities, such as India’s capital New Delhi, that are among the most polluted in the world. The pandemic drew global attention to the impact of air quality on health, with a focus on pathogens that spread indoors.
But hazy skies remind us that the outdoors pose an equal, if not worse, threat. Climate change increases catastrophic wildfires and other events, and outdoor air eventually penetrates the indoors. Air pollution affects everyone — yet protections from it remain inadequate nationwide.
Last month, the Centers for Disease Control and Prevention finally released long-awaited guidance on improving indoor air quality to limit the spread of infectious airborne pathogens. As a baseline for clean air, they recommended a minimum of five air changes per hour (ACH, referencing a flow equal to cycling through all air in an enclosed space) and upgrading air filters to a minimum efficiency reporting value (MERV) of 13 (a typical home, school or office has a MERV of 10 or less).
