How outdoor air pollution affects indoor air quality


A statistic that gets tossed around a lot lately is that indoor air can be two to five times more polluted than air outdoors. Considering so much time is spent indoors, this is certainly cause for alarm. However, indoor air quality and outdoor air pollution are often viewed as two separate issues despite being very much connected.

How does outdoor pollution get inside?

Outdoor air pollution is one of several significant contributors to poor indoor air quality. When we enter a facility from outside, we’re bound to bring in some pollutants with us, not just from the air, but also toxins on our shoes such as urban grime or lawn chemicals. We also bring in allergens, such as pollen, that might be clinging to clothes or hair.

The danger outdoor air pollution poses to lung health is exacerbated in areas close to heavy traffic or other sources of pollution, because it is more likely to enter indoors. According to the U.S. Environmental Protection Agency, outdoor air enters buildings three ways: infiltration, natural ventilation and mechanical ventilation.

However, the circulation of outdoor air is necessary to creating healthy indoor air quality. Recirculated air, if not properly filtered, allows contaminants to build up over time and become harmful to respiratory health. In other words, since there are so many contaminants emitted indoors from building materials, cleaners and other sources, outdoor air is needed to flush them out.

This is perhaps the most important connection between outdoor air pollution and poor indoor air quality. Unsafe outdoor environments means, air can’t be readily circulated indoors.  Before entering the building, the air will either have to be continuously or indoor air will have to be constantly recirculated and purified.

Essentially, the cleaner the outdoor air, the easier it is to use natural and mechanical ventilation to keep indoor air healthy.

Indoor air quality is an issue that has to be locally addressed by facility managers and demands more attention. Commercial grade air purifiers remove 99.9 percent of contaminants from indoor air, making them an efficient solution for removing airborne impurities in common areas where it’s needed most.