When particulate pollution reaches unhealthy levels, a pollution mask can be an effective way of preventing respiratory damage, especially in sensitive groups like children and older adults. But as the U.S. consumer grows more comfortable with the concept of using respirators, the corresponding number of choices is increasing as well. With multiple mask varieties, as well as several types of filters to choose from, how do you know which face mask for smoke or other pollution sources is going is going to provide adequate protection?

Puraka Clean Air Technologies, a Seattle-based air pollution research group, has developed a free, web-based “Pollution Mask Calculator” that allows you to quickly determine the filter and “fit factor” needed to protect your lungs at different Air Quality Index (AQI) levels.

Aaron Ansel, creator of the tool, says the purpose of the web app is to educate the public on common misconceptions about pollution. “Many people don’t realize that a masks fit is much more important than the filter”, Ansel said.

“For example, an N95 filter used with a quality fitted mask will be effective even when the AQI is over 200 (Very Unhealthy).”

“On the other hand, if your mask isn’t securely attached or is sized incorrectly, then even a P100 filter (designed to filter 99.9% of particulates) becomes practically useless.”

Ansel says it’s also helpful to understand that a higher-rated filter may actually be detrimental to your health compared to a lower-rated filter. This is because filters with higher ratings generally make your lungs work harder to draw air through filtering material, which can be dangerous for sensitive groups.

“If I can see that an N95 filters the air just as well as an N99 on non-hazardous days, I will make sure my sons are using N95 filters instead of N99 to avoid the extra strain on their lungs.”

The calculator can be accessed via your desktop or mobile browser on Puraka’s air quality resource site. The methodology and background research for the tool are available here.