When it's cold outside, most people use a humidifier without a second thought. But is it actually safe to humidify? Some people say that as long as you keep your home's relative humidity between 40 and 60%, you'll be okay. From a building science perspective, that recommendation is not only too general, it also can turn your home into a toxic environment in terms of mold growth and mycotoxin exposure.

In this video, I teach you how to approach humidification without ruining your indoor air quality. Also in this video, I talk to David Fontaine, a systems engineer who is chair of the scientific outreach committee at Change the Air Foundation. David will blow your mind about the health effects of mold.