The Dri-Eaz DefendAir is a HEPA-certified filter, which means that it is designed to protect those with allergies or asthma. It uses a natural activated carbon filter that can produce clean air without using dangerous chemicals. It has multiple speed levels so that the user may adjust it to their comfort level. It has more than 99% efficiency when filtering oily aerosol particles, so it is also ideal for keeping air clean in industrial work environments.