People are now accustomed to living and working indoors.
Lots of people, including college students, are only outside for short bursts of time. Some are only outside enough to walk to or from their cars. This phenomenon is exacerbated by cold weather. So, although people should spend much more time outside, the fact is that they don't, and indoor air quality is an important concern. Everything from chalk dust to asbestos, spray cleaner to volatile plastics assaults our sinuses and lungs all day every day.