Allergies and wildfires are very good reasons, thanks for getting back to me :)

I'm curious, I understand the point of dehumidifers, humidifiers when you have a cold/flu, but outside of a hazardous workspace e.g. laboratory, factory floor etc... or if you have a lung condition e.g. asthma or cystic fibrosis, why would you need an air filtration system? I've never had one, and I've never been able to think of a reason why someone (asides from the above) would want one, please help me understand.