Air quality is often unhealthy by contamination, think of particulates, odors, mold, bacteria, viruses and chemicals.

If there is smoked, it is important that as little as possible for the non-smoker (smoke and smell). A central ventilation system..

Whirling around, precipitating dust, fume or greasy (oil) nebulae are a common problem in many large industrial buildings...

In professional kitchens come fats and unpleasant odors that can accumulate in the exhaust. This is dangerous and unhealthy.