Fans prevent motion sickness?

I’d never heard of this before - according to this link:

Is this true - does positive pressure prevent motion sickness? What exactly is positive pressure? And how does it prevent motion sickness? Why doesn’t this have more commercial applications?

I tend to get motion sickness, and moving air definitely makes a difference. I feel much worse in the car if the windows are closed and the fans are off. I think it might be because motion sickness is caused by conflicting perceptions- some of your senses tell you you’re moving, some tell you you’re not. It’s not the pressure, though- it’s the moving air.

I can’t speak to the motion sickness aspect, but regarding the other part of your question: “positive pressure” just refers to the pressure of the room relative to the outside atmospheric pressure. If the room is at positive pressure, then it’s air pressure is greater that outside. Negative pressure means the room is at lower pressure than the exterior.

As an aside, we keep our laser labs at positive pressure so that dust from the outside has a harder time blowing in. On the other hand, fume hoods will be at negative pressure, to prevent (potentially hazardous) vapor from escaping.