are there legal requirements for factory ventilation?

[engineheat]

I wonder if there are legal requirements in the US when it comes to ventilation in factories, specifically regarding how much outside fresh air should be mixed with the indoor air in the HVAC system. What's to prevent a plant from using 100% recirculated air all the time and save money?

I understand there are OSHA requirements when there are hazardous particles or chemicals, but I'm wondering in a general sense if there are required minimum % of outside air that factories HVAC must abide by.

Thanks

[NiHaoMike]

There is no set number, what matters is making sure the air quality (most notably CO2 and VOCs) stays within acceptable limits. So basically it depends a lot on how much the processes inside are polluting the air.

That said, a HRV or ERV will go a long ways to cutting down on energy use in many cases.