Ventilation is a primary engineering control available to reduce the concentration of  gases, dusts, vapours, smoke, and fumes in the air. Dusts, fumes, vapours, and gases in the air are drawn into the ventilation system and carried to the collecting device by a pressure gradient created by the fan. The fan must have sufficient power to overcome the resistance to air flow created within the environment.

General ventilation is not suitable to control exposure to toxic substances because these systems actually spread the contaminant throughout the workplace before exhausting it.

General ventilation systems are used primarily to control temperature and humidity, to remove odours, and sometimes to remove traces of toxic substances and micro organisms emitted from carpeting, panelling, furniture and people.

Ventilation is to design a system capable of restricting the high-level temperature rise inside the building to a pre-determined level above the prevailing outside ambient temperature by creating a minimum air change rate per hour

These systems provide positive, fresh air movement to central working areas within the building that in turn provide evaporative cooling for the operatives at their respective workstations. Due to the relatively low capital cost, in relation to the highly desirable conditions achieved, this is the most common approach within industrial buildings today.

For general industrial ventilation systems, clean rooms or process ventilation can be provided by the use of centralised Air Handling Units.

These direct or indirect drive, backward or forward curved fan units are purposely designed and installed to incorporate supply and return ducting and can be fitted with various components such as mixing boxes, various types of filtration, heater batteries, cooling coils and heat recovery wheels.