The Definition of Ventilation
Ventilation is the process of supplying and removing air to control airborne contaminants, temperature, and humidity in a workplace.
Ventilation is the process of supplying and removing air to control airborne contaminants, temperature, and humidity in a workplace.

The engineering control of introducing fresh air and removing contaminated or stale air from a workspace, used to dilute or capture airborne hazards such as dust, fumes, vapors, and excess heat. Ventilation may be general (dilution) or local exhaust (capturing contaminants at the source).
A woodworking shop installs a local exhaust ventilation system directly at each saw station to capture sawdust before it becomes airborne, supplementing the building's general ventilation system.
General ventilation dilutes contaminants by mixing in fresh air throughout a space, while local exhaust ventilation captures contaminants at or near their source before they can spread — generally the more effective control for concentrated hazards.
Ventilation requirements vary by industry and specific hazard; OSHA mandates ventilation in certain contexts, such as welding, spray painting, and confined spaces, where airborne contaminant levels could otherwise exceed permissible limits.
Not always — for some highly toxic substances or oxygen-deficient environments, ventilation must be paired with respiratory protection and other controls to keep exposure at safe levels.