What type of ventilation should be used when working with hazardous substances?

When working with hazardous substances, local exhaust ventilation is the most effective means of providing a safe working environment. This type of ventilation system is designed to capture and remove contaminants at or near the source before they can disperse into the work area. By focusing on the specific area where hazardous materials are handled, local exhaust ventilation minimizes exposure to workers and helps maintain air quality.

General ventilation, while useful for removing heat and odors, does not effectively control specific contaminants because it dilutes and pushes them away rather than removing them. Natural ventilation relies on outdoor air circulation, which may not be sufficient in areas where hazardous substances are present, particularly if conditions outside are unfavorable. Cross ventilation, which employs the natural flow of air between openings in a structure, may assist in some situations but does not target the direct source of hazardous substances effectively. Therefore, local exhaust ventilation is the preferred method when managing safe practices around hazardous materials.