OHST Practice Exam

Which ventilation system is primarily designed to mitigate high concentrations of airborne pollutants at their point of origin?

1. Dilution ventilation

2. General ventilation

3. Local exhaust ventilation

4. Natural ventilation

The correct answer is: Local exhaust ventilation

The local exhaust ventilation system is specifically designed to control and reduce the concentration of airborne pollutants right at their source. This method involves the use of hoods, ducts, air cleaners, and exhaust fans to capture contaminants and draw them away from the work area before they can disperse into the larger environment. By placing the ventilation components close to where pollutants are generated, this system minimizes exposure risks to workers and effectively maintains air quality. In terms of functionality, local exhaust ventilation operates by creating a negative pressure in the area where pollutants are produced, directly capturing harmful substances like dust, fumes, or vapors. This targeted approach is crucial in industries such as manufacturing, welding, and chemical processing, where pollutant concentrations can become dangerous if not effectively managed at the point of generation. While other systems like dilution ventilation and general ventilation aim to improve air quality by mixing and dispersing contaminated air within a larger volume, they do not specifically address the pollutants at their source. Natural ventilation relies on passive air movement, which is less effective for controlling high concentrations of pollutants. Thus, local exhaust ventilation serves a unique and critical role in safeguarding health and safety in the workplace.