OHST Practice Exam

Under which condition is the use of dilution ventilation most appropriate?

1. The source is very toxic

2. The source of contamination is a heavy particulate

3. Employees are in close contact with the source

4. The source of contamination is constant

The correct answer is: The source of contamination is constant

Dilution ventilation is particularly effective when the source of contamination is constant. This method works by introducing a large volume of fresh air into the environment, which helps to reduce the concentration of contaminants in the air over time. When contamination is continuous and consistent, dilution ventilation can maintain air quality at safer levels without the need for more complex or intensive control measures. In contrast, if the source is very toxic, the immediate risk may require more aggressive responses, such as local exhaust ventilation, rather than relying on dilution alone. Similarly, with heavy particulates, dilution may not effectively control airborne particles, which may necessitate filtration or other methods. In situations where employees are in close contact with the source, dilution ventilation may not sufficiently protect workers from inhaling contaminants, making localized controls more appropriate. Therefore, a constant source of contamination creates a scenario where dilution ventilation is ideal for continually managing air quality.