OHST Practice Exam 2025 – The Comprehensive All-in-One Guide to Exam Success!

Dilution ventilation is a method used in various industrial and occupational settings to reduce the concentration of airborne contaminants by introducing a larger volume of fresh air into the environment. This method is particularly suitable for controlling low toxicity vapors, as it effectively dilutes them to a concentration that is below harmful levels.

The selection of low toxicity vapors as the correct answer recognizes that dilution ventilation is particularly effective in handling substances that do not pose immediate severe health risks at higher concentrations. By significantly increasing the volume of air in the space, the concentrations of these vapors are reduced to safer levels, thus making it easier to maintain air quality standards.

In contrast, controlling contaminants at their source, such as fume hoods or point source extraction, would be more effective for dealing with hazardous substances that pose immediate risks or are otherwise not amenable to dilution. Similarly, fumes from lead fusing and asbestos fibers present significant health hazards where traditional dilution methods may not be appropriate due to the toxicity and potential for long-term exposure-related health issues. Therefore, targeted systems that capture or filter these pollutants are more suitable than relying solely on dilution ventilation.