Category 8 Pesticide License Practice Test

Decreased relative humidity increases the rate of volatilization for substances, including pesticides. Volatilization is the process by which a substance transitions from a liquid state to a gas. When relative humidity is low, the air is less saturated with moisture, allowing volatile compounds to evaporate more easily.

This occurs because the driving force for evaporation in a lower humidity environment is enhanced, as there is a greater difference between the vapor pressure of the liquid and the atmospheric pressure exerted by the surrounding air. Essentially, when the humidity is low, the atmosphere can hold more vapor, enabling more molecules to escape from the liquid phase into the gas phase. As a result, the rate of volatilization increases significantly under these conditions, making the correct answer compelling in this context.