High humidity conditions _________ the volatility of a pesticide.

High humidity conditions _________ the volatility of a pesticide.

• A. Increase
• B. Do not affect
• C. Decrease
• D. Unknown

Answer: (C)

High humidity slows the evaporation of spray droplets, so the pesticide is less likely to vaporize into the air. Volatility depends on the evaporation process, which is driven by the vapor-pressure gradient between the droplet and the surrounding air. When the air is already saturated with water vapor, it can’t readily accept more vapor, reducing the rate at which pesticide molecules escape from the droplets. Temperature strongly affects volatility, but humidity can moderate it, leading to overall lower volatility under high humidity. That’s why the correct choice is that high humidity decreases volatility.

High humidity slows the evaporation of spray droplets, so the pesticide is less likely to vaporize into the air. Volatility depends on the evaporation process, which is driven by the vapor-pressure gradient between the droplet and the surrounding air. When the air is already saturated with water vapor, it can’t readily accept more vapor, reducing the rate at which pesticide molecules escape from the droplets. Temperature strongly affects volatility, but humidity can moderate it, leading to overall lower volatility under high humidity. That’s why the correct choice is that high humidity decreases volatility.