Which of the following best describes Vapor Drift?

• A. Not applicable
• B. Movement of spray droplets associated with application
• C. Physical movement of pesticide through air
• D. Movement of pesticide in vapor or gas form

Answer: (D)

Vapor drift is the movement of pesticide in vapor or gas form. When a chemical volatilizes, it can become a gas and travel with air currents, potentially moving far from where it was applied. This is different from spray drift, which involves the physical movement of liquid droplets that are sprayed during application. Understanding this distinction helps you recognize that even if droplets don’t drift, a volatile pesticide can still pose off-target exposure risks. Vapor drift is influenced by factors like temperature, wind, and the pesticide’s volatility, and can be reduced by using less volatile formulations, applying under favorable weather conditions, and employing drift-reduction practices.