In hazmat safety terms, what does 'upwind' mean?

• A. Wind direction is away from you
• B. Wind direction toward you
• C. Wind direction irrelevant
• D. Wind direction cycles every hour

Answer: (A)

Upwind is the direction from which the wind is coming relative to your position. In hazmat safety, you want to be on the upwind side of a release so that air currents carry any vapors away from you. If the wind direction is away from you, the air is moving away from your current location toward the hazard, so you’re in the upwind position and the plume would move away from you. This helps minimize exposure. The other ideas—wind blowing toward you (downwind), wind being irrelevant, or the wind cycling hourly—do not describe the immediate, practical relationship used to assess safety around a potential hazmat release.