Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. It indicates a chemical substance's volatility and tendency to evaporate into the atmosphere. Not to be confused with atmospheric pressure, vapor pressure is critical in assessing the behavior of hazardous materials during spill or release incidents. Understanding vapor pressure helps responders establish appropriate isolation zones and select suitable personal protective equipment (PPE) during hazardous materials (hazmat) and chemical, biological, radiological, and nuclear (CBRN) operations.