What term describes the ratio of a substance's vapor pressure to the pressure of the atmosphere surrounding it?

The term that describes the ratio of a substance's vapor pressure to the atmospheric pressure surrounding it is volatility. Volatility refers to how readily a substance evaporates at a given temperature; this property is critical in understanding how hazardous materials may behave in a variety of conditions. A substance with high volatility has a significant vapor pressure compared to atmospheric pressure, meaning it can easily transition from a liquid to a vapor, which is vital information for emergency responders when assessing risks and planning mitigation strategies during hazmat incidents.

In hazardous material operations, understanding volatility aids in predicting the potential for vapors to accumulate and become health hazards. Knowing whether a substance is volatile can help responders prepare appropriate measures to prevent exposure or ignition.