What does the term "expansion" refer to in the context of hazardous materials?

In the context of hazardous materials, "expansion" specifically refers to the increase in volume of a substance, particularly gases, during a leak or explosion. This phenomenon occurs when a gas is released from a pressurized container or through a breach in a hazardous materials storage unit. As the gas rapidly escapes, it can significantly increase in volume due to changes in pressure and temperature, leading to the potential for dangerous conditions.

This concept is crucial for first responders to understand, as it informs the assessment of risks associated with hazardous material incidents. For example, a leak might not only create a localized hazard but can also result in a rapid expansion of gas that could rapidly spread potentially harmful substances over a wider area, contributing to the severity of the incident.

Understanding this definition allows first responders to better evaluate the situation and take appropriate actions to mitigate risks associated with the escape of hazardous materials, ensuring both safety and effective response.