What is the vapor density of air?

The vapor density of air is defined as a reference point for measuring the density of other gases. It is established as a standard value of 1, which allows for easy comparison with other substances. Gases with a vapor density less than 1 will rise in air since they are lighter, while those with a vapor density greater than 1 will tend to sink. This concept is crucial for understanding how different gases behave in the atmosphere, especially in scenarios involving hazardous materials, where the behavior of a gas can directly impact safety and response strategies.

For example, knowing that air has a vapor density of 1 helps responders assess the risks of a released gas—whether it will disperse upward or settle closer to the ground, which influences decisions on ventilation, evacuation, and potential exposure to individuals in the vicinity.