The physical data term on a Material Safety Data Sheet (MSDS) that indicates if the vapor formed by a material is lighter or heavier than air is called __________.

Correct Answer: Option A — vapor density

Vapor density is the ratio of the weight of a volume of vapor to the weight of an equal volume of air. A value greater than 1.0 indicates the vapor is heavier than air and will accumulate in low-lying spaces, creating significant explosion and asphyxiation hazards in shipboard compartments.