Are gasoline vapors lighter or heavier than air?

Gasoline vapors are heavier than air. This property is significant in assessing risks associated with underground storage tanks (USTs) and potential vapor release during tank operation and any accidental leaks. When gasoline spills or leaks occur, because the vapors are heavier than air, they tend to accumulate in low-lying areas and can create hazardous conditions—this is particularly important for safety assessments and remediation strategies. Knowledge of vapor behavior assists professionals in implementing appropriate safety measures, such as ventilation or monitoring for vapor migration, which is critical in handling UST sites safely and effectively.