What physical characteristic of gasoline makes it particularly hazardous to have basements in service stations?

Gasoline is particularly hazardous in basements of service stations primarily due to its vapor density. Vapor density refers to the weight of the vapor compared to air. Gasoline vapors are heavier than air, which means that if gasoline spills or evaporates, these vapors can accumulate in low-lying areas, such as basements. If these vapors reach a sufficient concentration, they pose a significant risk of fire or explosion, especially if an ignition source is present.

This characteristic emphasizes the dangers of proper ventilation and the necessity to monitor vapor levels in enclosed spaces. Keeping basements free from gasoline vapors is crucial to ensure safety, as these vapors can linger at ground level, making it essential to have systems in place to prevent buildup.