How does vapor recovery technology work in relation to USTs?

Vapor recovery technology operates by capturing vapors that are displaced during the dispensing of fuel from underground storage tanks. As fuel is pumped into a vehicle, it creates space in the tank that must be filled by vapor. Without a vapor recovery system, these vapors would escape into the atmosphere, contributing to air pollution and potentially harming the environment. By utilizing a vapor recovery system, the captured vapors are either returned to the tank or processed in a manner that minimizes their release into the air. This process not only helps protect the environment but also improves the efficiency of fuel usage by ensuring that vapors do not escape.

The other options do not accurately describe the function of vapor recovery technology. Cleaning fuel from impurities refers to filtration processes, which are separate from vapor recovery systems. Increasing the storage capacity of USTs would involve structural modifications, whereas vapor recovery focuses on managing emissions, and measuring the temperature of stored fuel does not relate to vapor recovery at all. Thus, option A is the accurate description of how vapor recovery technology functions in relation to underground storage tanks.