Which device helps to control emissions from gasoline-powered vehicles?

The evaporative emission control system, commonly referred to as EVAP, plays a crucial role in controlling emissions from gasoline-powered vehicles. Its primary function is to capture and contain fuel vapors that might escape into the atmosphere from the fuel tank and fuel system, preventing pollutants from contributing to air quality degradation.

The system includes components such as a charcoal canister, which absorbs fuel vapors, and a series of valves and hoses that manage the flow of these vapors back into the intake system of the engine to be burned during combustion. By ensuring that these vapors do not escape into the environment, the EVAP system significantly reduces volatile organic compound (VOC) emissions, contributing to the overall reduction of smog and improving air quality.

Other devices listed, such as the fuel tank vent, help with the operation of the fuel system but do not specifically focus on controlling emissions. The oil filter is vital for maintaining engine health but is unrelated to emission control, and while the air conditioning compressor contributes to vehicle comfort, it does not play a role in reducing vehicle emissions. Thus, the EVAP system stands out as the primary technology designed specifically for emission control in gasoline-powered vehicles.