In the next two years, virtually every gas station in Connecticut will have to change the nozzles on its pumps to disconnect the vapor-recovery systems required by the Clean Air Act of 1991.

Those Stage II vapor recovery systems — a bellows or a disk near the handle — are no longer needed because of advances in car gas valves. In fact, the older nozzles actually work against the new technology, causing leakage of the same volatile organic compounds and toxins they were once meant to prevent, a state report says.