Pennsylvania will no longer require gasoline stations to install costly vapor-recovery systems, a fixture at fuel pumps for two decades.

The systems are no longer necessary because modern vehicles are equipped to capture emissions from fuel tanks, the state Department of Environmental Protection said Wednesday. Its announcement followed a directive in May from the U.S. Environmental Protection Agency that determined the systems were redundant.

Several other states have also moved to relax mandates to install the systems, which capture fumes released during refueling. Gasoline vapors, if allowed to escape, can contribute significantly to ground-level ozone.

"These so-called Stage II vapor-recovery systems must still be operated and maintained at existing facilities until further notice," DEP Secretary Mike Krancer said in a statement. "We will, however, use our discretion to not enforce these requirements for any new gas station in the greater Pittsburgh and Philadelphia areas because the diminishing benefits do not justify the cost of installing new systems."

The EPA estimates the vapor-recovery equipment, required since 1994, costs from $20,000 to $60,000 to install. For a typical gas station, the systems cost $3,000 a year to maintain.

About 70 percent of all vehicles now have onboard vapor-recovery equipment, which manufacturers began installing in 1998. All new vehicles have had the gear since 2006.