NATA is warning members that new air quality regulations issued by the California Environmental Protection Agency may lead to similar restrictions in other states. The new rules were issued via the state’s Air Resources Board and apply a fleet average emission level to off-road vehicles and equipment, which includes ground-services equipment used at airports, with gasoline and liquefied-petroleum engines that produce more than 25 hp. Diesel engines are covered by a separate rule, according to NATA.