Don't expect gas station attendants in Oregon to top off your gas tank.

New state environmental quality regulations forbid overfilling of gas tanks.

The ban on topping off is designed to reduce benzene and other toxic air pollutants from Oregon gas stations and other gasoline storage and dispensing facilities.

Topping off is when a gas station attendant continues to fill a gasoline tank after the nozzle clicks off.

According to a statement from the Department of Environmental Quality, topping off the tank does not equal more gas in the tank.

Topping off during fueling can cause gasoline to spill and release benzene, a known carcinogen, and other toxic air pollutants into the air. This is a health concern for gas station workers and drivers.

In addition, most modern pumps simply return the fuel back into the pump after the overflow click, which means drivers are paying for gas that does not get into the fuel tank.

In some cases, overfilling a gas tank can cause a vehicle's vapor control system to clog and stop working, which can require costly repairs.

The Environmental Quality Commission, DEQ's rulemaking and policy advisory board, approved and adopted the no topping off regulations in December 2008.

The new rules also require all larger Oregon gasoline storage and distribution facilities, those which dispense an average of 40,000 gallons per month or more, to use vapor capture controls similar to those currently required in the Portland, Medford and Salem areas.

DEQ's regulations follow on the heels of an Environmental Protection Agency rulemaking last year that tightened air quality regulations for fuel dispensing facilities nationwide. Oregon's tougher standards go beyond the federal rules to reduce benzene by an estimated 28 tons per year and volatile organic compounds by an estimated 1,610 tons per year. The federal standard applies only to facilities that dispense 100,000 gallons per month, and does not address topping off at the pump.

Information on the top off ban

For more information about Oregon's new top off ban and efforts to reduce toxic air pollution from gasoline vapors visit www.deq.state.or.us/aq/permit/vapor/vapor.htm.