AUGUSTA – The Department of Environmental Protection is proposing a new rule that would regulate which types of portable gas containers can be sold in Maine.

The proposal would require manufacturers and retailers to sell only cans that are less permeable and come with spill-proof spouts. If approved, the regulation would take effect in 2004.

Environmental officials said old leaky gas cans release hundreds of tons of emissions each year that contribute to ozone pollution.

Under the proposal, retailers would be given a year to sell all their old stock, and consumers may continue to use their old cans for as long as they last.

“If they last 100 years, they’ll be able to use them,” said Jeffrey Crawford of the department’s Bureau of Air Quality. “The fuel-can police are not going to take your gas can.”

Officials said they have concerns about gas cans because of their effect on the environment.

According to studies by manufacturers and the Ozone Transport Commission, a coalition of states working to reduce ozone pollution, portable fuel containers release an estimated 6.6 tons of volatile organic compound emissions per day in Maine. VOC emissions are a major component of ozone pollution.

Some of that pollution comes from spills and leaks, the rest from evaporation that occurs as the cans “breathe.”

“What happens is the gasoline can will expand during the day and contract at night when it cools off, so it’s basically pushing gas vapors out,” Crawford said.

The new DEP rule eventually would cut fuel-can emissions by 75 percent, a reduction on par with switching to reformulated gas.

The new standard will also cut people’s exposure to benzene, a known carcinogen, and other toxic substances found in gasoline.

The additional cost to the consumer is $6 to $10 per can. When the loss of gas through spills and evaporation over the life of the can is taken into account, the net cost is expected to be $1.33, Crawford said.

Some devices would be exempt from the rule, including fuel containers with a capacity of a quart or less, safety cans and portable marine-fuel tanks designed to be operated with an outboard motor.

Similar rules are already in effect in California, Delaware, Maryland, Pennsylvania, New York and New Jersey. More eastern states plan to adopt the standard as well. Manufacturers have not mounted any major efforts to oppose the rules in other states, Crawford and others said.