Cut the smog as you mow the lawn

A federal mandate requires that by 2011 most new lawn mowers must filter out dozens of pollutants.

It's time to clean up America's lawns – by cleaning up the lawn mowers. Americans spend 3 billion hours a year mowing lawns with machines that spew pollutants skyward, clouding summer skies with smog-causing exhaust.

But help is on the way. Thanks to a new rule unveiled by the Environmental Protection Agency this week, homeowners will finally be able to buy mowers that give their lawn a truly clean cut.

Acting under the Clean Air Act, the EPA mandated on Tuesday that by 2011 most new mowers sold in the United States must filter out an additional 35 pollutants, such as volatile organic compounds and nitrous oxides – in addition to the 60 percent reduction mandated last year,

As a result, most new mowers will likely have miniature versions of the catalytic converters used on automobile exhaust systems.

That's good, because US lawn mowers emit far more pollution than cars do. A simple walk-behind mower pumps out as much pollution as 11 cars every hour – and as much as 34 vehicles for a riding mower.

The new rule for small engines – which will also apply to recreational watercraft like jet skis – didn't come easily. Until recently, enginemakers and their allies in Congress blocked the rule. California broke the logjam in December when the EPA said the state could set pollution standards for small engines. This week's EPA ruling in effect applies the California standard nationwide.

It may cost homeowners a few dollars more for cleaner mowers, but they will chop 3.4 million tons of pollutants a year, the EPA estimates. Health benefits from better air quality will be worth $3.4 billion by 2030, it says.

"It will be a stretch goal to achieve everything being demanded," says Roger Gault, technical director of the Engine Manufacturers Association, a Chicago-based trade group. "But at this point it's a goal that people recognize needs to be achieved."