Given the enormity of the problems associated with global warming, lawnmower emissions may seem like a small issue. As the cliche goes, however, changing policy usually begins by picking the low-hanging fruit. Lawnmowers are such fruit, but the rules proposed this week by the Environmental Protection Agency would reduce emissions more than you might expect.

According to the EPA, a walk-behind mower emits as much pollution per hour as 11 cars. A riding lawnmower compares to 34 cars. Americans spend more than 3 billion hours per year using lawn and garden equipment, according to the agency.

The rules proposed this week would cut emissions from gas-powered lawnmowers by more than a third. That is on top of larger reductions as a result of rules that were fully in place last year. Even larger cuts would be required in recreational watercraft engines, which can emit as much per hour as 348 cars.

When fully implemented, the rule would result in an annual reduction of 2.7 million tons of carbon dioxide and would prevent 450 premature deaths each year, the EPA said in announcing the rule. The health care benefits would be about $3.4 billion by 2030. In addition nearly 200 million gallons of fuel would be saved each year, saving consumers about $350 million.

To meet the standards, manufacturers are expected to use catalytic converters for the first time in these engines. The devices, first widely used in cars in the 1970s to meet clean air requirements, convert pollutants in exhaust into less harmful components.

The Outdoor Power Equipment Institute Inc. says that comparing lawnmowers to cars is inaccurate because cars are used a lot more. While technically true, this is beside the point. When lawnmowers are used, they pollute a lot for the size of their engines. This isn’t necessary.

There are of course alternatives that don’t require rule changes. Electric mowers emit no pollution and can easily cover an average yard on a single charge. Old-fashioned push mowers also have no emissions and offer a chance for a bit of exercise, too.

Tougher pollution standards for lawnmower and boat engines won’t slow climate change on their own, but they are part of a policy that must require lower emissions from all sources.