"Mow down pollution."

"Do your share to spare the air."

"Mower exchange can save residents hundreds."

The rhetoric is flying, if not the fumes, as programs enticing you to trade in your gas mower for an electric model ramp up in time for prime mowing season and Earth Day.

We first reported on mower-exchange programs last year. You take your gas mower to a location and exchange it for an electric mower that you buy at a steep discount; some programs also allow you to buy a discounted electric mower without an exchange.

California is predictably in the forefront of mower swap, with programs all over the state offering $100 or more off a new electric mower. Similar programs exist in other states, including Colorado (Denver program shown), Texas, South Carolina, and Kentucky. (Louisville, Kentucky, even includes gas-powered string trimmers and blowers in its lawn-care rebate program.) And in Canada, Home Depot is running the Mow Down Pollution event for gas mowers and trimmers from April 23 to May 3. Find out about mower-exchange programs in your area by checking with the department of environmental protection in your state or a county or local agency.

If you have a modest-size property, there's a strong upside to unloading an old, gas-guzzling mower or other lawn gear. Some electric push mowers (ratings available to subscribers) we've tested were as good as all but the highest-rated gas models at cutting evenly, and on average they were as easy to handle. Among other advantages, they're especially quiet and don't need tuning up.

But an electric mower might not make sense if you have a large yard—most have a run time of about 45 minutes—or one with a lot of slopes. Models from Worx, Neuton, and Earthwise tested for our May 2009 report on mowers and tractors (report and ratings available to subscribers) did a lackluster job at mulching, bagging, and side-discharging. Also note that for corded electric models, schlepping around the power cord and having to plug it back in from time to time can be a nuisance.

The U.S. Environmental Protection Agency's Lawn Mower Exchange Program Calculator can help you determine how much better an electric or reel mower would be in terms of emissions than your current gas mower. The EPA itself has been tightening emissions regulations engines used in mowers, and any mower you've bought in the past few years—especially in California—will likely be more efficient as manufacturers phase out their manufacturing to meet the upcoming emissions changes.—Ed Perratore | e-mail | Twitter