By Roberta Burnes
Division for Air Quality
Photos courtesy of Shutterstock
Every year, Americans burn more than 800 million gallons of gasoline mowing their lawns. Our love affair with the perfect lawn comes at a hefty price for public health and the environment. Gas mowers emit hydrocarbons, particulate matter, carbon monoxide and carbon dioxide. The smaller engines in lawn mowers and other lawn care equipment also burn fuel less efficiently and emit far more of these pollutants than the average family car.
According to the U.S. Environmental Protection Agency (EPA), at least 5 percent of annual air pollution emissions for the entire U.S. come from lawn mowers. A single gas-powered push mower emits as much hourly air emissions as 40 cars (California Air Resources Board). Spilled fuel is another problem; the EPA estimates Americans spill some 17 million gallons of fuel every year while refueling lawn equipment – more than all the oil spilled by the Exxon Valdez in Alaska. Spilled fuel releases volatile organic compounds into the air which also contribute to smog-forming ozone.
Air pollution is unhealthy for everyone, but it can cause particular harm to the developing bodies of children as well as the elderly and those with existing health problems like asthma. Since most mowing takes place in the warmer months of the year – when our children are more likely to be outdoors, and when smog (ground-level ozone, plus other pollutants like particulate) is more likely to form – gas mowers can add significantly to the problem. Ground-level ozone forms under hot and sunny conditions, so if you do use a gas mower, mowing in the evenings (after 6 p.m.) can reduce your contribution to the asthma-triggering pollutant.
If you don’t mind a little extra work, human-powered, reel mowers are the greenest choice for the small lawn. A reel mower cuts your grass just like a pair of scissors, as opposed to the chopping and tearing that happens with a power mower. Reel mowers are extremely quiet, require little maintenance, and cost less than most power mowers. Best of all, they require no fuel other than human energy, and produce zero emissions. Reel mowers do not cut tall grass well, so don’t wait weeks between mowing!
A variety of electric lawn mowers are now available, some with cords and some without. Purchase prices are generally comparable to gas models, but operating cost is where electric mowers really shine. A typical electric mower costs only about $5 to $6 in electricity to power each year. Electric mowers also tend to be lighter than gas mowers, making handling easier. Many have convenient, all-wheel height adjustments with just one control. Like most mowers, they do best if the grass is not allowed to get too tall or wet. Mulching is generally their strong suit, but that varies depending on the type of mower.
In terms of power, the technology is improving. Electric mowers are rated in watts instead of horsepower (hp) , with 1 hp = 746 watts, and doing the math indicates that most electric mowers run in the 1.5 to 2 hp range for the basic model. Most gas mowers have at least 3 hp. Unless you’re mowing extra long or extra wet grass, the difference is probably negligible. The size of your yard may be your biggest limitation; electric mowers with cords are limited by their 100 foot cord length. Cordless models are more convenient but only hold a charge for 30 – 45 minutes of mowing, depending on grass height. This is easily solved by selecting a model with the capacity to easily switch batteries, then having an extra battery on hand to switch out if energy runs low.
If you live in the Louisville Metro area, rebates are available for electric and human-powered lawn equipment. Visit http://www.louisvilleky.gov/APCD/lawncare/ResidentialLawnCareRebates.htm for more information.