Maintain Lawns to Reduce Summer
By Carl Wilson, Horticulturist, Colorado State University Cooperative
Extension, Denver County
If you're in charge of maintaining a lawn, you have a role in minimizing Denver's summer
ozone pollution and its human health effects.
Ground level ozone forms under warm temperatures when a pollutant emitted by lawn mower
engines, VOC, is present with another pollutant, NOX, emitted by automobiles and
industrial sources. Ozone that is formed at ground level irritates breathing passageways
unlike beneficial stratospheric ozone that filters out skin-damaging UV rays high above
The small engines found in gasoline-powered lawnmowers, leafblowers, string trimmers and
other yard care equipment emit as much as 25 percent raw, unburned gasoline. An hour of
lawnmower operation produces as many emissions as a 1997 mid-sized car driven 125 miles.
During warmer summer weather, advisories will be called in the six county Denver Metro
area when ozone levels are high. Consider the following lawn care steps to minimize the
ozone health risks for everyone.
Other mowing options such as hand-pushed reel mowers, or electric mowers are excellent
alternatives that are not a concern during smog advisories. Sweeping with a broom is a
manual alternative to leaf blowers, as are hand shears instead of gasoline powered
trimmers. Note that EPA and CARB-certified mowers manufactured after 1999 are cleaner
burning and cut down on emissions.
Additional tips to minimize pollution include: avoid spilling fuel during filling
operations, fill tanks only 3/4 full to allow for expansion, tightly screw on the gas caps
of the mower and fuel can, place gas containers in a cool place out of the sun, and reduce
mower operating time to that essential to cutting the lawn.
Maintaining mower engines is key to burning fuel as cleanly as possible. Change oil after
25 hours of use and use 30W oil instead of a multi-weight type in warm weather. Clean or
replace the air cleaner element regularly, at least every 3 months or when the oil is
changed. Clean, re-gap or replace spark plugs. Keep the engine and underside of the mower
deck clean of grass buildup. Sharpen the mower blade regularly for cleaner cuts that
reduce pollution by requiring less fuel.
Thanks for doing your part to keep Denver's air clean and landscapes green.
Photograph courtesy of Judy Sedbrook.
Back to Lawns
Back to Home