Another reason lawns are bad

From the Economist:

Lawnmowers
It all adds up

As spring turns to summer, across America millions of small engines are coming to life, cranking out power and puffing out smoke as they mow America's lawns, whack its weeds and trim its borders. Each engine by itself has little effect on the atmosphere, and most are operated only for short spells. But together they contribute a lot of air pollution, a matter on which the federal government and the states are starting to focus.

Small engines--those under 25-horsepower--are much cleaner than they were 20 years ago. But unlike cars and lorries, they are largely uncontrolled; and their carbon-dioxide emissions, combined with escaping fuel vapours and leaking oil, make them remarkably dirty machines for their size. For example, regulators in California estimate that using a chain-saw for two hours produces as much pollution as ten cars each driving 250 miles--though the outdoor-power-equipment lobby, of course, vigorously disagrees.

Under the federal Clean Air Act, California is the only state that can set its own regulations, although other states may adopt them. California has been phasing in regulations for small engines since 1990. For years Senator Kit Bond of Missouri, determined to protect jobs at two factories in his state, blocked an effort to apply those standards nationally. But recently a compromise, allowing the federal Environmental Protection Agency to proceed with proposed new regulations, was reached. The small-engine lobby concedes that stricter regulations were inevitable, and that a national standard would make sense.

Other tactics are being tried as well. The South Coast Air Quality Management District, which covers Los Angeles and Orange County, is offering residents a $399 electric-powered lawnmower for $100 if they trade in an old petrol-burning lawnmower.

Alternatively, America could always give up lawnmowing altogether. Las Vegas residents are encouraged to abandon the unnatural practice of growing grass in a desert and let native plants re-establish themselves. And some have done what so many sweat-drenched people pushing a lawnmower in a Midwestern heatwave long to do; they have paved over their lawns and painted the concrete green.