The committee examined emissions standards governing so-called mobile sources, which include cars and light- and heavy-duty trucks; diesel-powered cranes, bulldozers, and tractors; and equipment such as lawnmowers that run on small gasoline engines. The committee concluded that despite the substantial progress in reducing emissions from mobile sources nationwide, more needs to be done to attain federal air-quality standards in many parts of the country.

URL: http://books.nap.edu/catalog.php?record_id=11586