The EPA released a new study in April of 2007 that would reduce hydrobcarbon, oxides of nitrogen, as well as carbon monoxide emissions  from small engines which includes lawn equipment like lawn mowers. Lawn mowers are heavy pollutants even if it is not as apparent but one has to imagine how often lawn mowers are used throughout the year. The new standards are proposed to start in 2011 and according to the EPA, “the small engine regulation will increase the cost of equipment by an average of $5-7 per unit.” For those interested in the EPA proposal, check out http://www.epa.gov/otaq/equip-ld.htm