To reduce airborne particulate pollution, EPA last week finalized a rule that cuts the sulfur content of diesel fuel and requires emissions controls on many types of diesel engines. The rule slashes the allowable sulfur content of diesel fuel from its current level of about 3,000 parts per million to 500 ppm in 2007 and to 15 ppm by 2010. This move will add about 7 cents per gal to the price of diesel, EPA estimates, but the net impact to diesel users is estimated to be about 4 cents per gal because ultra-low sulfur fuel can significantly reduce engine maintenance costs. The rule also sets emissions standards for diesel-powered engines in construction, agricultural, and industrial equipment--machines not used on roadways. Those limits will be phased in between 2008 and 2015 and will add 1 to 3% to the price of the diesel equipment. According to EPA, the public health benefits of the rule outweigh its costs by a ratio of 40 to 1. The agency says the rule will be equivalent to removing 2 million tractor-trailers from roads.