The exemption will save Alaskans millions of dollars in increased highway fuel costs. Low-sulfur diesel would help reduce the emissions of very fine particulate matter from highway diesel engines. Diesel engines produce three different types of particulate matter. Low-sulfur diesel would help reduce only one of these types of particulate, called sulfate particulate. Some stationary sources have to reduce sulfur dioxide emissions.
Sulfur dioxide is a gas and sulfate particulate is a solid.
Generally, sources reduce sulfur dioxide emissions by reducing the amount of sulfur in the fuel. Sulfate emissions can be reduced by combustion chamber design, fuel sulfur reduction, and certain types of exhaust traps. Anchorage does have a particulate problem, but it is not caused by diesel engines. The particulate in Anchorage is mostly road dust. Diesel particulate is less than 1 percent of the total particulate in the air in Anchorage.