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For the last 30 years, the federal government's Environmental Protection Agency (EPA)as well as the nation's engine manufacturers-have focused on controlling criteria pollutants. Emphasis has been on limiting the nitrogen oxides, carbon monoxide, volatile hydrocarbons, and particulates that engine exhaust put into the air.
That changed early this decade, when the EPA amended the Clean Air Act to include a specific list of hazardous air pollutants, or HAPs, totaling 188 compounds that can have potentially dangerous effects on people. The revised and expanded law stated that by Nov. 15, 2000, the EPA must have rules in place to deal with HAPs.
HAPs can be introduced into the environment through many methods, especially any process involving combustion. Only seven HAPs on the list currently appear to be of potential concern for gas fueled, internal combustion engines: acetaldehyde, acrolein, benzene, butadiene, ethyl benzene, formaldehyde, and naphthalene.
By far, the most significant of these for engine manufacturers is formaldehyde. It's a known precursor to photochemical smog that can also irritate the eyes, nasal membranes and sometimes the skin. Formaldehyde may also react with other trace HAPs to form suspected or known carcinogens.
Formed by the incomplete combustion of hydrocarbon fuels, low-level traces of formaldehyde are found in the exhaust of both gas and diesel engines, as well as gas turbines and other combustion sources. Typical emission levels of formaldehyde vary with whether the engine is a lean-burn or rich-burn model, speed, load, and other parameters, but a representative level for lean-burn, gas engines is 0.2 of a gram per horsepower per hour (g/bhp/hr).
Waukesha Engine anticipated regulatory scrutiny of HAPs, especially formaldehyde, as early as 1992. At that time, we unilaterally ran a testing program that included models from all four of our engine lines, VSG, VGF, VHP, and ATGL, looking for the presence of formaldehyde in the exhaust.
In 1996, the EPA formed the Industrial Combustion Coordinated Rulemaking (ICCR), a coalition of industry, environmental and regulatory groups called together to work toward helping the...