Gaseous Emissions from Unregulated Mobile Sources

The impact of gaseous exhaust emissions is determined for the following categories of mobile sources which are currently not covered by national emission regulations: 1) farm equipment, 2) merchant vessels, 3) locomotives, 4) lawn and garden implements, 5) snowmobiles, 6) outboard motors, 7) transport refrigeration units, and 8) helicopters. Mass emission rates of each category are tabulated and compared to other emissions from both mobile and stationary sources in selected Air Quality Control Regions. Also, projections are made as to the expected increase of emissions from each source category through 1990. The results show that in the near future some categories of mobile sources will be contributing substantial amounts of pollutants, on a mass basis, in regions with critical air pollution problems. As stricter emission standards on regulated sources continue to be implemented, the relative significance of these unregulated sources will increase. The major conclusion is that broad generalizations as to the amounts of air pollution contributed by these unregulated mobile sources nationwide may be grossly misleading. The only effective way to assess their impact is on a region-by-region basis. To this end, generalized computer programs are developed which permit the estimation of each category’s present and future mass emission rates in any Air Quality Control Region in the country