On top of looming tougher pollution rules for SUVs and other popular vehicles, an environmental engineer at Washington University in St. Louis now has devised a new measurement that could make both car owners and manufacturers nervous. It's called ppvm (pollutant per vehicle mile). It is a measurement of the total particulate matter emissions a vehicle makes per mile traveled. While ppvm won't appeal to the auto owner the way that mpg, rpm or mph do, it's likely to have a future impact on air pollution measures and standards nationwide.
Jay R. Turner, D.Sc., assistant professor of chemical engineering and civil engineering at Washington University and director of the university's Air Quality Laboratory, has performed an ambitious study of vehicular emissions in the St. Louis region. Emission measurements were taken for particles smaller than 2.5 micrometers in diameter, which is the size range for a standard issued by the U.S. Environmental Protection Agency (EPA) in 1997. Results from an urban interstate site and a nearby rural Illinois site that Turner surveyed indicate that an average urban vehicle, whether a motorcycle or diesel truck, emits between 30 to 40 milligrams of particulate matter per mile traveled; an average rural vehicle emits between 200 to 300 milligrams ppvm traveled. So much for fresh country air.
"We think there is much more heavy diesel traffic outside the city and there are greater road dust emissions in rural areas because of the proximity to open land, and those account for higher rural readings," Turner explains.
Road dust is more than the simple dirt a vehicle stirs up as it moves along the road. Besides dirt from soil, road dust also contains the suspended fine particulate matter created from tail pipe emissions. It is a major significant component of vehicular air pollution that the medical profession and the EPA are paying strict attention to these days. Upper respiratory illnesses, cardiovascu
Contact: Tony Fitzpatrick
Washington University in St. Louis