Does Clean Diesel Beat Out Hybrids?
Mercedes-Benz, Jeep, and Volkswagen all rolled out new diesel passenger vehicles at the 2004 New York International Automobile Show. Perhaps these car makers are thinking that higher gas prices and advances in diesel technology will convince more Americans to buy diesel vehicles, which currently make up 40 percent of auto sales in Europe.
The manufacturers also might be thinking that diesels will be a fix for meeting ever-stricter federal fuel economy standards. Jason Mark of the Union of Concerned Scientists explains some of the very features that make diesel engines more fuel efficient are the factors that cause increased air pollution. Under current emission standards for cars and trucks, diesels are allowed to emit more than twice as much nitrogen oxide as gasoline vehicles and 10 to 100 times more particulate matter.
Diesel Exhaust Causes Cancer
If the particulate matter emitted by diesel engines seems like just another abstract pollutant that may not have real effects on your health, then check out these facts published by the American Lung Association:
- Diesel exhaust is listed as a known carcinogen under California's Proposition 65.
- The extensive scientific literature demonstrates that exposure to diesel exhaust increases the risk of developing lung cancer, and accounts for more than 70 percent of the cancer risk from toxic air contaminants (in California).
- Diesel is a major contributor to ozone pollution, a powerful respiratory irritant that may lead to shortness of breath, chest pain, wheezing, and coughing.
- Children are among those most vulnerable to the health risks of diesel exhaust exposure.
Public health researchers are also starting to raise questions about the noncancer risks posed by diesel particulates. Preliminary research suggests that modern diesel engines emit substantially more of the smallest soot particles (ultrafines and nanoparticles) than gasoline vehicles over emission test cycles. The tiniest particles are thought to penetrate deeper into the lungs and pose greater noncancer health risks than the larger particles.
Obstacles to Bringing Clean Diesel to Market
These health risks have led to stricter government standards for diesel and represent major obstacles to increased reliance on diesels, according to Walter McManus, director, Automotive Analysis Division of the University of Michigan Transportation Research Institute (UMTRI). New ultra-low sulphur diesel is now widely available, but diesel engine vehicles will not be available in all 50 states until 2008. McManus concludes that "hybrids are here already and they've been here for a while. They have a big advantage over clean diesels in terms of awareness and consideration."
To many industry observers, clean diesel remains an oxymoron, because clean diesel is not nearly as clean as gasoline, even in its cleanest state. The probability of clean diesel matching or surpassing the low emission levels of hybrid vehicles is unlikely for some time.