[aopgajkag]
- This is a preview of the essay.
To view the full text you must login!
Diesel makes for more smog
Thursday February 12, 2004
The Guardian
Widespread use of diesel engines, often thought of as "greener" than petrol alternatives, would make the air smoggier, predictions suggest in Geophysical Research Letters.
Diesels typically emit less carbon dioxide than petrol vehicles, which reduces their contribution to global warming. But that doesn't necessarily make diesel an environmentally friendly alternative, says Mark Jacobson, who models atmospheric pollution at Stanford University in California. Diesels produce more nitrogen oxides than petrol-engined cars, he points out.
Smog is a soup of pollutants formed in the atmosphere from chemical reactions triggered by sunlight. Its main constituent is ground-level ozone, produced when hydrocarbons and nitrogen oxides from vehicle fumes react together. In the upper atmosphere, ozone shields us from harmful ultraviolet rays. But ground-level ozone is bad news.
Jacobson used a computer model of atmosphere quality to see what would happen if every US vehicle ran on diesel. Smog levels increased significantly - in most areas enough to push air quality from "moderate" to "very unhealthy" under environmental protection agency standards...