Nasty Leftover From Diesel Soot-catcher
Sydney Morning Herald
Wednesday May 29, 1996
The leading strategy for reducing the harmful soot in diesel vehicle exhaust may increase suspected cancer-causing chemicals four-fold, according to a new Australian study.
Automotive designers worldwide are testing an experimental method that cleans up diesel emissions by capturing the sooty particles in special ceramic filters inserted in the exhaust pipe. The trapped soot is then destroyed in a reaction triggered by copper, added in very small quantities to the fuel.
The results? "Particulates are down, and that's good, good, good," said combustion expert Dr Brian Stanmore , a chemical engineer at the University of Queensland.
But according to research reported today in the journal Nature by Dr Stanmore and University of Queensland doctoral student Mr Chris Clunies-Ross , there is a dangerous catch - the soot-busting copper also increases, by nearly four times, the formation of chlorinated compounds called dioxins which are produced, in minute amounts, by combustion of the diesel fuel.
The findings are "very useful", said Dr Simon Buckland , a senior policy analyst with the New Zealand Ministry for the Environment who is heading an assessment of the level of dioxins and other "organochlorine" contaminates in the New Zealand environment.
Dr Buckland said international concern had grown about dioxins since a 1994 review by the United States Environmental Protection Agency concluded that the "weight of evidence" was that they could cause cancer in people. As well, experiments with laboratory animals showed that dioxins could also suppress the immune system and cause skin lesions and reproductive difficulties, including low sperm counts.
Today, dioxins have no industrial use, although they once were an active ingredient in the defoliant Agent Orange, used by the US military in Vietnam. The most common sources are emissions from medical and industrial incinerators and the steel and pulp and paper industries.
Those emissions are controlled by a variety of systems that, for technical reasons, "are not the way to go with automobiles", Mr Clunies-Ross told the Herald. That is why Peugeot, Renault, Citroen, Fiat, Volkswagen and Volvo have jointly funded Dr Stanmore, Mr Clunies-Ross and Professor Patrick Giolot of the University of Haute Alsace at Mulhouse in France to tackle the soot problem. Their earlier results led to the recent dioxin work.
In their tests, Dr Stanmore and Mr Clunies-Ross collected the soot and dioxin produced by a small diesel engine, fuelled by copper-laced diesel.
© 1996 Sydney Morning Herald