Catalytic cancer

New Scientist, 13 December 1984:

The headline of your article, “Catalytic converters may cause cancer” is seriously misleading (This Week, 22 November, p 6). There is no evidence that catalytic converters increase hydrocarbon emissions. It may be that they have little or no effect on hydrocarbon-coated particles generated by poorly tuned engines. But that does nothing to alter the fact that catalytic converters reduce gaseous hydrocarbon emissions by over 90 per cent. Indeed, in the case of the major carcinogen, benzo-apyrene, gaseous emissions are reduced by over 99 per cent.

Nor is it true to argue that lean-burn engines are a better solution to emission control. Lean-burn technology may be effective at reducing carbon-monoxide emissions, but it is less effective at dealing with NOX, and has only a minimal effect on hydrocarbon emissions, the main concern of your article. Apart from their known carcinogenic potential, hydrocarbon emissions are of major environmental concern as they are ozone precursors and therefore contribute substantially to the forest damage observed in central Europe.

The proper solution to vehicle emissions is to combine lean-burn engines with catalysts which function as a three-way catalytic converter when the engine is running rich, and as an oxidative catalyst when the engine is running lean. Toyota already has such a car on the market.

Robin Russell-Jones
Stoke Poges
Buckinghamshire

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