On Sep 20, 11:04*am, "Dave Plowman (News)"
wrote:
In article
,
* *harry wrote:

Nitric oxide, Nitrogen dioxide, Hydrogen sulphide. Carbon monoxide,
Carbon dioxide, Carbon particles, Ammonia, Sulphur dioxide, VOCs +
numerous unburned hydrocarbons. Even with a catalyser.

Catalytic convertor. Apart from carbon dioxide, many of these are lower
from a car exhaust than those present in the average town.


The "cat" actually creates pollutants that weren't previously present.
http://en.wikipedia.org/wiki/Catalyt...nted_reactions
So they are not the be all and end all.