Question: what is the most harmful gas produced by engines

John Turner answered on 25 Nov 2021:

There are four main pollutants that are produced by engines that a catalytic converter removes. Carbon monoxide – which if breathes in can bind to your blood and can kill you if you breathe too much. Nitrogen oxides – these cause breathing difficulties and cause acid rain which can harm the environment. Unburned fuel – which can affect breathing as well and is a carcinogen, which means that it could cause cancer. Soot – unburned fuel particles that can cause breathing issues such as asthma if inhaled. The catalysts I work on can remove these so that the air coming out of the exhaust is clean and doesn’t cause pollution.

The most harmful in the short term is carbon monoxide as this will kill you! But it is important to remove all of these pollutants to keep the environment clean!