Does the exhaust system reduce harmful pollutants?

Because your car's engine runs on combustion (burning gasoline), it creates smoke. These fumes must be removed from the engine so that they do not suppress combustion and must be kept as far away from doors and windows as possible due to the high levels of carbon monoxide. Your exhaust also contains traces of many other chemicals, some of which pollute the environment. Your exhaust system parts are designed to reduce harmful emissions.

What parts?

First, understand that most of your exhaust is just meant to transport exhaust gases from one point (engine) to another (muffler). Your exhaust manifold, downpipe, pipe A, pipe B and muffler have nothing to do with reducing emissions. All of them are aimed at removing gases from the engine without exposing you and your passengers to them. The muffler's only job is to muffle the sound of the exhaust.

So which parts are responsible for reducing emissions? You can thank your EGR valve and catalytic converter. The EGR (exhaust gas recirculation) valve directs the exhaust gases back through the combustion chamber, mixed with fresh air, to burn more particulate matter (this also improves fuel economy by burning the smallest gasoline particles not burned during the initial combustion).

However, your catalytic converter is the real star of the show. It sits between your two exhaust pipes and its only job is to heat up. It gets so hot that it burns off most of the harmful gases that would otherwise come out of the muffler and pollute the air.

After all, your exhaust system is actually very good at cutting down on harmful chemicals that can pollute the environment (although it's not 100% efficient and degrades over time, which is why emissions testing is so important).