What are the simple methods to test exhaust emissions?

[OGrace]

Here are some simple methods to test exhaust emissions: Observe the color: Automobile exhaust is usually transparent. If black smoke or white mist appears, it definitely indicates excessive emissions. Check for particulate matter: You can place a cloth near the car's exhaust pipe to detect whether there are solid particles in the exhaust. If present, it likely indicates excessive emissions. Smell the exhaust: Exhaust gases purified by the three-way catalytic converter are mostly non-toxic gases such as carbon dioxide and nitrogen, which generally don't have a strong odor. If the exhaust is too pungent, it indicates excessive emissions.