What is done to reduce the harmful effects of heat engines?

During operation, any heat engine has several harmful effects on humans and nature. In the first place in terms of harmful effects are the exhaust gases formed during the combustion of fuel. To reduce the harmful effects, catalytic converters are installed, which, at the level of chemical reactions, convert harmful substances into harmless ones. Next in importance is the noise generated by the engines during operation. To reduce the noise level, noise-absorbing screens and housings are used. And one more significant harmful effect from the operation of a heat engine is vibration. To reduce it, the engine is installed on special shock absorbers that dampen vibrations.