What measures are taken to protect the environment from harmful emissions from heat engines?

Various measures are being taken to prevent harmful emissions into the atmosphere from heat engines. A special adjustment of the engines is carried out for more complete combustion of fuel, which leads to a decrease in the content of carbon monoxide in the combustion products and an increase in the efficiency of the engines themselves. Designs of heat engines operating on a mixture of oxygen and hydrogen, as well as electric vehicles are being developed. They do not emit harmful substances. So far, it has been possible to partially reduce pollution with the help of filters that are installed in car engines, at thermal power plants.