A filter that converts these gases to less toxic gases it called catalytic converter
In the ideal case, the #combustion inside vehicles #engine results a group of gases consisting of #carbon dioxide and #water vapor, but in the normal case, other gases such as carbon monoxide resulting from incomplete combustion (hydrocarbons) also result from incomplete combustion and Nitrogen oxides (NOx) resulting from high temperature inside the combustion chamber are produced.

These gases are highly toxic to the environment in general,