Since most nitrogen oxide emissions are from cars, catalytic converters must be fitted on cars to reduce this emission. The catalytic converter is mounted on the exhaust pipe. All the exhaust fumes pass though it. This converter looks like a honeycomb, but it is coated with either platimun, palladium, or rhodium. This changes nitrogen oxides, carbon dioxides and unburned hydrocarbons into a cleaner form.
To reduce sulfur dioxide emissions from factorys utility plants are required to do several steps to clean the air. Before combustion, these utilities plants have to go through a process call coal cleaning. This process is performed gravitationally. Meaning, it is successful in removing pyritic sulfur due to its high gravity, but it can't remove chemically bound organic sulfur. Another way to reduce sulfur dioxide before combustion is by burning coal with low sulfur content. Low sulfur content coals are called subituminous coal. This process in reducing sulfur dioxide is very expensive due to the high demand of subituminous coal.
