Which pollutant is not primarily targeted by catalytic converters?

• A. Ozone
• B. Carbon monoxide
• C. Hydrocarbons
• D. Nitrogen oxides

Answer: (A)

Catalytic converters clean the exhaust by targeting pollutants that come directly from the engine: carbon monoxide, unburned hydrocarbons, and nitrogen oxides. The catalysts promote reactions that turn CO into CO2, break down hydrocarbons into CO2 and H2O, and convert NOx into nitrogen and oxygen. Ozone is a secondary pollutant formed in the atmosphere from NOx and volatile organic compounds in sunlight, not something emitted directly by the engine. Because the converter acts on exhaust before it leaves the vehicle, it doesn’t remove ozone itself; its influence on ozone is indirect, through reducing the precursor emissions that can contribute to ozone formation.