Environmental catalyst is a substance that initiates a chemical reaction and enables it to proceed under different conditions (as at a lower temperature or faster rate) than otherwise possible. The catalyst itself is not consumed, but continues to perform its function in subsequent reactions. This catalyst is used to initiate the breakdown of pollutants into their harmless elements, as when catalytic converters turn hydrocarbons, carbon monoxide and nitrogen oxides coming from cars into carbon dioxide, nitrogen and water vapor.