What emissions output does the AIR (Air Injection Reaction) system aim to reduce during cold engine operation?

The AIR (Air Injection Reaction) system is designed to help reduce emissions of carbon monoxide (CO) and hydrocarbons (HC) during cold engine operations. When an engine is cold, it often runs rich, meaning there is more fuel in the air-fuel mixture than optimal for combustion, which can lead to increased emissions of CO and HC.

The AIR system injects additional air into the exhaust stream, which assists in the oxidation of these pollutants. By providing more oxygen, it helps to convert carbon monoxide into carbon dioxide and assists in burning off unburned hydrocarbons. This process effectively lowers the levels of these harmful emissions during the critical periods of cold engine operation when pollution output tends to be at its highest. The significant reduction of both CO and HC makes this system essential for improving air quality and meeting emission standards.

While the question mentions NOx emissions, the AIR system primarily focuses on reducing CO and HC during cold starts, as those are the primary pollutants emitted when the engine is not yet fully warmed up. Therefore, the correct response encompasses both CO and HC, accurately reflecting the function of the AIR system.