The major source of anthropogenic CO emission is:
Road vehicles are a major anthropogenic source of carbon monoxide because petrol and other carbon fuels undergo incomplete combustion when oxygen supply, mixing, temperature, or residence time is inadequate. Urban traffic therefore produces high exposures near roads, particularly from poorly maintained engines and congestion. Power stations generally achieve more complete, controlled combustion and are more strongly associated with carbon dioxide, sulfur oxides, nitrogen oxides, and particulates. Effective management combines cleaner fuels, emission standards, monitoring, urban planning, and p
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology