Which of the following is a non-vehicular pollutant?

Chlorofluorocarbons come mainly from refrigerants, aerosols and foam rather than vehicle exhaust, marking them a non-vehicular pollutant.

Carbon monoxide is a classic vehicular pollutant from incomplete fuel combustion in engines.

Suspended particulate matter is released heavily by vehicle exhaust along with dust and combustion.

Sulphur dioxide comes from burning sulphur-bearing fuels including diesel in vehicles.

The other three are all tied to road transport, unlike the industrial and household chlorofluorocarbons.

Chlorofluorocarbons are being phased out under the Montreal Protocol for their role in ozone depletion.