The use of marijuana while drinking alcohol lowers the BAC of the driver causing some impairment of driving ability
does not affect driving ability
may affect driving ability if both substances are taken in abundance
impairs driving beyond that usually related to the BAC of alcohol

significant amounts of nitrogen oxides, carbon monoxide, and other pollution

explanation:

passenger vehicles are a major pollution contributor, producing significant amounts of nitrogen oxides, carbon monoxide, and other pollution. in 2013, transportation contributed more than half of the carbon monoxide and nitrogen oxides, and almost a quarter of the hydrocarbons emitted into our air.

what's the question ?

so whats the answer