The most dominant source of benzene emissions in ambient air is

The largest source of benzene in outdoor air is vehicle exhaust from petrol combustion.

The cement industry emits dust and other pollutants but is not the chief benzene source.

Cigarettes release benzene indoors but do not dominate ambient outdoor levels.

Paints and varnish emit volatile compounds yet contribute far less benzene than traffic.

Benzene is a known carcinogen once added to petrol as an anti-knock component.

Benzene exposure is linked to leukaemia and other blood disorders.