Visibility and soiling: a comparison of the effects of leaded and unleaded gasolines.

The emissions from a fleet of late-model cars fueled with commercial, high-aromatic, unleaded gasoline caused nearly twice as much atmospheric light extinction as those from a matched fleet fueled with commercial, low-aromatic, leaded gasoline, when both were driven according to a consumer operating cycle in an idle traffic tunnel. The increased extinction and greater soiling potential result mainly from greater light absorption by the air-suspended particles from the unleaded fleet.