Bank Holiday Traffic Jam (IMAGE) University of Surrey Caption Research by the University of Surrey show car windows closed with the fan/heating off in traffic is the best ventilation setting leading up to a 76% reduction in in-car pollutants in traffic jams. Also, safest setting is the air being circulated internally only by the fan without drawing in polluted air from outdoors. Credit Getty Images Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.