A new study has revealed that long traffic jams causes exposure to toxic fumes and may increases the risk of developing the deadly disease cancer. As per World Health Organization (WHO), exposure to outdoor air pollution is among the top ten health risks faced by humans and is especially pronounced in urban concentrations. WHO on October, 2013 had classified that outdoor air pollution as being carcinogenic to humans.Researchers said the findings showed that when vehicles stop at red lights, they go through different driving cycles such as idling, acceleration and deceleration and emission of toxic fumes. These emissions take more time to disperse, especially in built-up areas and end up accumulating in the air at traffic signals. Thus, the people sitting inside cars, with closed windows but with fans switched on, can be at an increased risk of exposure to the outdoor pollutants, the researchers said. Switching on the fan sucks the dirty air from outside to inside the vehicle, resulting in an accumulation of pollutants in the car. However, it may be relatively safe to put fans onto the setting where they re-circulate air within the car without drawing polluted air in from outside, the study stated. “Where possible and with weather conditions allowing, it is one of the best ways to limit your exposure by keeping windows shut, fans turned off and to try and increase the distance between you and the car in front while in traffic jams or stationary at traffic lights,” said Prashant Kumar from the University of Surrey.