UK commuters spend an average of about 1.5 hours a day at the wheel. Road vehicles in particular are known to emit polluting nanoparticles which contribute to respiratory and heart diseases. Now, researchers at the University of Surrey have found that where drivers spend just 2% of their journey time passing through traffic intersections managed by lights, this short duration contributes to about 25% of total exposure to these harmful particles. The team monitored drivers' exposure to air pollutants at various points of a journey. Signalised traffic intersections were found to be high pollution hot-spots due to the frequent changes in driving conditions.