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Stopping at red lights exposes drivers to high levels of air pollution, new study finds

Research published in the journal Atmospheric Environment has found that drivers are exposed to dangerously high levels of air pollutants when stopped at red lights.

UK commuters spend an average of one-and-a-half 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 two per cent of their journey time passing through traffic intersections managed by lights, this short duration contributes to about 25 per cent of total exposure to these harmful particles.

The research team monitored drivers’ exposure to air pollutants at various points during a journey. Signalised traffic intersections were found to be high pollution hotspots due to the frequent changes in driving conditions. With drivers decelerating and stopping at lights, then revving up to move quickly when lights go green, peak particle concentration was found to be 29 times higher than that during free flowing traffic conditions. As well as concentration, researchers found that as cars tend to be close together at lights, the likelihood of exposure to vehicle emissions is also significantly increased.

“Air pollution was recently placed in the top ten health risks faced by human beings globally, with the World Health Organisation linking air pollution to seven million premature deaths every year,” said lead author Dr Prashant Kumar, Senior Lecturer in the Department of Civil and Environmental Engineering.  

“The time we spend travelling in cars remains pretty much the same now as it was from the past decade – despite encouragement to reduce it. This work provides an interesting insight into this problem of exposure at traffic intersections, and I thank my team, especially one of my PhD students, Anju Goel, for her hard work.

“It’s not always possible to change your route to avoid these intersections, but drivers should be aware of the increased risks at busy lights. The best ways to limit your exposure is to keep vehicle windows shut, fans off and try to increase the distance between you and the car in front where possible. Pedestrians regularly crossing such routes should consider whether there might be other paths less dependent on traffic light crossings. Local transport agencies could also help by synchronising traffic signals to reduce waiting times and consider alternative traffic management systems such as flyovers.”

You can read the full paper here. The research has also been outlined in The Conversation.

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