Research links air pollution to traffic accidents

A study by the London School of Economics, published this week (3 October), has linked high air pollution to an increase in traffic accidents. 

A rise in air pollution was found to increase the average number of accidents by 2%, with the biggest effect occurring in cities

Small increases in the level of nitrogen dioxide in the air are correlated with a rise in the number of traffic accidents in the United Kingdom, according to the study by the Grantham Research Institute on Climate Change and the Environment at LSE.

The research has been compiled by analysing a combination of atmospheric climate data, air pollution data from the UK Automatic Urban and Rural Network (AURN), road accident statistics from the Department for Transport (DfT) and additional weather data. The information was used to map incidences of high air pollution alongside the occurrence of road traffic accidents.

Analysis by researcher Lutz Sager, which is based on data for the period between 2009 and 2014, claims that a rise in the average concentration of nitrogen dioxide of just one microgramme per cubic metre is enough to increase the average number of accidents each day by 2%, with the biggest effect occurring in cities.

Mr Sager said: “Although it has already been shown that air pollution adversely affects human health and the ability to carry out mental tasks, this is the first published study that assesses the impact on road safety.”

Effects

While the analysis suggests a ‘causal’ effect of air pollution on road accidents, Mr Sager said he could only speculate about how air pollution might affect drivers.

Mr Sager said: “My main theory is that air pollution impairs drivers’ fitness. However, other explanations are possible such as air pollution causing physical distractions, perhaps an itching nose, or limiting visibility.”

He added: “Whatever the exact mechanisms responsible, the robust finding of a significant effect of air quality on road safety is important given the high cost of road traffic accidents through damage to vehicles and deaths and injuries to people every day.

“Although this analysis has used data for the United Kingdom, I think my findings are relevant to other parts of the world. These additional costs from traffic accidents strengthen the case for reducing air pollution, particularly in congested cities.”

The study has been published as a working paper and will be submitted to a journal for publication.

According to the calculations, in areas like west London, which suffers from some of the highest levels of air pollution, a cut of about 30% in the concentration of nitrogen dioxide could reduce the number of road accidents every day by almost 5%.

Mr Sager said: “My analysis suggests that the causal effect of air pollution on road traffic accidents measured in this study more likely stems from nitrogen dioxide or other pollutant gases rather than particulate matter.