Air pollution’s deadly effects on health are well known, but scientists now fear it could turn some people into violent offenders.
When the air is dirtier, more violent crime is committed, researchers found after conducting a huge study into 13 years of data on 86 million people in the United States.
Airborne particles and noxious gases could interfere with the proper functioning of the brain, making people more likely to act aggressively, the researchers believe.
When the air is dirtier, more violent crime is committed, researchers found after conducting a study on 86 million people in the United States (stock image)
The study, just published in the online version of the journal Epidemiology, is likely to lead to further calls for British cities to clean up their act, by showing that air pollution can affect behaviour, not just physical health.
Two million people in London alone are still living in areas with illegal levels of air pollution, according to a recent report from the London Atmospheric Emissions Inventory.
That crowded and polluted cities experience more violent crime is not surprising.
But researchers did not simply look at whether more violent crime was committed in polluted places. Instead, they looked at how recorded offences rose and fell over time in 301 diverse counties across the US – urban, suburban and rural – and whether there was any link to air pollution readings.
Put simply, they asked if crime went up when air pollution rose. For non-violent crimes such as theft, the answer was ‘no’. But for violent crime a correlation did emerge.
Airborne particles and noxious gases could interfere with brain functions, making people more likely to act aggressively (stock image)
The research team, from the University of Minnesota School of Public Health and Colorado State University, wrote: ‘Our study identifies an association between air pollution and county-level violent crime… We find that violent crime increases by 1.17 per cent for each 10-microgram-per-cubic-metre increase in daily [fine] particulate matter, and 0.59 per cent for each 10-parts-per-billion increase in daily ozone, with most of the effect driven by increases in assaults.’
Violent crime went up when the air was more polluted both in poor and rich areas. Previous studies in mice and dogs have found those animals exposed to high levels of fine particulate matter – found in diesel fumes – exhibit ‘increased aggressiveness, territoriality, and bias towards immediate rewards,’ they noted.
‘Likewise, air pollution exposure may increase anxiety, which can lead to criminal and unethical behaviour,’ they went on.
‘An impulsive and aggressive response may explain why air pollution is associated with increased violent, but not non-violent crime.
‘We cautiously interpret this result as evidence for acute neurological and behavioural health effects of air pollution and need to further investigate the effect pathway.’
They also pointed out that previous research has ‘indicated that metallic constituents of particulate matter, notably manganese and mercury, may contribute to more aggressive and violent behaviour’.