Air pollution can directly affect behaviour and dramatically increase crime levels, a series of studies conducted over several years have proven.
Haq, an associate professor at the University of York, says a decision to remove lead in petrol in the US in the 1970s has been linked with a 56% drop in violent crime in the 1990s.
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Two other reports directly link air pollution with antisocial behaviour. Short-term exposure to air pollution, especially sulphur dioxide, has been associated with a high risk of hospital admissions for mental disorders in Shanghai, while in Los Angeles, higher levels of particulate matter pollution were found to increase teenage delinquent behaviour in urban neighbourhoods.
It is now believed that exposure to air pollution can cause inflammation in the brain and increase anxiety levels, both of which lead to a rise in criminal or unethical behaviour and a spike in crime.
By comparing 1.8 million crimes recorded in London over two years with pollution data, researchers at the London School of Economics found that a 10-point rise in the air quality index increased the crime rate in the capital by 0.9%.
While the study relies on observational data and therefore cannot make definitive conclusions, The Independent says “it adds to a small but growing body of evidence linking pollution and crime”.
“There’s still a lot we don’t know about how individual air pollutants can affect health and behaviour, and how this differs with gender, age, class, income and geographic location,” admits Huq. With the World Health Organisation estimating nine out of ten people worldwide are now regularly exposed to toxic air, the link between air pollution and crime could have wide-ranging and potentially devastating effects for society in the years to come.