Researchers have found a link between air pollution and crime

Air pollution is a major driver of crime in London says new research by LSE.

According to the discussion paper, published by the Institute of Labor Economics (IZA), higher levels of air pollution increases the rate of most types of crime in the capital and, in particular, less severe kinds such as shoplifting and pickpocketing.

However, air pollution was not found to have a significant impact on the most serious crimes such as murder, assault causing severe bodily harm or rape.

The researchers found that a 10 point rise of the air pollution measure, the Air Quality Index (AQI), increases the crime rate by 0.9 percent. This means that the crime rate in London is 8.4 percent higher on the most polluted day (AQI 103.6) compared to the days with the lowest level of pollution (AQI =9.3).

An AQI of over 35, which happens in 1 out of 4 days on average, leads to 2.8 percent more crimes – equivalent to a 9 percent reduction in policing.

The research has implications for other major cities such as Chicago and New York which also suffer from high level of pollution and crime.

Dr Sefi Roth, Assistant Professor of Environmental Economics and co-author of the paper, said: “Our research suggests that reducing air pollution in urban areas could be a cost-effective way to reduce crime, in addition to the health benefits it would bring.

“We did not find that London’s ongoing spate of knife crime would be affected by improved air quality. However, if the number of less serious crimes could be reduced, the police could potentially be freed up to allocate more resources to these types of very serious incidents.

“The effect of air pollution on crime occurs at levels which are well below current regulatory standards in the UK and the US which suggests that it could be beneficial to lower these existing guidelines.”

In particular, London’s wealthiest neighbourhoods – which are the most polluted – were affected. The poorest neighbourhoods, although less polluted were also affected, which suggests that those that live in them are more sensitive to poor air quality. A similar sensitivity to poor air quality on health has already been established by other research.

Researchers looked at 1.8 million crimes over two years(1) and compared them with pollution data within boroughs and wards over time, to ensure like was compared with like. Their findings took account of factors such as temperature, humidity and rainfall, days of the week and different seasons.

The researchers also used wind direction, which blows pollution in and out of areas randomly, as a ‘natural experiment’ to exclude any other factor from being the cause of the link they observed between crime and air pollution.

The researchers suggest the link they found between air pollution and crime may be linked to the increases in the stress hormone cortisol that can occur in people exposed to higher levels of pollution.