The impact of air pollution on human health is well-documented. We know that exposure to high levels of air pollutants raises the risk of respiratory infections, heart disease, stroke, lung cancer as well as dementia and Alzheimer’s disease. But there is growing evidence to suggest that air pollution does not just affect our health – it affects our behaviour too.
Lead was removed from petrol in the USA in the 1970s in response to concerns that vehicle emissions could be contributing to behavioural problems, learning difficulties and lowered IQ among children. In particular, childhood exposure to lead increases traits such as impulsiveness, aggression and low IQ – which can influence criminal behaviour. Taking lead out of petrol has since been linked with a 56% drop in violent crime in the 1990s.
Short-term exposure to air pollution, especially sulphur dioxide, has been associated with a high risk of hospital admissions for mental disorders in Shanghai. And in Los Angeles, a study concluded that higher levels of particulate matter pollution increases teenage delinquent behaviour in urban neighbourhoods – though of course these effects are compounded by poor relationships between parents and children, as well as social and mental distress on the part of the parents.
It now believed that exposure to air pollutants can cause inflammation in the brain. What’s more, fine particulate matter is harmful to developing brains, because it can damage brain and neural networks and influence behaviour.