Air Pollution: an environmental risk factor for psychiatric illness?

It has become increasingly recognised that exposure to air pollution and poor air quality is having a detrimental impact on the health of millions in our society. The World Health Organisation estimates that outdoor air pollution is responsible for an estimated 4.2 million deaths per year as a result of respiratory and cardiovascular diseases, while the levels of air pollution in major cities appears to be rising . With better access to data on air quality and an increasing understanding of its physical health consequences and its biological mechanisms, the recent article by Khan et al is timely, describing potential associations between air pollution and mental health conditions following analysis of two datasets from the USA and Denmark. Their findings suggest that areas with higher levels of air pollution were associated with increased rates of several mental illnesses, with bipolar disorder showing a particularly strong association in the US data.