Haze, health and disease

With the increasing pace of industrialization and urbanization in Asia, there has been a marked increase in the severity of urban air pollution, making many Asian cities, particularly those in China, amongst the most polluted in the world (1). Levels of fine particulate matter (PM_2.5) are frequently in the levels of hundreds of micrograms per cubic meter in cities like Beijing, where there are now so few days where the air quality can be considered as being safe for health. Severe episodes of air pollution have enveloped large parts of China, a phenomenon that has been dubbed as episodes of haze or ‘Chinese haze’. As we write this article in November 2014, the Northern part of China has just had its most recent episode of haze when levels of PM_2.5 in Beijing had climbed to the levels of 450 to 600 μg/m³, up to 25 times above the recommended World Health Organisation (WHO) safe levels.