Hazy days are more likely to trigger fatal incidents among those with mental health issues such as dementia, bipolar disorder and depression, according to the first study in Hong Kong trying to establish a link.

For those with chronic diseases, it is well known that air pollution worsens their condition, but according to the study by Hong Kong Polytechnic University, which is looking at the relationship between hazy days and the mortality details of the deceased, those with mental problems were 16.4 to 26.5 per cent more likely to die on a day with severe air pollution.

Hong Kong is frequently covered in a thick blanket of smog owing to the air pollution, which contributes to reduced visibility.

Other than a psychological impact, a cold hazy day also posed physical harm to patients with heart and respiratory diseases, increasing their risk of death by up to 17 per cent, the study found.

“People usually feel very depressed and stressed on a gloomy day when compared with a bright, sunny day,” said one researcher, assistant professor Yang Lin of PolyU’s School of Nursing.

“Bad weather is likely to put more psychological stress on the population and trigger an acute situation.”

A total of 111 hazy days were recorded by the Hong Kong Observatory in the city between 2007 and 2014. It defines a hazy day as one when the visibility is reduced to below 5,000 metres by suspended particulates in an atmosphere with a relative humidity of 80 per cent or below.

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http://www.scmp.com/news/hong-kong/health-environment/article/2126371/hong-kongs-hazy-days-may-have-more-deadly-effect