Action call on smog, mental health link

"On seriously smoggy days, we suggest that patients, particularly those with depression, stay indoors and turn on the lights, even in the daytime," Pu said on Thursday.

Xiao Lei, a university student in Beijing, who has had depression for two years, told China Daily that smoggy weather affects her mood.

"On days of continuous smog, I feel despair. It's as if my life is shrouded in the cloying haze," said the 24-year-old, who was admitted to a hospital after attempting suicide.

Pu said some patients with depression are more sensitive to smoggy weather that can affect their mood.

Xiao added that sunshine can bring her considerable comfort. "I am thinking about leaving Beijing for somewhere with a better environment, particularly the air quality," she said.

Tian said that despite a lack of scientific data in China directly linking mental problems with smog, similar studies on weather and emotional and mental health are not rare internationally. He urged that more attention be focused on the issue.

He cited seasonal affective disorder, also widely known as winter depression and commonplace in northern Europe, as an example.

In November 2012, the town of Umea in northern Sweden began installing phototherapy lights at bus stops to help combat the shorter days and lack of sunlight.

A study published in the medical journal Neuropsychiatry and Clinical Neurosciences in 2005 estimated that winter depression in Sweden affected 8 percent of the population.

Wang Jian, a leading psychiatrist at Beijing Huilongguan Hospital, a mental institute in the capital, defines the mental impact of weather phenomena, including smog, as "ecological pressure".