Toxic air pollution in China impeding photosynthesis and could seriously affect country’s food supply, experts warn
27 Feb 2014
BEIJING — Scientists in China have warned that the country’s toxic air pollution is now so bad that it resembles a nuclear winter, slowing photosynthesis in plants — and potentially wreaking havoc on the country’s food supply.
Beijing and broad swathes of six northern provinces have spent the past week blanketed in a dense smog that is not expected to abate until today. Beijing’s concentration of PM2.5 particles — those small enough to penetrate deep into the lungs and enter the bloodstream — hit 541 micrograms per cubic metre yesterday afternoon, or “beyond index”, according to a United States Embassy pollution monitor, before falling to 165 in the “unhealthy” range last night.
The World Health Organization recommends a safe level of 25; the last time PM2.5 dropped below 150 in Beijing was on Feb 19.
Ms He Dongxian, an associate professor at China Agricultural University’s College of Water Resources and Civil Engineering, said new research suggested that if the smog persists, Chinese agriculture will face conditions “somewhat similar to a nuclear winter”. She has demonstrated that air pollutants adhere to greenhouse surfaces, cutting the amount of light inside by about 50 per cent and severely impeding photosynthesis, the process by which plants convert light into life-sustaining chemical energy.
She tested the hypothesis by growing one group of chilli and tomato seeds under artificial lab light, and another under a suburban Beijing greenhouse. In the lab, the seeds sprouted in 20 days; in the greenhouse, they took more than two months. “They will be lucky to live at all,” Ms He told the South China Morning Post newspaper.
She warned that if the pollution does not ease, China’s agricultural production could be seriously affected. “Now almost every farm is caught in a smog panic,” she said.
The Chinese government has repeatedly promised to address the problem, but enforcement remains patchy. In October, Beijing introduced a system of emergency measures if pollution levels remained hazardous for three consecutive days, including closing schools, shutting some factories, and restricting the use of government cars. According to China’s state newswire Xinhua, 147 industrial companies in Beijing have cut or suspended production. Yet schools stayed open and government cars remained on the road.
The heavy smog in the capital may draw new scrutiny to government pledges to ease pollution around the country as leaders gather for the annual meeting of China’s legislature, the National People’s Congress, which begins next Wednesday. At the end of last year’s event, Premier Li Keqiang promised to clean up pollution and said smog gave him a “heavy heart”.
One person not put off by the smog was President Xi Jinping, who made an unannounced visit on Tuesday to a trendy area popular with tourists. The visit prompted approving coverage in Chinese news reports, but also mockery on social media sites. “Xi Jinping visits Beijing’s Nanluoguxiang amid the smog: Breathing together, sharing the fate,” said a Xinhua headline.
Mr Li Guixin, a resident of Shijiazhuang, capital of Hebei province near Beijing, has sued the local environmental protection bureau for failing to rein in the smog, saying it owed him the 10,000 yuan (S$2,065) he spent on an air purifier, masks and a treadmill to exercise indoors. He is the first person to sue the government over pollution.
Ms Li Yan, a climate and energy expert at Greenpeace East Asia, said the case could bring exposure to polluted cities outside of Beijing. She said: “People ... in Beijing are suffering from polluted air, but we have the attention of domestic and international media. Shi-jiazhuang’s environmental problems are far more serious and this case could bring Shijiazhuang the attention it has deserved for a long time.” AGENCIES [
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