BEIJING (CHINA DAILY/ASIA NEWS NETWORK) - More schools are putting up fabric domes over their campuses to provide clean air for students, an increasingly popular trend in northern China, which is frequently engulfed by smog.
Beijing issued a red alert - the highest response level against severe air pollution - twice in December, forcing authorities to suspend classes at kindergartens as well as primary and middle schools.
Hou Wei, a teacher at Beijing Haidian Foreign Language Shiyan School said the air quality under the dome would stay within healthy levels even as pollution readings soar to hazardous levels outdoors.
"Many students and parents have voiced their warm support for our dome," she said, adding that the school plans to install more air purifying equipment on its compound in 2016.
The columnless white plastic dome, made of a high-tech PVC fabric, is propped up by air ejected by filtering devices from under the dome. The air pressure inside the dome is higher than outside, which also prevents dirty air from sneaking in.
Xiao Long, head of Broad-well, a company based in the southern city of Shenzhen that makes air domes for schools, said facilities are installed under the dome to purify air and provide heat.
In the event of a power outage, the dome will collapse slowly and safely, and reinflate when power returns, according to company literature. The hemispheric structure is also said to be resilient against snow, rain and strong winds.
The dome is expected to last for at least 20 years with little risk of collapse, Xiao said.
Currently, such domes can be found in a number of private schools and gyms in Beijing, as well as other cities in northern China.
Feng Yinchang, an environmental professor at Nankai University in Tianjin, said field testings have proven that such air-purifying domes are effective, but they are likely to be out of reach of public schools in the smog-prone northern China.
The first air dome in Beijing was built in the International School of Beijing in Shunyi district. Two gyms with air domes cost the school a cool sum of US$5 million (S$7 million), Xiao said.
Qu Xin, manager of a Beijing-based company that installs air domes, including the one at the Haidian school, said it costs around 10 million yuan (S$2.18 million) to set up a dome which comes with supplementary facilities, though locally made domes are cheaper.
China is often hit by heavy smog, mostly a result of coal burning.
Parts of Beijing on Tuesday (Dec 29) suffered air pollution more than 20 times recommended levels, but authorities refrained from issuing the highest smog alert, the AFP reported.
Counts of PM2.5 - harmful microscopic particles that penetrate deep into the lungs - reached 529, according to the US embassy, which issues independent readings.
The World Health Organisation's recommended maximum exposure is 25 over a 24-hour period.