This article was published on the Epoch Times web site
The social media comments of people in China’s megacities can give environmental scientists information about local pollution levels.
A new study shows that the frequency of key words like dust, cough, haze, mask, and blue sky can be used as a proxy measurement of the amount of airborne particulate matter in the country’s urban centers at any given time.
Rice University researchers culled the words from millions of posts to China’s Weibo, a popular microblogging platform. Rice computer scientists collected the data for a study on Chinese censorship of social media three years ago.
Rice researchers decided upon a set of bigrams — key terms in the form of two consecutive symbols – related to air quality and searched for them in a set of 112 million Weibo posts gathered between 2011 and 2013. The terms were collected from a database of 40 million Chinese bigrams and used to correlate pollution with air-quality reports from US embassies in four megacities. The 10 bigrams above are only part of the set they used.
“The big takeaway is that people grouse about air quality, and as it gets worse, people complain more,” says study leader Dan Wallach, a professor of computer science and electrical and computer engineering, whose lab collected the publicly available posts.
“When it’s really bad, it flattens out,” he says. “They’re as complained-out as they’re going to be. And if it gets good enough, few people complain. But there’s a zone in the middle where people really grouse, and we can measure that.
“A city the size of Beijing has air-quality meters, but not many,” Wallach says. “But if you have millions of people, you potentially have millions of meters. It’s a way of adding extra data.”
The researchers came up with a metric, the Air Discussion Index (ADI), based on the frequency with which pollution-related terms appeared in 112 million posts from 2011 to 2013 by residents of Beijing, Shanghai, Guangzhou, and Chengdu, where pollution is thought to be most troublesome in China.