Smog over Beijing's Forbidden CityWIKIMEDIA, BRIAN JEFFERY BEGGERLYThe brown haze that covers Beijing and surrounding areas is home to some 1,300 microbial species, according to a group of researchers in China who used genome sequencing to identify the biological makeup of a particularly thick January 2013 smog. While most of these species are believed to be harmless, some have been linked to allergies and respiratory disease in humans, the researchers reported last month (January 23) in Environmental Science & Technology.
“It’s a proof of principle that one can extract and identify these microbes at the species level,” coauthor Ting Zhu, a biologist at Tsinghua University in Beijing, told Nature. “It adds to our understanding of what we inhale every day.”
Over the course of a week during a severe smog event, Zhu and colleagues took 14 air samples, then filtered them based on size to isolate microorganisms less than 2.5 micrometers (PM2.5) and those up to 10 micrometers (PM10). On some days, the researchers measured PM2.5 levels at greater than 500 micrograms per cubic meter—20 times the World Health Organization’s air quality guidelines.
Extracting and sequencing DNA from the samples, the researchers were able to identify some 1,300 different microbial species, including the pneumonia-causing Streptococcus ...
