Beijing can have notoriously smoggy air, and researchers led by Tsinghua University's Ting Zhu turned to metagenomic approaches to analyze the microbes portion of particulate matter pollution there.
As they report in Environmental Science and Technology, Zhu and colleagues collected 14 samples over the course of seven days, and found that most of the microorganisms detected in the air were soil microbes and not pathogenic. However, they add that they did uncover some microbial allergens and pathogens in the air and that the relative abundance of those microorganisms increased on days with higher levels of particulate matter pollution.
Andrea Franzetti, a microbiologist at the University of Milan-Bicocca, tells Nature News that the microbes that Zhu's team found broadly matches what his group found in Milan's air, though Franzetti notes that the Zhu team found higher sequence levels. He adds that there is "increasing evidence that bacteria could play an important role in the health effects [of airborne particles]."
Still, Norman Pace, a University of Colorado Boulder microbiologist, tells Nature News that "the PM2.5 and PM10s are way more problematic than any of the microbes."