PhysOrg: "You cannot have a clean outdoor environment if a large percentage of the population is burning dirty fuels in households several times a day," said Kirk Smith, a professor with the University of California, Berkeley's School of Public Health who co-led the study with Tong Zhu of Peking University and Denise Mauzerall of Princeton University. "The smoke may start indoors, but soon leaves the house and becomes a significant part of regional air pollution."
Beijing's polluted air came to international...