Beijing Raises Smog Alert as Pollution Envelops North China
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Beijing raised its air pollution alert to orange, the second-highest level, triggering limits on some industrial production as smog enveloped northern China for a second day.
The concentration of PM2.5, fine particulates that pose the greatest risk to human health, was 445 micrograms per cubic meter at 5 p.m. near Tiananmen Square in Beijing, the Beijing Municipal Environmental Monitoring Center said on its website. The WHO recommends 24-hour exposure to PM2.5 at concentrations no higher than 25.