Chinese President Xi Jinping has arrived in Paris for climate talks just as Beijing -- and much of northern China -- are enveloped by a cloud of choking smog.

Air pollution in some parts of the Chinese capital on Monday reached the maximum on the government’s official index, which tops out at 500. At 4 p.m., seventeen of 33 official monitoring stations in Beijing showed readings of 500, or what the government calls “severely polluted.”

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