Facebook co-founder Mark Zuckerberg went on a morning jog through China’s smoggy capital, creating controversy for a slew of reasons. Beijing has made headlines for a weeklong string of “hazardous” air conditions. Zuckerberg, forced to work around Chinese government Internet filters, posted to Facebook a photo of his jog, writing: “It’s great to be back in Beijing! I kicked off my visit with a run through Tiananmen Square, past the Forbidden City and over to the Temple of Heaven.” An hour before that post, a monitor at the U.S. embassy in Beijing recorded the air-quality level “of PM2.5, ultrafine particles that damage respiration, at 305 micrograms per cubic meter,” according to The New York Times. That measurement is considered “hazardous” by U.S. standards. Comments on his Facebook post ranged from disapproval for his choice of the photo’s location to genuine concern about his health to questions about why he wasn’t wearing a face mask. “He climbed over the Great Fire Wall to breathe in smog. He’s trying too hard!” wrote one user on Weibo.