Shanghai’s air pollution went off the charts on Friday as a thick gray smog shrouded its famously luminous skyline, in the latest high-profile episode highlighting China’s pervasive environmental woes. Officials called for factory closures and curbs on official car use to counter hazardous levels of particulate matter in the air, while airlines delayed or canceled some flights, according to local authorities. Commuters wore face masks and some rushed to purchase air purifiers at supermarkets. Parks were left empty. Schools remained open, although the Shanghai Environmental Protection Bureau suggested children, the aged and people with heart, lung, or other chronic diseases stay indoors. “It’s too hazardous to let him go to the kindergarten on such a smoggy day,” said Shen Lan, a 32-year-old airport manager, referring to her five-year old son. “I have kept the air purifier working at home all day and night,” she said. “But that’s not enough. […]