Rose Kang describes that whenever a ceiling fan starts to spin, she vomits. After a few hours around any fan, she says, her cheeks start to swell and her head begins to pound. Yet, her experience is relatively minor. In South Korea, newspapers and a government agency report that the air blowing from an electric fan can cause death. “If you fall asleep with it going, you’ll die the next day,” says Kang, who moved from Seoul last year and now works at a hair salon in Toronto’s Koreatown. The daily newspaper in Ulsan, one of Korea’s largest cities, wrote...