（单词翻译:单击）
Spikes1 in air pollution around the country have caused parallel spikes in sales of air filters and face masks. On Taobao and Tmall, China's online shopping websites, nationwide sales of face masks over the last seven days are 9 times higher than they were during the same week last year.
Similarly, sales of air purifiers also jumped on Taobao. Almost three times as many were sold this week as were sold during the same period last year.
This month, smog has enveloped2 more than 100 large and medium-sized cities in 25 provinces. PM2.5 levels were more than 24 times higher than the World Health Organisation’s guidelines in some areas of the Yangtze River Delta3.
