Shanghai's quality watchdog seized 188 air purifiers at a chemical machinery company in Jiading District yesterday after tests showed some of them produced too much ozone.
The purifiers were produced by Shanghai Liangyuan Intelligent Technology Co.
One machine, priced at more than 2,000 yuan ($295) was found to have released 2,380 part per billion (ppb) of ozone, compared with China's national standard of no more than 50ppb of ozone .
Excessive levels of ozone could cause health problems, including respiratory irritation, skin allergies, and breathing difficulties, said Cui Hong, an official with Shanghai Quality and Technical Supervision Bureau.
