We report two cases of anosmia that were suspected to be caused by chronic chlorine exposure in cleansing works.

We examined the cases in order to assess the work-relatedness of their anosmia. We conducted olfactory threshold test and olfactory perception test repeatedly at one-month intervals. Using ion chromatography, we analyzed the detergent that the workers had been using for several years before their olfactory function decreased.

A 59-year-old male who had worked in a cleansing process for 10 years (1983–1993) and a 58-year-old female who had worked in the same process for 8 years (1987–1995) were diagnosed with anosmia. The cause of the anosmia was presumed to have been the chlorine gas that was generated from the process of heating the detergent-dissolved water, in which chloride was detected.

This is the first report on anosmia due to chronic chlorine exposure. Greater attention needs to be focused on the prevention of anosmia because there are many workers who have been exposed to chlorine gas in chlorine treating and generating processes.