Report of twenty-eight cases of mass hysteria 2 episodes from freezing room in frozen foods industry, Rayong province, Thailand

Abstract

On February 3^rd and 13^th, 2016, there were suspected patients exposed to chemical and got abnormal symptoms in total of 28 cases, 27 females and 1 male. The average age was 28 years old. While they were working in cold room about 30 - 90 minutes, they started to feel chest tightness 64%, difficult breathing 50%, headache/dizziness 25%, rapid breathing/hand contracture 18%. From physical examination, one case of lung wheezing was found, laboratory result was normal, investigation of working environment found plastic bag clogged in carbon dioxide ventilation system, which might cause dysfunction but the carbon dioxide concentration was not exceed the time-weighted average. The diagnosis was mass hysteria, after treatment, their vital status were improved and were discharged 13 cases at that day, the others were in-patients. Only one case of using bronchodilator was observed for 24 hours. One day after event, all patients were discharged including the one who was observed.

Key words: Mass psychogenic illness, Freezing room, Chemical exposure, Threshold limit values, Ventilation system