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Two patients with occupational asthma who returned to work with dust respirators
  1. Yasushi Obase,
  2. Terufumi Shimoda,
  3. Kazuko Mitsuta,
  4. Hiroto Matsuse,
  5. Shigeru Kohno
  1. The Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki, Japan
  1. Dr Yasushi Obase, The Second Department of Internal Medicine, Nagasaki University School of Medicine, 1–7–1 Sakamoto-machi, Nagasaki 852–8501, Japan email obadann-ngs{at}


OBJECTIVES To assess the efficacy of dust respirators in preventing asthma attacks in patients with occupational asthma (asthma induced by buckwheat flour or wheat flour).

METHODS The effect of the work environment was examined in two patients with occupational asthma with and without the use of a commercially available mask or a dust respirator. Pulmonary function tests were performed immediately before and after work and at 1 hourly intervals for 14 hours after returning to the hospital.

RESULTS In patient 1, environmental exposure resulted in no symptoms during and immediately after work, but coughing, wheezing, and dyspnoea developed after 6 hours. Peak expiratory flow rate (PEFR) decreased by 44% 7 hours after leaving the work environment, showing only a positive late asthmatic reaction (LAR). In patient 2, environmental exposure resulted in coughing and wheezing 10 minutes after initiation during bread making, and PEFR decreased by 39%. After 7 hours, PEFR decreased by 34%. The environmental provocation tests in both patients were repeated after wearing a commercial respirator. This resulted in a complete suppression of LAR in patient 1 and of immediate asthmatic reaction (IAR) and LAR in patient 2.

CONCLUSIONS Two patients with asthma induced by buckwheat flour or wheat flour in whom asthmatic attacks could be prevented with a dust respirator are reported. Dust respirators are effective in preventing asthma attacks induced by buckwheat flour and wheat flour.

  • asthma: buckwheat flour: wheat flour
  • environmental provocation test

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