Two patients with occupational asthma who returned to work with dust respirators

Objectives-To assess the efficacy of dust respirators in preventing asthma attacks in patients with occupational asthma (asthma induced by buckwheat f lour or wheat flour). Methods-The effect of the work environment was examined in two patients wit h occupational asthma with and without the use of a commercially available mask or a dust respirator. Pulmonary function tests were performed immediat ely before and after work and at 1 hourly intervals for 14 hours after retu rning 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 a fter leaving the work environment, showing only a positive late asthmatic r eaction (LAR). In patient 2, environmental exposure resulted in coughing an d wheezing 10 minutes after initiation during bread making, and PEFR decrea sed by 39%. After 7 hours, PEFR decreased by 34%. The environmental provoca tion tests in both patients were repeated after wearing a commercial respir ator. This resulted in a complete suppression of LAR in patient 1 and of im mediate asthmatic reaction (IAR) and LAR in patient 2. Conclusions-Two patients with asthma induced by buckwheat flour or wheat fl our in whom asthmatic attacks could be prevented with a dust respirator are reported. Dust respirators are effective in preventing asthma attacks indu ced by buckwheat flour and wheat flour.