[TWO CASES OF ASTHMA INDUCED BY SMOKE FROM BURNING RICE STRAWS AND RICE HUSKS]

Two patients-a 40-years-old man and a 48-years-old woman- presented with dyspnea, a severe cough, and wheeze due to the inhalation of smoke from burning rice straws and rice husks. Systemic corticosteroids are often administered to relieve these symptoms. Since rice straws and rice husks are burned in some rice-producing districts of Japan during early autumn, both patients had previously been hospitalized twice due to the worsening of their symptoms in September-November. These symptoms are also caused by the inhalation of smoke from burning incense sticks, fragrances from lilies, and fragrances from air fresheners. These environmental substances include volatile organic compounds (VOCs), such as formaldehyde, acetaldehyde, benzene and benzyl alcohol. Multiple chemical sensitivity (MCS) may be associated with these symptoms. However, forced expiratory volume in one second (FEV₁) fluctuated by more than 0.6l in both cases during the treatment period, indicating variability in airflow obstruction. The 40-years-old man causes wheezing. Although wheezing was not clear in the 48-years-old woman, the methacholine provocation test indicated airway hyperresponsiveness development. Based on these results, both patients were diagnosed with asthma due to VOCs. The peripheral eosinophil counts and fractional exhaled nitric oxide levels were not elevated, indicating no association with eosinophilic airway inflammation. Symbicort maintenance and reliever therapy was effective in reducing the systemic steroid dose in both cases.