A cohort study was conducted on 27 patients suffering from chronic obstructive pulmonary disease (COPD) and visiting outpatient medical facilities within Osaka Prefecture, to elucidate meteorological factors related to their complaints of dyspnea and disease exacerbation.

Measurements in patientsʼ bedrooms made daily between 00:00-06:00 from July 1 to August 31, 2012 showed that the percentage of patients exposed to a wet-bulb globe temperature (WBGT) of ≧ 28°C increased between mid- and late July, reaching a one-day peak of 21%. In addition, 62.5% of patients experienced a WBGT of ≧28 °C at least once during the monitored hours in the same period. The results of applying a logistic regression model to data from June 1 to September 30, 2012 showed that the minimum WBGT in a patientʼs bedroom, even when controlled for daily minimum temperature, has statistically significant association with complaints of dyspnea and bad physical condition. This finding demonstrated that regulating a patientʼs bedroom environment is very important in the summer season.