A comparative study on the health effects of smoking and indoor air pollution in summer and winter.

This study was performed by a comparison between summer and winter for the purpose of demonstration the actual conditions of health effects of indoor air pollution with special reference to NO2 and smoking, on the subjects composed of 820 school children and their 546 mothers in the two areas with different ambient NO2 concentrations. In either case, examination was carried out with standardized questionnaire test for respiratory symptoms, personal NO2 exposure measurement using the filter badge by Yanagisawa, and analysis of urinary hydroxyproline and creatinine in two areas with different ambient NO2 levels. Personal NO2 exposure level in winter season was 2-3 times higher than that in summer, particularly NO2 level among residents living in homes with non-vented stove for space heating was substantially higher from those of residents with vented stove. Wives with vented stove had a moderate exposure level in winter season by the contribution of NO2 originated from the kitchen and poor ventilation rate. Since the hydroxyproline to creatinine ratio (HOP-ratio) of children increased more, their household location were nearer to any heavy traffic roads in summer, health effects from automobile exhaust were suggested only in summer season. In summer season, personal NO2 exposure level were almost the same with the ambient NO2 concentrations over both areas. These results suggest that indoor air pollution in winter season may be separated from outdoor air pollution. It was a matter of course that hydroxyproline to creatinine ratio in winter season was higher than that in summer, in any group and in any area, but the range of variation of hydroxyproline to creatinine ratio was smaller by far than that of personal NO2 exposure level. Judging from urinary hydroxyproline to creatinine ratio, health effects of active smoking and passive smoking increased with increasing the number of smoked, dose-dependently in any season. According to stepwise multiple regression analysis, hydroxyproline to creatinine ratio had significant relation to either NO2 and active or passive smoking, but personal NO2 exposure level had no relation to cigarette smoking. NO2 and cigarette smoke were seemed to make hydroxyproline to creatinine ratio increase, independently each other.