Abstract
In recent years, the population of Japan has experienced an increase in allergy-type ailments such as asthma and other forms of respiratory distress, particularly among members of the younger generation. There are several reasons behind this upsurge in allergy-type diseases, and it is deemed likely that indoor dampness provides some of the strongest contributory factors. In order to clarify the association between child allergic diseases and indoor dampness, a cross-sectional survey has been conducted to 4 - 12 years old children through the internet survey. Questionnaires were distributed on the web to the 6, 618 houses in all prefectures of Japan on February of 2013, and the 5,071 completed questionnaires were sent in five days. The response rate was 76.6%.
This paper firstly described the estimation method of indoor dampness using the results of occupants' self-reported answer to questions about visible vapor condensation, visible mould growth, perception of mouldy odor and so on during winter season. This dampness index proposed in this paper was calculated as the value from 0 to 24 points and its values classified into four kind of rank on the basis of the quartile. Rank 4 presented the house which had the most serious problems related to indoor dampness. The dampness index revealed the association between indoor dampness and allergic disease such as asthma and rhinitis.
Secondly, from the questionnaire the prevalence of current asthma on the basis of diagnosis of a doctor was around 8.0% among children. The prevalence of allergic rhinitis was increasing as they grew up and it was 20.5% among 10 - 12 years old boys. This tendency was seen in the prevalence of hay fever and allergic conjunctivitis. In general, boys had higher prevalence of allergic disease than girls. On the other hand, the prevalence of chemical sensitivity and SHS(Sich House Syndrome) are much less than that of allergic disease, and these symptoms were less than 1%.
Finally, the association between adverse health effect and influencing factors related to indoor dampness was discussed. Adjusted Odds Ratios(hereinafter referred to as ORs) was calculated using a multivariable logistic regression model adjusted for gender, age, location of house, a yearly income and so on. Adjusted ORs of current asthma (OR = 1.46 and 1.81, p < 0.001) was statistically significant in both rank 3 and rank 4 of the dampness index. In this analyzed results, the increased risk of asthma due to indoor dampness was estimated (p for trend <0.01). In addition, adjusted ORs allergic rhinitis in from rank 2 to 4 was statistically significant in higher rank of the dampness index. The dose-response relationships between indoor dampness and both current asthma and allergic rhinitis were presented using the dampness index proposed in this paper. Analyzed results revealed that the operation of a mechanical ventilation (p for trend < 0.05) and living near arterial roads (p < 0.05) were associated with current asthma. The living near industrial factory (p < 0.01) and river (p < 0.01) were associated with allergic rhinitis, as well. We could conclude that children who were living in dampness are at significant risk for allergic diseases such as asthma and rhinitis.
