FY 2007 Annual Report of Environmental Health Surveillance for Air Pollution

The MOE has been implementing environmental health surveillance for air pollution every year since 1996 in response to the amendment of the Pollution-related Health Damage Compensation Law (amendment to the Law Concerning Special Measures for the Relief of Pollution-related Health Damage) of 1988. It aims to regularly and continuously observe the correlation between the health conditions of local populations and air pollution, and to take measures as necessary.
The FY 2007 surveillance targeted 3-year-old children (hereinafter, "3-year-old survey") and first-year primary school children (hereinafter, "6-year-old survey") as in the previous year. A cross-sectional analysis was performed using the results of these surveys (FY 2007), and a longitudinal analysis was performed using the results of 3-year-old surveys from FY 1996 to FY 2007. Additionally, a follow-up analysis was performed on 6-year-old children who also responded to the 3-year-old survey conducted in FY 2003 and FY 2004.
The 3-year-old survey targeted approximately 92,000 3-year-old children in 38 regions throughout Japan (75,000 respondents), and the 6-year-old survey targeted approximately 89,000 6-year-old children also in 38 regions throughout Japan (73,000 respondents).
As a result of the above analyses, no significant correlation was observed between air pollution and asthma in the 3-year-old survey, but a study of factors influencing asthma symptoms in the 6-year-old survey indicated a significant correlation between air pollution (SPM) and asthma (odds ratio 1.10; 95% confidence interval 1.03 - 1.17). Meanwhile, no significant correlation was observed in the past 3 6-year-old surveys although the odds ratio was greater than 1, and in the 3-year-old survey, the odds were less than 1, or no significant correlation was observed although the odds ratio was greater than 1. Furthermore, there was no indication that asthma prevalence increases along with increasing concentrations of air pollutants, neither in the analysis of respiratory symptom prevalence at each background concentration level for each subject group, nor in the correlation between average background concentration and respiratory symptom prevalence in each survey area for each subject group.
As shown above, the 3-year-old survey and 6-year-old survey as a whole indicated that higher concentrations of air pollutants do not necessarily result in wheezing or higher rates of asthma prevalence and incidence. Nevertheless, the correlation of SPM and asthma, particularly in the 6-year-old survey, should continue to be observed carefully.

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