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FY 2008 Annual Report of Environmental Health Surveillance for Air Pollution

July 16, 2010

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.
[Overview of the FY 2008 Surveillance Result]
The FY 2008 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 2008), and a longitudinal analysis was performed using the integrated results of 3-year-old surveys from FY 1996 to FY 2008 and 6-year-old surveys from FY 2004 to FY 2008. Additionally, a follow-up analysis was performed on 6-year-old respondents who also responded to the 3-year-old survey conducted in FY 2004 and FY 2005.
The 3-year-old survey targeted approximately 90,000 3-year-old children in 38 regions throughout Japan (74,000 respondents), and the 6-year-old survey targeted approximately 93,000 6-year-old children in 39 regions throughout Japan (75,000 respondents).
Among the respiratory symptoms surveyed, the results of analyses relating to asthma were as follows.
In the 6-year-old survey, a significant correlation between air pollution (SPM) and asthma was observed for the first time last year, but not this year. On the other hand, in the 3-year-old survey, no significant correlation was observed for the past 13 years although odds ratios were greater than 1, but this year, a study of odds ratio indicated a significant correlation between air pollution (SPM) and asthma (odds ratio 1.09; 95% confidence interval [1.01 - 1.18]). In regard to air pollutants other than SPM, neither the 3-year-old survey nor 6-year-old survey showed a significant correlation between these air pollutants and asthma again this year. Meanwhile, the exposure assessment revealed a general downward trend in air pollution (SPM), and the exposure assessment and health survey combined showed no clear trend between high asthma prevalence and high air pollutant concentrations, 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.
With respect to symptoms other than asthma, the frequency of catching a cold (more than 5 times) tended to increase with higher air pollutant concentrations, but the same trend was not observed with cases of wheezing (both associated and not associated with a cold)
[Future Issues]
1. SPM
In the 3-year-old survey (FY 2008) and last year's 6-year-old survey (FY 2007), a study of factors influencing asthma prevalence indicated a significant correlation between SPM and asthma. Moreover, SPM was clearly related to an increase in asthma prevalence in some survey regions. Therefore, the correlation between SPM and asthma should continue to be observed carefully, also in consideration of the characteristics of each survey area.
2. Emerging environmental factors
1) Photochemical oxidants
In recent years, photochemical oxidant warnings are being issued mainly in western Japan, and there are growing concerns about the influence of photochemical oxidants on people's health. In other countries, standards for photochemical oxidants are being revised. Thus, future developments need careful watching.
2) PM2.5
Environmental quality standards for PM2.5 were promulgated last September, and the development of continuous surveillance systems is expected to move forward hereafter. Based on the progress of establishment of a valid air pollution monitoring system for PM2.5, studies of PM2.5 should be made as needed, also in reference to SPM.

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