August 4, 2005
The Ministry of the Environment (MOE) has been implementing environmental health surveillance for air pollution every year since 1996. This surveillance is settled in response to the amendment of the Pollution-related Health Damage Compensation Law (revised to the Law Concerning Special Measures for the Relief of Pollution-related Health Damage) in 1988. It aims to watch health condition of local population and air pollution regularly and continuously, and to take measures in case of necessary. In FY 2003, the surveillance targeted at 94,000 3-year old children in 38 areas throughout Japan. Cross-sectional (FY 2003) and longitudinal (from FY 1996 through FY 2003) analyses were conducted.
The result of FY 2003, did not indicate the relation between concentration of the air pollutants and prevalence of asthma of children. This was same as those of the past surveys. In addition, changes in asthma prevalence due to changes in air pollutant concentration were not observed.
Health survey and exposure assessment were conducted.
- Health survey |
| ATS-DLD simplified questionnaires (MOE version) were sent to all households with 3-year old children in the survey areas. They were filled out by childrens' parents and recovered by staff of 38 local municipalities. |
| Using annual average concentration of NO2, NOx, SO2 and SPM at ambient air pollution monitoring stations in and surrounding the study areas, concentration of these pollutants at residential points of all study subjects was estimated. |
| (1) |
Number of children surveyed and recovery rate |
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94,241 children were surveyed and 79,730 questionnaires were recovered (recovery rate 84.6%). |
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Prevalence of asthma aggregated in each level of concentration of air pollutant for all subjects did not show clear tendency. (Fig. 1) |
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Average concentration of all subjects and prevalence of asthma in each area
Correlation between average concentration of all subjects and prevalence of asthma in each area was analyzed. No positive relationship between air pollutant concentration and prevalence of asthma was observed. (Fig. 2) |
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Study of factors influencing asthma symptom
The study indicated that following factors, sex, smoking habit of mother at home, housing structure, pets at home, daytime caretaker, feeding before 3 months old, allergic history of the subject and parents, contribute to the prevalence of asthma. As a whole, the result indicated that higher concentration of air pollutant does not necessarily result in higher prevalence. (Table 1) |
| (3) |
Longitudinal analysis |
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Utilizing the data collected in the past 8 years (FY 1996 - FY 2003), MOE performed analysis of transitional changes and comprehensive analysis by utilizing database compiled by aggregating yearly data. The results indicated, same as the result of FY 2003 data, no correlation between concentration changes in air pollutant and changes in asthma prevalence was observed. |
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