FY2017 Annual Report of Environmental Health Surveillance for Air Pollution

The results of the FY2017 Environmental Health Surveillance for Air Pollution have been compiled and are presented below.

The Ministry of the Environment (MOE) has implemented the surveillance every year since Fiscal Year (FY) 1996 along with the Partial Revision of the Act on Pollution Health Damage Compensation in 1987 (delisting of the Type-1 designated areas) to regularly and continuously monitor the correlation between the health conditions of local populations and air pollution, and take measures required when necessary.

1. Overview of the Surveillance Report

As in previous years, the survey for 3-year-old children (hereinafter, "3-year-old survey") and first-year primary school children (hereinafter, "6-year-old survey") was performed. A single-year analysis was performed using the results of the FY2017 survey, and longitudinal and comprehensive analyses were performed using the integrated results of the 3-year-old surveys from FY1996 to FY2017 and the 6-year-old surveys from FY2004 to FY2017. A follow-up analysis was performed on 6-year-old respondents in the FY2017 survey who also responded to the 3-year-old survey conducted from FY2013 to FY2014.

The single-year analysis and assessment of photochemical oxidants (Ox) was performed based on the FY2017 report.

The number of the targeted 3-year-old children was approximately 83,000 in 36 areas (about 71,000 respondents) and the number of the targeted 6-year-old children was roughly 84,000 in 37 areas (around 71,000 respondents) in Japan respectively.

The survey results related to asthma among respiratory symptoms were as follows:

Both in the 3-year-old and 6-year-old surveys, the single-year analysis showed no tendency of increase of prevalence of asthma associated with increase of air pollutant concentrations in each area, in the study of prevalence of respiratory symptoms according to background concentration levels and of average background concentrations and prevalence of respiratory symptoms in each survey area. No significant positive correlation was found between air pollution and asthma prevalence on examination of odds ratios.

In the longitudinal analysis of air pollutant concentrations and prevalence of respiratory symptoms, no area shows the increase of asthma prevalence.

The comprehensive analysis showed no tendency of the increase of prevalence of asthma associated with the increase of air pollutant concentrations, in the study of prevalence of respiratory symptoms according to background concentration levels and of average background concentrations and prevalence of respiratory symptoms in each survey area. On examination of odds ratios, no significant positive correlation was observed between air pollution and asthma prevalence both in the 3-year-old or 6-year-old survey.

The same analyses were performed regarding the incidence of asthma by a follow-up analysis and its longitudinal analysis (excluding comprehensive analysis), and no significant positive correlation was noted.

Apart from air pollutants, the prevalence of asthma was significantly positively correlated with a history of allergies for children and their parents in the 3-year-old and 6-year-old surveys, with an odds ratio of approximately 2. Examination of odds ratios using integrated data also yielded similar results.

With regard to prevalence of respiratory symptoms other than asthma, on examination of odds ratios, no significant positive correlation was found both in the 3-year-old and 6-year-old surveys.

2. Future Issues

In the previous survey reports, some results occasionally suggested a significant positive correlation of air pollution (SPM) with asthma or history of asthma within the past two years, in the single-year analyses of 3-year-olds (in total 22 times between FY1996 and FY2017) and 6-year-olds (in total 14 times between FY2004 and FY2017)[*], but such a positive correlation has not been consistently observed. The results of comprehensive analysis showed no correlation of the increase of prevalence of asthma associated with increase of air pollutant concentrations, in the study of prevalence of respiratory symptoms according to background concentration levels and of average background concentrations and prevalence of respiratory symptoms in each survey area. On examination of odds ratios, no significant positive correlation was observed between air pollution and asthma prevalence both in the 3-year-old and 6-year-old survey. In the follow-up analysis (in total 14 surveys conducted from FY2004 to FY2017), a significant positive correlation between air pollution (NO₂, NO_x) and asthma incidence was obtained once in the past[†]^**, but such correlation has not been consistently observed.

According to exposure assessment, though it generally shows downward trend in air pollution, the correlation between air pollution and asthma will continue to be carefully monitored referring to regional characteristics.

In respect of longitudinal and comprehensive analyses, analytical methods are investigated in consideration of long-term trends in air pollution: for example, longitudinal comparison using 5-year integrated data. The methods will continue to be studied.

Concerning the follow-up analysis, due to accumulation of data for more than 10 years, longitudinal analysis with the incidence and persistence of asthma has been added since FY2016. Methods for the evaluation and handling of data in follow-up and comprehensive analyses will be further examined.

On the subject of particulate matter (PM_2.5), the exposure index and estimation method are concluded based on the report of "Environmental Health Surveillance for Air Pollution in Consideration of Future Study Methods of Localized Air Pollution (Interim Report No.5) --- Evaluation to Add PM_2.5 ---" set by a working group under the "Council of Health Effects for Environmental Health Surveillance and Localized Air Pollution." Based on this report, analysis and assessment of PM_2.5 will be initiated as part of the exposure assessment.

Another report on the Epidemiologic Studies on Health Effects of Localized Air Pollution in Japan ("SORA Project") pointed out that it is necessary to note the scientific findings and results accumulated by SORA Project should be fully utilized to have the survey more effective. In response, the working group continues to research investigational methods in consideration of localized air pollution.

* Asthma: (3-year-old survey) FY 2008, 2013; (6-year-old survey) FY2007, 2009

Asthma (within the past two years): (6-year-old survey) FY2007, 2009, 2013

**FY2013

Attached materials

FY2017 Annual Report of Environmental Health Surveillance for Air Pollution (Overview) [PDF ***KB]
<Reference> FY2017 Survey areas [PDF ***KB]

For Japanese

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