FY2021 Annual Report of Environmental Health Surveillance for Air Pollution
The results of the FY2021 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.
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 FY2021 survey, and longitudinal and comprehensive analyses were performed using the integrated results of the 3-year-old surveys from FY1997 to FY2021 and the 6-year-old surveys from FY2004 to FY2021. A follow-up analysis was performed on 6-year-old respondents in the FY2021 survey who also responded to the 3-year-old survey conducted from FY2017 to FY2018.
The number of the targeted 3-year-old children was approximately 77,000 in 35 areas (about 65,000 respondents) and the number of the targeted 6-year-old children was roughly 78,000 in 36 areas (around 68,000 respondents) in Japan respectively.
The survey results related to asthma among respiratory symptoms were as follows:
In the single-year analysis, prevalence of respiratory symptoms according to background concentration levels and average background concentrations and prevalence of respiratory symptoms in each survey area were examined. Both the 3-year-old and 6-year-old surveys showed no tendency of increase of prevalence of respiratory symptoms associated with an increase of air pollutant concentrations. On examination of odds ratios, a statistically significant (p<0.05) correlation was observed between SO2 and asthma in the 3-year-old survey, with anodds ratio exceeding (odds ratio = 1.11, 95% confidence interval =1.04-1.19). Meanwhile, in the 6-year-old survey, no statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between air pollution and asthma prevalence.
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 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 statistically significant (p<0.05) correlation with an odds ratio over 1 was observed both in the 3-year-old and 6-year-old surveys.
Apart from air pollutants, the prevalence of asthma was statistically significantly correlated (p<0.05) 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 2-3. Examination of odds ratios using integrated data also yielded similar results.
With regard to the prevalence of respiratory symptoms other than asthma, on examination of odds ratios, a statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between SO2, Ox8, and PM2.5 and “the number of times of catching a cold (5 or more times),” between OxY and "wheezing," and between SO2, SPM and “wheezing (with no cold symptoms) + asthma” in the 3-year-old survey. Also, a statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between OxY and "wheezing," "wheezing (with no cold symptoms)," and "wheezing (with no cold symptoms) + asthma" in the 6-year-old survey.
The number of the targeted 3-year-old children was approximately 77,000 in 35 areas (about 65,000 respondents) and the number of the targeted 6-year-old children was roughly 78,000 in 36 areas (around 68,000 respondents) in Japan respectively.
The survey results related to asthma among respiratory symptoms were as follows:
In the single-year analysis, prevalence of respiratory symptoms according to background concentration levels and average background concentrations and prevalence of respiratory symptoms in each survey area were examined. Both the 3-year-old and 6-year-old surveys showed no tendency of increase of prevalence of respiratory symptoms associated with an increase of air pollutant concentrations. On examination of odds ratios, a statistically significant (p<0.05) correlation was observed between SO2 and asthma in the 3-year-old survey, with anodds ratio exceeding (odds ratio = 1.11, 95% confidence interval =1.04-1.19). Meanwhile, in the 6-year-old survey, no statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between air pollution and asthma prevalence.
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 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 statistically significant (p<0.05) correlation with an odds ratio over 1 was observed both in the 3-year-old and 6-year-old surveys.
Apart from air pollutants, the prevalence of asthma was statistically significantly correlated (p<0.05) 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 2-3. Examination of odds ratios using integrated data also yielded similar results.
With regard to the prevalence of respiratory symptoms other than asthma, on examination of odds ratios, a statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between SO2, Ox8, and PM2.5 and “the number of times of catching a cold (5 or more times),” between OxY and "wheezing," and between SO2, SPM and “wheezing (with no cold symptoms) + asthma” in the 3-year-old survey. Also, a statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between OxY and "wheezing," "wheezing (with no cold symptoms)," and "wheezing (with no cold symptoms) + asthma" in the 6-year-old survey.
2. Future Issues
In the previous survey reports, some results occasionally suggested a statistically significant (p<0.05) correlation with an odds ratio over 1 of air pollution (SPM) with asthma or a history of asthma within the past two years, in the single-year analyses of 3-year-olds (in total 25 times between FY1996 and FY2020) and 6-year-olds (in total 17 times between FY2004 and FY2020)1, but such a statistically significant (p<0.05) correlation with an odds ratio over 1 has not been consistently observed. In this fiscal year, a statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between SO2 and asthma in the 3-year-old survey, while no statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between air pollution and asthma prevalence in the 6-year-old survey. The SO2 concentration has been reduced to an extremely low level in recent years and its correlation with health damage is becoming less apparent, but we will continue to carefully monitor it as a research subject. 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 statistically significant (p<0.05) correlation with an odds ratio over 1 was observed both in the 3-year-old and 6-year-old surveys. In the follow-up analysis (in total of 18 surveys conducted from FY2004 to FY2021), a statistically significant (p<0.05) correlation with an odds ratio over 1 was observed between air pollution (NO2, NOx) and asthma incidence once in the past2, but such correlation has not been consistently observed.
According to exposure assessment, it generally shows downward trend in air pollutant concentrations3 for NO2, NOx, and SPM. The SO2 concentration has remained low. Going forward, the correlation between air pollution, including Ox and PM2.5, and respiratory symptoms such as asthma will be carefully monitored referring to regional characteristics and the study will be conducted in a working group under the Council of Health Effects for Environmental Health Surveillance and Localized Air Pollution.
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.
According to exposure assessment, it generally shows downward trend in air pollutant concentrations3 for NO2, NOx, and SPM. The SO2 concentration has remained low. Going forward, the correlation between air pollution, including Ox and PM2.5, and respiratory symptoms such as asthma will be carefully monitored referring to regional characteristics and the study will be conducted in a working group under the Council of Health Effects for Environmental Health Surveillance and Localized Air Pollution.
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.
1 Asthma: (3-year-old survey) FY2008, 2013; (6-year-old survey) FY2007, 2009
Asthma (within the past two years): (6-year-old survey) FY2007, 2009, 2013
Asthma (within the past two years): (6-year-old survey) FY2007, 2009, 2013
2 FY2013
3 The NO2, NOx, SPM, and SO2 concentrations are the background concentrations measured during the survey periods between FY1996 and FY2021.
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