Researches on asthma
have found that air pollution increased asthma prevalence among sensitive
age groups, including school children, and exposed them to the recognized
health impacts. The aim of this study is to examine the association between
elevated annual mean concentration of PM2.5 (particulate matter with aerodynamic
diameter less than 2.5 micrometers) and surface ozone and asthma prevalence
among school children in Japan from 2006 to
2009. Annual rates of asthma prevalence among preschool and school children
(5 to 11 years) are obtained from the
database of the Ministry of Education, Culture, Sports, Science and Technology—Japan
(MEXT). Data on the concentrations of PM2.5 and surface ozone were obtained
from 1,183 stations of air quality monitoring distributed in 47 prefectures.
Annual means of these concentrations were compared to annual variations in
asthma prevalence by using Pearson correlation coefficient. We found different
associations between the annual mean concentration of PM2.5 and surface ozone
and the annual rates of asthma prevalence among preschool and school children
from 2006 to 2009. The positive values of the correlation coefficient in prefectures
such as, Gumma, Shimane, and Niigata, are consistent with the previous knowledge.
However, significant inverse associations
were found in many prefectures. Our study suggests that the association between elevated concentrations of PM2.5 and surface ozone and asthma prevalence
among school children in Japan is not strong enough to assume concretely
a plausible and significant association.