The body of evidence keeps growing that higher ozone levels lead to higher asthma risk. In this recent study it was found that the prevalence of asthmatic symptoms was about 4% higher at high ozone sites as compared to low ozone sites. In order to neutralize the effects of the other components of air pollution in the analysis sites were chosen with low levels of nitrogen dioxide and volatile organic compounds.
This study was reported in the July issue of the Journal Allergy and was conducted by a team from the University of Porto in Portugal lead by Dr. Maria Alvim-Ferraz. The researchers studied a group of 478 children between the ages of 6 and 13 years from four “remote” geographical sites with high and low ozone levels.
The children living in low ozone level areas experienced asthma symptoms at the rate of 3.5%. Those living in high ozone areas had asthma symptoms at the rate of 7.1%. The researchers monitored ozone levels and used questionnaires to collect data on asthma prevalence.
The authors stated that it was difficult to compare their results with those of previous studies because the parameters of analysis were not standardized. Also, they added that other possible factors in asthma development such as mould and pollen concentrations were not included in the analysis and should be considered in future studies.
This study is interesting in that it has a relatively large sample size and tries to focus just on the effects of ozone. The lack of other data on allergen levels and factors such a PM2.5 levels is a negative. In and of it itself the study is not conclusive but when you add this to the studies of Bell et al. , Triche et al. and others you continue to develop knowledge of the effects of ozone on respiratory health.