ACUTE RESPIRATORY EFFECTS OF LOW-LEVEL SUMMER SMOG IN PRIMARY-SCHOOL CHILDREN

We aimed to study the possible effects of exposure to a summer smog ep isode on the respiratory health of 212 school children, Furthermore, t he suitability of the forced oscillation technique (FOT) to demonstrat e such effects was evaluated. Acute respiratory symptoms were evaluate d by questionnaire and lung function was assessed by spirometry and re spiratory impedance measurements, For each child, comparisons were mad e between measurements performed at baseline (low levels of air pollut ant: 55 mu g . m(3) for SO2 and 58 mu g . m(-3) for NO2 (maximum 24 h means); O-3 levels ranged from 2-56 mu g . m(-3) (8 h mean)); and afte r a summer smog episode (characterized by 8 h O-3 levels > 120 mu g . m(-3) (163 mu g . m(-3)) and 1 h levels > 160 mu g . m(-3) (215 mu g . m(-3)). No significant effects were observed on the prevalence of acu te respiratory symptoms. When individual changes in lung function indi ces (Delta LF) were regressed on changes in previous day ozone (8 h me an) and changes in mean daily temperature (Delta MTemp), using multipl e linear regression analysis, a significant negative association was o bserved with peak expiratory flow (PEF), but not with other spirometry indices, Although significant associations were observed with reactan ce at 8 Hz (Xrs8), resonant frequency (f0) and frequency dependence of resistance (FD), the signs of the beta s were opposite to the directi on expected when O-3 adversely affected the impedance outcomes. In con clusion, in this study short-term exposure to moderately high levels o f ozone did not result in clear adverse effects on the respiratory hea lth of the children. Further research into the applicability of the BO T in this type of field studies still seems to be advisable.