ABSTRACT
This cross-sectional study aimed to determine a possible relationship between different categories of passive exposure to environmental tobacco smoke among children and both large and small airway function as an objective parameters of lower respiratory tract affection. This work included 80 children with history of exposure to indoor smoking [from one or more smoker's member of the family] as a passive smokers group and 40 age, sex, residence housing and social class matched children without history of exposure to indoor smoking as a control group. The different categories of passive exposure to environmental tobacco smoke were determined by both questionnaire about the degree of the active family member smoking and measurement [of urine cotinin [major metabolite of nicotine] level [ng/ml]. Large airway function was estimated through measurement of FEV[1]% pred where small airway function was determined by measurement of both FEF[25-75%] and FEF[50%] pred In this work, the source of active indoor smoking in the families [of passive smokers children was the father only in 87.5% and the father and others in 12.5% of families the urinary cotinin level [ng/ml] was increased in passive smokers than in controls [418.18 +/- 295.76 and 111.9 +/- 93] respectively, which was found to be corresponding with the degree of paternal or maternal active smoking There was a significant increase in the frequency of respiratory illness among passive smokers [43.7%] than in the controls [22.5%]. Also, the percentage of passive smokers with history of recurrent wheezy chest and chronic cough were [22.5% and 6.25%] respectively, compared to [5% and 0%] among controls respectively. In this study, FEV[1]% pred. was found to be decreased significantly in passive smokers children than in controls [100.86 +/- 16.7 and 108.0 +/- 16.4] respectively .Moreover, among passive smokers, as the degree of tobacco smoke exposure increased, FEV[1]% pred decreased As regards small airway function, FEF[25-75]%% pred. was very high significantly decreased in passive smokers than in controls [106.96 +/- 28.79 and 128.8 +/- 18.11] respectively. Also, FEF[50]% pred was very high significantly decreased in passive smokers than in controls [I10.58 +/- 29.85 and 128.7 +/- 20 37] respectively .As regards the association between urinary cotinin level and pulmonary function data among passive smokers with decreased pulmonary functions compared to those with normal pulmonary functions, it was [959.0 +/- 714.9 and 166.9 +/- 103.79] respectively.It was concluded that passive exposure to enviromental tobacco smoke must be considered one of the causes of pulmonary morbidity in children