Introduction:
Worldwide, 40% of children, 33% of male non-smokers, and 35% of female non-smokers were exposed to second-hand smoke in 2004. This exposure was estimated to have caused 165,000 from lower respiratory infections, 36,900 from asthma, and 21,400 from lung cancer. The main objective of the study was to determine the impact of passive smoking on the population of three to five-year-old children from the Bratislava region. The side objective was to determine the effect of second-hand smoke on the incidence of pneumonia or bronchitis in the same group.

Methods:
The data were available from selected ELSPAC (the European Longitudinal Study of Pregnancy and Childhood) questionnaires. The study group consisted of 1,286 boys and girls between the ages of three and five from the Bratislava region exposured to passive smoking. 1,273 children were evaluated about the effects of passive smoking on occurrence of pneumonia and bronchitis and 763 were evaluated about the effect of passive smoking on height of children.

Results:
We did not confirm a statistically significant relationship between passive smoking and the occurrence of pneumonia or bronchitis p=0.285 (exposure to passive smoking over the weekend); p=0.166 (over the week) in our cohort. We did not confirm significantly lower height among children who had been exposed to passive smoking during weekend (p=0,373) nor during week (p=0,874). Out of 1,034 parents, guardians and legal representatives answered the question concerning the number of smokers in households. 57.4% answered that no one smokes in the household, 25.9% that there is 1 smoker in the household, 16.7% answered that at least 2 household members smoke in the household.

Conclusion:
Children are the most vulnerable group to the effects of passive smoking. We do believe that the need for further studies aimed at monitoring the impact of passive smoking of children is still urgent.