Predictors of Asthma Exacerbations in Children

Inclusion Criteria: * Informed consent * Age \>3 and \<7 years * Diagnosis of intermittent asthma * In the last 24 months, at least 6 weeks of treatment with a controller medication (inhaled steroid and / or leukotriene receptor antagonist Singulair ®), or in the last 12 months, at least three episodes with an use of controller medications (inhaled steroid and / or the leukotriene receptor antagonist Singulair ®) * The ability to perform three reproducible spirometries * Examination in infection-free interval (\> 4 weeks infection-free) * Minimum distance to the following asthma medications: * Short-acting beta 2-agonists: 8 hours * Ipratropium bromide: 24 hours * Long-acting beta 2-agonists: 24 hours * steroids: 4 weeks * leukotriene antagonist: 4 weeks Exclusion Criteria: * Age older than 6 years or younger than 4 * The inability to perform spirometry * Other chronic diseases or infections (eg. HIV, tuberculosis, malignancy) * Participation in another study