Samples of sputum from asthmatic children, between 5-17 years, will be collected during two years of the study period to perform tests Particle Size Distribution (PSD) and Shape Analysis (SA) of the particulate matter in the sputum and a biochemical reaction to evaluate the activity of Heme Oxygenase-1 protein in sputum cell supernatants.

Each child will perform Pulmonary Function Testing (PFT) and Induced Sputum (IS) as a routine part of diagnosis of asthma.

Parents will be asked to complete a questionnaire including questions on their child's respiratory symptoms in the last 12 months as well as socioeconomic factors. Parents will be asked to give informed written consent for their child's participation in the study.

Inclusion Criteria:

• •All children, between 5-17 years, performing a routine diagnosis of asthma in Tel Aviv Sourasky Medical Center that there parents gave informed written consent for their child's participation in the study.

Exclusion Criteria:

• None.

Children, between 5-17 years, performing a routine diagnosis of asthma in Tel Aviv Sourasky Medical Center