1. Induced sputum (IS) - will be done after pretreatment with short acting beta-2 agonist and 3% saline will be administrated by an ultrasonic nebulizer for up to 20 min. Differential cell count, particle size distribution test of the particulate matter (with a Eyetech Analyzer (Ankersmid, Yokneam, Israel)will be done from IS samples and evaluation the activity of Heme oxygenase 1 (HO-1) protein from IS supernatants.