All participants who provide signed consent will then proceed to spirometry (simple spirometry without bronchodilator response) and study data collection. After the baseline visit, participants enter a 12-months period of follow-up with visits at months 3, 6, 9, and 12. Participants will be asked to attend one of the study centres and data on the quality of life and asthma-related resource utilization will be gathered. On the final visit, participants will undergo spirometry for objective diagnosis of asthma with possible methacholine challenge test for the participants whose asthma cannot reliability be included or excluded.