5. evidence of reversible airflow obstruction: (a) forced expiratory volume in 1 second (FEV1) < 80% predicted at the time of screening or within the 3 years prior to this screening, and (b) improvement with bronchodilator: either (i) an increase of >15% and 200ml in FEV1 with asthma treatment over the previous 3 years or (ii) after 4 puffs of albuterol by MDI (or 2.5 mg by nebulizer), an increase in FEV1 or FVC >12% and 200 ml in FEV1 within 30 minutes,