Main inclusion Criteria:  written informed consent male and female subjects with documented diagnosis of asthma age 18 to 65 years ACT score 19 or less at screening treatment wih oral corticosteroids or hospital or emergency department admission due to asthma exacerbation within the past year subject's able to use Easyhaler inhalers and comply with study requirements  Main exclusion Criteria:  recent (within 1 month) asthma exacerbation concomitant major respiratory disease which may complicate the measurement of asthma control >20 pack-year history of smoking recent upper or lower respiratory tract infection pregnant or lactating female subjects