Are inhaled long-acting Beta-agonists (laba) really harmful in adult asthmatics?

Mr. SS, a 32 year old Chinese male, is a known case of moderately severe persistent asthma since the past 17 years. He is a palm oil plantation worker for the past 6 years. He is a nonsmoker, non-hypertensive and has no history of diabetes mellitus. There is a family history of bronchial asthma in both his mother and maternal grandfather. On examination, the patient appears tachypnoeic, with a respiratory rate of 30 breaths per minute. His pulse rate is 110 beats per minute. Peak expiratory flow done at the time of clinical examination is 200 L/min. He is currently on a combination of fluticasone propionate (250 mcg) and salmeterol (50 mcg) administered by an inhaler device twice a day. He has heard that the use of inhaled long-acting beta agonists (LABA) is considered controversial and potentially damaging and is therefore concerned about further usage of this therapy.