Another presumed risk factor for accelerated decline in pulmonary function was the presence of hyperreactive airways, although it was not clear whether the mere presence of hyperreactive airways contributed to the accelerated decline, or whether the decline resulted from the reaction of the airways to various irritants over a long period of time. It is possible that if the hyperreactive airway was kept non-reactive by pharmacological means over a period of years, the expected abnormal decline might be lessened. This effect might be enhanced by the cessation of cigarette smoking.