Smoking cessation—but not smoking reduction—improves the annual decline in FEV1 in occupationally exposed workers

SummaryIntroductionIndividuals exposed both to cigarette smoke and respiratory pollutants at work incur a greater risk of development of airway hyperresponsiveness (AHR) and accelerated decline in forced expiratory volume in 1s (FEV1) than that incurred by subjects undergoing each exposure separately. We examined whether smoking cessation or smoking reduction improves AHR and thereby slows down the decline in FEV1 in occupationally exposed workers.MethodsWe examined 165 workers (137 males and 28 females) participating in a smoking cessation programme. Nicotine tablets were used for smoking cessation or smoking reduction. Respiratory symptoms were assessed by questionnaire, FEV1 by spirometry and AHR by methacholine challenge test. At 1 year, subjects were classified into quitters, reducers, or continuing smokers.ResultsSixty-seven subjects completed the study (32 quitters; 17 reducers; 18 continuing smokers). Respiratory symptoms improved markedly in quitters (P