Factors affecting respiratory symptoms were sex, age, smoking, and work section. Women had more abnormal symptoms than men (OR ช 1.888, 95% CI: 1.227 e2.905). A previous study indicated a
higher prevalence of asthma and bronchitis in female workers. Abnormal symptoms proportionally increased with age [29] . Workers who smoked had more abnormal symptoms than non-smokers (OR ¼ 1.607, 95% CI: 0.924e2.793) Smoking aggravated respiratory symptoms while working cold environments. Chronic diseases such as musculoskeletal pain, respiratory disease, Ray-naud’s phenomenon, cardiovascular disease could become worse while working under cold condition [2,5,13,30]. Moreover, smoking was a risk factor of Raynaud ’s phenomenon