Low plasma CC16 levels in smokers are associated with a higher risk for chronic bronchitis.
Petersen H, Leng S, Belinsky SA, Miller BE, Tal-Singer R, Owen CA, Celli B, Tesfaigzi Y. Low plasma CC16 levels in smokers are associated with a higher risk for chronic bronchitis. Eur Respir J. 2015 Nov; 46(5):1501-3.