We would like to thank the journal for the opportunity to respond to a letter to the editor concerning our study.1 ,2

The original criterion for inclusion into the cohort was employment time of ≥180 days.3 But this includes also apprenticeship (started usually at age <18 years) and military service. For the analysis, we only considered data from those spirometries performed at age ≥18 years. The time series of spirometric data were validated for each study subject by one of us (NK) blinded with respect to the exposure. If there were two or more spirometries during a period of less than 6 months, only the spirometry with the higher values was kept. Moreover, the time series were checked for outliers using Cook’s distance. Outliers, almost exclusively low values, were also excluded. These procedures sometimes resulted in only one data record …