Introduction Respiratory symptoms at work are common among hairdressers throughout the world. However, their ties to clearly identifiable causes have been less compelling. Among others ammonium persulfate (AP), a common compound of hair dyes, has been reported to cause occupational asthma. But other chemical, allergenic and irritative substances and unfavourable air conditions (damp, dust, fume) are widespread in hairdressing saloons as well, making even the underlying pathomechanisms ill-defined. For a better understanding of work related airway diseases the objective of this study is to describe common features and potential causes in affected hairdressers.

Methods Hairdressers with respiratory symptoms at work who were referred to a specialised outpatient clinic between May 2012 and May 2017 were consecutively included in a case series. During presentation various anamnestic data as well as medical examinations including pulmonary function and allergy testing were compiled. Data were analysed using SPSS Statistics.

Results Hairdressers comprised 53% (n=105) of the patients referred to our clinic for occupational respiratory diseases. The hairdressers were predominantly female (91.4%) with a mean age of 39.2 (18–70). 15.2% showed a clear positive reaction to AP in the skin prick testing, while another 1,9% had an externally documented positive finding.

Conclusion This is to our knowledge the largest examined collective of symptomatic hairdressers and is therefore an important source to identify similarities and possible causes. A classification into four different subgroups can be suggested: 1. Patients with an obstructive airway disease (OAD) and proven AP-sensitisation; 2. Patients with OAD, no AP-sensitisation and no other known extra-professional condition explaining the symptoms; 3. Patients with OAD and a known extra-professional condition; 4. Symptomatic patients without verifiable OAD. Therefore, the cause for the work-related symptoms could not always be entirely clarified but a causal relationship seems likely for group 1 and possible for group 2.