A well working voice is an essential tool for healthcare professionals to achieve high levels of patient satisfaction and safety, yet the prevalence of hoarseness, influenced by factors like noise, acoustics, and pollutants, remains under-researched. The overall purpose of this study was to investigate the prevalence and risk factors associated with hoarseness among healthcare professionals, with a particular focus on issues of indoor environmental quality (IEQ). This thesis consists of two elements, a nationwide survey based on random sampling (Studies I and II) and a clinical section (Studies III and IV), which also included a follow-up. In the first part of the study, the health data were collected with a questionnaire answered by Finnish health care professionals (N=15,553) and in the clinical part, all the participating buildings (N=33) were inspected by qualified construction prior to being classified as “exposed” or “reference” buildings. Additionally, for the Study IV, skin prick tests were performed and/or blood samples were taken from all volunteers (N=496).

Results revealed that 30% of professionals reported frequent hoarseness, with variations evident across occupational subgroups and between different buildings. Midwives experienced the highest prevalence, while laboratory nurses had the least. A significant correlation was observed between perceived IEQ issues and hoarseness, especially in exposed buildings. Over a decade, hoarseness did not increase in environments with good IEQ but was six times higher in exposed buildings.

Major risk factors for hoarseness included unresolved IEQ problems, age, smoking, allergies, and asthma. Contrary to popular belief, the results of this study suggest that hoarseness largely results from larynx irritation rather than allergic reactions. Interestingly, professions with higher chemical exposure, like dental nurses, did not show increased hoarseness. Remedying exposed buildings decreased hoarseness prevalence, but not to levels in reference buildings. Given the high prevalence and the potential health and productivity impact, the findings underscore the urgent need for IEQ improvements, particularly in ventilation and moisture damage repair, in order to ensure safer and healthier working conditions for healthcare professionals.