Potential health risks of uncontrolled indoor air quality in public salt chambers for children

Salt inhalation therapies in salt rooms are increasingly popular for prevention and as complementary therapy for individuals with impaired respiratory conditions. “Active” salt rooms apply devices that disperse dry sodium chloride aerosol or nebulized saline into the indoor air, while “passive” salt rooms contain large amounts of salt. However, their therapeutic efficacy remains controversial, and general operating standards are lacking. This study aimed to (i) survey environmental conditions in kindergartens’ salt rooms using a standardized checklist; (ii) investigate indoor air quality during operation; and (iii) identify common problems related to their operation. In our national survey, salt rooms were reported in 500 out of 3372 inspected kindergartens in Hungary. Most of these spaces were characterized by high occupant density and poor ventilation. Air quality was measured in 19 salt rooms. Salt particle concentrations were significantly higher in “active” salt rooms compared to “passive” ones. The maximum carbon dioxide concentration exceeded 1500 ppm during therapy sessions in most rooms. In all cases, the indoor airborne concentration of bacteria significantly exceeded outdoor levels, with a median indoor/outdoor concentration ratio of 48.7. In 7 out of 19 rooms, the concentration of fungi was also above the threshold level. In conclusion, salt rooms can potentially serve as sources of illness and infection due to inadequate indoor air quality. Therefore, the use of individual inhalers or nebulizers is recommended when medically indicated.