Characterization of ultrafine particle and chlorine emissions from sodium hypochlorite disinfection: Experimental measurements and exposure modelling in healthcare settings

Disinfectants, such as sodium hypochlorite, are routinely applied in healthcare settings to prevent healthcare-associated infections; however, their implications for occupational exposure to airborne particles and chlorine during routine disinfection activities remain poorly characterized. This study experimentally quantifies particle and chlorine emissions during surface disinfection under varying environmental conditions, including temperature, illumination, and the presence of organic contaminants. Occupational exposure of healthcare workers, as well as potential patient exposure in a typical healthcare environment, was subsequently modelled using a mass balance approach based on measured emission rates. Results indicate that high temperature (38 °C) and strong illumination (1200 lux) lead to the highest exposure to ultrafine particles, with concentrations of about 2.0 × 105 part. cm−3 under poor ventilation conditions. The presence of such high particle concentrations is attributed to nucleation, which generates new ultrafine particles with a mode diameter of 10–30 nm. In contrast, emissions from surfaces with contaminants were substantially lower. Chlorine emissions and resulting concentrations in the healthcare scenario were highest in the presence of vomit and urine. For both particle and chlorine exposure, ventilation plays a significant role; at high air exchange rates, their concentrations are reduced. Overall, this study provides a toxicological exposure assessment relevant to occupational health, highlighting the role of environmental conditions and ventilation in mitigating exposure to particles and chlorine during sodium hypochlorite-based disinfection in healthcare settings.