Integrated Assessment of Indoor Air Pollution and Associated Health Risks in a Hemodialysis Unit

Indoor air quality (IAQ) is critical for protecting occupant health, particularly in healthcare settings such as hemodialysis (HD) units, where patients spend prolonged periods indoors. This study assessed IAQ in an HD treatment room over 1 year, identified pollutant sources using indoor/outdoor (I/O) ratios, and evaluated associated health risks for patients and healthcare staff. IAQ was assessed using approximately 1400 time‐resolved measurements of CO ₂ , O ₃ , and particulate matter (PM _0.3 , PM _2.5 , and PM ₁₀ ), together with 12 monthly sampling campaigns for volatile organic compounds (VOCs). Simultaneous outdoor measurements were used to calculate I/O ratios, whereas indoor temperature ( T ) and relative humidity ( RH ) were monitored to assess thermal comfort. T (23.2°C–25.5°C) and RH (36.5%–63.9%) generally remained within acceptable comfort ranges. Indoor CO ₂ concentrations frequently exceeded the threshold established by Spanish regulations, with indoor‐outdoor differences above 350 ppm and peak values exceeding 1100 ppm, indicating insufficient air renewal. Indoor O ₃ , PM _2.5 , and PM ₁₀ generally presented I/O ratios below 1, suggesting a predominantly outdoor origin, whereas PM _0.3 concentrations remained low. Although average O ₃ and PM concentrations were generally below World Health Organization guideline values, occasional concentration peaks were recorded. Following patient disconnection and cleaning activities, indoor O ₃ concentrations decreased, likely due to reactions with VOCs emitted by cleaning products. Most VOCs exhibited I/O ratios above 1, indicating substantial indoor sources. Health risk assessment showed that carcinogenic risks associated with benzene and ethylbenzene were below the benchmark value of 10 ⁻⁶ for both patients and healthcare staff. Hazard indices for both groups were below 1, indicating no significant noncarcinogenic risk. These findings highlight ventilation deficiencies and substantial indoor VOC emissions, emphasizing the need to improve mechanical ventilation performance and implement continuous IAQ monitoring in HD units.