Determinants of indoor air quality in hospitals : impact of ventilation systems with indoor - outdoor correlations and health implications.

Abstract

Indoor air quality (IAQ) is highly affected by outdoor emission sources particularly in congested urban areas invariably associated with vehicle-induced emissions as well as construction and industrial emissions. Since people spend most of their time indoors, the effect of IAQ on personal exposure and human health is often more pronounced than outdoor air. On the other hand, IAQ in certain sensitive environments such as hospitals is a critical factor for its occupants that could negate the purpose of the visit if IAQ deteriorates. Hospitals act as specific indoor environments with highly vulnerable individuals potentially exposed to various harmful air contaminants exacerbating health risks. Hence, this study involved a seasonal exposure assessment of IAQ determinants including temperature (T), relative humidity (RH), carbon monoxide (CO), carbon dioxide (CO₂), sulfur dioxide (SO₂), nitrogen oxides (NO-NOx), particulate matter (PM₁₀ and PM₂.₅), and total volatile organic compounds (TVOCs) in hospital environments with particular emphasis on indoor-outdoor (IO) correlations, effective ventilation modes and associated health implications. Then air quality indices (AQIs) were tested and compared using field data from twelve hospital zones and the most robust index was obtained when coupling IAQ indicators with the effect of thermal comfort. This study also assessed the presence of influenza and respiratory syncytial viruses (RSV) in air samples collected inside patient rooms and investigated the potential risk for transmission for healthcare professionals (HCPs) and visitors. The results indicated that while indoor and outdoor CO levels were below air quality standards, measured PM₂.₅ and PM₁₀ concentrations at several locations exceeded the standards by 2 to 3.5 fold. We generally recorded higher indoor PM levels during the warm season, particularly during regional desert storm events. The ingress of particles from the outdoor to indoor environment was ev