INDOOR AIR QUALITY IN HOSPITALS: PM AND AIRBORNE BACTERIA

Abstract

The effect of air quality on personal exposure and human health is often more pronounced indoors than outdoors because people spend most of their time inside. In this context, hospitals represent a sensitive environment with highly vulnerable individuals. In this study, indoor air quality (IAQ) is characterized in Intensive Care Units (ICUs) with emphasis on assessing the levels of particulate matter (PM10, PM2.5) and airborne bacterial levels with corresponding diameter sizes, while also characterizing physical parameters including temperature, relative humidity, distance away from patient and level of activity. Correlations between measured pollutant levels and physical parameters were quantified and used to develop representative multivariate regression models (MLRs) that predict the pollution levels. Measured concentrations of PM10, PM2.5 and total bacteria ranged from 10 to 65 µg/m3, 10 to 54 µg/m3 and 20.4 to 134.3 CFU/m3, respectively. These levels exceeded in many instances international guidelines set for IAQ. Total Bacterial Loads (TBL) varied significantly as a function of room occupancy and the number of trips conducted by the nursing crew. While TBL and PM levels exhibited a weak correlation indicating potential different sources, the concentrations of the heavy bacteria showed a positive correlation with the level of activity in the room. The TBL regression model was able to explain 77% of the variability observed in the measured bacterial concentrations in a typical ICU room with evident high correlation with the distance away from the patient and the level of activity in the ICU rooms.