Particle concentration and indoor air quality in naturally ventilated patient rooms-A field study in a hospital building in Bucharest, Romania

In response to the COVID-19 pandemic, there has been a significant emphasis on improving indoor air quality (IAQ), particularly within hospital buildings. Despite developments in integrated central advanced mechanical ventilation and filtration technologies in new hospital buildings, challenges persist in installing them in existing and old hospital buildings relying on traditional natural ventilation. In this context, portable air purifiers have been developed and utilised in hospital facilities as a solution to reduce airborne particulate matter (PM) concentrations and the potential airborne infection risk. However, there have been a limited number of IAQ studies in hospital buildings due to the unique operational environments of hospitals and the associated risks for researchers while conducting in-situ research in hospital facilities, especially in naturally ventilated hospital buildings. This has resulted in a knowledge gap concerning the measured effectiveness of portable air purifiers in traditionally naturally ventilated hospital buildings. To address this gap, a one-week measurement campaign was conducted at a naturally ventilated hospital building in Bucharest, Romania. The campaign aimed to assess PM concentrations before and after utilizing portable air purifier units in two distinct patient rooms — an intensive care unit (ICU) and an isolation room. Additionally, the study involved measuring various aspects of indoor environmental quality (IEQ) parameters, including CO2 levels, temperature, and relative humidity. Values of measured parameters were used for infection risk calculation. The effectiveness of the air purifier units was determined by comparing indoor and outdoor (I/O) PM concentration ratios before and after using the air purifiers. PM measurement results indicated a significant reduction in PM2.5 I/O ratios of (78% - 93%) with air purifier use. The findings from the infection risk assessment highlight the potential benefits associated with the employment of portable air purifiers featuring high-efficiency particulate air (HEPA) filters in reducing PM concentration and increasing the total Air Changes per Hour (ACH) in naturally ventilated patient rooms.