Indoor Air Quality and Sustainability Management – 2 case study in three Portuguese Healthcare Units

: Adequate management of indoor air quality (IAQ) in healthcare units has relevant 11 impacts on sustainability performance due to its effects on patient safety, occupational health and 12 safety, and energy consumptions. This study sought to identify improvement opportunities on 13 IAQ management by collecting and analyzing experimental data of selected parameters in three 14 healthcare units in Portugal: two general hospitals and one primary healthcare center. Indoor air 15 temperature, relative humidity, CO 2 , bacteria, and fungi concentrations were measured in summer 16 and winter campaigns in June /July 2017 and in January /March 2018. Results show that the 17 exclusive use of natural ventilation is not adequate when the affluence of users is high, but the 18 analyzed parameters revealed acceptable results under low occupation intensity conditions. 19 Results also show that keeping low indoor air relative humidity has a significant impact in 20 reducing fungi concentration, and that there is a significant correlation at the 0.05 level between 21 indoor air CO 2 concentration and bacterial loads. Therefore, as opportunities to improve 22 sustainability, IAQ management in healthcare facilities should consider natural ventilation as a 23 complement to mechanical ventilation systems and should focus on adequate control of indoor air 24 relative humidity and CO 2 concentration to reduce the risk of airborne infections.


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Sustainable healthcare systems need to balance economic, social and ecological interests, in a 29 comprehensive approach and with a long-term focus [1]. Healthcare sustainability management

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Ventilation systems play an important role in IAQ management, as they are used to provide 59 thermal comfort by controlling temperature and humidity in indoor environments, and by diluting 60 indoor air pollutants with outdoor air (if of good quality), lowering their concentration to minimize 61 negative health impacts. Indoor CO2 concentration is an indicator of the level of ventilation with 62 outdoor air, and is frequently used to characterize indoor air quality [12,13,24,25]. Inadequate 63 ventilation is one of the causes of poor indoor air quality, with negative consequences for the health 64 and wellbeing of the occupants [26,27]. Ventilation systems may use mechanical or natural forces to 65 promote indoor airflow. Natural ventilation systems have zero energy costs, but are difficult to 66 predict and control [8,28]. In a research study involving mechanical and naturally ventilated 67 buildings in Austria between 2010 and 2012, Wallner et al. [25] conclude that indoor air quality is 68 significantly better in mechanically ventilated homes than in those using exclusively natural 69 ventilation. On the other hand, Jurado et al. [12] report that the CO2 concentration levels in 70 university classrooms in Brazil were significantly higher in rooms ventilated through 71 air-conditioning when compared with natural-ventilated classrooms. However, there is no evidence 72 that these air-conditioning systems received fresh-air from the exterior.

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The use of natural ventilation for IAQ management in healthcare facilities has been widely 78 Qian et al. [8] report field measurements in naturally ventilated hospital wards in Hong Kong

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showing that natural ventilation can achieve adequate ventilation rates for infection control; 80 Gilkeson et al. [27] conducted experiments with a tracer gas in hospital wards in the UK, and 81 concluded that natural ventilation is effective for controlling airborne infection risks. However, 82 natural ventilation systems in healthcare facilities are not effective if the appropriate ventilation rates 83 cannot be achieved, either due to window and door closing due to unfavorable outdoor 84 meteorological conditions, or to uncontrolled flow patterns [27,28]. One important factor to be 85 considered in natural ventilation systems is outdoor air quality. Several studies report higher fungal 86 concentration in natural ventilated rooms, associated to outdoor fungal infiltration [12,25,31]. The 87 influence of outdoor air in indoor fungal levels has been proven by several studies regarding IAQ in 88 hospitals [17,24,31].

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The aim of this study was to identify improvement opportunities in IAQ management in   week days, and urgent care is available on week nights and weekends.

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In hospitals H1 and H2 indoor air quality is assured by mechanical ventilation, with air

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When the air sample was collected for the microbiological determinations, other indoor air 130 parameters, in the scope of IAQ management, were registered: temperature, relative humidity and 131 CO2 concentration. These parameters were measured using a calibrated KIMO probe connected to a 132 data logger KIMO AQ 200 (Saurmann Industrie, Chevry-Cossigny, France).

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Sampling followed the technical recommendations of the ISO 16000 series [32-34]: the 134 measurement location in each room was separated by at least 1 to 2 m from the walls, the influence 135 of possible interferences was avoided, and the sampling devices were located 1.5 m above ground 136 level for evaluation at the breathing zone. In all campaigns in hospitals H1 and H2, duplicate 137 samples were collected to ensure sampling accuracy. However, in the health center HC it was not 138 possible to collect duplicate samples due to experimental constrains.

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The time of the day selected for sampling followed the recommendations of the healthcare staff 140 and management, in order to be representative of typical conditions in each sampled room: all 141 rooms had been in regular use for at least two hours, and room occupancy was stable during sample 142 collection.

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Campaigns were planned to characterize the selected IAQ parameters on:

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The summer campaigns took place in June and July 2017, and the winter campaigns were 152 performed between January and March 2018.

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The results obtained with the indoor sampling campaigns for all locations and analyzed 168 parameters are presented in Table 1

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CFU.m -3 for bacteria, and between 5 CFU.m -3 and 395 CFU.m -3 for fungi. Room occupancy was a 172 concern in the IAQ characterization campaigns and, therefore, similar rooms were analyzed in 173 equivalent occupancy ranges (Table 1).

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Portuguese legislation on indoor air quality [36] sets the limit of 1250 ppm for CO2 175 concentration, requires fungi concentration to be lower in indoor air than in outdoor air (fungi in-out 176 < 0 CFU.m -3 ), and sets the difference between bacteria concentration in indoor air and outdoor air 177 (bact in-out) to be below 350 CFU.m -3 . The results presented in Table 1 show that limits provided by were not always verified at these healthcare facilities: in the health center HC, RH was systematically 185 above 50%, H2 showed several results in which RH was below 30% in the winter season, and in H1 186 all sampled rooms had RH above 50% in the summer. showed that there is an interaction between the effects of the factors "healthcare unit" and "working 193 condition" on most of the analyzed parameters, except for indoor air temperature and relative 194 humidity (Table 2). Figure 1 and Figure  Given that the effect of the factor "healthcare unit" depends on the effect of the factor "working  in-out and fungi in-out differences; indoor air temperature was lower in HC.

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To exclude the effect of the "healthcare unit" factor, a one-way ANOVA compared the results of 222 the analyzed parameters in hospital H2 under normal and under emergency /urgent care working 223 conditions. The same test was performed on the analyzed parameters in the health center HC for 224 both these working conditions (Table 2).     summer. Figure 4 also shows that the differences found between indoor and outdoor 255 microbiological loads are higher in the winter when windows are more frequently closed and, 256 therefore, less outside air is introduced by natural ventilation processes.

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A t-test confirmed significant differences (p<0.05) between summer and winter results for most 258 parameters analyzed (Table 3) [12,17,25,28,31,40,41]. Figure 5 shows the experimental results of indoor air relative humidity and 301 indoor fungi concentration, illustrating a significant moderate positive correlation between these 302 IAQ parameters (ρPearson = 0.562, p-value (two-tail) = 0.002). The highest values for indoor fungi 303 concentration occur for RH above 50% ( Figure 5). Therefore, keeping relative humidity below this 304 value is expected to reduce airborne infection transmission risks.