AIR QUALITY
Figure 4: Comparison of the air quality of air-flow from the VH-AC system and the MCD attached VH-AC system.
medium at 26°C for 48 hours. The quantity of microorganisms was measured as the number of colonies after cultivation, and the mean of the three plates is shown in the results. The sampling points of airborne microorganisms were outside the air inlet, humidifier inlet, humidifier outlet, and inside the room. The quantities of airborne
microorganisms in the airflow from the VH-AC and MCD attached VH-AC systems are shown in Figure 4. Throughout the operation period, there were less than 50 CFU/0.1 m3
general bacteria in the fresh air. The amount of fungus in the fresh air was much higher at 100–200 CFU/0.1 m3
in August, and less than 50 CFU/0.1 m3 in the other months. In
the airflow from both systems, the quantities of general bacteria and fungus were higher in the humidifier outlet air at the start of the experiment, and decreased thereafter. The quantities of airborne microorganisms in the rooms aired by both systems were almost the same and much less than the regulation level prescribed in HEAS-02-2004.
Discussion The results, using actual systems, indicated that there was no difference in air quality from a steam-type humidification air conditioner and a vapourisation-type humidification air conditioner. The quantities of airborne microorganisms in the airflow from the SH-AC and VH-AC systems were much lower than the regulation level prescribed in HEAS-02-2004, showing that
IFHE DIGEST 2015 of
both systems perform adequately as humidification air conditioning systems for hospitals. The quality of the air from the airflow of
the vapourisation-type humidification air conditioner, which was not recommended in HEAS-02-2004 for hospitals, could maintain much lower quantities of airborne microorganisms than the level prescribed in HEAS-02-2004 during the experiment period from July to March. This observation indicated that the vapourisation-type humidification air conditioner performs adequately as a humidification air conditioning system of a hospital. From the continuous measurement, there was no change in the quality of air from VH-AC system, for a period of two years after the opening of the new Mie University Hospital (data not shown). In a hospital environment suitable for
patients with low immunity, the counter- measures for an infectious disease resulting from microorganisms are important. In the investigation using the experimental machine, the increase in bacteria was recognised in the humidification elements by running the vapourisation-type humidification air conditioner for a long period (data not shown). From the observations made, as a method for safer use of a vapourisation-type humidification air conditioning system, we measured the change in the air quality of the airflow from the MCD attached VH-AC system for a long period.
The quantity of airborne microorganisms
in the airflow from the MCD attached VH-AC system tended to be lower than from the normal VH-AC system, but the difference in the two systems was quite slight. However, in the long-term operation of the VH-AC system, adhesion of the microorganisms to the humidification element could occur and might adversely affect the air quality of the airflow. Consequently, we recommend that a suitable counter-measure against an increase in microorganisms in the air conditioning system should be introduced. In this study, the comparison between the performance of the SH-AC and VH-AC systems was conducted as a two-week experiment and the performance evaluation of the VH-AC system in the new Mie University Hospital was performed over one season of operation. Because each experiment was performed over relatively short periods, observation in the new hospital is continuing and the results will be announced in the near future.
Acknowledgements The author would like to thank Masazumi Godo, Jiang Zhang, Research & Development Center, Shin Nippon Air Technologies Co. Ltd, and Haruki Sumi, Healthcare & Educational Facilities Depertment, Takenaka Corporation for valuable comments. The author also thanks Jumpei Kawajiri, Suzuka University of medical science for research assistance.
53
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96