SYSTEMS-LEVEL QUALITY IMPROVEMENT

Evaluation of Electromagnetic Fields in a Hospital for SafeUse of Electronic Medical Equipment

Kai Ishida1 & Tomomi Fujioka2 & Tetsuo Endo2 & Ren Hosokawa3 & Tetsushi Fujisaki4 &

Ryoji Yoshino4 & Minoru Hirose3

Received: 30 August 2015 /Accepted: 16 November 2015 /Published online: 7 December 2015# Springer Science+Business Media New York 2015

Abstract Establishment of electromagnetic compatibility isimportant in use of electronic medical equipment in hospitals.To evaluate the electromagnetic environment, the electric fieldintensity induced by electromagnetic radiation in broadcastingspectra coming from outside the hospital was measured in anew hospital building before any patients visited the hospitaland 6 months after the opening of the hospital. Various incom-ing radio waves were detected on the upper floors, with nosignificant difference in measured levels before and after open-ing of the hospital. There were no cellphone terminal signalsbefore the hospital opened, but these signals were stronglydetected at 6 months thereafter. Cellphone base stations signalswere strongly detected on the upper floors, but there were nosignals at most locations in the basement and in the center ofthe building on the lower floors. A maximum electrical inten-sity of 0.28 V/m from cellphone base stations (2.1 GHz) wasdetected at the south end of the 2nd floor before the hospitalopened. This value is lower than the EMC marginal value for

general electronic medical equipment specified in IEC 60601-1-2 (3 V/m). Therefore, electromagnetic interferencewith elec-tronic medical equipment is unlikely in this situation.However, cellphone terminal signals were frequently detectedin non-base station signal areas. This is a concern, and under-standing signal strength from cellphone base stations at a hos-pital is important for promotion of greater safety.

Keywords Electromagnetic environment . Immunity . Radiowave . Cellphone .Measurement

Introduction

Establishment of electromagnetic compatibility (EMC) is im-portant for safe use of electronic medical equipment in hospi-tals because of possible electromagnetic interference (EMI)with this equipment caused by radio waves coming from out-side the hospital [1–5]. EMI may also occur between electron-ic medical equipment and radio waves emitted fromcellphones, wireless local area networks (W-LANs), and radiofrequency identification (RFID) tags [6–9].

Use of cellphones is restricted in most Japanese hospitalsbased on the BGuidelines for Use of Mobile Handsets toPrevent EMI with Electronic Medical Equipment^, publishedin 1997 by the Council for Countermeasures AgainstUnnecessary Electromagnetic Waves Japan [10]. However,usage regulation has liberalized gradually due to progressionof electronic medical equipment immunity and improvementof cellphone performance. By July 2012, all second genera-tion (2G) cellphone services had terminated, and only third(3G) and subsequent generation cellphones are now used inJapan. Electricity in the cellphone terminal varies dependingon the distance from the base station. The maximum electricalradiation emitted from a Japanese 2G cellphone (Personal

This article is part of the Topical Collection on Systems-Level QualityImprovement.

* Kai Ishidak-ishida@thcu.ac.jp

1 Division of Healthcare Informatics, Faculty of Healthcare, TokyoHealthcare University, Setagaya 3-11-3, Tokyo 154-8568, Japan

2 Advanced Technology Development Section, Building TechnologyDevelopment Department, Technology Center, Taisei Corporation,Nase-cho 344-1, Yokohama 245-0051, Japan

3 Department of Medical Safety Engineering, School of Allied HealthScience, Kitasato University, Kitasato 1-15-1, Sagamihara 252-0373,Japan

4 Environmental Survey Office, Shinbashi 3-7-7, Tokyo 105-0004,Japan

J Med Syst (2016) 40: 46DOI 10.1007/s10916-015-0411-3

Digital Cellular) terminal is 800 mW, and this could potential-ly invoke EMI with electronic medical equipment [10].However, the maximum emission from a Japanese 3Gcellphone terminal is only 200 or 250 mW. This value alsodecreases by a few mW if the terminals receive base stationsignals with good reception. Emission is much lower with aPersonal Handyphone System (PHS, maximum of 80mWandaverage of 10mW). Thus, EMI with electronic medical equip-ment is now relatively less likely.

In August, 2014, the old guidelines were replaced by theBGuidelines for Use of Mobile Phones and Other Devices inHospitals for Secure, Safe Use of Wireless CommunicationDevices in Hospitals^, which were announced at the JapanElectromagnetic Compatibility Conference (EMCC) [11].These new guidelines address key issues with regard to safeand secure use of cellphones, including separation, public use,protecting personal and medical information, an improvedstructure for EMC, and setting area-specific usage rules.Based on the new guidelines, use of cellphones in Japanesehospitals is expected to increase markedly.

Despite these improvements, the potential for EMI betweenelectronic medical equipment and a cellphone in a poor signalarea is still a concern. For example, it was reported that a ven-tilator can breakdown due to maximum electricity radiationfrom a Japanese 3G cellphone terminal at a distance of 50 cm[12]. This suggests that rapid deregulation may increase thepotential for EMI and indicates that knowledge of signalstrength from cellphone base stations in a hospital is importantto ensure greater safety in use of cellphones and electronicmedical equipment. Additionally, use of W-LAN and RFID-based clinical support systems, such as those used for electronichealth records, biological monitoring, location detection, andphysical distribution management, has also expanded in recentyears [13–18]. Thus, proof of the compatibility of electronicmedical equipment with communication devices is needed ashospitals introduce such wireless technology and products.

Each hospital needs to understand their current circum-stances to take adequate measures with regard to the back-ground electromagnetic environment. However, accuratemeasurement of this environment is difficult because radiowaves are also emitted in operation of electronic medicalequipment and communication devices, which are constantlyrunning, and patients and visitors bring electronic communi-cation devices that emit radio waves, such as cellphones, mo-bile routers, personal computers, and handheld games.

Therefore, to establish the basis for promoting greater safetyin use of cellphones and to evaluate the electromagnetic envi-ronment, measurements should be made after completion ofconstruction of a hospital, but before the opening of the hos-pital to patients, and again after opening of the hospital. In thisstudy, we had an opportunity to measure electromagneticwaves under these conditions, which allowed investigationof the electromagnetic environment at a newly-built hospital.Herein, we report the results of these measurements.

Methods

Location and Study Protocol

The hospital in which we measured the electromagnetic envi-ronment was the newly-built Kitasato University Hospital(KUH), located in Sagamihara, Kanagawa, in eastern Japan.Sagamihara is a mid-sized city with a population of 700,000,but KUH was built outside the metropolitan area. KUH has1000 beds in 21 wards, 20 operation rooms, a rooftop heliport,and about 2200 staff members. The new building has 14above-ground floors and one basement floor, with floors 7 to14 housing wards. All floors are 100 m in length and orientedeast to west. The total floor area is 92,776 m2 and the buildingis 70 m tall. The hospital opened in May 2014. The medicalschool of Kitasato University (a nine-story building) is locatednext to KUH. There are no buildings exceeding 70m in heightaround KUH.

The study included wideband measurements and cellphonebase station measurements. Both types of measurements wereconducted before and after opening of the hospital, during theday (from 9 a.m. to 5 p.m.). Wideband measurements weremade in February toMarch 2014 and August 2014. Cellphonebase station measurements were made in February 2014 andFebruary 2015. After the hospital opened, we had to considerthe care and privacy of patients. Therefore, we did not mea-sure locations in which medical care was provided, such aspatient rooms, intensive care units (ICU), consultation rooms,physiological laboratories, and X-ray examination rooms.

Wideband Measurements

To determine the pure electromagnetic environment before thehospital opened (propagating only from incoming radio

Table 1 Measurements detail inthe wideband measurements Frequency range RBW VBW Antenna type Distributor Remarks

30 to 300 MHz 100 kHz 100 kHz ARA01 York EMC Service Dipole antenna

300 to 1000 MHz 100 kHz 100 kHz AT1222 ANTTEC Biconical antenna

1 to 3 GHz 1 MHz 1 MHz AT1223 ANTTEC Biconical antenna

RBW Resolution band width, VBW Video band width

46 Page 2 of 11 J Med Syst (2016) 40: 46

waves, since electronic equipment was not in operation), thefrequency distribution of the electric field intensity induced byradio waves coming from outside was measured at 73 loca-tions in the building, including outpatient clinics, wards,

corridors, operation rooms, treatment rooms, and ICUs. Thesame measurements were performed 6 months after the hos-pital opened to determine the affect of operation of electronicequipment and traffic. In both measurements, the frequency

Table 2 Measured radio waves before the hospital opened

Frequency (MHz) Purpose Locations

B1 1F 3F 4F 12F 14F

C N E W S C DT S C OP N E W S S

13.56 RFID for authentication

76–90 FM radios ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○95–108 Multimedia broadcast ○120 Aeronautical radios ○ ○126.3 Automatic terminal information service (ATIS) ○ ○ ○ ○155.8 Police scanner ○ ○ ○ ○ ○ ○ ○ ○ ○170–205 Public wideband mobile communication systems ○ ○ ○ ○ ○ ○ ○ ○ ○205–220 Multimedia broadcast ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○222–253.8 Public wideband mobile communication systems ○ ○ ○ ○ ○270–275 Public mobile communication ○ ○ ○ ○ ○ ○ ○ ○ ○ ○278–285 Aeronautical radios ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○335–347 Public affairs radio ○ ○ ○ ○ ○ ○351 Convenience radios ○ ○ ○ ○ ○ ○360 Police scanner ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○384 Public affairs radio ○ ○ ○ ○ ○ ○406 Mobile satellite service ○ ○ ○ ○ ○ ○ ○ ○ ○425.4 Medical telemeters ○430–440 Ham radios ○ ○ ○ ○ ○ ○ ○440–450 Medical telemeters ○450–459 Public affairs radio ○ ○ ○ ○ ○ ○ ○ ○466.3 fire radios

488–566 UHF televisions ○ ○ ○ ○ ○ ○ ○815–845 Cellphone units

850–890 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○900–915 Cellphone units ○ ○945–950 Cellphone base station ○ ○ ○ ○ ○1090.5 Aeronautical radios ○ ○1255 Broadcast system ○ ○ ○ ○1300–1400 Space service radios ○ ○ ○ ○1427.9–1462.9 Cellphone units

1475.9–1510.9 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○1749.9–1784.9 Cellphone units

1839–1879 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○ ○1884–1919 Personal handyphone system (PHS) ○ ○ ○ ○ ○ ○ ○ ○1920–1980 Cellphone units

2110–2170 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○2400–2500 Wireless LAN ○ ○ ○ ○ ○ ○ ○2550–2650 WiMAX base station ○ ○ ○ ○ ○

N, E, W, S: North, East, West, South ends of the hospital; C: Center (center of floor); DT, Dialysis treatment (located in the northeast corner of the 3rdfloor); OP, Operation room (located in the southwest corner of the 4th floor)

J Med Syst (2016) 40: 46 Page 3 of 11 46

ranged from 30MHz to 3 GHz. The electric field intensity wasmeasured in vertical and horizontal polarizations with a spec-trum analyzer (MS2721B, Anritsu) and specific antennas. Theantenna was erected 150 cm above the floor. Antenna types,

resolution bandwidth (RBW) and video bandwidth (VBW) ineach frequency range are shown in Table 1. The strongestelectrical intensity for all measured frequencies was recordedusing a maximum hold function for half a minute. After

Table 3 Measured radio waves after the hospital opened

Frequency (MHz) Purpose Locations

B1 1F 3F 4F 12F 14F

C E W S C DT S C OP N E W S S

13.56 RFID for authentication ○ ○ ○ ○76–90 FM radios ○ ○ ○ ○ ○ ○ ○ ○ ○95–108 Multimedia broadcast ○120 Aeronautical radios ○126.3 Automatic terminal information service (ATIS) ○ ○ ○ ○155.8 Police scanner ○ ○ ○ ○ ○ ○170–205 Public wideband mobile communication systems ○ ○ ○ ○ ○ ○205–220 Multimedia broadcast ○ ○ ○ ○ ○ ○ ○ ○222–253.8 Public wideband mobile communication systems ○ ○ ○270–275 Public mobile communication ○ ○ ○ ○ ○ ○278–285 Aeronautical radios ○ ○ ○ ○ ○ ○ ○ ○ ○335–347 Public affairs radio ○ ○ ○ ○ ○351 Convenience radios ○ ○ ○ ○ ○360 Police scanner ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○384 Public affairs radio ○ ○ ○ ○ ○406 Mobile satellite service ○ ○ ○ ○ ○425.4 Medical telemeters ○ ○ ○ ○ ○430–440 Ham radios ○ ○ ○ ○440–450 Medical telemeters ○ ○ ○ ○450–459 Public affairs radio ○ ○ ○ ○466.3 fire radios ○ ○ ○ ○ ○ ○ ○488–566 UHF televisions ○ ○ ○ ○ ○815–845 Cellphone units ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○850–890 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○900–915 Cellphone units ○ ○945–950 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○1090.5 Aeronautical radios ○ ○ ○1255 Broadcast system ○ ○ ○1300–1400 Space service radios ○ ○ ○ ○ ○1427.9–1462.9 Cellphone units ○ ○ ○ ○ ○ ○ ○ ○1475.9–1485.9 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○ ○1749.9–1759.9 Cellphone units ○ ○ ○ ○ ○ ○ ○1839–1879 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○ ○1884–1919 Personal handyphone system (PHS) ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○1920–1980 Cellphone units ○ ○ ○ ○ ○ ○ ○ ○2110–2170 Cellphone base station ○ ○ ○ ○ ○ ○ ○ ○ ○ ○2400–2500 Wireless LAN ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○2500–2600 WiMAX base station ○ ○ ○ ○ ○ ○ ○ ○ ○

N, E, W, S: North, East, West, South ends of the hospital; C: Center (center of floor); DT, Dialysis treatment (located in the northeast corner of the 3rdfloor); OP, Operation room (located in the southwest corner of the 4th floor)

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measurement, we determined the usage of recorded signalsfrom a frequency table and analyzed the frequency dis-tribution and electric intensity related to cellphone ter-minals and base stations at each location [19]. Datawere recorded in dBm units and the results were convertedto V/m to match the immunity evaluation unit for electronicmedical equipment.

Cellphone Base Station Measurements

Single frequency bands from cellphone base stations wererecorded to determine the change of signal strength due tocellphone terminals in each location. The measured frequencyranged from 2.13 to 2.15 GHz. This frequency band isassigned to the 3G cellphone system (Wideband CodeDivision Multiple Access). Electric intensity was measuredwith a spectrum analyzer (MS2713E, Anritsu) and dipole an-tenna (ED-B033S-C3, ANTTEC). Data were recorded indBμV units. Measurements were performed at 230 locationsbefore the hospital opened and at 112 locations after the hos-pital opened. Measured locations were selected for as manyfloors as possible.

Results

Wideband Measurements

Radio waves detected at each location before and after thehospital opened are shown in Tables 2 and 3, respectively.Frequency modulated (FM) radio signals (70 to 85 MHz),aeronautical radios (278 to 285 MHz), community wirelesssystems (270 to 275 MHz), multimedia broadcasting servicesfor cellphones (207 to 220 MHz), police scanners (360 MHz),ultra-high frequency (UHF) televisions (488 to 566 MHz),cellphone base stations (850 to 900 MHz, 1475.9 to1510.9 MHz, 1844.9 to 1879.9 MHz, and 2.11 to2.17 GHz), and Worldwide Interoperability for MicrowaveAccess base stations (2.55 to 2.65 GHz) were recorded at highintensity at the windows of upper floors. Cellphone base sta-tions were particularly detected at all points on upper floors.On the lower floors, cellphone base stations were detected at

many locations, but broadcast waves were rarely recorded.Automatic terminal information service (126.3 MHz) was de-tected at windows on the south side. This signal was comingfrom Camp Zama (a United States Army base located in thecities of Zama and Sagamihara, about 5 km south of KUH).There were no incoming radio waves in spaces enclosed bymetallic materials, such as operation rooms and radiologicalareas. There was no significant difference in these recordedlevels before and after the hospital opened. However,cellphone terminal signals and W-LAN using the 2.4 GHzband were frequently detected at various locations after open-ing of the hospital.

The frequency, value, polarization, and radio wave usageof detected electric field intensities of >0.1 V/m (100dBμV/m) are shown in Table 4. The maximum electrical in-tensity measured in this study was 108.796 dBμV/m (0.28 V/m) associated with cellphone base stations (2127 MHz),which was observed on the south end of the 2nd floor beforethe hospital opened. After the hospital opened, cellphone basestation signals were recorded at many locations, but there werevery few signals in the operation rooms, dialysis treatmentcenter, center of the building, and basement. Cellphone termi-nal signals were recorded at 42 locations and 210 signals were

Table 4 Measured radio waves with intensity ≥0.1 V/m

Timing Floor Location Room Frequency (MHz) Intensity (V/m) Purpose Polarization

Before the hospital opened 2 End of south side Meeting room 2127 0.28 Cellphone base station Vertical

2 End of south side Meeting room 2127 0.15 Cellphone base station Horizontal

After the hospital opened 12 Southwest of east side Ward Corridor 1848 0.11 Cellphone base station Horizontal

12 Center of west side Nurse station 1897 0.14 PHS Horizontal

4 End of south side Staff lounge 2115 0.1 Cellphone base station Vertical

2 Center of hospital Main hallway 2416 0.14 W-LAN Vertical

Table 5 Detected cellphone unit frequencies with no correspondingbase station signals

Floor Location Frequency (MHz) Remarks

B1 Elevator hall 834.2 3G/4G

B1 Elevator hall 1932.8 3G/LTE

B1 Elevator hall 1954.5 3G

2F Corridor 833.5 3G/4G

2F Corridor 1430 3G

3F Dialysis treatment 1945.7 3G/LTE

3F Dialysis treatment 1975.67 3G

3F Corridor 1950.4 3G/LTE

3F Elevator hall 1450.2 4G

3F Elevator hall 1780.3 LTE

4F Corridor of Operation Room 1943.6 3G/LTE

4F Entrance of Operation Room 832.9 3G/4G

4F Entrance of Operation Room 1773.6 LTE

J Med Syst (2016) 40: 46 Page 5 of 11 46

detected, of which 13 did not correspond to base station sig-nals (Table 5).

Cellphone Base Station Measurements

Measured electric field intensities on each floor before andafter the hospital opened are shown in Figs. 1, 2, 3, 4, and 5.The color of circles indicates the received strength: blue indi-cates good reception with intensity of 60 to 70 dBμV; redindicates poor reception, but possible communication, withintensity of 20 to 30 dBμV; and black indicates no reception

or out of service, with intensity <20 dBμV. Before the hospitalopened, electric field intensity indicating good reception wasdetected at various locations on the upper floors. On the lowerfloors, the intensity was high near the windows, but decreasedin the center of building. Out of service measurements weremade at most locations in the basement. After the hospitalopened, the overall electric field intensity was lower, but no-table intensity was detected in the center of the building on thelower floors. From before to after the hospital opened, signalsdecreased by a mean of 3 dBμVat all locations, but those onfloor 14 decreased by a mean of 6 dBμV.

Fig. 1 Cellphone base stationsignal strength (B1F) before (up-per panel) and after(lower panel) the hospital opened

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Discussion

Previous measurements of the electromagnetic environmentin hospitals have been conducted at only one time point, eitherbefore or after opening of the hospital. In this study, we mea-sured electromagnetic waves at a newly-built hospital prior toopening and then repeated the measurements after opening ofthe hospital. Changes in the electromagnetic environmentwere found after opening of the hospital due to operation ofelectrical and communication devices and turnover in the pop-ulation. Japanese radiofrequency clearance has changed sig-nificantly over the past years, in part through expansion of

frequency bands allocated for cellphones resulting from ter-mination of the analog TV broadcasting service in 2012. Thus,our results provide a current model for evaluation of the elec-tromagnetic environment at a modern Japanese hospital.

Before the hospital opened, incoming radio waves werefrequently recorded, but there were few signals from commu-nication devices brought in by patients, visitors or medicalstaff. None of the measuring crew used a cellphone, PHS, orother communication devices. Thus, the results before thehospital opened reflect the electromagnetic environmentbased only on incoming radio waves in the hospital, with noeffects of communication device signals and device-driven

Fig. 2 Cellphone base stationsignal strength (1F) before(upper panel) and after(lower panel) the hospital opened

J Med Syst (2016) 40: 46 Page 7 of 11 46

radio waves or noise. At some locations, PHS and 2.4 GHzband radio waves were occasionally detected before the hos-pital opened, but these were relatively weak and came from anold building next to the new building.

After the hospital opened, PHS, cellphone terminals, andradio waves in the 2.4 GHz band were detected frequently andrelative strongly. Medical staff also used a PHS. Many W-LAN access points had been installed at KUH and these radi-ated 2.4 GHz band radio waves for use of the hospital infor-mation system, computerized patient and nursing records, anda picture archiving and communication system in most loca-tions. Medical staff, patients, and visitors also brought their

own communication devices, including cellphones, which arealmost always powered, even if not in use.

A survey at a modern urban university hospital in Japanfound a maximum electrical intensity of 200 V/m at 2.79 GHzfrom airport surveillance radar waves [4]. This value is ex-tremely high and could invoke EMI with electronic medicalequipment. However, other radio waves such as UHF televi-sion signals, land mobiles, and cellphone base stations werealmost always <1 V/m in this hospital. At an urban universityhospital located about 600 m from the Tokyo Tower (a com-munication tower that radiated broadcasting waves until2013), the maximum electrical intensity was <1 V/m in the

Fig. 3 Cellphone base stationsignal strength (2F) before(upper panel) and after(lower panel) the hospital opened

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170 to 222 MHz band from analog TV broadcasting [5]. At afew US hospitals, the average electrical intensity due to in-coming radio waves was found to be about 0.03 V/m [3]. Ourresults are similar to these findings. The maximum electricalintensity detected in this study was 109 dBμV/m (0.28 V/m),associated with cellphone base stations (2127 MHz). Thisvalue is lower than the EMC marginal value of general elec-tronic medical equipment, as specified in IEC 60601-1-2 (3 V/m) [20]. Therefore, a serious problem of EMI with electronicmedical equipment is extremely unlikely in this situation.Moreover, after the hospital opened, the maximum electricintensities were 0.14 V/m, associated with PHS terminalsand W-LAN. This value was higher than that for incoming

radio waves, which indicates that radio waves from inside thehospital were more important than incoming radio waves.

Electrical intensity associated with cellphone terminals issubject to the electrical intensity of the base station radiowave. While out of service, Japanese 3G cellphone terminalsradiate a maximum electrical intensity (200 or 250 mW)searching for base stations with which to communicate. Thiselectrical intensity could potentially invoke EMI with elec-tronic medical equipment. In KUH, use of a cellphone (fore-mail, internet, and games) is allowed in all areas, except forconsultation rooms, operation rooms, ICUs, and emergencymedical care centers. This is because electronic medicalequipment susceptible to EMI, such as remote patient

Fig. 4 Cellphone base stationsignal strength (4F) before(upper panel) and after(lower panel) the hospital opened

J Med Syst (2016) 40: 46 Page 9 of 11 46

monitors, infusion and syringe pumps, and electrocardio-graphs, are used in these rooms. Telephone calls are allowedin cafeterias, waiting rooms, corridors, elevator halls, and pa-tient rooms. However, using a smartphone as a Wi-Fi router,commonly known as Btethering^, is restricted in KUH toavoid interference with the hospital W-LAN.

In this study, weak signals radiating from the 2.13 to2.15 GHz band from cellphone base stations were recordedafter the hospital opened, but not before opening. Dependingon traffic and installation of certain equipment, incoming ra-dio waves reaching the center of the building were proportion-ally damped. There were no cellphone base station signals inthe basement, in part of the corridor (in the center ofthe hospital), in operation rooms, and in the hemodial-ysis unit. However, strong cellphone terminal signalswere detected in several locations, including these areas,in which electronic medical equipment is routinely used.Therefore, our results indicate that EMI with electronicmedical equipment by a cellphone terminal is a poten-tial concern.

The EMCC suggested a separation distance of about onemeter from a cellphone to electronic medical equipment [11].van Lieshout et al. suggested that the policy of keeping

cellphones one meter from critical care bedside equipment incombination with easily accessed areas of unrestricted is suf-ficient to eliminate most EMI of 3G cellphone terminals withelectronic medical devices [21]. The EMCC suggested that ifhospitals can confirm safety based on their own results andusing instruction manuals for specific electronic medicalequipment, a separation distance of lower than one metermay be acceptable [11].

Establishing femtocell base stations is likely to expandcoverage inside hospitals with poor signal quality [22].Around a femtocell base station, the radiation level of cellularaccess to the base station becomes lower under specific con-ditions, compared with a distant base station. There is lessEMI with radio waves from a cellphone for surrounding elec-tronic medical equipment. KUH plans to install these basestations in the near future. However, this installation is costlyand improvement of the electromagnetic environment may belimited. If the hospital permits the use of all types ofcellphones, base stations will have to correspond to all fre-quencies of signals and all communication systems, excludingthose before 2G. Presently, there are 6 frequency bands pro-vided by 4 service carriers in Japan. It would be useful foreach hospital to have femtocell base stations, but the cost,

Fig. 5 Cellphone base stationsignal strength (12F) before (up-per panel) and after(lower panel) the hospital opened

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limited improvements, and the need to facilitate all servicesprohibit introduction of these base stations in many hospitals.

Our results suggest that use of cellphones was safe on theupper floors, but that this use requires consideration on thelower floors, and especially in the basement and in the centerof the building. To promote greater EMC safety, it would bedesirable for each hospital to measure the electrical intensityof cellphone base station signals in areas in which electronicmedical equipment is used and to establish appropriate rulesfor use of cellphones based on measurement of the electro-magnetic environment.

Conclusion

The electromagnetic environment in a new university hospitalbuilding was compared before and after the hospital opened.No radio waves with extremely strong intensity signals weredetected. There were also no cellphone base station signals,but very strong cellphone terminal radio waves were detectedon several floors. This is a concern for EMI and it would bedesirable to improve these conditions.

Acknowledgments This work was supported by JSPS KAKENHIGrant Number 15 K21461.

Compliance with Ethical Standards

Conflict of Interest The authors declare that they have no conflict ofinterest.

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