**5. Results**

*E V AF ATT* =+ + (1)

*<sup>E</sup> S EH* = = (2)

(3)

. The EIRP was calculated using

Where E is the electric field strength (dBuV/m), V is the measured voltage (dBuV), AF is the antenna factor (dBm−1), and ATT is the cable attenuation (dB). After obtaining the horizontal and vertical components, the total field strength was calculated. The power density was

> 2 377

Where the unit of S is W/m2 and E has now been converted to linear units. The EIRP of each tested device was calculated for comparison with the emission limit of 16.4 mW set by standard regulations [15][17]. EIRP is the power that would have to be emitted if the antenna were isotropic in order to produce a power density equal to that observed in the direction of

> 2 max *EIRP r S* = 4p

Where EIRP is in units of W, r is the distance to the antenna in meters, and Smax(r) is the

the maximum measurement of power density, so the measurements of the electric field

This research addresses the characterization of EM environments that are actually present in households, taking into account an analysis of the potential safe usage of domestic telemedi‐ cine systems. The data had been analysed with regard to potential risks and operational

The field strength recorded from the tested devices have been compared with the correspond‐ ing International Commission on Non-ionizing Radiation Protection (ICNIRP) reference levels

It is also useful to compare the obtained levels with the thresholds for the safety and basic performance of the electromedical equipment. The International Electrotechnical Commission (IEC) Standard IEC 60601-1-2 [19], sets a minimum immunity level of 3 (V/m) for non-life

After calculating the parameters that characterize the emissions of the social alarm devices under testing, the results recorded are compared with the limit values set by the national and international bodies: Commission Implementing Decision of 8 December 2011 amending

values defined for the general public depending on the working frequency [18].

derived using the following equation:

152 Telemedicine

maximum gain of the actual antenna.

The EIRP is obtained from the power density as follows:

maximum power density measured at each distance in W/m2

strength were realized in the direction of maximum radiation.

disturbances in accordance with existing European standards.

**c. Compliance with exposure levels threshold**

supporting devices.

#### **a. Review of literature**

Although most of the papers collected only partially cover the subject matter, the research performed for this chapter clearly demonstrates the high number of publications related to SRD in healthcare during recent years.

The number of papers seems to have increased significantly since 2001 as Figure 6 shows. The 248 papers finally included in our review were classified into six categories.

**Figure 6.** Papers which mention SRD technology in healthcare from 2001 to 2011 (Npapers: 248)

However, it is important to note the lack of publications which evaluate the effectiveness of SRD in real healthcare scenarios and most of the studies found only cover technological issues as is shown in Figure 7.

In this work, the two categories which are of most interest to the authors are AAL and monitored environments. Both characterize more complex scenarios, where SRD are combined with sensors to work together in a wireless network, finally connected to remote information repositories of data and software, as presented in Figure 1. Reducing hospital admissions and length of stay are main objectives in order to save economic and human resources, as well as to improve a patient's quality of life. However, most of these outpatients are elderly, or have

**Figure 7.** Applications Areas in terms of functionality (Npapers: 248)

a temporary or permanent disability, and many have no caregivers to help and technological advances can be very useful to fulfill that goal. From 2007, as shown in Figure 8, the number of papers dedicated to these two categories has been increased.

**Figure 9.** Technologies shown in papers for healthcare environments (Npapers: 95)

Different types of social alarm devices have been analyzed taking into account their emission features, the type of wireless technology, etc... This work presents a comparison of these systems in terms of their working conditions, and parameters that provide information about

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Figure 10 shows the variation of the power density as a function of the distance for the tested devices operating at 869.21 MHz. The power density calculated from an EIRP equal to 16.4 mW limit is shown for comparison. The ordinate axis is represented in logarithmic scale to improve the comparison between the obtained results and the set limit of 16.4 mW. Overall,

**b. Measurements: electromagnetic laboratory evaluation**

the emission levels.

**Figure 8.** Papers dedicated to AAL and monitored environments (Npapers: 95)

Figure 9 shows the different technologies that can provide useful help to patients, healthcare professionals, caregivers and families in emergent healthcare environments. There is a lack of published papers in the years 2001 and 2003.

**Figure 9.** Technologies shown in papers for healthcare environments (Npapers: 95)

#### **b. Measurements: electromagnetic laboratory evaluation**

a temporary or permanent disability, and many have no caregivers to help and technological advances can be very useful to fulfill that goal. From 2007, as shown in Figure 8, the number

Figure 9 shows the different technologies that can provide useful help to patients, healthcare professionals, caregivers and families in emergent healthcare environments. There is a lack of

of papers dedicated to these two categories has been increased.

**Figure 7.** Applications Areas in terms of functionality (Npapers: 248)

154 Telemedicine

**Figure 8.** Papers dedicated to AAL and monitored environments (Npapers: 95)

published papers in the years 2001 and 2003.

Different types of social alarm devices have been analyzed taking into account their emission features, the type of wireless technology, etc... This work presents a comparison of these systems in terms of their working conditions, and parameters that provide information about the emission levels.

Figure 10 shows the variation of the power density as a function of the distance for the tested devices operating at 869.21 MHz. The power density calculated from an EIRP equal to 16.4 mW limit is shown for comparison. The ordinate axis is represented in logarithmic scale to improve the comparison between the obtained results and the set limit of 16.4 mW. Overall, the power density plots calculated from maximum electric field strength as a function of distance broadly follow the expected inverse-square dependence on the distance. power density calculated from an EIRP equal to 16.4 mW limit is shown for comparison. The ordinate axis is represented in logarithmic scale to improve the comparison between the obtained results and the set limit of 16.4 mW. Overall, the power density plots calculated from maximum electric field strength as a function of distance broadly follow the expected inverse-square

Different types of social alarm devices have been analyzed taking into account their emission features, the type of wireless

Figure 10 shows the variation of the power density as a function of the distance for the tested devices operating at 869.21 MHz. The

**D(m) E(mV/m) S(mW/m2) PIRE(mW) E(mV/m) S(mW/m2) PIRE(mW)**

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**D(m) E(mV/m) S(mW/m2) PIRE(mW) E(mV/m) S(mW/m2) PIRE(mW)** 1 83,361 0,018 0,232 125,115 0,042 0,522 1,1 85,096 0,019 0,292 104,006 0,029 0,436 1,2 76,252 0,015 0,279 72,701 0,014 0,254 1,3 73,644 0,014 0,306 83,463 0,018 0,392 1,4 73,285 0,014 0,351 68,100 0,012 0,303 1,5 64,293 0,011 0,310 94,780 0,024 0,674 1,6 75,860 0,015 0,491 84,643 0,019 0,611 1,7 59,532 0,009 0,341 81,043 0,017 0,633

**Table 2.** Maximum electric field strength, power density, and EIRP for two models of the tested devices: (a) AMIE+

The recorded values of EIRP are well below the level that would be expected based on 16.4 mW, set by the national and international regulations: Commission Implementing Decision of 8 December 2011 amending Decision 2006/771/EC on harmonisation of the radio spectrum for use by short-range devices (2011/829/EU) [15], and the Spanish National Table of Spectrum Location (ITC/332/2010) [17], so the tested social alarm devices operate in safe conditions under

This research identifies relevant studies which exemplify the penetration of SRD in new healthcare environments in real work flows. The evaluation of the methodological quality of studies has not been an easy task because of the heterogeneity of the papers included in the

0,2 310,662 0,256 0,129 419,038 0,466 0,234 0,3 249,879 0,166 0,187 283,527 0,213 0,241 0,4 219,518 0,128 0,257 289,373 0,222 0,447 0,5 196,383 0,102 0,321 267,815 0,190 0,598 0,6 164,764 0,072 0,326 243,292 0,157 0,710 0,7 142,712 0,054 0,333 215,788 0,124 0,761 0,8 134,910 0,048 0,388 138,447 0,051 0,409 0,9 105,952 0,030 0,303 146,854 0,057 0,582

**Device (a) Device (b)**

**Device (a) Device (b)**

Tunstall, (b) Neat Atom

the set limits of EIRP.

**6. Discussions**

Figure 9. Technologies shown in papers for healthcare environments (Npapers: 95)

**b. Measurements: electromagnetic laboratory evaluation** 

Figure 10.Variation of the power limit and the EIRP limit in function of distance for the five tested alarm devices: (a) AMIE+ Tunstall, (b) Neat Atom, (c) TX4 Bosch, (d) S37 TeleAlarm and (e) System 5000 Smart Call. **Figure 10.** Variation of the power limit and the EIRP limit in function of distance for the five tested alarm devices: (a) AMIE+ Tunstall, (b) Neat Atom, (c) TX4 Bosch, (d) S37 TeleAlarm and (e) System 5000 Smart Call.

Table 2 shows the values of the maximum electric field strength (E), power density (S), and EIRP as a function of the distance, for two of the selected models of the social alarms devices, (a) AMIE+ Tunstall, and (b) Neat Atom.

#### **c. Compliance with exposure levels threshold**

dependence on the distance.

ICNIRP guidelines contain reference levels expressed as values of the electric field strengths and power density that can be compared with measured or calculated values. All the field strengths recorded in this study are well below the corresponding ICNIRP reference level of 40 V/m defined for the general public at the working frequency (869.21 MHz) [18]. It means that electric field strength levels in healthcare home environments are apparently safe according to the health and safety requirements on the exposure of patients, professionals and the general public for protection against possible health effects from nonionizing radiation. The exposure levels thresholds stablished by the ICNIRP are shown in Figure 11.

The reference levels are not intended as limits, but are designed in such a way that complicance with them should ensure compliance with more fundamental basic restrictions.

One prominent concern to take into account is the possible interferences with medical devices. The IEC electromedical devices standard, IEC 60601-1-2 (IEC, 2002), permits radiatedimmunity testing of non-life-supporting and life-supporting equipment from 80 MHz to 2,5 GHz, and safety distance limits for patient-coupled devices. This standard sets a minimum immunity level of 3 V/m for non-life supporting devices [19]. Examining the results, the maximum value of the electric field is much lower than the 3 V/m.

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**Table 2.** Maximum electric field strength, power density, and EIRP for two models of the tested devices: (a) AMIE+ Tunstall, (b) Neat Atom

The recorded values of EIRP are well below the level that would be expected based on 16.4 mW, set by the national and international regulations: Commission Implementing Decision of 8 December 2011 amending Decision 2006/771/EC on harmonisation of the radio spectrum for use by short-range devices (2011/829/EU) [15], and the Spanish National Table of Spectrum Location (ITC/332/2010) [17], so the tested social alarm devices operate in safe conditions under the set limits of EIRP.

## **6. Discussions**

the power density plots calculated from maximum electric field strength as a function of

**Power density**

**Distance (m)**

**Figure 10.** Variation of the power limit and the EIRP limit in function of distance for the five tested alarm devices: (a)

Table 2 shows the values of the maximum electric field strength (E), power density (S), and EIRP as a function of the distance, for two of the selected models of the social alarms devices,

ICNIRP guidelines contain reference levels expressed as values of the electric field strengths and power density that can be compared with measured or calculated values. All the field strengths recorded in this study are well below the corresponding ICNIRP reference level of 40 V/m defined for the general public at the working frequency (869.21 MHz) [18]. It means that electric field strength levels in healthcare home environments are apparently safe according to the health and safety requirements on the exposure of patients, professionals and the general public for protection against possible health effects from nonionizing radiation.

The reference levels are not intended as limits, but are designed in such a way that complicance

One prominent concern to take into account is the possible interferences with medical devices. The IEC electromedical devices standard, IEC 60601-1-2 (IEC, 2002), permits radiatedimmunity testing of non-life-supporting and life-supporting equipment from 80 MHz to 2,5 GHz, and safety distance limits for patient-coupled devices. This standard sets a minimum immunity level of 3 V/m for non-life supporting devices [19]. Examining the results, the

The exposure levels thresholds stablished by the ICNIRP are shown in Figure 11.

with them should ensure compliance with more fundamental basic restrictions.

maximum value of the electric field is much lower than the 3 V/m.

Different types of social alarm devices have been analyzed taking into account their emission features, the type of wireless technology, etc... This work presents a comparison of these systems in terms of their working conditions, and parameters that

Figure 10 shows the variation of the power density as a function of the distance for the tested devices operating at 869.21 MHz. The power density calculated from an EIRP equal to 16.4 mW limit is shown for comparison. The ordinate axis is represented in logarithmic scale to improve the comparison between the obtained results and the set limit of 16.4 mW. Overall, the power density plots calculated from maximum electric field strength as a function of distance broadly follow the expected inverse-square

> 16.4mW limit device (a) device (b) device (c) device (d) device (e)

Figure 10.Variation of the power limit and the EIRP limit in function of distance for the five tested alarm devices: (a) AMIE+ Tunstall, (b) Neat

distance broadly follow the expected inverse-square dependence on the distance.

Figure 9. Technologies shown in papers for healthcare environments (Npapers: 95)

**b. Measurements: electromagnetic laboratory evaluation** 

Atom, (c) TX4 Bosch, (d) S37 TeleAlarm and (e) System 5000 Smart Call.

AMIE+ Tunstall, (b) Neat Atom, (c) TX4 Bosch, (d) S37 TeleAlarm and (e) System 5000 Smart Call.

provide information about the emission levels.

dependence on the distance.

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**Power density mWm‐2**

(a) AMIE+ Tunstall, and (b) Neat Atom.

**c. Compliance with exposure levels threshold**

This research identifies relevant studies which exemplify the penetration of SRD in new healthcare environments in real work flows. The evaluation of the methodological quality of studies has not been an easy task because of the heterogeneity of the papers included in the

provided by harvesting devices alone, rendering power and energy-aware wireless sensor node design even more important. As well as this, the sensors need to be carried conveniently without disturbing the users' normal way of life: small in size, with low power consumption,

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159

The fact that in the field of healthcare applications the most studied technology is Bluetooth, as shown in figure 9, and that the percentage of studies dedicated to the assessment of the technology is higher than any other, leads to an important lack of publications on EM risk

The use of SRD in assisted environments provides a lot of benefits and an important advance in the monitoring of patients and the elderly, improving the efficiency and the quality. But these successful factors may be accompanied by drawbacks if thresholds of exposure to electromagnetic fields are exceeded and if wireless networks cause degradation in electronic medical devices, which could potentially result in deaths, serious injuries, or administration of inappropriate treatment. The study of these critical successful factors can guide not only in the promotion, but also in the prevention in the use of SRD in healthcare applications. Therefore, the new implemented healthcare solutions must consider issues with respect to

Concretely, the conclusion of the analysis of Figure 7 and Figure 9 is that there are no previous studies about AAL and monitored environments based on social alarms devices operating at 869.21 MHz, and even less about the evaluation of the EMF levels in healthcare environments, despite the fact that these social alarm devices are very widely spread in the monitoring of

Therefore, one of the main objectives of this study is to quantify the exposure of people, and to analyse the compatibility between equipment and networks in monitored environments by social alarms devices. The electric field strength and the EIRP are well within the guidelines set by the ICNIRP, the IEC, and the thresholds set by standard regulations. It means that electric field strength levels in healthcare home environments are apparently safe according to the operational, health, and safety requirements on the exposure of patients, professionals and the general public for protection against possible health effects from nonionizing radiation.

Although one of the findings of this study is the development of an environmental study of the working conditions of the social alarm devices, it is also important to consider the absorp‐ tion of radiofrequency energy in the body of a person that wears the device. ICNIRP guidelines are also expressed in terms of specific absorption rate (SAR), measured in W/Kg, in the body tissues. To address this, a parallel study should be carried out to measure the localized SAR

On the whole, this chapter presents an overview of the current literature regarding the ratio of penetration as well as their real effectiveness. It provides physicists, patients and healthcare

arising from social alarm devices in the people that wear them.

exposure and EMC between wireless networks and medical equipment.

and using wireless communications.

EMC and regulatory compliance.

daily activities of the elderly.

**7. Conclusion**

**Figure 11.** ICNIRP reference levels and the lower limit at working frequency of social alarm devices (869.21 MHz)

review. There are a lack of published papers in the years 2001 and 2003, as is shown in Figure 6. Most of the papers included only partially cover the subject matter.

The research performed for this chapter clearly demonstrates the high number of publications on technology assessments. However, despite the large number of studies found, there is a lack of publications evaluating effectiveness of SRD and most of the studies only cover technological assessment issues as can be observed in Figure 7. The absence of homogeneous criteria among authors to choose keywords to describe their papers may have an undesirable consequence: an indeterminate number of papers may have been omitted by search engines.

After reviewing the works it can be stated that wireless sensor nodes will play a key role in enabling the ubiquitous and proactive health monitoring and health care services of the future. To achieve the small form factors required, the reduction of node power consumption eliminates the need for large batteries and increases the energy autonomy of the node, hence reducing the amount of maintenance required. In this work several short range technologies for biomedical monitoring have been described in detail.

Future SRD and wireless sensor network applications in the health care domain are likely to require an even greater amount of data derived from a multitude of different sensors. The algorithms employed within these applications will become computationally more complex, resulting in a higher processing effort. Also, depending on the use of case scenarios, multi‐ sensory applications put higher demands on radio transmission. At the same time, the new care environments should operate on very small energy budgets, occasioanly using energy provided by harvesting devices alone, rendering power and energy-aware wireless sensor node design even more important. As well as this, the sensors need to be carried conveniently without disturbing the users' normal way of life: small in size, with low power consumption, and using wireless communications.

The fact that in the field of healthcare applications the most studied technology is Bluetooth, as shown in figure 9, and that the percentage of studies dedicated to the assessment of the technology is higher than any other, leads to an important lack of publications on EM risk exposure and EMC between wireless networks and medical equipment.

The use of SRD in assisted environments provides a lot of benefits and an important advance in the monitoring of patients and the elderly, improving the efficiency and the quality. But these successful factors may be accompanied by drawbacks if thresholds of exposure to electromagnetic fields are exceeded and if wireless networks cause degradation in electronic medical devices, which could potentially result in deaths, serious injuries, or administration of inappropriate treatment. The study of these critical successful factors can guide not only in the promotion, but also in the prevention in the use of SRD in healthcare applications. Therefore, the new implemented healthcare solutions must consider issues with respect to EMC and regulatory compliance.

Concretely, the conclusion of the analysis of Figure 7 and Figure 9 is that there are no previous studies about AAL and monitored environments based on social alarms devices operating at 869.21 MHz, and even less about the evaluation of the EMF levels in healthcare environments, despite the fact that these social alarm devices are very widely spread in the monitoring of daily activities of the elderly.

Therefore, one of the main objectives of this study is to quantify the exposure of people, and to analyse the compatibility between equipment and networks in monitored environments by social alarms devices. The electric field strength and the EIRP are well within the guidelines set by the ICNIRP, the IEC, and the thresholds set by standard regulations. It means that electric field strength levels in healthcare home environments are apparently safe according to the operational, health, and safety requirements on the exposure of patients, professionals and the general public for protection against possible health effects from nonionizing radiation.

Although one of the findings of this study is the development of an environmental study of the working conditions of the social alarm devices, it is also important to consider the absorp‐ tion of radiofrequency energy in the body of a person that wears the device. ICNIRP guidelines are also expressed in terms of specific absorption rate (SAR), measured in W/Kg, in the body tissues. To address this, a parallel study should be carried out to measure the localized SAR arising from social alarm devices in the people that wear them.
