Health and Safety
You might have heard the claim that cell phone use can lead to
cancer or other illnesses. This claim has caused many users to be leery of using
any radio devices, including WLAN systems. Because RF can be hazardous to the
human body, there have been studies to try to analyze exactly what levels of RF
are safe and acceptable. The FCC and other regulatory bodies around the world
have done studies on this and provide some guidelines on the subject. In the
U.S., the American National Standards Institute
(ANSI), the Institute of Institute of Electrical and
Electronics Engineers (IEEE), and the National
Council on Radiation Protection and Measurements (NCRPM) offer guidelines
on specific absorption rate (SAR), which is the
rate at which a body absorbs RF energy. Based on the input from these
organizations, the FCC has identified what is the maximum SAR for portable RF
devices, including 802.11 radio transmitters.
This limit for the workplace is 400 mW/kg when the entire body
is exposed, and 1.6 W/kg for partial exposure. Devices such as cell phones,
cordless phones, two-way pagers, and 802.11 devices fall into the
partial-exposure category.
Because of the limited transmitter power of a typical 802.11
transmitter, the levels are well below those of either limitation. Add to this
the fact that the transmitter of an 802.11 device is typically in transmit mode
a very limited amount of time (it is normally in receive mode), and the overall
exposure is even less.
The bottom line is that although users should be concerned
about the health and safety considerations of any radio device, they should also
be aware that years of research has been conducted in this area and the findings
of this research have been incorporated into the applicable regulations.
Everyone is familiar with a cellular phone, and when comparing them to an 802.11
device, the 802.11 device delivers a fraction of the transmit power of a typical
cellular telephone. The energy exposure of the body is also a fraction of that
delivered by the cellular device, and the differing usage patterns of a 802.11
device leads to far less exposure time than would be typical for a cellular
telephone.
Even with the preceding health and safety information, keep in
mind that high-gain antennas do intensify the energy levels to a very narrow
beam. Therefore, it is always wise to not stand in front of, or near, high-gain
antennas any longer than absolutely necessary if you are not fully cognizant of
the operational parameters of the antenna.
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While on the subject of health and WLANs, it is important to
point out that a new law called the Health Insurance
Portability and Accountability Act (HIPAA) was enacted in the U.S. in
2003. Among the provisions of this law are regulations regarding privacy of
patient information. Although this is really a security issue, I think it is
necessary to include here as part of the regulation chapter.
Because WLANs use the airwaves to transmit signals, there is
the possibility of these signals, and the information contained in them, being
received by an unwanted party. As you may have heard, various security breaches
of WLAN systems have occurred. Many of these resulted from users not
implementing any type of security, at most, or a minimal security scheme.
If the system you are installing is going to be used for any
type of patient information, you need to be sure the security scheme selected
provides adequate measures to protect the data. Many papers and books cover
security for wired and wireless LANs, and it is beyond the scope of this book to
discuss WLAN security in detail. At a minimum, any system used for sensitive
data, including those that need to meet HIPAA regulations, should use some type
of authentication and encryption scheme. Several are currently available, such
as Extensible Authentication
Protocol-Transport Layer Security (EAP-TLS), Lightweight EAP (LEAP), Protected EAP (PEAP), and Wi-Fi Protected Access (WPA), with better and tighter
security and encryption schemes in development all the
time. |
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