Latest News
Updated: 04/21/2003
Is 802.11 Ready for VOIP?
5-Minute Security Advisor - Strengthening Wireless Authentication
Catch-22 of WLANs
eWEEK Excellence Awards: Networking Infrastructure
IEEE Plots Speedier WLAN
Extreme Springs Switch Surprise
Nortel Launches WWAN-WLAN Products
Nortel Preps 'Security Switch'
Wi-Fi Developers Pursue Plans for More Services
How to Fine-Tune Your VPN Strategy
Cisco to Buy Linksys
Verizon's Surprise Evolution
WLANs Spur Security Questions
Verizon Plans 2.4-Mbits/s Wireless Rollout
Study Exposes WLAN Security Risks
Roaming From WLAN to WAN
Wireless Clouds Of Connectivity
WLAN: The Four S's
Cisco Bolsters Its WLAN Hand
Cisco to License WLAN Technology
Telesuite Virtual Conference Room
IBM Connects Wireless Networks, Enterprise Systems
Ten Steps to a Secure Wireless Network
Top Vulnerabilities in Web Applications
Hospital Cures WLAN Insecurity
System Boosts WLAN Security

FCC Issues Relating to Electromagnetic Interference in Hospital Medical Devices

Wireless Devices and Electromagnetic Interference in Hospitals, Urban Myth?

Full article

ith the increasing pervasiveness of cell phones and wireless local area networks, and the current push to wirelessly connect handheld computers with local and wide area wireless networks, the topic of these devices possibly interfering with medical equipment seems like a timely one.

There has been a great deal of misinformation and hearsay associated with reports about cell phones, wireless local area networks (WLAN), and wide area networks (WAN) in hospitals. Most hospitals have bans on the use of cellular phones inside their facilities, despite the absence of any comprehensive scientific information supporting the impression that cell phones are dangerous in hospitals.

Radio frequency waves, that which are used to carry the intelligence of cell phone calls, television, and radio broadcasts is energy transmitted through space. This energy is comprised of the alternating waves of electric and magnetic fields, hence the term electromagnetic energy, or EM for short. Electromagnetic energy manifests itself only when it is interacts with matter. EM energy can only interact with certain types of matter. The types of matter with which EM energy can interact are dependent upon the frequency of the EM waves.

For years, the FDA and FCC have known that EM radiation from various sources could interfere with delicate medical equipment. Requirements for shielding this equipment have long been part of the FDA's requirements to market such gear. It has been only lately that the source of transmission for EM radiation could have been in such close proximity to the medical equipment itself. Having a cellular or walky-talky device within feet of a piece of sensitive medical equipment is very different than being twenty miles from a radio tower. As with all EM radiation, the strength of the field decreases with the square of the distance from its source. That is to say that the field strength at one meter from a transmitter is four times as strong as the strength only another meter away.

Early on in the life of cellular phones, analog systems operated with fairly substantial outputs. There were reports of interference with electric wheelchair circuits, cardiac pacemakers, and anesthesia equipment. Of course, telemetry equipment was particularly susceptible. It was then that a fear of cellular phones in hospitals was borne. Apparently, as at least one source states it, a sign company propagated the rumor of an FCC ban on cell phones in hospitals for the purpose of selling its signs. It appears to have worked, and the ban on cell phones in hospitals has grown to become one of the "urban myths" of our society. But, there is no such ban.

The FCC has authority over all forms of equipment that is capable to transmit electromagnetic (EM) energy. The FDA has authority over all forms of medical equipment (both disposable and durable), medications, and associated delivery systems or devices. The FDA has never, and is prohibited from doing so by its charter, banned any communications equipment. They have however, placed pre-market requirements on medical equipment (i.e., shielding requirements). The FCC has never banned transmitters (of any type) from hospitals; providing that the equipment falls into FCC radiation flux level compliance.

There have been numerous discussions, meetings, publications, and suggestions regarding the use of portable communications equipment in the vicinity of medical equipment over the past 5 or so years. Most of these dealt with the early problems reported in electric wheelchairs, pacemakers, and anesthesia machines; which, due to inadequate shielding, malfunctioned briefly while exposed to EM interference (EMI).

Participants at the recent Health Canada medical devices roundtable reached several conclusions. They agreed that a total ban of radio-frequency transmitters in hospitals was not justified, and suggested susceptible equipment should be removed if the source of EMI cannot be controlled. They also recommended rational management of wireless telecommunication devices used in hospitals.

Medical devices in use today in our modern hospitals have long since been upgraded to shield themselves from EMI that exists in the typical urban environment. Proof that this is the case can be found in the fact that many hospitals have lifted their cell phone bans, and some have even installed local area cellular networks for use by their medical and nursing staffs.

In perhaps the most complete report yet published by a US regulatory agency, the FDA explains in,"Medical Devices and EMI: the FDA Perspective," that it has worked, and will continue to work with various other agencies and industry groups to ensure that medical equipment is properly shielded against the constant barrage of EM energy they are subject to. There is no mention of a ban, or consideration for a ban, on EM sources (that comply with FCC criteria) in hospitals.

Back to top