Are There Any Health Hazards if Multiple Readers Are Placed Within a Hospital Ward?

Active RFID systems involve tags with low-level output, and the tags do not emit energy all of the time, so there is likely to be little impact on a person's health. Cell phones, for instance, emit more energy and are held close to the head. A tag on an oxygen pump, on the other hand—which emits much less energy, and sits at the foot of a person's bed—is unlikely to affect health.

Passive tags emit energy. Daniel W. Engels, the former director of the University of Texas at Arlington's Radio Frequency Innovation and Technology Center, wrote a paper, along with Darmindra D. Arumugam, titled "Specific Absorption Rates in the Human Head and Shoulder for Passive UHF RFID Systems at 915 MHz." Their research revealed that an ultrahigh-frequency (UHF) RFID reader located 10 centimeters (3.9 inches) from a human head could present a health risk. Most hospitals do not utilize passive UHF systems within rooms in which patients are present—but those that do should keep reader antennas several feet or more away from patients, in order to avoid any risk.

Another potential risk to patients involves RF interference with medical equipment. In 2008, a study published by the Journal of the American Medical Association warned that RFID could disrupt the operation of defibrillators and other medical equipment, and occasionally induce "potentially hazardous incidents in medical devices." Experts not involved in the study, however, noted that no injuries related to electromagnetic interference (EMI) have ever been reported in an actual clinical setting—though they recommended that before deploying a specific RFID system, a hospital should first test it to determine if it has any effect on the medical devices that facility operates (see Researchers Warn RFID May Disrupt Medical Equipment).