In the modern word, people migrate toward areas with wireless Internet, or Wi-Fi, to try to stay plugged in. They sit, hot coffee at hand, for hours on end in cafes with signs proclaiming to be wireless hotspots.

But some people have the opposite reaction to the wireless movement. Instead of seeking out the freedom to log on anywhere, anytime, they run away.

"If I walk into a room or building that has Wi-Fi, my most immediate sign is that the front of my right thigh goes numb," said Arthur Firstenberg, 57, of Santa Fe, N.M. "If I don't leave, I'll get short of breath, chest pains and the numbness will spread."

Firstenberg is one of a small group of people who believe they have Electromagnetic Hypersensitivity (EHS), a condition in which they are highly sensitive to electromagnetic fields and experience pain or other symptoms when they encounter them.

People with electromagnetic hypersensitivity claim to experience a variety of non-specific symptoms, including headache, fatigue, nausea, burning and itchy skin, and muscle aches. These symptoms are subjective and vary between individuals, which makes the condition difficult to study.

"There are those who believe that the various and sundry electronic devices have these magnetic waves that affect the nervous system," said Dr. James Toole, professor of neurology and public health sciences at Wake Forest University School of Medicine in Winston-Salem, N.C.

But experts are divided about the validity of such claims.

In October 2004, the World Health Organization (WHO) conducted a workshop in Prague to take a closer look at these studies. What researchers found was that the most reliable studies showed that EHS symptoms did not appear to correlate with exposure to electromagnetic fields.

Furthermore, the studies indicated that most of those who claimed to have EHS could not detect electromagnetic fields any more reliably than those who did not have EHS.

"There are also some indications that these symptoms may be due to pre-existing psychiatric conditions as well as stress reactions as a result of worrying about believed EMF health effects, rather than the EMF exposure itself," the editors of the WHO workshop wrote.

But, they added, "Whatever its cause, EHS is a real and sometimes a disabling problem for the affected persons."

Catch a Wave

Electromagnetic fields exist all around us, emanating from power lines, televisions and microwaves. Wi-Fi is a type of radio wave, operating at either 2.4 or 5 gigahertz. These wave frequencies are slightly higher than the radio waves on which appliances like cellular phones or televisions operate. This allows for the transmission of large amounts of data, but as a result Wi-Fi radio waves emit greater electromagnetic fields than things like televisions and microwaves.

Experts argue back and forth on whether these waves are harmful or benign. Studies on cell phone use over time and brain tumor growth — which have thus far proved no connection between the two — are just one example of this relationship.

"People have studied whether there are adverse effects from living in a vicinity of high tension wires. There is none," said Dr. George Newman, chairman of neurosensory sciences at Albert Einstein Medical Center in Philadelphia.

But limited research, both physiological and psychological, on exposure to electromagnetic fields has shown that some people report varied physical reactions when they encounter electromagnetic fields.

Firstenberg says his responses to electromagnetic fields, and to Wi-Fi networks in particular, are immediate, almost like an allergic reaction, and can last for several hours.

But lack of concrete evidence to explain a mechanism for these reactions leaves most experts unconvinced.

"It is still in the realm of suspicion rather than proof," Toole said. "Research should be encouraged in a scientific way rather than hearsay."

Still, Firstenberg and his group, the Santa Fe Alliance for Public Health and Safety, are working to prevent the local government from installing wireless Internet access in several public buildings, including libraries and the city hall. The Santa Fe City Council will be discussing and voting upon the issue in June.