Was I being practical, or paranoid?
SHOULD I keep my Geiger counter running during dinner? Will its constant clicking keep me up at night?
Those are the kinds of questions I've been asking myself since a black plastic Geiger counter, a camera-size device designed to measure gamma, alpha, beta and X-rays, arrived last week. All I had to do was switch it on and set it on my dining table.
The clicks -- about 10 per minute -- announced the presence of background radiation (generally considered harmless) in my Greenwich Village apartment. In a nuclear emergency -- an attack or a reactor meltdown -- the rhythm would become more urgent.
''At 100 clicks a minute, I'd start to worry,'' said Tim Flanegin of Mineralab in Prescott, Ariz., who sold me the $279 unit.
Geiger counters, it seems, are the new Cipro. ''Since 9/11, orders have doubled,'' said Mr. Flanegin, whose company uses the Web address www.geigercounters.com. Prices start at $170 for a kit and climb past $900 for a particularly sensitive model.
The company's original customers were mineral collectors, Mr. Flanegin said, ''but then this whole other market developed.'' First came Sept. 11, he said, and then another surge this spring, as tensions rose between India and Pakistan, and the Justice Department announced that it had foiled a plot to set off a crude radioactive weapon -- a ''dirty bomb'' -- in the United States.
International Medcom, a manufacturer in Sebastopol, Calif., that also sells units to the public at www.geigercounter.com, is having trouble meeting demand, said its president, Dan Sythe. ''We're hiring people and trying to increase production,'' he said.
In my case, the decision to buy a counter followed a decision to buy potassium iodide, a drug that reduces the chances of thyroid cancer after exposure to fallout from a reactor. More than a dozen states plan to distribute the drug to people near nuclear power plants.
Once I got the pills -- a three-month supply, available on the Internet for $18 -- I began wondering how I would know when it was time to take them.
''The question is, do you trust the government to keep you informed?'' asked Lionel Zuckier, director of nuclear medicine at the New Jersey Medical School in Newark. Even assuming a policy of full disclosure, there might be delays -- possibly breakdowns in communication -- in getting information to the public.
Debbie Baker, who lives near the nuclear power plant at Three Mile Island in Pennsylvania, has kept a Geiger counter on her window sill for 14 years.
In 1979, when an accident at the plant released radiation into the atmosphere, Ms. Baker recalled angrily, ''We didn't get information for three days.'' At the time, she said she had a 9-month-old daughter at home. The window-sill counter ''represents peace of mind,'' said Ms. Baker, who is president of a citizens' monitoring committee.
Not everyone, though, thinks the Geiger counter should take its place alongside the home smoke detector.
David Allard, who oversees radiation-disaster preparedness for Pennsylvania, advises against the purchase of personal Geiger counters. For one thing, ''you have to know how to interpret the data,'' he said.
''If someone who had just ingested radioactive material in connection with a medical procedure walked past your house, the thing would start clicking like crazy,'' Mr. Allard said. ''And there are trucks that carry nuclear material in the normal course of things. You'd be in a constant state of alarm.''
For an actual emergency, ''there are plans in place, response teams that know what to do,'' he said. ''The best thing is to turn on the TV and follow official instructions.''
Told of Mr. Allard's advice, Ms. Baker scoffed. She said her detector is set to sound whenever radiation hits three times the background level in her area, an event that she said typically occurs once a year, after a heavy rainfall brings down naturally radioactive dust.
So if a bona fide alarm went off, what then?
Dirty bombs, nuclear weapons and reactors present different issues, of course. The Council on Foreign Relations, in an encyclopedia of terrorism on the Web (www.terrorismanswers .com), states, ''In the case of a dust cloud thrown up by a dirty bomb, experts stress the importance of prompt decontamination -- taking off outer layers of clothing and washing any exposed skin.''
In the case of ''penetrating radiation'' like gamma rays or neutrons, the site advises those affected ''to minimize the duration of their exposure by getting as far away from the radiation source as possible.''
In other words, act quickly.
Still, $279 is a lot to spend for an alarm that probably will never sound. So what about some sort of communal early-warning system: public Geiger counters transmitting data around the clock?
One such network, in central Pennsylvania, was installed in the early 90's by Ms. Baker's nonprofit group, the Three Mile Island Citizens' Monitoring Network. It posts the readings at www.tmi-cmn.org/map.htm, although Ms. Baker said that recent thunderstorms had knocked out part of the system.
A larger network with 178 counters has been operating for more than a decade in France, which relies heavily on nuclear power; it can be monitored at www.opri.fr/html_opri /web_mesure_som.htm. About eight years ago, the designers of the French system, called T�l�ray, installed a unit atop a federal building at Varick and Houston Streets in Manhattan for the United States Department of Energy. The department has since added its own monitors at the site, and posts results, updated every 15 minutes, at www.eml.doe.gov/homeland.
Mitchell Erickson, director of the department's Environmental Measurements Laboratory, said his agency was trying to secure $5 million to install some 30 monitors around the city. ''We don't have that kind of money in our budget,'' he said.
Dr. Zuckier of the New Jersey Medical School said he had proposed such a system for the city over three years ago. Linked by the Internet, the units could generate a kind of weather map of radiation. But he said he got nowhere, in his view because officials feared that real-time information could cause panic. But that was before Sept. 11. Francis McCarton, deputy commissioner of the city's Office of Emergency Management, said this week: ''We have a new commissioner in place. We'd be happy to take a look at the plan.''
Dr. Zuckier's own demonstration unit, at Jacobi Hospital in the Bronx, feeds data to a graph at www .awel.com/nyc. A disaster would send the line on the graph shooting up, Dr. Zuckier said.
Certainly, during an emergency, the radiation monitor or its Internet connection could fail. (Indeed, if the attack generated an electromagnetic pulse, most Geiger counters would be rendered useless. Some older models, including government surplus counters, would probably survive a pulse, according to Radmeters4U.com, a company that says it has 100,000 counters from the 60's and 70's at its warehouse in Gonzales, Tex.)
For a newer, PC-compatible model, Dr. Zuckier referred me to Brian Boardman of Aware Electronics of Wilmington, Del., the company that made the unit at Jacobi (www .aw-el.com). Aware's Geiger counters lack dials or displays and feed information to PC's instead. (Other companies make similar models for Macs, including Black Cat Systems, which is online at www.blackcatsystems.com.)
For $149, I ordered Aware's RM-60, which arrived the next day. Connecting it to my PC took less than five minutes. Almost immediately I had a graph of radiation levels in my bedroom -- a chilling if fascinating sight. Mr. Boardman advised that as long as the reading remained flat, at around 15 microroentgens per hour, there was nothing to worry about. (The unit can be programmed to sound alarms or even send e-mail warnings when radiation levels increase.)
Mr. Boardman had enclosed an egg-size rock containing uranium ore. When I held it near the small round opening on top of the RM-60, the line on the graph shot up. The same radioactive stone helped me confirm that my hand-held counter from Mineralab was working.
Of the two devices, the RM-60, at half the price of the stand-alone unit, seemed the better buy. Its PC feed allows you to compare radiation levels over time and to check data accumulated while you are sleeping or otherwise engaged.
And yet, if I needed to evacuate in an emergency, I would want to take my Geiger counter with me. Mr. Boardman recommended that I buy one of two accessories -- an attachment that generates audio clicks, for $19, or an L.C.D. display for $159 -- or that I connect my RM-60 to a palmtop instead of my desktop computer.
I went ahead and ordered the $19 attachment. It has been a week since my first Geiger counter arrived, and I am beginning to find its slow click reassuring.