Dr. Marc answers readers’ questions every other week. To send a query, click here.

Dear Dr. Marc,

If I seal the house, how long will it take before I run out of oxygen and suffocate? If it’s less than three days, do I really need the three days’ worth of food and water? I am never sarcastic.

CORINNE SABO San Antonino, TX

Dear Corinne,

Fortunately for you, the major duct-tape manufacturer is a big Republican contributor who seems much more interested in turning a profit than in providing tape of a sufficiently high quality to actually seal your house.

Dear Dr. Marc,

The Washington Post reports that almost half the duct tape sold in the United States comes from a company whose founder gave more than $100,000 to Republicans in 2000.

Is that the secret connection between the so-called terror threat and the Bush Administration’s recommendation that we all go out and buy duct tape? I honestly cannot think of any other reason to have it around in case of a “terror attack.” I think a little Valium or Ativan would be a much wiser investment, don’t you?

KEVIN MARTIN Los Angeles, CA

Dear Kevin,

Yes I do.

Dear Dr. Marc,

I have been reading about potassium iodide. I have heard that it is good to have around and to take it in the event of exposure to radiation. OK, so maybe this is the equivalent of duct tape, but if it may possibly in fact help prevent some kinds of cancer, thyroid I think they said, would it be worth it to find some? How much should an adult take? How about my 13-year-old son? Are there things to think about that might help if we do get fallout? I expect if we are the target, we might as well stand on the roof and watch it go. Judging from what I have seen there isn’t anything that can help at the center of a radiation attack. I grew up with this fear. I sure wish it wasn’t upon us again.

MARGARET STEPHENSON Ann Arbor, MI

Dear Susan,

The fear you describe can be treated with a sober assessment of the risks, which are very small to the individual. Far greater risks are associated with worrying about this. Does having this stuff around make you feel better? If it makes you feel better to keep around these items of limited value in the event of an almost inconceivable event actually occurring on a large-scale basis, then keep the stuff around. But know this, the risk of something catastrophic actually occurring was much greater when two lunatics like Nixon and Brezhnev had the ability to launch hydrogen bombs. We still have that capacity of course, but the only face we see right now is our own in the mirror. The way to treat the panic is to concentrate on other things–go about your normal activities, try to do something fun. Humor is a great antidote. Stay in control of your life. Resist the temptation to see yourself as a victim–we’re not victims, we have the power to resist this propaganda and a First Amendment right to do so. Arm yourself with probabilities. Remember that it’s very unlikely that biological or chemical weapons could be delivered here on a mass scale. I can’t imagine any way in which sarin gas will be blowing down your street. The delivery system to do so isn’t in place. If you still can’t reassure yourself with the knowledge that the statistical risks of something happening to you are extremely low, then consult your physician. Doctors are in the business of assessing the risks of an illness occurring. Believe me, I am not the only doctor who realizes that the pathogen here is fear. I am dispensing plenty of sedatives to help people through the night with the knowledge that the effect of all these “boy who cried wolf” alerts will slowly wear off. We will wise up, believe me, one way or the other. In the meantime, the duct tape and vaccine manufacturers get richer.

Dear Dr. Marc,

What practical measures can be taken in the event of radiation releases from nuclear plants? Is it sensible to stock some form of iodine pill in the medicine cabinet in the event of a TMI/Chernobyl-type release? I recall once learning that shelf-life is a big problem with “in case of emergency” pills.

TOM JACOBSON Jamaica Plain, MA

Dear Tom,

Those pills protect the thyroid only, and only in certain cases against certain types of radiation. The danger with storing them, more than a short half-life, is that you’re bound to see them as more of a protection than they really are, or to start to believe, as a result of having these pills, that something is in the offing. This may well raise your anxiety level, not lower it. I hope to see it lowered.

Dear Dr. Marc,

We live about fifteen miles from a nuclear power facility in southern California. My husband and I want to get iodine pills in the event that there is an accident or terrorism involving the release of radiated vapor. (The winds generally blow in our direction.) I heard that iodine can be toxic if an improper dose is ingested so I have some questions:

1) Where can we get iodine pills to keep on hand in the event of a nuclear-vapor release?

2) Do we need a prescription?

3) If a prescription is not needed, what dosage should we take and for how long?

4) When should we begin the dosage?

5) How do we store it? Will it break down or lose potency?

DEBORAH LaTORRE San Diego, CA

Dear Deborah,

Iodine pills are not likely to be that helpful. They’ll protect your thyroid against long terms cancer risks only in the event of certain kinds of radiation exposure. Plus there are numerous parts of the body likely to be exposed to short-term radiation in that instance, like the lungs and heart, which would not be protected by the pills. You can get Potassium Iodine without a prescription but I’m not recommending stockpiling it. If something happens to the plant, your best bet is to beat a path away from the area as quickly as possible. Or if you’re stuck, station yourself in a lead-lined room or concrete basement, if possible.

Dear Dr. Marc,

Is there really a supply kit that we could assemble that would provide any protection or assistance at all in the event of a nuclear, chemical or biological attack? Is there a plan of behavior that you would recommend in the event of such an attack? Or should we just pray?

BRETT RICHTER New York, NY

Dear Brett,

Your level of concern has probably been stoked by the media. As far as I can tell, the risk of a large-scale attack is extremely small, so the risk to you as an individual is extremely low. I think assembling a supply kit might add to your anxiety. If I am wrong about that, then pack up your favorite food and favorite books just in case a public panic occurs and you have to escape that.

Dear Dr. Marc,

In the event of a biochemical attack, what will be the effects, lethal or otherwise, at various distances from the epicenter or release point? And for how long will such lethal effects last?

PHILIP T. GNATOWSKI Lincoln, MA

Dear Philip,

It depends totally on what weapon is used, but I assure you, it’s probably a lot less than you’re probably thinking. The fairly recent example of the sarin gas attacks in Tokyo in 1995, in which tweleve people were killed, is a good example of the difficulties in employing weapons of this sort.

Dear Dr. Marc,

If a chemical or biological weapon were used in the United States, how long would the agent persist in the environment? Would sealing windows and doors with plastic sheeting and duct tape keep the germs or chemicals out long enough for the agent to be cleaned or diluted to nonlethal levels?

LINDA WALTERS Springdale, PA

Dear Linda,

These chemical agents dissipate rapidly on their own before they would reach your duct-taped door. Beware of a mailman in a full body suit and gas mask. Otherwise, I recommend going about your daily business. As far as biological agents, there decontamination could play a role, except in certain parts of New Jersey where no amount of decontamination would work.