In the nation's post offices, and your own office mail room, clerks don latex gloves. In the nation's airports, National Guard soldiers carry M-16 rifles.

In Washington, Senate employees test positive for anthrax; the U.S. House shuts down; six office buildings are closed. Police stand on every corner of every street near the Capitol, streets blocked by concrete barriers. The windows of congressional offices are coated with Mylar.

At Disneyland and Walt Disney World, you can't visit Mickey and Minnie until your bags are searched. At the Mall of America, a few minutes from downtown Minneapolis/St. Paul — or at your local airport or courthouse — you can't park at the curb.

I appreciate these efforts as, I'm sure, do you. They are intended to make us safe and to make us feel safe. While I am grateful for these efforts, they don't make me feel safe and secure. They make me feel paranoid.

As the joke goes, "I'm not paranoid; I know they're out to get me."

So, in the interest of physical and mental health, what's the difference between being vigilant and being paranoid? Is it vigilant to buy a gas mask? Or wacky?

Vigilance is rational; facts are attached. A fear is rational if it concerns something that is harmful and actually could happen, says Shane Thye, a sociologist at the University of South Carolina.

Paranoia is irrational. Paranoia is a fixed belief in something that is patently untrue, not real, not a threat, says Stephen McLeod-Bryant, a psychiatrist and medical director for the South Carolina Department of Mental Health. You insist on this fixed idea despite evidence to the contrary.

Here's the evidence to the contrary on gas masks: The Centers for Disease Control and Prevention says there's no point in buying one. First, to work, a gas mask has to fit you. Second, to work, the gas mask has to be worn all the time. By the time you found out an attack was under way, it would be too late. Third, if it's breathing anthrax spores that's worrying you, look at the delivery system. The U.S. Postal Service handles 680 million pieces of mail a day. So far, we can count on our fingers — the pieces of mail that endangered people. And that mail was aimed at politicians and national media outlets. The odds are with you.

Or, as Gene Stephens, a University of South Carolina criminal justice professor, wants you to know: You are 71,500 times more likely to die in a car crash than from exposure to anthrax. Your chances are one in 3 million lightning will get you; one in 100 million a shark will; one in 500 million anthrax will, according to actuarial tables.

So why are we so paranoid?

Something horrible happened. Thousands of people died. We are grieving and fearful in our grief. And it's all we hear about, so it's all we think about.

"So much attention is on this crisis," Thye said. "Consequently, we spend much of each day thinking about or worrying about each development."

According to recent Gallup polls, 83 percent of Americans believe more attacks are likely; 68 percent are more concerned about their safety; half admit they are more suspicious of strangers. Three-fourths of Americans cite terrorism, fear of war and national security as the nation's most important problems.

Drugs, wages, education, race, the federal debt, the energy crisis? Forgotten. We're focused, instead, on a shock a day.

Stephens notes, "I always say, 'You're not reporting the usual in the media; you're reporting the unusual.' If the usual was reported, we'd hear constantly about larceny, which represents 57 percent of all crimes in the Uniform Crime Report. "Rape, murder, assault, robbery, which you are always hearing about, they represent 10 percent."

So our view of reality is skewed. We worry about things that likely won't harm us. We don't worry enough about the things that will.

Consequently, this is what Stephens suggests as reasonable vigilance: "Eat a healthful diet. Not eating junk food is probably the most vigilant thing you could do." That's because, even after Sept. 11, your greater danger is heart attack and stroke, not terrorists. Your chances of dying within a year of heart disease are 1 in 400; of cancer, 1 in 600; of stroke, 1 in 2,000.

Vigilance is useful; it helps us stay alive. Fear can be a good thing; it encourages us to take sensible precautions. But there is a solid line between awareness and constant, irrational fear.

Our minds and bodies are designed to help us stay alive. When something scary happens, we feel anxious or fearful, and our eyes widen to see better; our blood vessels dilate to get more blood to muscles. We enter what's called the "fight or flight" stage.

But we can't stay there day after day. "When this gets to the point it interferes with our normal activities, with love and work, it's not adaptive. It's counter-productive," says McLeod-Bryant.

Look at your life as a whole to measure how far you've moved from vigilance and toward paranoia. It might be reasonable to cancel a family reunion that requires travel, but you should still telephone and e-mail family. You're over the edge if you withdraw from social interaction.

It might be vigilant to stay up on the news and instructions on safety.

Stephens says you should do what you always should do: Use good sense and caution.

On the other hand, "If fear means you . . . don't go out, that's a bad thing."

It's enough to be careful.

Claudia Smith Brinson is a columnist for The State in Columbia, S.C. Readers may write to her at: The State, P.O. Box 1333, Columbia, SC 29202, or by e-mail at