Gerald Arnold is one of the millions of Americans who can't bear tobacco smoke. His customers include some of the other millions who don't understand how anybody can dislike or be allergic to tobacco smoke.

Some smokers know about smoke allergies and try to be considerate. Some don't know, and inflict discomfort unwittingly. Some know but don't care. They think that if you're allergic to smoke, that's your problem, not theirs.

On one occasion, I heard a large young man rebuked by a woman for smoking in an elevator. He bristled. "If you were allergic to seafood," he asked coldly, "would that also be my feault?" I felt like saying, "Yes, you big clod, if you forced seafood into the lady's nostrils, it would be your fault." But of course I kept my mouth shut. I'm a devout coward.

Gerald Arnold is a nonsmoker who has a special problem. He drives a cab. He must inhale what his fares exhale.

Instead of getting into repeated personal confrontations with his passenger, Gerald hit upon the idea of posting a neat gold-and-black 'No Smoking' sign in the rear of his cab. It was a partial success.

Many people smoked and explained that they hadn't noticed the sign in the dark. So Gerald put a second sign on the outside of his back door, on the curb side.

Thereafter, a man who got in on the other side, took the position that he hadn't seen any sign so the prohibition didn't apply to him. Gerald put a sign on the other back door.

Pretty soon he picked up a passenger who shared the front seat with him and filled the entire front end of the cab with smoke.

Gerald bought another sign and posted it in the front of the cab. This one said, "Thank You For Not Smoking."

Gerald figured that unless somebody crawled in through the trunk, he had covered all bases.

Then he picked up a woman who said, "I would be inclined to obey your 'No Smoking' signs, but I just can't take the one up front that thanks me for for not smoking, so you'll just have to put up with my smoking." His next passenger was a blind man who lit up a cigarette the instant he got into the cab.

The latest from Gerald is that when he returned from vacation the other day he found that the interim driver had taken down all his signs. Gerald reports, "The ashtrays were stuffed, there were ashes all over the seats and stamped-out butts on the floors. The cab smelled as if a tobacco auctioneer's convention had been held in it. So I have now put up some home-made signs that say 'NO SMOKING' in big red letters, and we'll see how that works."

Well, good luck, pal. You might be interested to know that the American Cancer Society is sponsoring its third annual Great American Smokeout in a few days. It will take place on Thursday, Nov. 15, in Lafayette Park, and will begin at 12 noon. The Surgeon General of the United States will again "declare war" on cigarette smoking and call for volunteers willing to give up smoking for at least one day.

That, I have found, is one of the secrets of quitting. First you must exercise your intelligence; decide whether you do or do not want to stop. Then you must exercise your won't power; you won't smoke for this one day. The rest is repetition until you get out of the habit of smoking and into the habit of not smoking. At the point, you don't have to think about it any more.

Smoking is like living in one respect. You do it one day at a time. Or, if you really want to, you can refrain from smoking one day at a time.

Try it. It won't kill you to refrain for a day. But it could kill you if you don't. THESE MODERN TIMES

Jane B. has forwarded to me two printed items that were sent to her recently. One, from the D.C. Board of Elections, said in closing, "Your ANCSMD number is on the lable on the reverse side." The other was from a parent-teacher association to urge attendance at an upcoming meeting. It began with the heading, "Are You Concerned About Your Children's writing level, reading level, math level?" Spelling wasn't mentioned. SHORT AND SWEET

I think we can stop waiting for Indian summer. That must have been what we had on that nice afternoon a few days ago. POLITICAL NEWS

As I understand it, Teddy wants to be president because he knows how to end inflation by slowing down the economy without getting us into an economic slowdown.

And while we're talking about politics: Larry King quoted somebody as saying he was relieved to know that Jerry Ford isn't running. King's friend had been afraid that if Ford were elected, "the first thing he'd do would be to pardon Carter."