THE WAR in the Persian Gulf and the threat of terrorism have thrown the airport security system in the United States and much of the world into a state of high alert. Inevitably, this has made travel more difficult for those who are carrying cameras and film. But there are some simple steps you can take to protect your pictures, your equipment and your fellow passengers.

Bracing for a threatened wave of terrorism, the Federal Aviation Administration announced shortly after the gulf war began that it was putting 435 U.S. airports on the most severe security alert, known as Level 4. This means more rigorous security measures everywhere, including increased scrutiny of passengers and their bags at check-in. Overseas, as well, there are redoubled efforts to screen travelers at the terminal gates, and passengers can now assume that their luggage is being X-rayed as well.

The added hassles mean you can't any longer just dash for your plane and hope to make it. The best way to cope is to take the security measures calmly and seriously. After many years of hauling all kinds of computer and camera gear through airports, I have come to the conclusion that the best way to avoid frustration is to arrive early and be patient.

Can airport X-rays hurt your film? Theoretically, yes. X-rays are electromagnetic radiation, just as light rays are, and because they are a shorter wavelength, they penetrate more materials. Unlike the light rays that leave selective images, however, the X-rays cause an overall increase in density, or "fog." But the extent of this depends on how big a dose of X-rays your film is subjected to.

Last year, a group of experts on X-ray machines, airport security and film looked at the question of how big a dose is too much. The experts were members of the Committee on Security Systems and Equipment of the American Society for Testing and Materials. They concluded that most airport screening devices in the United States will not affect film of ISO 400 or less during a single screening. However, such guarantees cannot be made for higher speed films, or for X-ray machines in other countries. Another danger to film could be multiple screenings, which could gradually cause film to fog. The FAA requires signs at U.S. airports warning about dangers to film.

If you are traveling with high-speed films or anticipate your film will receive multiple doses of X-rays, try to avoid exposure to both exposed and unexposed rolls by asking for a hand inspection, which you are entitled to under FAA rules. This means setting your film down outside the X-ray machine for visual scrutiny by airport personnel. If the line is long, you may be asked to wait. Abroad, it's also a good idea to ask for hand inspection, but it's not always as easy.

Remember, color negative film is most vulnerable to X-rays. Fuji recommends that you avoid exposure to film of ISO 1600 and higher; Kodak suggests you avoid X-rays for anything over ISO 1000. Black-and-white and slide films are less susceptible. There is still a lot of debate among professional photographers about the exact threshold of safety. Some pros say their practice is to always ask for hand inspection, but film experts say it is probably not necessary for ISO 100 films going through the X-ray machine just once.

Always get ready in advance. Professional photographers who travel often suggest taking film rolls out of their containers and putting them in a plastic zip-lock bag. This makes the film easy to see and prevents the obvious trouble of having to open every little container while the passengers behind you are fuming.

However troublesome it may seem, it's a good idea to travel through airports without film in your camera, so, if need be, it can be opened quickly for inspection. There should be no harm in putting the camera itself through the X-ray. According to the FAA, under the new procedures, passengers may be subjected to more questioning about the contents of their luggage, so it's also prudent to have all your gear easily available to enable it to be inspected if necessary. It's not uncommon to be asked to advance your camera a frame and press the shutter, so that security people can see that it's a working machine. They may also want to look through auxiliary lenses or through the viewfinder.

In earlier times, it was often a good idea to put in your checked baggage things like radios and excess batteries. But even checked luggage is now routinely X-rayed, in part because the bomb that downed Pan Am 103 was contained in a tape player in a suitcase, and the presence of such items could cause you and your bag to get yanked from the flight. The same goes for those lead bags that were often used to protect film. Because they protect the film so well, they could look suspicious on X-ray screens and cause you or the bag or both to miss the flight while security people check it out. It's best to bring with you, in your carry-on bag, anything that could be questioned.

Another way to avoid damage to your pictures is to have the film developed as soon as you get back. If it has been fogged, the situation will only deteriorate if you wait. How do you know if film has suffered X-ray damage? This kind of "fog" will not only be within the frame, but in the areas between the frames that are normally not exposed.

Yes, security can be a bother, but it's a necessary one, and the best way to deal with it is to be prepared, be careful and be patient.

Weekend's new photography columnist David Hoffman is a member of The Washington Post national staff. Each week he'll discuss topics of interest to novices and advanced amateurs. If you have questions or topics you'd like to know more about, write him c/o Weekend, The Washington Post, 1150 15th St. NW, Washington, DC 20071.