PERHAPS RIGHT NOW you're reading this while traveling as a passenger in a car. Probably the last thing you want to hear about is death on the holiday highways. Rest assured -- and buckled in, please -- that we'll not offer any sermonette on safe driving today; most people figure that they are not in danger, anyway -- that those messages are for the brainless motorists out there who insist on doing foolish things in transit. It happens that this assumption is incorrect, which in itself may help to explain why an estimated 420 to 520 people will be killed on the roads this weekend.

A few more numbers, just for the record: the safety experts figure that another 17,000 to 21,000 people will suffer disabling injuries over the next three days. These same experts also offer one way to reduce one's chances of joining this unfortunate group: the use of lap and shoulder safety belts can cut by about half a person's risk of death or serious injury. If even 70 percent of the people used safety belts, an estimated 3,500 lives could be saved, and 59,000 fewer disabling injuries would occur.

Various national organizations -- from auto makers and dealers to the National Association of Governors' Highway Safety Representatives, insurance companies and the U.S. Conference of Mayors -- have joined in an effort to boost safety belt use to a minimum of 70 percent by 1990. A current estimate, based on a 19-city survey, shows use at about 40 percent.

This group's goal is modest if you consider that highway crashes are the No. 1 cause of death and crippling injury among Americans betweenthe ages of six months and 35 years. And aslong as most people continue to discount the dangers and go beltless, that top ranking isn't likely to change. Neither is the grim holiday tradition of heart-breaking news stories from roadside. Do we hear a few more clicks of buckles out there?