Do you remember the predictions of a paperless office? Well, it didn't happen.

According to Ashley Mattoon of the Worldwatch Institute, ''The average office worker in this country uses more than 12,000 sheets of paper a year.''This is an amazing change from how people used to use paper. For a long time, people treated it as a scarce and expensive commodity. Generally, they only used it for important documents - ones they intended to have last a long time.

Today we throw so much of it away that paper now accounts for almost 40 percent of our municipal solid waste.

To Mattoon and her colleagues at Worldwatch, the enormous use of paper is an unrecognized but serious problem. ''The impact of a single envelope or magazine or box may seem unimportant,'' she says. ''But the process of making it puts a heavy toll on the world's land, water and air.''

She points out that almost one-fifth of the world's total wood harvest goes to making paper. Further, making paper devours vast amounts of chemicals, water and energy. The paper industry ranks among the highest in pollution generation, yet it all goes to make a product that is usually discarded after one use.

But there is some good news in all this. Our recycling efforts are paying off. Today, 43 percent of paper is recycled. In fact, so many newspapers are being recycled that some people look at cities as ''urban forests'' since the newspapers in cities are becoming such a good source of paper pulp.

Recycled paper not only saves trees, it takes fewer resources to produce. Because recycled paper has already been processed, making it requires far less energy and chemicals. In fact, making paper from used paper requires only 10 percent to 40 percent of the energy required for making it from virgin wood.

Also, some paper companies have reduced their use of energy and water by 50 percent. And others have found substitutes for the environmentally dangerous chlorine traditionally used to bleach paper.

Mattoon's colleague, Janet Abramovitz, is encouraged that many companies are finding that the new technologies are not only good for the environment, but that they save money as well.

However, despite the good news that we're recycling more and we're working on manufacturing paper in a more environmentally sound way, the gains we've made are more than offset by the increase in our demand for paper. To have an actual reduction in the amount of paper we use, we'll need to go on a paper diet and use less.

Mattoon and Abramovitz hope that we'll be conscious of the amount of paper we use and figure out how to use less. One way is to reduce the amount of unwanted advertising mail we get.

''The average American household receives 850 pieces of advertising mail a year,'' Abramovitz points out.

If that's more than you want, you can write to the Direct Marketing Association's Mail Preference Service in Farmingdale, N.Y., and request that your name be removed from national mailing lists.

The Mail Preference Service won't eliminate all advertising mail, and it takes about three months for it to start working. Still, people who have tried the service report a substantial reduction in the amount of their unwanted mail.