Paper towels billowing out of bathroom dispensers is, for some environmentalists, a painful symbol of waste.

Rob Gogan, the recycling and waste manager at Harvard University, estimated that paper towels often account for 20 to 40 percent of waste (by volume) from an office building or a dorm. The university is trying to cut down their use. In some buildings, Harvard urges students to use fewer, with a sticker saying “use wisely, paper equals trees.”

The slogan is borrowed from the University of Oregon, Mr. Gogan said.

“It’s a delicate game because we don’t want to be seen as anti-sanitary or restricting people’s freedoms,” he said. Mr. Gogan himself carries two handkerchiefs — one for use as a tissue and the second, as a towel.

In other buildings Harvard has installed blow-dryers. These use electricity, of course. Nonetheless, Mr. Gogan said he had done the math, and the “lifecycle” energy use of a blow-dryer is lower than that of paper towels, which are produced at energy-intensive mills and then shipped to their destination. A Slate writer reached the same conclusion earlier this year — though much depends on the energy-efficiency of the blower and how long it is running.

Recycling is not an easy option. Not only are paper towels often mixed in with gunk, but also, “There’s hardly any fiber left in them to recycle, so it’s not worth it,” said Jim Gogek Grogek , a spokesman for the University of California at San Diego, in an e-mail message, citing the expertise of Alonso Noble, the university’s recycling guru. “That’s doubly true now that the price for recyclables has dropped.”

Harvard is considering composting paper towels — something tried only rarely. Since 2002, several Canadian government buildings have had special bins for paper towels in bathrooms, which are composted and then spread over the refuse at landfills. San Francisco State University is undertaking a pilot project for paper towel recycling in two locations (including a student center), but there are hurdles. “It is expensive to set up a new waste stream,” said Caitlin Steele, the university’s recycling coordinator. “But we have so many paper towels that we are testing out the effect it will have on our trash compactor rates.”

Mr. Gogan says that paper towels are very compostable and will take care of some of the extra moisture in, say, supermarket produce. However, there is still the problem with tampons and dental floss mixed in.

“You have to have the right kind of building, with the right population and get them trained properly, with probably a special receptacle,” he added.

Could that right population be Harvard’s facilities headquarters, where Mr. Gogan works? Not yet, he said: “We haven’t had the nerve to do it even here.”