Ever since energy costs began to rise about seven years ago, the experts have been telling us to button up our homes.

"Add insulation, weatherstripping, caulk, vapor barriers and storm windows," they advised, and you will save money on heating and cooling.

Now a different set of experts is telling us that tightening our homes has created a new problem: indoor air pollution. It comes in several forms:

Formaldehyde seeps out of improperly applied urea-formaldehyde insulation, and from the glues used to make plywood and particleboard.

Carbon monoxide gas and nitrogen oxides come from gas stoves and gas and oil furnaces.

The bacteria that live in the moist, warm drip pan under your refrigerator is a more mundane pollutant.

An exotic pollutant is radioactive radon gas, an element found naturally in stone concrete and even domestic water supplies.

All these pollutants start at relatively low levels. In most cases, the normal flow of air through your home will carry them off before they have a chance to build up much. But in exceptionally tight homes, the pollutants don't get the chance to escape. Over time they can build up to levels above those set by the Environmental Protection Agency as safe for outdoor environments.

How serious is the problem? Research in this area has just begun, so it's hard to say. But some of the early research shows that the problem is real.

For example, a study in England has shown that chidren living in homes with gas stoves had a higher incidence of colds and bronchitis than children living in homes with electric stoves.

Formaldehyde levels in homes newly insulated with urea-formaldehyde have been high enough to cause nausea, dizziness, rashes and nosebleed. Formaldehyde levels in mobile homes have also reached irritating levels because of the air-tightness of the homes and the large amount of plywood and particleboard used in trailer construction.

Randon? Researchers studying an especially airtight home in Maryland found that it had indoor radiation levels more than a hundred times that of the natural background level outdoors, The same home also had such high levels of humidty that mildew. And mold were growing on the walls.

Probably the most direct attack is to provide ventilation to carry off the pollutants. According to Gary Roseme of the Lawrence Berkeley Laboratory in California, changing the air in your home every hour or two will take care of all but the most severe problems.

Of course, blowing fresh air through your home is the very thing that you sought to prevent with weatherstripping, caulking and so on. That fresh air will have to be heated in winter, and cooled if you air-condition during the summer. And that will cost you extra energy dollars.

One solution is an air-to-air heat exchanger. It will take the heat from the air being exhausted from your home and transfer most of it to the cool fresh air coming into your home during winter. In summer it will do the opposite. Thus you can ventilate without wasting a lot of energy. But there are a few more things, less exotic, that you can do to fight indoor air pollution.

Seal any bare, exposed particleboard and plywood you can get to with shellac. That will prevent the flow of formaldehyde out of the adhesives in these products. Use your range hood whenever you use your gas stove or oven. Clean the drip pan under your refrigerator periodically. And use a dehumidifier if you have excess humidity in your home.