A well-designed and properly maintained house has efficient weather-stripping. It also has snug-fitting storm windows and doors installed to minimize air filtration and heat losses from inside to outside.

As a result, indoorair often tends to become uncomfortably polluted with dust, dirt, smoke and odors - so much so that in some cases the indoor air is actually more polluted than the outside air, even for people who live in heavily populated urban areas.

This problem is frequently aggravated by the energy crisis and the high cost of fuel. In cold weather, when the beat is on, people are reluctant to open windows (to let "fresh" air in) because they don't want to waste heat. In hot weather when air conditioners are working, they also avoid opening windows because they don't want to increase the amount of power consumed.

However, more and more people are discovering that they can solve thisproblem of creating a comfortable and pleasant indoor environment in closed rooms and houses by installing one of the various electronic air cleaning appliances which are sold for just this purpose.

Long used in commercial and industrial buildings, as well as in restaurants, theaters and other places where people congregate (and often smoke), these units are much more than mechanical air filtering devices which "strain" the air through a porous filter of some kind. The electronic air cleaner is a highly efficient unit that will remove anywhere from 85 to 95 per cent of airborne dust, dirt, smoke, pollen, soot, fumes and other particles from the air - including microscopic particles that are too small to be seen.

The cleaner air that results is not only more comfortable and pleasant to live with - in the case of allergy or asthma sufferers it can also be more healthful. The tax laws, in fact, state that if a doctor prescribes one, the cost of the unit is deductible.

Cleaner air inside the home also reduces cleaning and other maintenance costs. By trapping and removing airborne dirt before it can settle onto furniture, drapperies, carpets, walls, ceilings and furniture, the need for frequent cleaning and painting is greatly minimized. Furnishings remain clean and new-looking longer.Redecorating with new paint and wallpaper becomes a chore that can be postponed much longer than would otherwise be the case.

Electronic air cleaners treat the air in stages. As it is drawn in through one side (or end) of the unit, the air is passed through a porous foam-type pre-filter which catches the largest particles of dust and dirt (this pre-filter may not be part of some of the smaller units). Then the air travels through the electronic ionizing section or cell, which is really the heart of the system.

Here the small airborne particles pass through the comparatively coarse filter to a powerful electric field, which impacts a strong positive charge to each piece. The air then flows past a series of metal plates which have a negative electric charge. These plates attract the positive-charged particles much in the way that a magnet attracts iron filings. As a result, the charged particles are held firmly on the plates (in the collecting section) and the air that passes through leaves these particles behind.

In its final stage, the air flows through an activated charcoal or carbon filter, which removes odors, so that the air that is finally discharged is clean and free of odors, pollen and other contaminants.

For those who do not have forced air systems (houses with electric, hot water or steam heat), the solution is a portable unit. There are separate central units which can be suspended under a ceiling in a central location, but these are intended mostly for commercial use in stores, shops and offices, and are not really practical for a home.

Portable units come in two basic sizes - console models that sit on the floor and look something like a small cabinet or end table, and table-top models which can be easily carried about. Available from some appliance dealers and department stores, as well as through the catalog or large mail order houses, table-top models range from just under $100 from $195 to $375, depending on size and brand.

The portable models do not have the capacity of the larger central units. They are basically room units, rather than whole-house units, although some of the larger console types will cean the air in two or three rooms of average size if there is a free movement of air between them. Most have two- or three-speed fans, which permits varying the amount of air treated, as well as how fast the air is cleaned (use higher speeds when many people are smoking, for example).

However, even the smaller table-top units will do an amazing job of getting rid of cigarette smoke and odors in an average size living room (about 300 square feet). These units, as well as the console units, can be easily moved about from the one room to another, completely cleaning all the air in a room of that size about four to five times each hour.

All of them plug into a standard household electric outlet and consume very little electricity - about the same as a 60-watt bulb in many cases.

The electronic cell which traps the smallest particles has to be removed after about three or four months of normal use for cleaning. It is permanent unit that is cleaned by soaking in a tub of dishwasher detergent solution for about 30 minutes. The cell of the larger central units can be washed in an automatic dishwasher.

The charcoal or carbon filter which removes odors is not washable; when it is exhausted (six months to a year) it must be replaced. These filters cost from $4 to $8. The only other maintenance required on some models is an occasional lubrication of the fan motor.