For an occasional problem-odors left after a party, for instance-there are several remedies: a good airing, aided by a fan; aerosol sprays; or a dish of ammonia or vinegar to cover offensive smells with fresher ones. Burning candles at the party (perhaps scented ones) may help.
Where smoking is constant, consider an air purifier. Small, inexpensive ones that circulate air through carbon filters are best used near the smoke source. True air cleaners are more costly; they circulate air and capture smoke, pollen, and dust particles electrostatically. They can be free standing or mounted on a wall or ceiling and must be adequately sized and properly placed to be effective. If you have a warm-air heating system, you can have an air purifying unit attached to it to clear smoke from the entire house.