There are many reasons why the air quality in a building may fall well short of what it was intended to be, explains Trevor Callen.

Home renovation is a positive action "Which can bring out the best of an older home's original character, and provide the occupant with modem comfort and efficiency. Renovation work can, however, uncover unpleasant surprises in the existing construction which require special precautions to avoid health hazards. One such unpleasant surprise is the presence of lead-based paint. Lead-based paint was used in virtually all older houses. The renovation of painted surfaces by most conventional means can create a distinct health hazard to both the renovator and the occupants of the home.