Persistence of Indoor Air Pollutants
Many porous building materials and furnishings, such as carpeting, couches, drapes, and wallboard, absorb cleaning chemicals, fragrances, pesticides, and other air pollutants. Chemicals adsorb to virtually all indoor surfaces but more strongly to rough rather than smooth surfaces. These processes are known as the "sink effect". These chemicals can be re-emitted into the air for long periods of time leading to prolonged air pollution. For example, it is not uncommon for a building to retain the odor of a fragrance-emitting device (FED) months after it has been removed. Similarly, residual tobacco smoke can still be detected in buildings long after a no-smoking policy is implemented. Air pollutants clear more readily from buildings that contain a higher percentage of hard impermeable surfaces.