Discolored areas on carpet and walls have been reported to Home Innovation Research Labs’s ToolBase hotline and other sources from locations throughout the United States. Discoloration is characterized by localized darkening of the original color of walls, carpet and other interior surfaces. Carpet discoloration often occurs at the perimeter of the room and along the base of doors. The discoloration of walls can be diffuse, or appear as “ghosting” – a darkened line along the studs in the walls.
Discoloration is caused by accumulation of small particles that are present in the air of homes. Vacuuming or washing usually cannot remove discoloration. However, professional cleaning equipment with enzyme based agents has been shown to be effective at removal on some cases of carpet soiling.
Identification of the particles that cause discoloration is limited and requires expensive laboratory testing. Researchers of the discoloration problem have identified compounds typically found indoors and outside of homes. Examples include particles from tobacco smoke, candle smoke, wood-burning smoke; from dust, such as drywall dust from construction, normal house dust, and dust from household projects such as sanding, grinding, and finishing; and air-borne particles such as pollution, organic material, automotive exhaust, and road dust.