Off-gassing is a common health hazard associated with synthetic rugs made from polypropylene or olefin. Carpet fibers made from synthetic materials emit volatile organic compounds into the air that cause symptoms such as breathing difficulties, dizziness, headaches and nausea. Long-term exposure may cause cognitive problems, hearing loss and lymphomas.
Area rugs sometimes use fibers made from olefin or a backing made from the material that is attached to a rug made from a different fiber. Many rugs have a new carpet smell that is the result of chemicals releasing vapors into the air. Chemicals contained in olefin rugs irritate eyes and the respiratory tract, potentially leading to a range of symptoms. After installing new area rugs containing olefin, rooms must be properly ventilated for several hours to disperse noxious fumes. Rooms with new rugs can be ventilated by opening doors and windows or allowing air conditioning systems to run continuously.
Rugs made with olefin materials are naturally water-resistant, which makes them a good choice for damp areas such as basements and pools. Olefin rugs do a poor job of resisting dirt and tend to be difficult to keep clean. An olefin rug also attracts grease and oil, which leads to traffic patterns showing on the rug's surface. Dragging furniture across an olefin rug can create scorch marks due to its low melting point.