Low smoke zero halogen (LSZH, LSOH, LS0H, LSFH and OHLS for short) is the classification of wire sheath materials in the wire and cable industry.Low smoke halogen free wire sheath is composed of low smoke emission when heated and does not contain halogen itself thermoplastic or thermosetting.

Most network wire cladding is composed of polyethylene, polyvinyl chloride or thermoplastic polyurethane.In case of fire, chlorinated plastic will release toxic hydrogen chloride, and in case of water, hydrochloric acid will be produced.Low-smoke halogen-free materials do not release hydrogen halide or other acids on fire.

Low smoke halogen-free material can reduce the toxic and corrosive gas produced in its combustion.Low-smoke halogen-free materials are often used in poorly ventilated environments such as aircraft, train carriages or ships.Low-smoke halogen-free materials are also commonly used in the railway industry because there are high-voltage lines or signal lines transmitting the train's position under the railway.The use of low smoke halogen-free materials also reduces the accumulation of toxic gases when the circuit is damaged by fire or short circuit.

For example, in the railway industry or the shipbuilding industry, an important requirement is to protect personnel and equipment from toxic and corrosive gases. In these cases, low-smoke halogen-free materials will be required for the outer layer of cables.[1]