An operating theatre light comprising at least one environmental sensor. The operating theatre light includes a sensor housing attached to the operating theatre light. The sensor housing defines an enclosure containing the at least one environmental sensor. The sensor housing is protected (e.g. sealed) against the ingress of liquid to the enclosure. The operating theatre light may have a transmitter or transceiver or wired connection for transmitting environmental sensor data produced by the at least one environmental sensor. An operating theatre system comprising the operating theatre light and a control panel comprising a receiver or transceiver configured to receive environmental sensor data transmitted by the operating theatre light.