This European Standard applies to apparatus for the detection and/or the measurement of carbon monoxide (CO), nitrogen monoxide (NO) and nitrogen dioxide (NO2) intended to control a ventilation system and/or to give an indication, alarm or any other signal to warn of a toxic hazard. These three gases are generically called "target gases" for the purpose of this European Standard. National and local regulations might not require detection of NO or NO2 and might require detection of other gases or vapours. This European Standard includes requirements for remote gas sensors (RGS) to be used in car parks and tunnels and requirements for the control unit (CU) to be used in car parks. This European Standard specifies general requirements for construction and testing and describes the test methods that apply to fixed apparatus for the detection and/or the measurement of the concentration of the target gases in car parks and tunnels. This European Standard may also be applied to similar applications where the concentration of the target gases could lead to a risk to health, for example loading areas for trucks and underground bus stations. This European Standard also applies when an apparatus manufacturer makes any claims regarding superior performance that exceeds these minimum requirements. This European Standard applies to apparatus, including the sampling system if applicable. This European Standard does not specify requirements for apparatus to be installed in hazardous areas. This European Standard does not apply for applications already covered by the following standards: - domestic premises, covered by EN 50291-1; - boats, craft, caravans or mobile homes, covered by EN 50291-2; - workplace atmospheres, covered by EN 45544 series; - emissions of heaters, covered by EN 50379 series; - motor vehicles emissions, covered by ISO/PAS 3930; - monitoring of the LEL level of combustible gases, covered by EN 60079-29-1. This European Standard does not apply for the following applications and technologies: - confined spaces not accessible to people; - laboratory or analytical equipment; - apparatus used to control industrial processes; - portable and transportable apparatus; - open path gas detection; - tunnel construction; - monitoring of particulates and dust; - monitoring of combustible gases; - CO monitoring for fire detection.