The air quality in buildings can be checked and logged using appropriate measuring devices. This would indicate excessive levels of dangerous gases, such as carbon monoxide. Checks could then be carried out immediately on ventilation and air conditioning systems. Gas leak detectors establish the gas concentration in the air and may warn of elevated values with a colour LED display. It only takes a few seconds for them to detect dangerous concentrations of gases such as propane or natural gas that could be hazardous to health. They have many applications in heating, climate and building technology. For example, users can use this type of measuring device to check pipes in the home or in vehicles such as mobile homes.