To observe and check progress or quality of something over a period of time, to keep under systematic review. In gas detection, this pertains to a device that monitors the concentration of its target substance in real-time, notifying its user when the detected concentration falls outside preset thresholds. All portable gas detectors with few exceptions fall into this category, which means the number of gas monitors is vast. Monitors can have subtly different characteristics as to their monitoring specifications, making it important to obtain expert advice as to which monitor to use in specific situations. 7Solutions, with its decades of experience in every gas detection situation imaginable, is ideally placed to provide this advice.