PDM+ is a personal sustainable single gas detector designed to detect oxygen deficiency and presence of toxic gas in the ambient environment. The PDM+ is sustainable, hence its battery and sensor can be replaced. When turned on, PDM+ continuously monitors ambient air for the presence of a specific gas and alerts the user to potentially unsafe exposure with LED, vibrating, and audible alarms in the event that gas concentration exceeds alarm set points. After use, the instrument can be turned off. .