Embodiments of a sensor device, method and system employ a multiplicity of environmental sensors as a single monitoring and alerting mechanism, operable to provide a profile of any contaminant in terms of various gases and particles in the atmosphere, quantified in terms of relative concentrations. In various embodiments, the sensor device can comprise hardware and firmware elements, including an electronic control system, a case, a shield and a cover. The environmental sensors can be secured as part of the electronic control system and the shield can be formed so as to facilitate proper channeling of air and sound for effective operation.