A method, comprising: defining a set of geographic coordinates of a work area and a set of geographic coordinates of a mustering zone; determining the geographic location of each of a plurality of portable wireless sensors of an environmental monitoring system, each carried by a person within the work area, each having a geographic positioning system and each determining its geographic location; detecting a threat within the work area by one of the plurality of portable wireless sensors; evaluating the threat posed by activation of each sensor via a response file; depicting the location of each of the plurality of wireless sensors on a map along with an indication of the threat detection state of the sensor provided by the portable wireless sensors; generating, by a processor, an alert for each of the plurality of portable sensors that have not arrived within the mustering area within a predetermined time after the detected threat; identifying by the processor a missing person within a secured area of the safety system via a portable wireless sensor of the plurality of wireless sensors carried by the missing person; identifying by the processor a last known location of the missing person via a most recent signal from the portable wireless sensor; identifying by the processor any nearby persons of the missing person via a portable wireless sensor carried by each of the nearby persons during a time of the most recent signal from the wireless sensor of the missing person; and determining by the processor a status of the portable wireless sensor carried by the missing person at the time of the most recent signal from the portable wireless sensor. defining a set of geographic coordinates of a work area and a set of geographic coordinates of a mustering zone; determining the geographic location of each of a plurality of portable wireless sensors of an environmental monitoring system, each carried by a person within the work area, each having a geographic positioning system and each determining its geographic location; detecting a threat within the work area by one of the plurality of portable wireless sensors; evaluating the threat posed by activation of each sensor via a response file; depicting the location of each of the plurality of wireless sensors on a map along with an indication of the threat detection state of the sensor provided by the portable wireless sensors; generating, by a processor, an alert for each of the plurality of portable sensors that have not arrived within the mustering area within a predetermined time after the detected threat; identifying by the processor a missing person within a secured area of the safety system via a portable wireless sensor of the plurality of wireless sensors carried by the missing person; identifying by the processor a last known location of the missing person via a most recent signal from the portable wireless sensor; identifying by the processor any nearby persons of the missing person via a portable wireless sensor carried by each of the nearby persons during a time of the most recent signal from the wireless sensor of the missing person; and determining by the processor a status of the portable wireless sensor carried by the missing person at the time of the most recent signal from the portable wireless sensor.