A device (1) for gas measurement in a measuring environment (7) with a first camera (3) configured to detecting an invisible image area (33) in the measuring environment (7) and with a second camera (5) configured to detecting a visible image area (55) in the measuring environment (7). A control unit (13) initiates a detection of invisible image information (33′) within at least one detection area (11, 33, 55) and a detection of visible image information (55′) in the detection area (11, 33, 55). The control unit (13) determines special image areas (66), which indicate individual persons (9) or a plurality of persons (9). The control unit (13) is configured to determine at least one gas concentration (21′) on the basis of the image information (33′), taking into account the special image areas (66).