A wearable mobile monitoring device, comprising - a gas measurement device, which is designed to read a value of a measured gas property of a gas, the gas being in the environment around the mobile monitoring device, and to provide a gas measurement signal dependent on the read value of the measured gas property; - a body measurement device, which is designed to read a value of a measured physical body property of a body of a person wearing the mobile monitoring device, and to provide a body measurement signal dependent on the read value of the measured body property; and - a control unit, which is designed to receive the gas measurement signal and the body measurement signal and to control the mobile monitoring device; wherein the control unit includes a correlator, which is designed to determine a correlation signal dependent on a degree of correlation in time between a gas signal derived from the gas measurement signal and a body signal derived from the body measurement signal, wherein the degree of correlation is determined by an interval of time between the occurrence of a deviation of the gas signal from a gas signal threshold value and the occurrence of a deviation of the body signal from a body signal threshold, wherein based on the correlation signal the control unit is configured to decide whether an alarm signal is to be generated, wherein the control unit is further configured to decide whether to put the mobile monitoring device into an energy-saving mode, and wherein for the purpose of producing the alarm signal and determining whether putting the mobile monitoring device into an energy saving mode the control unit considers said gas signal and said body signal simultaneously. - a gas measurement device, which is designed to read a value of a measured gas property of a gas, the gas being in the environment around the mobile monitoring device, and to provide a gas measurement signal dependent on the read value of the measured gas property; - a body measurement device, which is designed to read a value of a measured physical body property of a body of a person wearing the mobile monitoring device, and to provide a body measurement signal dependent on the read value of the measured body property; and - a control unit, which is designed to receive the gas measurement signal and the body measurement signal and to control the mobile monitoring device; wherein the control unit includes a correlator, which is designed to determine a correlation signal dependent on a degree of correlation in time between a gas signal derived from the gas measurement signal and a body signal derived from the body measurement signal, wherein the degree of correlation is determined by an interval of time between the occurrence of a deviation of the gas signal from a gas signal threshold value and the occurrence of a deviation of the body signal from a body signal threshold, wherein based on the correlation signal the control unit is configured to decide whether an alarm signal is to be generated, wherein the control unit is further configured to decide whether to put the mobile monitoring device into an energy-saving mode, and wherein for the purpose of producing the alarm signal and determining whether putting the mobile monitoring device into an energy saving mode the control unit considers said gas signal and said body signal simultaneously.