Natural gas from gas fields around the globe often contains mercury, along with a large number of other harmful substances (CO2, H2S, RSH, COS, etc). Mercury's potentially harmful effect on humans and on the ecological system as a whole as well as the technological risk regarding very sophisticated and expensive process equipment and catalysts make its removal imperative. There is a need for the highest efficiency for mercury removal and for permanent improvement and enhancement of technological and control procedures, including analytical instruments and measurements. Mercury concentration measurements in the ambient air performed during natural gas processing confirm that the design of the system at the Molve gas plant is adequate to meet the mercury removal objectives. The obtained results also illustrate in an excellent way the use of the portable instrument to identify and prevent potential mercury generated hazards linked to specific industrial processes.