A field mountable online fumigation gas monitoring system for detection and continuous monitoring of different fumigant gases at mitigation locations. The inbuilt multi sampling ports capable of drawing sample from a distance of 100 meters provides fumigators with an option to cover multiple Silo's from a single point. It gives a digital output signal that can be connected to any suitable control system(Uniphos controller, DCS, PLCs etc) by RS-485 MODBUS RTU. It also gives an industry standard 4-20mA analog output signal, in addition it also provides digital input/output for PLC control. It is available for Phosphine and Methyl Bromide.