Apart from the need to monitor fumigant concentrations for health and safety reasons at the time of applying the fumigant and outside the fumigated structure, the need to monitor concentrations inside the fumigated structure to ensure successful fumigation is equally important.

These gases if not monitored will have serious consequences. Hence, the dangers of fumigants are very real for human beings. It can lead to a fatal accident if someone enters a building being fumigated or that has not been properly vented afterward.

Few of the gases that are used as fumigants are: 

• Phosphine and Sulfuryl Fluoride, which are both extremely toxic 
• Methyl bromide, which apart from being toxic also depletes the ozone layer. 

The main reasons that we need to detect and/or monitor fumigants are 

For personal safety and protection 

Poor warehouse design, uneven stack, or defective fumigation covers can cause leakage of the fumigants from the fumigated space and thus causing fumigation failure. Even minimal inhalation of these fumigants by working personnel can cause a feeling of sickness, nausea, and tightness in the chest, and extended exposure can have long term negative effects on their health. Hence checking for leaks during the entire fumigation period is of utmost importance for personal safety and protection. Here one needs to monitor fumigant levels in the TLV levels, which are in the sub-ppm or low-ppm levels. 

For process control measurement 

The fumigant is supposed to be confined for the intended duration of exposure at a pre-defined concentration to achieve the lethal dose needed to control the target pests in Containers, Bulk storages, Silos, etc. To ensure successful fumigation, the need to continuously monitor the gas concentration of Fumigants in the fumigated area is of utmost importance. Here one needs to monitor fumigant levels in lethal concentration levels, which are in hundreds and thousands of ppm.