Phosphine is a toxic gas that has been used for insect control in stored grain and other structures. The poisoning symptoms can range from respiratory or heart failure to a painful death from respiratory arrest. Phosphine is not an airborne contaminant but can be transferred through direct contact with skin. Workers should be kept out of areas where phosphine is being used. The gas is also flammable and can explode when mixed with oxygen or other oxidizers such as halogenated hydrocarbons, phosphorous, and aluminum.

One method of monitoring phosphine sensor levels is to use a phosphine sensor. These sensors are battery-operated and detect the presence of PH3 in the air. They are easy to use and can be worn around the neck or wrist. These detectors also come factory-calibrated and are water resistant.

A small-scale test was conducted to evaluate the repeatability of a commercially-available system that wirelessly measures phosphine. Four wireless sensors were positioned close together inside of a 208 L barrel filled with 70 kg of hard-red winter wheat. Each sensor was paired with a hand-held meter (model X-am 5000, Drager, Lubeck, Germany). The phosphine concentration of the wheat was measured using the monitor lines and the hand-held meter during fumigation for 7 days.

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The results showed that the wireless sensors were within 30 ppm of each other and were accurate in measuring phosphine concentrations. In comparison to the manual measurements with the monitoring lines and the hand-held meter, the wireless sensors were more efficient and provided data on local phosphine concentrations over a longer period of time. The automated measurement system may be useful in monitoring phosphine levels for fumigation treatments and providing more detailed information for evaluation of fumigation efficacies.