A cryosampling system together with a low temperature GC-ICP-MS method have been developed for the determination of phosphine for industrial hygiene purposes. The effect of sampling temperature on the collection efficiency of PH 3 was investigated. Two trapping mechanisms were differentiated for temperature ranges from 2190 to 2160 uC and from 2110 to 235 uC. A cartridge filled with NaOH was used during the analytical desorption step to separate CO 2 from phosphine. Phosphine recovery was found to be better than 98% with peak area and retention times RSD values better than 4% and 2%, respectively. The use of a Nafion 1 drying membrane before cryogenic trapping induced losses of PH 3 of about 15%. Sample conservation in a cryocontainer at 2190 uC over a period of 15 days did not lead to significant losses of PH 3 . For field experiments, air samples were collected in the fumigation room of a tobacco factory after fumigation, and outside the fumigation room during fumigation, using both cryogenic sampling and standard filters impregnated with silver nitrate. The results showed that phosphine concentrations in the tobacco factory were below the limit values for occupational exposure to phosphine (VME (France) and TLV-TWA (USA)) and also below the detection limit of the silver impregnated filter-ICP-AES method. Cryogenic trapping in combination with GC-ICP-MS allowed us to determine phosphine concentrations. The concentrations in ambient air are estimated to be about 1 ng m 23 and the detected concentrations in the vicinity of the fumigation room during the fumigation process are lower than 10 ng m 23 . PH 3 in air reacts with HOx radicals and is removed by this mechanism with a half time of 5-28 hours, depending on the conditions. 1 The sunshine increases the OHx radicals concentration and may reduce the half-life to less than 5 hours. The following reaction of phosphine with OHx may occur:This reaction is dependant on PH 3 concentration and is very rapid, with a reaction rate constant at room temperature of about 1.5 6 10 211 cm 3 mol 21 s 21 . 9 The final product of the