This analytical method is a validated measurement procedure for the determination of ethylene oxide [75-21-8] in workplace air averaged over the sampling period after personal or stationary sampling. A defined volume of air is drawn through two adsorption tubes packed with Chromosorb 106 and connected in series. For sampling the flow rate of the flow-regulated pump is set to 5 ml/min with an air sample volume of 200 ml (which corresponds to a sampling period of 40 min). For the following analysis the ethylene oxide is thermally desorbed and analysed by means of gas chromatography (GC) with a flame ionisation detector (FID). The quantitative evaluation is based on a calibration function obtained by means of a multiple-point calibration. The relative limit of quantification (LOQ) is 15 μg/m³ ethylene oxide for an air sample volume of 200 ml. The mean recovery was 100% and the expanded uncertainties were between 24 and 27% over the entire measurement range.