A one hour integrated flask sampling system to collect air in automated NOAA/ESRL12-flask packages is described. The integrating compressor system uses a mass flowcontroller to regulate the flow of air through a 15 l volume, thus providing a mixture of air5 collected over an hour-long period. By beginning with a high flow rate of 3800 standardliters per minute and gradually decreasing the flow rate over time to 290 standardliters per minute it is possible to obtain a nearly uniformly time averaged sample of airand collect it into a pressurized 0.7 l flask. The weighting function determining the airmixture obtained is described in detail. Laboratory and field tests demonstrate that the10 integrated sample approximates a simple mean of air collected during the one-hoursampling time.