Measurements of atmospheric N2O concentrations in and around Ann Arbor, Michigan, between August 1976 and September 1977 yielded 329.5 ppb (parts per billion) (mole fraction in whole air samples) as the average with a standard deviation of 3.3 ppb. No seasional or overall trend is discernible. Small, marginally significant diurnal variations of N2O concentrations in the lowest 0.5 m of atmosphere can be seen in our data. Gas collectors applied to soils near our laboratory provided evidence that soils can consume atmospheric N2O under some conditions. Soils were seen to be N2O sources more often than sinks. Stronger source activity was evident in compost piles. Exhaust samples taken from several conventional vehicles showed less than ambient N2O concentrations, while catalytic converter equipped autos produce N2O. Samples of steaming volcanic vent air from Hawaii indicate that volcanoes are probably a source of atmospheric N2O, although emissions at the Sulphur Bank contain much less than ambient values of N2O. All measurements were made by electron capture-gas chromatography: techniques and equipment are described.