This Bureau of Mines publication describes a passive personal sampling device for NO2 in air, developed by the New York University Medical Center under Bureau Grant GO133066. The sampler has been successfully demonstrated in the field and in the laboratory. In corroborative laboratory trials the agreement with reference method is excellent. The overall accuracy is approximately +/-5 pct of reading to a precision of about +/-1 pct. All evidence indicates that these samplers should indicate the time-weighted-average NO2 concentration to the above accuracy and precision equally well in the field since effects of wind velocity and relative humidity are negligible and the effects of temperature are about 0.1 pct per deg f. The duration of exposure and the approximate temperature are the only data that need to be collected in the field. A two-step analysis procedure in field or service laboratory is then used to obtain the total cumulated exposure to NO2 in parts per million- hours (ppm times hours), which can be converted to the time-weighted- average concentration of NO2 in ppm by dividing cumulated exposure by the duration of the exposure.