A fundamental part of the URBAN 2000 experiment, conducted during the month of October in Salt Lake City, UT, was the release and subsequent measurement of SF₆ in the single building/urban/suburban environment. In order to study nocturnal urban/suburban atmospheric transport and dispersion, 60 whole-air bag samplers were deployed on light poles at every street corner in a 5x5 block area of downtown and at several mid-block intervals near the release point. An additional 40 bag samplers were placed on 2, 4, and 6 km arcs. These arcs were placed in the suburban portion of the city in a northwest direction from the release point. An appropriate complement of duplicate, control, and blank samplers were also deployed for quality control purposes. In addition to the bag samplers, 6 mobile real-time SF₆ analyzers were deployed during the six major intensive observation periods (IOPs). Four of these analyzers traversed the three arcs mentioned previously as well as a so-called 1 km arc on the edge of the urban area. Two additional units were quasi-stationary, and were placed near the SF₆ release point to monitor SF₆ plume meander and dispersion characteristics in street canyons.

SF₆ was released in three one-hour intervals beginning usually at 0100 hours MDT and continuing until 0600 hours. Each release was interspersed with one hour with no SF₆ release to permit the material to be transported out of the study region. IOPs were determined in cooperation with the VTMX study group. The IOPs were selected to occur when the surface winds were southeasterly. This approach ensured that the SF₆ would be transported through the downtown area out to the 2, 4, and 6 km sampling arcs deployed to the northwest of the city.

Five IOPs were conducted under conditions of light winds. At times, the wind meandered outside of the study domain and the mobile analyzers were redeployed in order to continue the measurement of the SF₆ plume. Other results show street canyon preferential flow. Suburban measurements also indicate the effect of plume meander and dispersion.