The recent marriage of tandem mass spectrometry (MS/MS) to mobile trace atmospheric gas analyzer (TAGA) technology has resulted in an analytical system capable of real-time direct air analysis for toxic air pollutants (TAP), volatile organic compounds (VOC), and odor compounds at concentrations as low as a few parts per trillion. This direct analytical approach obviates problems associated with conventional trapping methods. The latest design of a mobile MS/MS laboratory comprises a customized 9-m (30-ft) transit motor coach configured with a TAGA 6000EM MS/MS system and ancillary equipment. This paper discusses the incorporation of a sorbent cartridge purge unit into the TAGA system to assist in rapidly distinguishing between isomeric compounds (for example, ethylbenzene and xylene) using gas chromatography (GC/MS/MS. This paper also describes combining real-time TAP analysis with meteorological data to rapidly and accurately characterize plume profiles and emission frequencies. The mobility of the TAGA detector permitted the precise location of point source and fugitive emissions. Examples are provided for industrial emissions of methyl ethyl ketone and dimethyl sulfide. A simple method of on-site calibration was used, based upon headspace syringe injection. Under interactive computer control, calibration constants were determined in about 5 min per compound within the ambient air matrix. Other recent software developments are discussed, including the ability to simultaneously monitor up to 128 different compounds with real-time output in concentration units.