The use of suites of real-time trace gas and fine particle instruments (~1 s response times) deployed aboard mobile laboratories to map ambient pollutant distributions and detect, fingerprint, and quantify pollutant emission sources have proven to be valuable in large urban/industrial areas over the past ~15 years. One of the earliest demonstrations of mobile lab utility for major city air quality research occurred in 2002 and 2003 during a collaborative research program in the Mexico City Metropolitan Area (MCMA) led by Mario Molina's group at the Massachusetts Institute of Technology (MIT). This activity also included several Mexican and US academic and government research groups and featured mobile labs outfitted and operated by scientists from Aerodyne Research, Inc. (ARI). The Molina led MCMA-2002 and MCMA-2003 field campaigns in the largest megacity in North America served as a major test-bed to develop and demonstrate novel mobile lab pollutant measurement methods.
A large fraction of major air quality campaigns worldwide now feature mobile laboratory deployments to characterize ground level pollution distributions and sources. Recent evolution of both gaseous and fine particle pollutant real-time measurement capabilities and mobile lab measurement strategies will be illustrated with examples from recent field campaigns, including the 2015 Benzene and other Toxics Exposure (BEE‐TEX) Study in Houston Texas.