The availability of portable, direct reading nitric-oxide (10102439) (NO)/nitrogen oxides (NOx) meters with a range of 5 to 200 parts per million (ppm) concentration levels was examined through a market survey of this field. The results of the survey were presented along with use techniques which were recommended for each of the meters. Construction and performance standards were recommended for portable NO-NOx meters suitable for Occupational Safety and Health compliance testing. The meters evaluated included the Enolyzer Model 7100 Prototype, Analyzer Model N-322 (IBC), Mast Model 724-11, McMillan Model 2100 (MEC), Purad Prototype, Thermo Electron Model 8A (TECO), and UEI Model 7030. The only completely portable meter was the Enolyzer and it was also one of the better meters evaluated. The MEC ranked second only because the prototype evaluated was not battery operated. It had a performance which was comparable to the Enolyzer and other advantages. The IBC performance was at least as good as or better than the Enolyzer or the MEC except for an increased susceptibility to interferences. The IBC alone measured both NO and nitrogen-dioxide (10102440) (NO2), but was not portable, did not have an internal sampling system, and its multirange readout was only marginally suitable for NO and less so for NO2. The TECO was an excellent NO meter but did not measure NO2. The Mast measurements were inferior and the equipment was not portable, responded only to NO2, and was nonlinear. Neither the UEI or the Purad meters were fully evaluated and neither was portable.