Field evaluations of newly available "interference-free" monitors for nitrogen dioxide and ozone at near-road and conventional National Ambient Air Quality Standards compliance sites.

Unlabelled: Long-standing measurement techniques for determining ground-level ozone (O) and nitrogen dioxide (NO) are known to be biased by interfering compounds that result in overestimates of high O and NO ambient concentrations under conducive conditions. An increasing near-ground O gradient (NGOG) with increasing height above ground level is also known to exist. Both the interference bias and NGOG were investigated by comparing data from a conventional Federal Equivalent Method (FEM) O photometer and an identical monitor upgraded with an "interference-free" nitric oxide O scrubber that alternatively sampled at 2 m and 6.

Laboratory and field evaluation of crystallized DOW 704 oil on the performance of the Well Impactor Ninety-Six fFine particulate matter fractionator.

Subsequent to the 1997 promulgation of the Federal Reference Method (FRM) for monitoring fine particulate matter (PM2.5) in ambient air, U.S.

Potential interference bias in ozone standard compliance monitoring.

The U.S. Environmental Protection Agency has established a federal reference method (FRM) for ozone (O3) and allowed for designation of federal equivalent methods (FEMs).