Testing of New Ozone Photometers Ozone Transport Commission/MANEVU Fall Meeting November 14, 2013 Washington, DC Will Ollison 1220 L Street, NW Washington, DC

Testing of New O3 Photometers Do we know what the O 3 monitor’s really measuring? EPA currently certifies FEM photometers with up to 60 ppb interference bias, 24- hour zero/span drifts of 20 ppb, LODs of 10 ppb, and noise levels of 5 ppb but notes in the 2013 ISA (EPA 600/R-10/076F) that these criteria “…should be revised to more accurately reflect the necessary performance requirements for O 3 monitors used to support the current NAAQS”. NIST staff notes (Norris et al JAWMA 63: ) that “…regular audits currently provide reliable measures of field monitor precision and bias in response to challenges of O 3 in zero air, although not of sample matrix effects arising from ambient humidity and interfering species (Spicer et al JAWMA 60: )”. New monitor testing suggests actual NAAQS attainment is better than reported and affordable photometer scrubber upgrades will improve O 3 measurement accuracy Ollison et al JAWMA 63: ; Johnson et al JAWMA (in press). 2

Ozone Monitor Types EPA is currently evaluating the NO-scrubbed 2B Technologies 211 photometer and the Teledyne-API 265E NO-O 3 chemiluminescence monitor as potential new ozone Federal Reference Methods 1220 L Street, NW Washington, DC

Percent O 3 Monitor Share U.S. Network ( ) 1220 L Street, NW Washington, DC

TE49C-211 Hourly Difference & Collocated NO & VOCs 1220 L Street, NW Washington, DC Ollison et al. (2013) JAWMA 63:

211 ME Factor (211F) & Difference (205D) Home Activity Johnson et al. (2013) JAWMA (in press) 1220 L Street, NW Washington, DC

GPT Scrubberless Module™ Drop-in NO-scrubbers are commercially available from 2B Technologies to convert Teledyne-API & Thermo photometers to “interference-free” (H 2 O, Hg, aromatic VOCs) O 3 monitors L Street, NW Washington, DC