Effects on Network Photometers Ozone Transport Commission - PowerPoint PPT Presentation

O 3 Scrubber Upgrade & Inlet Height Effects on Network Photometers Ozone Transport Commission OTC/MANE-VU Committee Meeting September 10, 2015 Washington, DC Will Ollison 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 1

Upgraded O 3 Photometer & Inlet Height Measurements • Current network O 3 photometers are subject to positive interference bias (Hg, H 2 O, Aryl VOCs) raising O 3 design values Spicer et al. JAWMA 60: 1353 – 1364 (2010); Johnson et al. JAWMA 64: 360-71 (2014). • Nitric oxide-gas phase titration (NO-GPT) O 3 scrubber upgrades ( http://www.twobtech.com/model_GPT.htm ) raise accuracy (Note #40 http://www.twobtech.com/products.htm ) and NAAQS compliance Ollison et al. JAWMA 63: 855 – 863 (2013). • U.S. O 3 monitor inlet heights average 5.4 meters ( Richard Wayland – personal communication ); but it’s thought that 2 meter inlets better (1) approximate outdoor nose level exposure and (2) appear to better comply with ambient O 3 NAAQS. 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 2

Distribution of O 3 Compliance Monitor Inlet Heights (m) Richard Wayland – Personal Communication 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 3

Westport, CT Upgraded O 3 Monitor and Inlet Height Study 1. A collocated NO-scrubbed upgraded Teledyne-API T400 photometer, with alternate 5-min sampling (4-min before 6/29/15) at 2m and 6.2m inlets, is compared to the conventional Westport site TAPI T400. 2. Measured O 3 levels adjusted daily for relative monitor drift. 3. Preliminary findings: o Upgraded NO-scrubbed photometer O 3 peaks decrease with inlet height during stable meteorological conditions o Collocated upgraded NO-scrubbed photometer O 3 peaks generally decrease with respect to conventional photometer values. 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 4

Westport, CT Monitoring Site Google Maps 41.118201, -73.336713 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 5

Westport, CT Monitoring Site Google Maps 41.118201, -73.336713 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 6

Westport, CT Monitoring Site Alan Leston – Personal Communication 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 7

2 Meter Westport Inlet Alan Leston – Personal Communication 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 8

6.2 Meter Westport Inlet Alan Leston – Personal Communication 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 9

100 -40 -20 20 40 60 80 0 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 6/16/15 0:00 6/17/15 0:00 6/18/15 0:00 8h Adj O3 6/19/15 0:00 6/20/15 0:00 6/21/15 0:00 6/22/15 0:00 6/23/15 0:00 6/24/15 0:00 6/25/15 0:00 6/26/15 0:00 6/27/15 0:00 6/28/15 0:00 6/29/15 0:00 6/30/15 0:00 Collocated 6.2m Inlet Height Rolling 8-Hour O 3 Values (ppb) 7/1/15 0:00 7/2/15 0:00 7/3/15 0:00 8h Adj O3 2m 7/4/15 0:00 7/5/15 0:00 7/6/15 0:00 7/7/15 0:00 7/8/15 0:00 7/9/15 0:00 7/10/15 0:00 7/11/15 0:00 7/12/15 0:00 7/13/15 0:00 7/14/15 0:00 7/15/15 0:00 7/16/15 0:00 7/17/15 0:00 7/18/15 0:00 7/19/15 0:00 7/20/15 0:00 7/21/15 0:00 8h Adj O3 6m 7/22/15 0:00 7/23/15 0:00 7/24/15 0:00 7/25/15 0:00 7/26/15 0:00 7/27/15 0:00 7/28/15 0:00 7/29/15 0:00 7/30/15 0:00 7/31/15 0:00 8/1/15 0:00 8/2/15 0:00 8/3/15 0:00 8/4/15 0:00 8/5/15 0:00 8/6/15 0:00 8/7/15 0:00 8/8/15 0:00 8/9/15 0:00 8h Adj O3-6m Diff 8/10/15 0:00 8/11/15 0:00 8/12/15 0:00 8/13/15 0:00 8/14/15 0:00 8/15/15 0:00 8/16/15 0:00 8/17/15 0:00 8/18/15 0:00 8/19/15 0:00 8/20/15 0:00 8/21/15 0:00 8/22/15 0:00 8/23/15 0:00 8/24/15 0:00 8/25/15 0:00 8/26/15 0:00 8/27/15 0:00 10 -5 0 5 10 15 20 25 30

100 -40 -20 20 40 60 80 0 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 6/16/15 0:00 6/17/15 0:00 6/18/15 0:00 6/19/15 0:00 6/20/15 0:00 8h Adj O3 6/21/15 0:00 6/22/15 0:00 6/23/15 0:00 6/24/15 0:00 6/25/15 0:00 6/26/15 0:00 6/27/15 0:00 6/28/15 0:00 6/29/15 0:00 6/30/15 0:00 Measured at 2m Inlet Height Rolling 8-Hour O 3 Values (ppb) 7/1/15 0:00 7/2/15 0:00 7/3/15 0:00 7/4/15 0:00 8h Adj O3 2m 7/5/15 0:00 7/6/15 0:00 7/7/15 0:00 7/8/15 0:00 7/9/15 0:00 7/10/15 0:00 7/11/15 0:00 7/12/15 0:00 7/13/15 0:00 7/14/15 0:00 7/15/15 0:00 7/16/15 0:00 7/17/15 0:00 7/18/15 0:00 7/19/15 0:00 7/20/15 0:00 7/21/15 0:00 7/22/15 0:00 8h Adj O3 6m 7/23/15 0:00 7/24/15 0:00 7/25/15 0:00 7/26/15 0:00 7/27/15 0:00 7/28/15 0:00 7/29/15 0:00 7/30/15 0:00 7/31/15 0:00 8/1/15 0:00 8/2/15 0:00 8/3/15 0:00 8/4/15 0:00 8/5/15 0:00 8/6/15 0:00 8/7/15 0:00 8/8/15 0:00 8/9/15 0:00 8h Adj O3-2m Diff 8/10/15 0:00 8/11/15 0:00 8/12/15 0:00 8/13/15 0:00 8/14/15 0:00 8/15/15 0:00 8/16/15 0:00 8/17/15 0:00 8/18/15 0:00 8/19/15 0:00 8/20/15 0:00 8/21/15 0:00 8/22/15 0:00 8/23/15 0:00 8/24/15 0:00 8/25/15 0:00 8/26/15 0:00 8/27/15 0:00 11 -5 0 5 10 15 20 25 30

EPA Inlet Height Considerations The 2006 Ozone CD notes, based on the information derived from non-urban studies, that the degree of atmospheric stability is important as “ there was a decrease of about 20% in going from a height of 4m down to 0.5m above the surface during stable conditions, but O 3 decreased by only about 7% [ i.e., by about 5 ppb at 70 ppb O 3 ] during unstable conditions.” While there is some information indicating decreasing ozone concentration with decreasing monitor probe height, there are too few studies available at this time with the appropriate data to develop a reasonable quantitative relationship for adjusting ozone data (or design values) in urban areas. Richard Wayland – Personal Communication 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 12

Recommendations • EPA regulatory staff recognize increasing vertical O 3 gradients above 2m and the need to adjust monitored values to better reflect actual human outdoor exposures at this level. • The Westport data show a persistent, although meteorologically variable, positive O 3 gradient upwards from the 2m AGL values thought to be more representative of outdoor human exposures than current monitor inlet heights in the 4m to 6m range. • SLTs should consider moving O 3 monitoring inlets to the 2m level now as a timely, practical remedy of this positive O 3 gradient bias, given EPA’s acknowledged lack of adequate gradient data to downward adjust high inlet urban O 3 design values appropriately. 1220 L Street, NW • Washington, DC 20005 - 4070 • www.api.org 13