Fire impacts – Natural event data exclusions/ozone monitoring

1. Fire impacts – Natural event data exclusions/ozone monitoring Colleen Delaney, Utah Division of Air Quality March 11, 2004

2. Background • Utah’s urban area has had ozone problems for many years • Salt Lake and Davis County • Designated nonattainment in 1977 • SIPs developed in mid ’80s and mid ’90s • Redesignated to attainment in 1997

3. Background • Utah’s population is concentrated along the Wasatch Front • Surrounding rural area is sparsely populated for hundreds of miles • Pollution problems were considered local issues, unaffected by transport

5. Ozone Formation in Utah • Emissions generated in the urban core move out over the Great Salt Lake in the morning • Heat and sunlight drive ozone formation • The air mass moves back over the Salt Lake Valley in the afternoon • The air mass sloshes around the valley, affecting different monitors at different times

7. July 2000 Episode • One week episode in 2000 • Unusually high values • Entire monitoring network was elevated • High temperatures, but not exceptional • Visible smoke in valley during this entire episode

11. July 2000 Episode • High ozone values would have violated the 1-hour and 8-hour ozone standards • Nonattainment designation would have a significant impact • Contingency measures • Possible need for additional control measures • Difficult to justify additional control measures if smoke was a big factor in this episode, and the high values were not a recurring problem

12. July 2000 Episode • Started rethinking our assumptions • Smoke may increase ozone precursors and transport ozone rather than just decreasing uv radiation • Distant fires, not just local emissions may affect ozone • UAM Modeling of past episodes required high boundary conditions – fire or regional transport may have been an unknown factor • No precedence in Utah or in Region VIII to use as a guideline for evaluating impact of fire

13. 1998 EPA Guidance – Mexican Fires • Severe fires in May 1998 affected entire eastern US • Technical Guidance for deciding whether plume impacted ozone concentrations • TOMS satellite data • GOES satellite data • Other corroborating data (could also cast doubt on demonstration) • Particulate measurements • Visibility or visibility range • Meteorological and other pollutant information

15. How to Evaluate Smoke Impact? • Was smoke in the area? • Satellite images • PM measurements • Visual images • Fire records • Did smoke affect ozone? • Unusual nature of episode

16. Possible Interference with Monitors? • UV Ozone monitors may measure other compounds as ozone • Very fine particles • Organic compounds • DAQ does not know if this was a factor in 2000 • Further controlled studies are needed to see if ozone measurement methods are overpredicting ozone levels during smoke episodes

27. Exceptional Event Demonstration • New issue for Utah and EPA Region VIII • Region coordinated with OAQPS • Put together all of the monitoring data and other supporting information that we could find • Many discussions with EPA and with Utah fire experts • Discussions with Forest Service research staff in Missoula regarding monitoring issues and possible impacts of fire

28. Exceptional Event Demonstration • EPA concurred with the State’s demonstration that the high ozone values were due to an exceptional event • It was not possible to determine what the ozone values would have been without the fires (we know they would have been elevated) • The data for the the entire week and the entire monitoring network were flagged

29. On-going Efforts to Flag Ozone Data due to Smoke Impacts • We are now noticing that there is smoke in the valley on some high ozone days • Each potential event is evaluated on a case-by-case basis • Suspect that elevated ozone values in rural areas could be partially due to fire impacts

30. August 19, 2002 Episode • Elevated ozone levels were measured at a number of monitors • Smoke was visible in the valley • PM measurements were elevated

37. August 19, 2002 Episode • EPA has not yet concurred with Utah’s exceptional event demonstration • Concerns that the impact was not reginoal • Satellite data did not show impact (TOMS, visual images) • Entire monitoring network was not affected • We will continue discussions with EPA on this episode

38. Conclusions • Fire is a factor on some high ozone days • Fires are prevalent due to drought and prescribed burning • EPA guidelines address large, regional events • Satellite data • Lots of supporting data • Local events are more difficult to demonstrate

39. Further Work is Needed • A method of analyzing smoke impacts is needed that can address both regional and local events • The fire tracking system developed through the WRAP will help • Timing of data availability may be an issue for flagging data • Effects of smoke on ozone monitors needs further evaluation to see if this is an issue (funded by EPA)

40. Further Work is Needed • Regional ozone modeling is needed to see if fire is causing elevated ozone in rural areas • Urban areas may be affected by rural background levels