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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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