INTRODUCTION Members of the Air Quality Monitoring Unit of the Oklahoma Department of Environmental Quality, Air Quality Division (AQD) have been reviewing the high PM2.5 value recorded at McAlester AQS site 401210415 on March 7, 2007. While the sample value of 37.3 ug/m3 appears to be valid data for quality assurance purposes, influences from local open burning may qualify as exceptional events. Also, after comparing the value with other PM2.5 data, the magnitude of the data point suggests an exceptional event. The demonstration of an exceptional event not only allows the State to attach validity flags to the data (Appendix A) but also for EPA “to exclude the data from use in determinations of exceedances and NAAQS violations…”


The AQD intends to provide EPA with documentation of an exceptional event and a demonstration of the relationship between the exceptional event and the air quality data in question. As found in the Federal Register of Thursday, March 22, 2007, 40 CFRPart50.1(j) (see Appendix B)defines an exceptional event as “an event that affects air quality, is not reasonably controllable or preventable, is an event caused by human activity that is unlikely to recur at a particular location or a natural event, and is determined by the Administrator in accordance with 40CFR50.14 to be an exceptional event. It does not include stagnation of air masses or meteorological inversions, a meteorological event involving high temperatures or lack of precipitation, or air pollution relating to source noncompliance.”

McALESTER SITE 415 LOCATION AQS Monitoring Site 401210415 is located on the McAlester Airport property. The site is located on the south side of McAlester, on the east side of US 69 (Appendix C). There are four air monitors located at the site. The pollutants monitored include ozone, PM-2.5 (FRM and continuous) and PM-10. There are no stationary air pollution sources located in the vicinity of the airport. US Hiway 69 runs southwest to northeast through the area and is located approximately 500 feet to the northwest at its closest point. There is a county road oriented north and south just to the west of the airport property. There are houses, two schools and a baseball field accessed from this county road. The area is rural in nature.


Mesonet Climatological Data Summaries provide accurate and dependable weather data for selected cities throughout Oklahoma. AQD uses the data collected at these locations for determining run day average station pressure and temperature for data calculations at PM-10 sites and for determining wind speed and direction in other air pollution studies. The closest Mesonet station is located on the same airport property as the air monitoring site. It is approximately .3 mile, approximately 1600 feet, to the southeast of the air monitoring site. Aerial photographs of the area with the two facilities marked in red are included as Appendix C. The weather data from the Mesonet site should give an excellent record of the weather parameters present at the site. The Mesonet data indicate the wind speed and direction for the whole day in five minute averages and is included in Appendix D. Included as Appendix E is the Daily Data Reports from all of the state PM-2.5 continuous monitors which includes the data from Site 401210415. This report contains the hourly averages for the continuous monitors at the site, ozone and continuous PM-2.5(FDMS and TEOM). The hourly averages from the two PM-2.5 continuous monitors at Site 401210415 indicate high concentrations occurred during the early morning hours, between 1 am and 9 am. The Mesonet wind data during that period indicate the wind to be consistently from the south southwest(182 to 215 degrees) with speeds ranging from 1.7 to 4.0 meters per second (3 to 8 miles per hour).


There are no stationary air pollution sources within several miles directly south of the monitoring site according to records of inspections and permits found in Department of Environmental Quality TEAM Data Base. The Mesonet wind data support the location of the source of particulates during the period of high readings to have been located just to the south of the monitoring site. Possible area source emissions include those from mobile sources, such as automobiles and trains, open burning and fugitive dust. However, the number of automobiles and trains traversing the area is very low. And, there were no barren tracts of land in the area or areas of construction where dirt work was occurring.


The validity flag used on the data in question, R, is for cleanup after a major disaster. The emissions from open burning, while not quantifiable, were definitely present and significant during the day in question and for several weeks during the spring of 2007. A major ice storm devastated the area in January 2007(see Appendix F). There was damage to the trees in several of the eastern counties of Oklahoma including Pittsburg County, where McAlester is located. Clean up of the debris from the disaster took several months. Most of the debris consisted of tree limbs. Most of the tree limbs that fell in the McAlester City limits were transported to the McAlester land fill where they were burned. However, some of the debris was burned in the city proper as evident by the 42 open burning permits that were issued by the McAlester Fire Department during February, March and April. The fire departments jurisdiction does not extend to the area just south of the airport, so unfortunately, no records of open burning for the day in question exist. Because the area to the south of the airport is out of the city limits of McAlester, the debris from the area did not go to the landfill and was disposed in other ways. The monitoring site operator did observe smoke from such burning on every trip made to the site during the months of February, March and April of 2007. On the day after the day in question, March 8, 2007, the site operator observed a pile of smoldering limbs less than 200 yards away from the monitoring site on airport property. While this particular instance of open burning probably had no influence on the data in question it does show that burning of this nature was occurring in close proximity to the site. DATA ANALYSIS

PM-2.5 data was plotted for all of the DEQ sites for the first quarter of 2007. Only the data collected on the one in three schedule is plotted and included as Appendix G. The concentrations vary greatly from west to east across the state on the day in question with the highest readings found in the east. Site 401210415 is the only site to have measured PM-2.5 over 35 micrograms per cubic meter. The Oklahoma City sites, 035 and 037, measured less than half that amount. As previously mentioned, the continuous PM-2.5 data indicates high concentrations present during the early morning hours only. Data for the rest of the day shows concentrations typical of the rest of the state. This suggests that site 401210415 was directly in a particle plume during those early hours.

QUALITY ASSURANCE All reasonable quality assurance checks show the data in question to be valid. Calibrations, flow checks and audits before and after the sample date were within acceptable limits. The AQD is confident that the sample was properly collected and processed.

SUMMARY The AQD plans to submit the PM-2.5 data in question with an “R” flag for cleanup after a major disaster. This flag seems most appropriate for the circumstances surrounding this PM-2.5 value. While some contributions from regional PM-2.5 area and point source emissions cannot be ruled out, the AQD is focusing on continuous PM-2.5 data, meteorological conditions and site operator observations in determining the concentrations recorded were the result of a localized event. The data shows that an exceptional event most likely contributed to the high PM-2.5 value on March 7, 2007 at site 401210415.

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