Sites Impacted by ‘Special’ Events (over NAAQS w/ flags, under NAAQS w/out) Special Events = Exceptional Events + Natural Events 8 sites / counties would not be exceed the NAAQS if flagged data were excluded Only 1 area affected at CMSA / MSA / County level Assuming all events are verified & Regions concur, the NA counts would change…. 120 violating counties – 8 = 112 counties 59 violating areas – 1 = 58 areas AQSSD is encouraging States to consider violating counties adjacent to violating metropolitan areas (C/MSA) as one distinct area for designations / planning purposes. Since Hardin County, KY is adjacent to Louisville MSA (which is violating), the number of hypothetical nonattainment areas (56) would not change due to the exclusion of event flags.

Design Value Recalculation for Natural Events 760 sites meet NAAQS completeness criteria for 2000-2002. More than 600 of these sites would have the same design value if natural event flagged data were excluded (if even present) . Only 3 sites would have a 1 ug/m3 or more difference; all 3 sites meet the NAAQS with the event data included Effect (removing flagged data) No change .1 ug/m3 .2 .3 .4 .5 .6 .7 .8 .9 1 Count 606 70 50 16 7 3 2

100 Highest PM2.5 Values, 2000-2002

PM2.5 Sample Counts – By Concentration Range & Flag Type Most samples are low values 47% < 10.0 ug/m3 70% < 15.0 ug/m3 99.8% < 65.0 ug/m3 Only a small percentage of data is flagged for events 0.16% flagged for natural events

Data Flagging - AQS Exceptional Events Regional Concurrence There are really 2 types of 'exceptional' events, natural events (forest fires, high winds, etc) and true exceptional events (construction, large gatherings, etc). For PM, there are different policies for the 2 groups and thus, we want to distinguish between the two….. in general & in AQS In the future, the combined group may simply be termed 'event' flags (or 'special events'); AQS subsets will be NAT and EXC Regional Concurrence AQS currently allows either ‘ ‘ (blank, no entry) or ‘Y” as valid entries in the CONCURR field For the nulls, users (e.g., OAQPS) cannot discern between a ‘no’ (Region disagrees with the flag) and non-decision (Region has not yet evaluated the flag yet, or Region awaiting documentation / clarification) AQS being enhanced to allow ‘N” as valid entry. The ‘N’ will tell users that the Region has reviewed the event situation and disagreed with the flag

Data Flagging - AQS AQS will soon factor both Regional concurrence and the segregation of the 2 event types into retrieval report options. Using the existing EDT_IND's 1 & 2, the options will be: All data - Include Event flagged data (concurrence ignored) - 2 Exclude Event flagged data (concurrence ignored) – 1 Exclude Exceptional Event flagged data (concurrence ignored) - 3 Exclude Natural Event flagged data (concurrence ignored) - 4 Exclude approved Event flagged data (concurrence = 'Y') - 5 Exclude approved Exceptional Event flagged data (concurrence = 'Y') - 6 Exclude approved Natural Event flagged data (concurrence = 'Y') - 7 (The 'all data ' option will be the default.) For the ‘350’ standard retrieval raw data reports, exceptional data codes will be displayed in lower case when the concurrence indicator is null, and in upper case when 'Y'. If the concurrence is 'N', we have suggested that AQS show an asterisk (both on the report and in the file versions). The asterisk will tell the user that there was an event flag but that it was disapproved by the Region. If the user want to know what the flag is, they will have to browse AQS, or use Discover, SAS, etc.