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| [[Exceptional_Air_Pollution_Event_Analysis_Community_Workspace|< Back to Exceptional Event Workspace]]<br> | | [[Exceptional_Air_Pollution_Event_Analysis_Community_Workspace|< Back to Exceptional Event Workspace]]<br> |
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| + | [[Evidence for Flagging Exceptional Events|Required Evidence for Flagging Exceptional Events]] |
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− | ==Definitions according to EE Rule ==
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− | (j) '''''Exceptional event''''' means 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 40CFR 50.14 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.
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− | (k) '''''Natural event''''' means an event in which human activity plays little or no direct causal role.
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− | (l) '''''Exceedance''''' with respect to a national ambient air quality standard means one occurrence of a measured or modeled concentration that exceeds the specified concentration level of such standard for the averaging period specified by the standard.
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− | ==What is na Exceptional Event? (EE)==
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− | The Exceptional Events Rule requires states that flag data to satisfy the requirements of 40 CFR 50.14 (c)(3)(iii) to provide evidence that:
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− | # The event satisfies the criteria that it was not reasonably controllable or preventable
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− | # There would have been no exceedances or violation '''''but for''''' the event.
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− | # Tthe event is associated with a measured value in excess of historical values
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− | # There is a clear casual relationship between the measured value and the event
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− | === 1. Not Reasonably Controllable or Preventable ===
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− | [[image:ForestSmokePic.png|200px]] [[image:DustFrontPic.png|200px]] [[image:Volcano.png|200px]] [[image:July4th_04_S.png|200px]]
| + | === PM2.5 Concentration Trend 2000-2006 === |
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− | === 2. No Exceedance or Violation ''But For'' the Exceptional Event ===
| + | Three-year aggregates of PM2.5. Left Images: Annual average PM10: Right Images: 98th Percentile. |
− | According to the EE Rule, observationas can be EE-flagged if the concentration exceeds the standard due to the exceptional event.
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− | * The leftmost figure shows a case when the 'exceptional' concetration raises the level above the standard.
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− | * In the next case, the concentration from controllable sources is sufficient cause the exceedance. Such an exceedance is not a 'but for' case and should not be flagged.
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− | * In the third case, there is no exceedance, hence no justification for EE flag.
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− | [[Image:EE_ButForSchematics.png|200px|The 'exceptional' concetration raises the level above the standard]]
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− | [[Image:Image-EE NoButFor1Schematics.png|200px|The 'exceptional' concetration raises the level above the standard]]
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− | [[Image:Image-EE NoButFor2Schematics.png|200px|The 'exceptional' concetration raises the level above the standard]]
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− | <br>
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− | Illustration Exceptional Events, EE and non-EE events by the EE Rule.
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− | === 3. The Event is in excess of the Historical Values ===
| + | Note the remarkable decline of both PM2.5 matric in the period 2000-2006 |
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| + | [[Image:2000_04_FRMPM25_Avg.png|400px]] [[Image:2005_08_FRMPM25_Avg.png|400px]] |