AQS Users,

In January 2008, I distributed an email "AQS Modifications to Implement the Exceptional Event Rule". This memo is also available on the web site below:

http://www.epa.gov/ttn/airs/airsaqs/memos/

The first step to the project was completed in January with the definition of the new codes. In review, the first step was to define 2 different qualifier types: (1) informational - INFORM and (2) exclusion - REQEXC. The new codes were assigned to events that meet the definition in the Exceptional Event Rule. The same events were defined with both INFORM and REQEXC qualifier types. The INFORM flags are available for any pollutant while the REQEXC are available for pollutants with National Ambient Air Quality Standards (NAAQS) and allow flagged data values to be excluded from design value consideration whenever EPA concurs that the event meets the requirements of the Exceptional Event Rule. The other part of the first step was to get users to begin to transition to the new codes. This process has been successful.

Although the software changes are not complete, we want to complete the first step of the implementation: "Stop accepting the old exceptional (EX) and natural (NAT) event flags". In order to continue the transition to the new codes, the codes that were originally type "EX" or "NAT" will not be available for use after October 15, 2008. To continue to provide a mechanism to flag data values for the exclusion/concurrence process, the "REQEXC" qualifier type has been converted to either "EX" or "NAT". This will allow them to be used for flagging sample values and also be processed by the concurrence process.

Attached is a listing of the INFORM, EX, and NAT type qualifier codes as they will be available after October 15. The "I" under "Status Ind" means that those codes will not be available after October 15.

After the software has been modified, the new codes will be converted back to "REQEXC" and the old codes (EX OR NAT) will be converted to INFORM or will be completely discontinued and converted to the new "INFORM" code.

Please notify me if there is a problem with making the old codes inactive on October 15.

Thanks,

Jake Summers

National Air Data Group

OID/OAQPS/OAR/EPA

C339-04

Research Triangle Park, NC 27711

(919) 541-5695 (Phone) (919) 541-7674 (Fax)

summers.jake@epa.gov