10/27/2014

Overview of proposed changes and solicitations of comment included in the draft O3

NAAQS proposal 

 Primary Standard 

o Section II.D.5 proposes that the current primary O3 standard of 0.075 parts per 

million (ppm) is not adequate to protect public health, and that it should be 

revised to provide increased public health protection. 

 Solicits comment on retaining the current standard. 

o Section II.E.4 proposes to revise standard by setting the level to within the range 

of 0.065 to 0.070 ppm. 

 Solicits comment on alternative standard levels below 0.065 ppm, and as 

low as 0.060 ppm. 

 Secondary Standard 

o Section IV.D.3 proposes to revise the current secondary standard to provide 

increased protection against vegetation-related effects on public welfare. 

 Solicits comments on retaining the current secondary standard, without 

revision. 

o Section IV.E.5 proposes to revise the level of the current secondary standard to 

within the range proposed for the primary O3 standard (0.065 to 0.070 ppm), in 

order to maintain three-year average W126 index values at or below 13-17 ppmhrs. 

 Solicits comments on setting the level of the secondary standard to 

maintain three-year average W126 values below 13 ppm-hrs, and as low 

as 7 ppm-hrs. 

 Solicits comments on revising the form of the secondary standard to the 

W126 index, averaged across three consecutive years, with a level within 

the range of 13 ppm-hrs to 17 ppm-hrs. 

 Solicits comments on revising the form of the secondary standard to the 

W126 index, averaged across three consecutive years, with a level 

extending as low as 7 ppm-hrs. 

 Air Quality Index (AQI): Section III proposes conforming changes to the AQI for O3

by setting the AQI value of 100 equal to the level of the 8-hour primary standard, and by 

making proportional changes to the AQI values of 50, 150, 200 and 300. 

 Data Handling: Section V.C proposes several revisions to data handling conventions for 

O3, including a proposed Appendix U that explains the computations necessary for 

determining when the proposed primary and secondary O3 NAAQS are met at an ambient 

air quality monitoring site with regard to data selection, reporting, and handling.

 Exceptional Events: Section V.E proposes changes to exceptional event schedules 

related to implementing any revised O3 standards, and proposes to extend the new 

schedule approach to other future revised NAAQS and to remove obsolete regulatory 

language associated with expired exceptional event deadlines for historical standards for 

O3 and other NAAQS pollutants. 

 O3 monitoring seasons: Section VI.B proposes changes to the O3 monitoring seasons. 
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 Federal Reference Method (FRM): Section VI.D proposes changes to the FRM for 

monitoring O3 in the ambient air. 

 Photochemical Assessment Monitoring Stations (PAMS) network: Section VI.D

proposes changes to the PAMS network design. 

 Federal Equivalent Method (FEM): Section VI.E proposes revisions to FEM testing 

requirements, including making the requirements for nitrogen dioxide consistent with the 

requirements for O3 and removing an obsolete requirement for the annual submission of 

documentation by manufacturers of certain particulate matter monitors. 

 Prevention of Significant Deterioration (PSD): Section VII.D proposes to add a 

provision grandfathering certain pending permits from certain requirements with respect 

to the proposed revisions to the O3 NAAQS.