MEMORANDUM

TO: Docket No. EPA-HQ-OAR-2012-0918 

Air Quality Designations for the 2012 Fine Particulate (PM2.5) Standards

FROM: Beth W. Palma 

Air Quality Policy Division, OAQPS 

SUBJECT: Florida Deferred Area Air Quality Designations for the 2012 PM2.5 National 

Ambient Air Quality Standards (SAN 5706)

This memorandum provides the rationale for the U.S. Environmental Protection Agency’s use of 

the additional time available to it under section 107(d)(1)(B) of the Clean Air Act (CAA) to 

obtain additional information and further evaluate air quality monitoring data before 

promulgating initial area designations for the 2012 primary annual fine particle National 

Ambient Air Quality Standard (2012 annual PM2.5 NAAQS)1in Florida. 

In accordance with section 107(d) of the CAA, the EPA must promulgate designations for all 

areas of the country. In particular, the EPA must identify those areas that are violating a NAAQS 

or contributing to a violation of the NAAQS in a nearby area. The EPA designates these areas as 

“nonattainment” areas. Additionally, through the designation process, the EPA identifies areas 

that are meeting the NAAQS and those areas without sufficient data for the Agency to make a 

determination. The EPA uses a designation category of “unclassifiable/attainment” for areas 

where air quality monitoring data indicate attainment of the NAAQS and for areas that do not 

have monitors but for which the EPA has reason to believe are likely to be in attainment and are 

not contributing to nearby violations. The EPA reserves the category of “unclassifiable” for areas 

where the EPA cannot determine based on available information whether the area is meeting or 

not meeting the NAAQS or where the EPA has not determined whether the area contributes to a 

nearby violation. 

As described in more detail in the memorandum, “Data Quality Issues in Florida Affecting Air 

Quality Designations for the 2012 PM2.5 National Ambient Air Quality Standards,” the EPA has 

identified potential data completeness issues for areas across the state of Florida.

2 These potential 

data issues were revealed after the EPA announced its intention to designate the entire state of 

Florida as unclassifiable/attainment. Given these potential data completeness issues, the EPA is 

deferring designations for all counties in the State of Florida until the Agency can assess whether 

a valid design value can be calculated for areas in the state. The EPA is basing designation 

decisions for most areas across the country on design values for the 2011-2013 time period. 

Without the confidence to calculate a valid design value, the EPA cannot determine whether 

 

1 On December 14, 2012, the EPA promulgated a revised primary annual PM2.5 NAAQS (78 FR 3086, January 15, 

2013). In that action, the EPA revised the primary annual PM2.5 standard, strengthening it from 15.0 micrograms per 

cubic meter (μg/m3) to 12.0 μg/m3.

2 Memorandum from Liz Naess, Group Leader, Air Quality Analysis Group, US EPA Office of Air Quality 

Planning and Standards, to EPA Docket EPA-HQ-OAR-2012-0918, Air Quality Designations for the 2012 PM2.5

Standards, titled, “Data Quality Issues in Florida Affecting Air Quality Designations for the 2012 PM2.5 National 

Ambient Air Quality Standards.”
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these areas are meeting or are not meeting the NAAQS. Accordingly, the EPA is deferring 

designations and using the additional time available to it as provided under section 107(d)(1)(B) 

of the CAA to assess these data and promulgate a designation for the identified areas.

The EPA will work with Florida to finalize the designations for these counties as soon as 

complete certified data are available, which the EPA anticipates will allow for promulgation of 

these designations in accordance with section 107(d). When complete air quality monitoring data 

are available and have been certified, the EPA invites the State to submit revised designation and 

boundary recommendations, as appropriate. If at that time the EPA believes that it is necessary to 

modify the State’s recommendation and to promulgate a designation different from the State’s 

recommendation, then the EPA will notify the State at least 120 days prior to promulgating the 

final designation and the EPA will provide the State an opportunity to comment on the potential 

modification. The State will then have an opportunity to respond to the EPA’s proposed

designations and boundaries. Pursuant to section 107(d), the EPA cannot promulgate the 

designation for these areas less than 120 days from the date of the EPA modification letter. 

While the EPA is finalizing designations for most areas of the country, designations for all areas 

in the state of Florida will be promulgated at a later date in a separate final rule.

Approach

In determining the appropriate set of neighboring counties to include with the set of monitored 

counties for which the EPA is deferring designations, the EPA conducted a hypothetical analysis 

assuming that the monitors with the incomplete data were violating the 2012 standard of 12.0 

μg/m3. The EPA is proceeding under this assumption under the precautionary principle that 

because it is unclear whether there is a violation in this area due to data incompleteness, then for 

purposes of conducting the contribution analysis the EPA will presume that there may be such a 

violation. The EPA’s contribution analysis for these hypothetical violations focused on counties 

within the same Core Based Statistical Area (CBSA) as the affected monitor because these 

counties would be most likely to contain nearby sources that contribute to any violations. 

Specifically, the EPA evaluated all counties in the same CBSA as the county with the monitors 

in question, in order to determine whether these presumptively “nearby” counties (beyond the 

county with the incomplete monitoring data) contain emissions sources that would be relatively 

likely to contribute to any hypothetical violation of the standard in the area with those monitors.

Using information similar to the information used for determining nonattainment area 

boundaries,3the EPA evaluated the information available for these CBSAs, including Air 

Quality Data; Emissions and Emissions-related Data; Meteorology; and 

Geography/Topography.4 One of the EPA’s primary boundary considerations for determining 

whether to defer a final designation decision for these counties is whether the agency believes 

 

3 Memorandum dated April 16, 2013, from Gina McCarthy, Assistant Administrator, to Regional Administrators, 

Regions 1-10, titled “Initial Area Designations for the 2012 Revised Primary Annual Fine Particle National Ambient 

Air Quality Standard.” 

4 The EPA did not consider jurisdictional boundaries for purposes of deferred designations because jurisdictional 

boundaries are most helpful for nonattainment planning purposes, and this analysis concerns the preliminary 

dividing line between deferred and unclassifiable/attainment counties. No counties in Florida are being designated 

nonattainment pursuant to this analysis, although that could change in the future if forthcoming data reveal a 

NAAQS violation. 
3

the emissions in those nearby counties are highly likely to contribute to the potential violations, 

and whether the meteorological data support a case that those emissions could significantly 

impact the affected monitor. Where available evidence indicates that emissions in adjacent 

counties could likely have the potential to contribute to monitors with data incompleteness, the 

EPA is deferring the designation for those counties as well as for the county with the affected 

monitor. At this time, the EPA is still evaluating the data for Florida statewide and thus does not 

have enough information to make a designation decision for any area in the State.