PH**l07.83-04_2~_~** UNITED STATES ENVIRONMENTAL. PRO'i::C'iION AGENCY wlISHINGTO'i. O.C**Z~'IO** APR 21 1SS3 

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MEMORANDUM SUBJECT: SAetion 107 Designation Policy Summar,y**~,4'.~~** FROM: Sheldon Meyers,-DirttfOr

-- Office ofAirQuality Planning and Standards 

### (ANR-443) TO: Director, Air and Vaste Management Division Regions 

### II-IV, VI-VIII, X Director, AirManagement Division Regions 

## r, V, IX On February 3, 1983, theAgency' published aFederal Register notice regarding the status ofall areas designated nonattainment under Part 0 of the C1ean AirAct. This notice indicated that for a significant number ofnonattainment areas States are**ant1~ipated** to be ableto demonstrate attainment ofthe primary nationa' alDfent air quality standards. Accordingly, for those areas, States hav. been encouraged to update their Section 107 designations'. In addition, a number of nonatta1nment areas were identified in the February 3, 1983, notice as ·unlikelyto attain standarc1s. u The Federal Register also stated that the basic existing pol1e,y will generally be**con~inued** for redesignation. This memorandua sum.arizlS and clarifies existing pol1cy for reviewing designations and provides new guidance on processing these actions. Policy ForReviewing 107 Designations 1. Data: In general, all available information relative to the attainment status ofthe area should be reviewed. These data should include the most recent eight (8) consecutive quarters ofquality assured. representative ambient air quality**dat~** plus Ividence of an impl.mented control strategy that EPA had fully approved. Supplemental information. including air quality mod.,ing emissions data, etc., should be used to deterunne if the monitoring data accurately characterize the worst**~as.** air quality in the area. Also, the following items can be considered in special situations•

.An attainment designation can be made using only the most recent four (4) quarters of ambient data if an acceptable state ofthe art modeling analysis (such as city-specific EKMA for ozone) is provided showing that the basic SIP strategy is sound and that actual, enforceable emission reductions are responsible for :he recent air quality improvement.

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### For nonattainment designations which were originally based solely on mOdeling. redesignation to attainment is possible even ifless than four (4) quarters of**ambie~t** 

### data are available provided that a referente modeling analysis tonsidering the sourtes' legal emission l'imits shc.s attainment of the standards.**Informat~on** 

### must also bepresented showing that the sources causing the problem are in compHance with the enforceable SIP lIItasures.

. Although the current ozone standard 

### tlllPl1es thl need for thrH

### y.ars of data for attainment designations, twoYlars ofdati with no .xceldanclS is an acceptable surrogate. As discussed previously. this should b. accompanied by 

### .vidence of an impl_nted control strate", that EPA had fully approved. 2.**~ected** 

### Future Violations: Projections offuture nolations tan provide the basis for tontinuing nonattainment designations. This concept is'particularly important betause ofthe current econoarit downturn. InfoMmation submitted to support !·ta;nment redesignations must adequately and accurately reflect anticipate, operating rates. Areas should remain nonattainment where such projections reveal air quality violations. 3. Modelina: In mest 502 cases, monitoring data .10newill not be sufficientfor areas do.inated by point sources_ A.-.11**n~r** 

### of ambient monitors usually is not representative ofthe airquality for th. entire area. Dispersion modeling employing the l.gally enforc.abl.

## S02 SIP liarits will generally be n.cessar,y to evaluate compreh.nsively the sources'**;~Iets** 

### as well as to identify the areas ofhighest concentrations. Ifeitherthe mod.';ng or monitoring indicates that S02 airquality stlnGardS are being violated. the Irea should remain nonattlin

..nt. 4. 

### Boundar;es: Current policies on appropriate boundaries for designation of nonattainment areas by EPA remainin effect. ;.e•• generally political boundaries such as city or county for TSP and S02. county as aminimumfor rural ozone, entire urbanized area and fringe areas of**~eY,'op** 

### ..nt for urban ozone, and urban core area for

### CO. When States redesignate. EPA will continue to accept reasonabl. boundaries which are supported by 

### appropriate data. such as specific new mOnitoring and/ormodeling data 

### or evidence ofimprovement due to control strategy**i~l** 

### ...ntation. Monatt.1nment areas for ozone should include the significant

### vac sourc.s. 5. Oisoersion Techniques: Areas whith are projected to attain theTSP or 502 

### standards because ofthe use of unauthorized dispersion techniques should continue to be designated as nonattainment.

107 8-23 Policy for Processing 107 Redesianations 1. SIP Review Actions: Section 107 designations have generally been classified as minor actions, with only afew ofthe more significant ones being processed as moderate. In the future, redesignations ofTier II nonattainment areas should be classified as major actions so that they can receive a comprehensive review to help ensure regional consistency. Rede5ignation ofTier 1 nonattainment areas should continue**~o** be handled as minor or moderate actions, as appropriate. 2. ·Unclassifiable- Areas: Since EPA and the States have had nearly five years to resolve discrepancies 

### for nonattainment designations, it is now inappropriate to redesignate any area from nonattainment to unclassifiable. There has been ample time since the first designations were made in 1978 to thoroughly study each nonattainment area. Sufficient data should now exist to either make a redes1gnation to attainment or to keep the nonattainment designation.

. Ifyou have any questions, please contact TomHelms at (FTS) 629-5525.

cc: Regiona' Administrator. Regions I-X Chief, Air Programs Branch. Regions 

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