1 BACKGROUND INFORMATION DOCUMENT

ADDITIONAL OPTIONS CONSIDERED FOR CLASSIFICATION OF

NONATTAINMENT AREAS U NDER THE 2008 OZONE NAAQS

Docket ID No. EPA-HQ-OAR-2010-0885

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF AIR AND RADIATION

OFFICE OF AIR QUALITY PLANNING AND STANDARDS

RESEARCH TRIANGLE PARK, NC

January 20122 INTRODUCTION

In the notice of proposed rulemaking for cl assification of the 2008 8-hour ozone National Ambient Air Quality Standards (NAAQS), EPA is pr oposing a set of classification thresholds for the standard level of 0.075 ppm. The threshol ds are based on the same general methodology for adjusting the classification thresholds in Table 1 of the Clean Air Act (CAA) to account for an 8-

hour standard that was used for the 1997 ozone NAAQS. That methodology was: Determine the percentage by which each classification thresh old in Table 1 of CAA section 181 exceeds the 0.12 ppm 1-hour ozone standard and set the 8-hour thres hold value at the same percentage above

the level of the 8-hour ozone standard. For ex ample, the threshold separating Marginal and Moderate areas in Table 1 is 15 percent above th e 1-hour standard, so for an 8-hour standard of 0.075 ppm, we would set the Moderate area lowe r threshold value at 15 percent above the 0.075 standard (at 0.086 ppm). The other classification thresholds woul d be adjusted in a similar

manner.

The EPA also considered a number of other options for adjusting the classification table

for the 2008 standard. A number of other alte rnatives were suggested in comments on that proposed implementation rule for the 1997 standa rds and we re-opened the comment period on

that rule to take comment on several alternative classification approaches. 1 In the final Phase 1 rule for the 1997 standard, EPA noted the rationa les for the alternativ e methods that were

recommended for that standard were either not as consistent with the methodology of the Clean

Air Act’s own table or would have undesirable c onsequences, and therefore were not ultimately adopted. Several other concepts have been sugg ested since then. This paper describes several alternative classification approaches and, wh ere appropriate, provide s example results of applying the scheme to a set of hypothetical nonattainment areas derived from 2010 ozone design values. 2

1 Federal Register of October 21, 2003 (68 FR 60054).

2 Background Information Document - Developmen t of Hypothetical Nonattainment Areas for Illustrating Proposed Classifica tion Thresholds for Areas Designated Nonattainment for the 2008 0.075 ppm 8-hour Ozone National Ambient Air Qua lity Standard. January 2012 draft, Docket ID No. EPA-HQ-OAR-2010-0885.3 ADDITIONAL CONCEPTS CONSIDERED

1. Ratio of Thresholds Method

A number of commenters on the implem entation rule for the 1997 ozone NAAQS

recommended that EPA consider a classification approach that w ould place more areas in higher classifications in order to provide maximum timefr ames for areas to attain. In light of these circumstances, EPA also considered a method for translating the CAA’s cl assification table such that more areas would be placed in higher classi fications, which we refer to as the “ratio of thresholds” method. This method uses actual air quality data from areas that we anticipate will be designated nonattainment to establish the lower threshold for extreme areas (i.e., selecting the design value from one or more areas with the highest ozone levels as the threshold for the extreme area classification) and then establishe s the other thresholds based on ratios of the

Extreme threshold and the values in Table 1 of the CAA. This method for classification of nonattainment areas is based on Table 1 in the CAA for a 2008 ozone NAAQS. In adjusting the design value threshold levels for each classificat ion, this method accounts for the change in the

standard and also for the relative amount of reduction in ozone con centration needed to attain the standard. This method is based on the principl e that a classification table for the 2008 ozone NAAQS should account for not only the level of ozone classification threshold Design values above the level of the standard, but also the absolute spread of design values that we actually

measure in the air at the time we establish the cla ssification table. Doing so would classify areas based upon how much reduction in ozone concentra tions an area needs to achieve attainment relative to the areas with the highest design value.

Under the 1-hour ozone NAAQS, Extreme areas needed to reduce ozone levels by about 3
0.160 ppm (0.280 ppm – 0.120 ppm) or more to lo wer their design value to or below the

commensurate level of the standar d. In contrast, 1-hour Marginal areas only needed to reduce their DV by at most 0.017 ppm (0.137 ppm - 0.120 ppm) to achieve the same results. This is only 10.6 percent of the minimum reduction needed (0.160 ppm) for an Extreme area. Moderate areas needed at most 24.3 percent (100 * (0.159 ppm - 0.12 ppm) / 0.160 ppm) reduction in ozone levels of the 0.160 ppm minimum re duction needed by an Extreme area.

Under this alternative a pproach, a ratio would be calcu lated using the following:

[the difference between a specific classification th reshold and the lowest threshold (Marginal) in CAA Table 1] divided by

[the difference between the highest threshold (t he bottom of the Extreme classification) and the

lowest threshold (Marginal) in CAA Table 1]

3 The rounding technique allowed a 0.124 DV to meet the NAAQS. This approach is based on the design values listed in the CAA design va lue thresholds for 1-hour ozone areas.4 The ratio would then be used in co njunction with the 2008 ozone NAAQS. For a standard of 0.075 ppm, we know the bottom threshol d of Marginal will be the lowest violating DV (0.076 ppm). The highest 8-hour design value record ed for the period 2008-2010 is in Los Angeles: 0.112 ppm.

Under this method, a ratio would be cal culated using the following ratio:

[the lower threshold of each classificati on - the Marginal lowe r threshold (0.121 ppm)]

divided by

[the Extreme threshold (0.280 ppm) - the Marginal lower threshold (0.121 ppm)]

This ratio would then be applied to th e 0.075 ppm 8-hour standard, using current air quality data, to determine the upper range for th e classification (the bo ttom threshold for the Extreme classification). For the purposes of the ex ample, we presented the 8-hour thresholds for

each classification that result from this option using Extreme threshold of 0.112 ppm.

Area class CAA design value

thresholds 1-hour ozone ppm (Col A) Percent above

1-hour ozone

NAAQS Ratio of range of (class threshold to min) to (range of max to min thresholds)

(Col B) 8-hr thresholds (ppm)

0.076 + Col B * (0.112 - 0.076)

Marginal from 0.121 NA 0.076

up to 1 0.138 15 0.107 0.080

Moderate From 0.138 15 0.107 0.080

up to 1 0.160 33.333 0.245 0.085

Serious From 0.160 33.333 0.245 0.085

up to 1 0.180 50 0.371 0.089

Severe-15 From 0.180 50 0.371 0.089

up to 1 0.190 58.333 0.434 0.092

Severe-17 From 0.190 58.333 0.434 0.092

up to 1 0.280 133.333 1.000 0.112

Extreme equal to

or above 0.280 133.333 1.000 0.112

1 but not including

EPA is not proposing this method, in part, be cause the results would vary depending on the years of data used for the design values in calculating the ratios in the 8-hour thresholds design values.5 2. Adjustment of the percentages above the standard used to se t the classification

thresholds.

One observer suggested that the percentage a bove the standard be reduced by the average ratio of 8-hour design values to 1-hour design va lues that are recorded. The observer suggested that this ratio is generally 0.7. In actuality, an analysis of 8-hour and 1- hour design values from

all ozone monitors with both values from the year 2005 (based on 2003-2005 data) yields an average of 0.78 rather than 0.7. The 2010 de sign values (based on 2008-2010 data) yield an average of 0.80. Using 2010 design values fo r classifications and assuming hypothetical nonattainment areas, if the threshold percen tages were indeed reduced by 0.80, only 1 area

would be classified different than under th e proposed classification method. One area in

California would be classified as serious rather th an as Moderate. We anticipate that a number of the major metropolitan areas (including Philadelphia, New Yo rk, Washington (DC), Charlotte) that were classified Moderate under the 1997 stan dard and that were not able to demonstrate attainment by their maximum attainme nt date would be classified as Marginal

under either the Percent-Above-Standard method we are proposing or under this approach. Thus, this method would not appear to result in classifications that woul d allow areas more time

to attain the 2008 ozone standard than would be provided under the percent-above standard

method.

The EPA is not proposing this option because the results would vary based on the years of analysis used to derive the thresholds, and also because the method does not generally result

in classifications different than the more straight-forwar d approach we are proposing.

3. Base the classifications on the amount of ti me each individual area is projected to need to attain the NAAQS or on the relative amount of emission re ductions needed to attain the NAAQS.

This possible method has the advantage of basing the classification system on the projected difficulty of attainment of the standar d. However, it has a number of drawbacks. The CAA’s classification system, as enacted in 1990, is applied virtually without judgment—areas are classified “by operation of law” based on so lid physical data—their ozone design values. The only judgment provided under the Act is the provision under 181(a)(4) that allows for reclassification upward or downward if an area’s design value is within 5 percent of the next higher or lower threshold. Allowi ng additional judgment to enter into the classification process would negate any “operation of la w” perception or action. In addi tion to appearing inconsistent with the approach contemplated in the Act, the very fact that a predic tive method is used that relies on judgment concerning projected emissions, meteorology, and a model that does not depict actual reality would requi re significant data gatheri ng and judgment in setting the

classification which would be ti me consuming, complex, and likel y contentious and using such an approach could delay th e designation process.6 4. Set the classification thresholds such that each classification range is a fixed ppm amount (such as 0.005 ppm).

The EPA is not soliciting comment on this option because EPA believes this method is entirely arbitrary and not consistent with th e methodology employed in the CAA’s classification
system.

5. Retention of classification under 1-hour ozone standard if requested by State .

Because of the concern at th e time of the Phase 1 Rule th at some areas should be in higher classifications because they need more time to attain, EPA also considered another method for classifying areas that was based on a comment received on the 2003 proposal. Under this method, an area that had a higher classification for the 1-h our ozone standard could choose to receive either that higher cl assification for the 2008 8-hour standa rd or the classification that it

would receive under the revised cl assification table. Applying th at concept here, we could use the current 1997 ozone standard as setting the classi fication that the State could request. Thus, if a state requested the higher 1997 classification for the area, the higher classification would apply

to the entire nonattainment area regardless of whether all or only a portion of the 2008 8-hour area had the higher classificati on for the 1997 8-hour standard. Areas that do not contain a

former 1997 8-hour nonattainment area or contai n a 1997 8-hour standard nonattainment area that had a higher classification would receive the classification from the revised classification table under the percent a bove standard proposal.

The EPA is not proposing this approach in part because while it might reflect past difficulties encountered by an area, it does not necessarily account fo r an area’s current ability to

achieve the 2008 8-hour 0.075 ppm standard.

6. Method that would rely on the same proportion of areas in each classification as in the original 1991 classifications.

In a letter of August 26, 2008 (see Appendix A), the Texas Commission on Environmental Quality (TCEQ) s uggested another alternative met hod for classification that they feel would better represent the degree of di fficulty that areas faced in lowering ozone concentrations. Their method and rationale is presen ted in detail in their letter, but in short it relies on placing areas into classifications such that the same proportion of areas would be in

each of the five classifications for the 2008 ozone st andard that were in those five classifications

when 1-hour areas were classified by operation of law in 1991.

The EPA is not proposing this option, in part, because the basis for the method relies on the situation that existed in 1990, which is not necessarily similar to the situation faced by

nonattainment areas under the 2008 standard. Als o, the method would require the areas to be ranked in ascending design values. Many hypothetic al nonattainment areas at the lower design values have the same design value. Since the ar eas with the same design value should be placed in the same classification, the same proportion of hypothetical areas in each of the five7 classifications could not be achieved. This method to determine thre shold cut points would require more judgment in setting the cl assification than the CAA contemplated.

7. Method that would rely on the range of cla ssification thresholds and the range of design

values.

The EPA also considered another method fo r classification of nonattainment areas under the 2008 8-hour ozone NAAQS that is based on Ta ble 1 in the CAA that would account not only for the change in the standard, but also the spre ad of design values similar to the method used originally to develop the classi fication table in the CAA. This method is based on the principle

that a classification table for the 2008 ozone st andard should account for not only the relative ozone design values above the level of the standar d, but also the absolute spread of design values higher than the standard that we actually meas ure in the air at the time we establish the classification table. Doing so would grad e areas based upon how much reduction in ozone

concentrations an area needs to achieve attain ment relative to the worst possible area.

Under the 1-hour ozone NAAQS, Extreme areas needed to reduce ozone levels by 0.160 ppm (0.280 ppm – 0.120 ppm) or more to get the DV at or below the commensurate level of the standard. The 1-hour DV, available to Congress at the time of CAA drafting, for the South Coast for the 1988-1990 period was 0.340 ppm, Thus, th e actual reduction leve l needed for South Coast’s then-presumptive Extreme area to reach attainment turned out to be (0.340 ppm - 0.12 ppm = 0.220 ppm. 4 ) In contrast, 1-hour Ma rginal areas only needed to reduce their DV by at most 0.017 ppm (0.137 ppm - 0.12 ppm) to achieve the sa me results. This is only 10.6 percent of the minimum needed (0.160 ppm) for an Extreme area. Moderate areas needed at most 24.3 percent (100 * (0.159 ppm - 0.12 ppm) / .0160 ppm) reduction in ozone levels of the 0.160 ppm minimum reduction needed by an Extreme area.

Under this alternative, a ratio w ould be calculated using the following:

[the difference between a specific classification th reshold and the lowest threshold (Marginal) in CAA Table 1]

divided by

[the difference between the highest DV measured at the time of setting the classification table and the lowest threshold (Marginal) in CAA Table 1]

The ratio would then be used in conjunc tion with the 2008 ozone standard. For that standard, we know the bottom threshold of Marg inal will be the lowest violating DV (0.076 ppm). The highest 8-hour DV recorded for th e period 2008-2010 data is in Los Angeles: 0.112

ppm.

4 Clean Air Act Amendments of 1990. Report of the Committee on Energy and Commerce. U.S. House of Representatives on H.R. 3030 together with Additional, Supplemental, and Dissenting Views. May 17, 1990. 101 st Congress, 2d Session. Rept. 101-490 part 1. Page 230.8 The resulting table would be as follows:

Area class CAA DV threshol ds 1-hour ozone ppm Tr anslated 8-hour DV ppm

Marginal from 0.121 0.076

up to 1 0.138 0.079

Moderate From 0.138 0.079

up to 1 0.160 0.082

Serious From 0.160 0.082

up to 1 0.180 0.086

Severe 2 From 0.180 0.086

up to 1 0.280 0.102

Extreme equal to or above 0.280 0.102

1 but not including

2 Section 181(a)(2) of the CAA provides that, in the case of a Severe area with a DV between 0.190 and 0.280 ppm, the attainment date shall be 17 years (in lieu of 15 years) after November 15, 1990 Th e comparable range using this classification method is 0.087 ppm up to but not including 0.102 ppm.

Note that this method is similar to, but diffe rent from the “Ratio of Thresholds” method. EPA is not proposing this method in part because the results would vary depending on the years of data used for the design values in calcula ting the ratios in both of the columns above (CAA DV thresholds 1-hour ozone ppm, and the translat ed 8-hour design values). This amount of variability does not appear consistent with the CAA’s concept of classifi cation “by operation of

law.”

8. Method that would rely on exceedances of the NAAQS as well as design values.

In a letter of May 26, 2009 (see Appendix B), the California Air Resources Board (CARB) suggested another alternative method for classification that would rely on exceedances of the NAAQS as well as design values. The Ca lifornia Air Resources Board (CARB) staff provided a recommended classifi cation method that relies not onl y on ozone design values, but

also the number of exceedances of the level of the 8-hour ozone st andard. The rationale for this method rests in part on the CAA’s provision in section 181(a)(4) that allows reclassification downward of an area within 90 days after design ation if an area’s desi gn value is within 5 percent of a classification’s lowe r threshold and reclassification upw ard if the area’s design value is within 5 percent of a classifi cation’s upper threshold. One of th e criteria for consideration in allowing such reclassification is the number of exceedances of the standard in the area. While

the Act does allow consideration of exceedance s for the reclassifica tion provision, the Act’s

basic classification table does not account for th e number of exceedances. Thus, EPA believes

that the classification method ba sed on threshold levels that EP A is proposing is more closely

tied to the structure in Table 1 in the CAA.9 9. Administrator’s Discretion To Reclassi fy Areas Under 5 Percen t Bump-Up Authority Concept.

EPA considered an approach that would auto matically apply an upward classification to any hypothetical nonattainment area with an initial design value within 5 percent of the upper

threshold of their initial classification. This a pproach could be applied to any final classification scheme for purposes of initial area designations. The Administrator has di scretion to use section 181(a)(4) to place areas that have design values th at are within 5 percent of the upper threshold

of their initial classification into the next higher classification. The CAA sets forth criteria for EPA to consider in applying the 5 percent cl assification adjustment: (1) the number of exceedances of the national primary ambient air qua lity standard for ozone in the area, (2) the level of pollution transport betw een the area and other affected areas, including both intrastate and interstate transport, (3) the mix of sources in the area, and (4) the mix of air pollutants in the

area. The statute does not limit EPA to considering only those factors.

EPA’s past practice in applyi ng the 5 percent cla ssification adjustment was described in the preamble to the designations and classificat ions for the 1997 ozone standard and in the rulemaking in which EPA applied the 5 percent ad justment provision to se veral areas under the

1997 ozone standard. 5 Although that exercise of the sect ion 181(a)(4) provision was only done for cases that were requested by the States and only as downward reclassifications, EPA could, if we followed this approach, apply upward reclassi fications in the absence of state requests and based on available information that would strongly suggest that the initia l classification for an area likely would not provide suffici ent time for the area to attai n. In fact, in the April 30, 2004 designation and classification rule making, we said, “EPA will consider bumping up areas subject to the five percent provision on our own initiative where there is evid ence that an area is unlikely to attain within the period allowed by their classification. In making this determination, EPA

would consider criteria similar to that listed above (adjusted to consider bump ups rather than bump downs) regarding discontinu ity, attainment, emissions reduction and trends.” However,

EPA did not exercise that discretion on its own initiative at that time.

Based on hypothetical nonattainment areas usin g 2010 design values and a standard of 0.075 ppm, approximately 9 Marginal areas, 2 Moderate areas and 1 Serious area would potentially qualify under the Pe rcent-Above-Standard method (see Appendix C) for an upward classification adjustment. Howeve r, we believe that to codify the 5 percent upward classification provision as an automatically executing adjustment (i.e., so that it would occur “by operation of law/rule”), would require EPA to conclude th at the CAA criteria lis ted above have been assessed, and/or articulate so me other overriding criteria, without knowing exactly which potential nonattainment areas w ould be affected. In the abse nce of advance certainty about which areas would be affected, EPA believes th at for initial area desi gnations for the 2008 NAAQS that it would be more appropriate to use the section 181(a)(4) provision on a case-bycase basis (rather than automatically) using information relevant to each affected area.

5 April 30, 2004 (69 FR 23585 at 23863) ; September 22, 2004 (69 FR 56697).10 10. Establish a relationship between the 1-hour and 8-hour monitored values or design values based on measured air quality data.

The EPA evaluated this concept in 2003 6 and was critical of it at the time based on a high degree of “scatter” (relation of i ndividual actual 1-hour to 8-hour values would differ from the relationship established from all monitors, counties, or areas). We did not attempt to re-evaluate this method for the 2008 NAAQS, which is still an 8-hour form.

6 Additional Options Considered for “Proposed Ru le to Implement the 8-Hour Ozone National Ambient Air Quality Standard.” U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Pa rk, NC. March 2003. Docket document EPA-HQOAR-2003-0079-0070.11 APPENDIX A Method Using Same Proportions as 1991 Classification

Recommendation from the Texas Co mmission on Environmental Quality12131415161718192021 APPENDIX B

Method that Relies on Exceedances of th e NAAQS as well as Design Values

Recommendation from the Calif ornia Air Resources Board222324252627282930313233343536 Appendix C 8-hour Ozone NAAQS Hypothetical Nonattainme nt Areas That Could Be Reclassified Under CAA Section 181(A)(4) ( 5% Adjustment Provision).

Section 181(a)(4) provides that an area may with in 90 days after the initial classification receive a lower (or higher) classification if its design value is within 5 percent of the low (or high) threshold for the initial classification. Although we are not proposi ng this as a specific option, we did look at how many potential Margin al and Moderate areas might have design

values within 5% of the threshold for the next higher classification. This is based on an 8-hour standard of 0.075ppm and the perc ent-above-standard classification method. This would mean that any Marginal area with an 8-hour desi gn value of 0.082 ppm (up to 0.086 ppm) could be classified by EPA as Moderate , any Moderate area with an 8- hour design value of 0.095 ppm (up to 0.100 ppm) could be classified by EPA as Seri ous and, any Serious area with an 8-hour design value of 0.107 ppm (up to 0.113 ppm) could be classified by EPA as Severe.

Under this method, 9 of the hypothetical Marginal nonattainment areas, 2 of the hypothetical Moderate nonattainment areas, a nd 1 of the hypothetical Serious nonattainment areas would have design values within 5 pe rcent of the next hi gher classification. The hypothetical Marginal, Moderate, and Serious nonattainment area s, along with their 2010 design values, are shown in the following table.

8-Hr Ozone NAAQS Hypothetical Nonattainment Areas That Could Be Reclassified Under CAA Section 181(A)(4) (5% Adjustment Provision)

Hypothetical Nonattainment Area 2010 DV (ppm) Classification

Charlotte-Gastonia- Rock Hill, NC-SC 0.082 Marginal Amador and Calaveras Cos (Central Mtn), CA 0.083 Marginal Kern Co (Eastern Kern), CA 0.083 Marginal Mariposa and Tuolumne Cos (Southern Mtn),CA 0.083 Marginal Philadelphia-Wilmin-Atlantic Ci, PA-NJ-MD-DE 0.083 Marginal Houston-Galveston-Brazoria, TX 0.084 Marginal Nevada Co. (Western Part), CA 0.084 Marginal New York-N. New Jersey-Long Isla nd,NY-NJ-CT 0.084 Marginal San Luis Obispo-Paso Robles, CA 0.084 Marginal

Riverside Co, (Coachella Valley), CA 0.095 Moderate Los Angeles-San Bernardino Cos(W Mojave),CA 0.099 Moderate

Los Angeles South Coast Air Basin, CA 0.112 Serious