### Draft

– Do Not Cite or Quote lxxviii June 2012 

## LEGISLATIVE AND HIST ORICAL BACKGROUND

Legislative Requirements for the NAAQS Review

Two sections of the Clean Air Act (CAA) govern the establishment and revision of 

### 1

the National Ambient Air Quality Standards (NAAQS). Section 108 (42 USC §7408) 

### 2

directs the Administrator to identify and list certain air pollutants and then to issue air 

### 3

qual ity criteria for those pollutants. The Administrator is to list those air pollutants 

### 4

that in her “judgement; cause or contribute to air pollution which may reasonably be 

### 5

anticipated to endanger public health or welfare;” ... ”the presence of which in the 

### 6

amb ient air results from numerous or diverse mobile or stationary sources” and “for 

### 7

which ... [the Administrator] plans to issue air quality criteria...” ( CAA, 1990a ) . Air 

### 8

quality criteria are inte nded to “accurately reflect the latest scientific knowledge 

### 9

useful in indicating the kind and extent of identifiable effects on public health or 

### 10

welfare

, which may be expected from the presence of [a] pollutant in ambient air

... ” 

### 11

[42 USC §7408(b)]. 

### 12

Section 109 ( CAA, 1990b ) directs the Administrator to propose and promulgate 

### 13

“primary” and “secondary” NAAQS for pollutants for which air quality criteria have 

### 14

been issued. Section 109(b)(1) defines a primary standard as one “the attainment and 

### 15

maintenance of which in the judgment of the Administrator, based on such criteria 

### 16

and allowing an adequate margin of safety, are requisite to protect the public 

### 17

health.” 1 A secondary standard, as defined in section 109(b)(2), must “specify a level 

### 18

of air quality the attainment and maintenance of which, in the judgment of the 

### 19

Administrator, based on such criteria, is required to protect the public welfare from 

### 20

any known or anticipated adverse ef fects associated with the presence of [the] 

### 21

pollutant in the ambient air.” 2 

### 22

The requirement that primary standards include an adequate margin of safety was 

### 23

intended to address uncertainties associated with inconclusive scientific and technical 

### 24

information available at the time of standard setting. It was also intended to provide a 

### 25

reasonable degree of protection against hazards that research has not yet identified. 

### 26

See Lead Industries Association v. EPA, 647 F.2d 1130, 1154 (D.C. Cir 1980), cert. 

### 27

denied, 4 49 U.S. 1042 (1980); American Petroleum Institute v. Costle, 665 F.2d 

### 28

1176, 1186 (D.C. Cir. ( 1981), cert. denied, 455 U.S. 1034 (1982). Both kinds of 

### 29

1 The legislative history of section 109 indicates that a primary standard is to be set at “the maximum permissible ambient air level . . . which will protect the health of any [sensiti ve] group of the population,” and that for this purpose “reference should be made to a representative sample of persons comprising the sensitive group rather than to a single person in such a group” [S. Rep. No. 91

- 1196, 91 st Cong., 2d Sess. 10 (1970)].

2 Welfare effects as defined in section 302(h) include, but are not limited to, “effects on soils, water, crops, vegetation, ma n

- made materials, animals, wildlife, weather, visibility and climate, damage to and deterioration of property, and hazards to trans portation, as well as effects on economic values and on personal comfort and well

- bein g ” ( CAA, 2005 )

.

### Draft

– Do Not Cite or Quote lxxix June 2012 uncertainties are components of the risk associated with pollution at levels below 

### 1

those at which human he alth effects can be said to occur with reasonable scientific 

### 2

certainty. Thus, in selecting primary standards that include an adequate margin of 

### 3

safety, the Administrator is seeking not only to prevent pollution levels that have 

### 4

been demonstrated to be harm ful but also to prevent lower pollutant levels that may 

### 5

pose an unacceptable risk of harm, even if the risk is not precisely identified as to 

### 6

nature or degree. The CAA does not require the Administrator to establish a primary 

### 7

NAAQS at a zero

- risk level or at background concentration levels, see Lead 

### 8

Industries v. EPA, 647 F.2d at 1156 n.51, but rather at a level that reduces risk 

### 9

sufficiently so as to protect public health with an adequate margin of safety. 

### 10

In addressing the requirement for a margin of safe ty, EPA considers such factors as 

### 11

the nature and severity of the health effects involved, the size of the sensitive 

### 12

population(s) at risk, and the kind and degree of the uncertainties that must be 

### 13

addressed. The selection of any particular approach to prov iding an adequate margin 

### 14

of safety is a policy choice left specifically to the Administrator’s judgment. See 

### 15

Lead Industries Association v. EPA, supra, 647 F .2d at 1161

- 1162 ; Whitman v. 

### 16

American Trucking Associations, 531 U.S. 457, 495 (2001)

. 

### 17

In setting s tandards that are “requisite” to protect public health and welfare, as 

### 18

provided in Section 109(b), EPA’s task is to establish standards that are neither more 

### 19

nor less stringent than necessary for these purposes. In so doing, EPA may not 

### 20

consider the costs of implementing the standards. [See generally, Whitman v. 

### 21

American Trucking Associations, 531 U.S. 457, 465

- 472, 475

- 76. (2001)]. Likewise, 

### 22

“[a]ttainability and technological feasibility are not relevant considerations in the 

### 23

promulgation of national ambie nt air quality standards.” American Petroleum 

### 24

Institute v. Costle, 665 F. 2d at 1185. 

### 25

Section 109(d)(1) requires that “not later than December 31, 1980, and at 5

- year 

### 26

intervals thereafter, the Administrator shall complete a thorough review of the 

### 27

criteria published under section 108 and the national ambient air quality standards ... 

### 28

and shall make such revisions in such criteria and standards and promulgate such 

### 29

new standards as may be appropriate...” Section 109(d)(2) requires that an 

### 30

independent scientific re view committee “shall complete a review of the criteria ... 

### 31

and the national primary and secondary ambient air quality standards ... and shall 

### 32

recommend to the Administrator any new ... standards and revisions of existing 

### 33

criteria and standards as may be appropr iate ...” Since the early 1980s, this 

### 34

independent review function has been performed by CASAC. 

### 35

### Draft

– Do Not Cite or Quote lxxx June 2012 

## History of the NAAQS for Ozone

Tropospheric (ground

- level) O 3 is the indicator for the mix of photochemical 

### 1

oxidants (e.g., peroxyacetyl nitrate, hydrogen peroxide ) formed from biogenic and 

### 2

anthropogenic precursor emissions. Naturally occurring O 3 in the troposphere can 

### 3

result from biogenic organic precursors reacting with naturally occurring nitrogen 

### 4

oxides (NO X ) and by stratospheric O 3 intrusion into the troposphe re. Anthropogenic 

### 5

precursors of O 3 , especially NO X , and volatile organic compounds (VOCs), originate 

### 6

from a wide variety of stationary and mobile sources. Ambient O 3 concentrations 

### 7

produced by these emissions are directly affected by temperature, solar rad iation, 

### 8

wind speed, and other meteorological factors. 

### 9

NAAQS are comprised of four basic elements: indicator, averaging time, level, and 

### 10

form. The indicator defines the pollutant to be measured in the ambient air for the 

### 11

purpose of determining compliance wi th the standard. The averaging time defines the 

### 12

time period over which air quality measurements are to be obtained and averaged or 

### 13

cumulated, considering evidence of effects associated with various time periods of 

### 14

exposure. The level of a standard defines the air quality concentration used (i.e., an 

### 15

ambient concentration of the indicator pollutant) in determining whether the standard 

### 16

is achieved. The form of the standard specifies the air quality measurements that are 

### 17

to be used for compliance purposes (e.g

., the annual fourth

- highest daily maximum 

### 18

8

- hour concentration, averaged over 3 years), and whether the statistic is to be 

### 19

averaged across multiple years. These four elements taken together determine the 

### 20

degree of public health and welfare protection affo rded by the NAAQS. 

### 21

Table III Summary of primary and secondary NAAQS promulgated for ozone during the period 1971

- 2008

Final Rule Indicator Avg

Time Level (ppm) Form

1971 (36 FR 8186) Total photochemical

oxidants 1

- h 0.08 Not to be exceeded more than 1 hour per year

1979 (44 FR 8202) O 3 1

- h 0.12 Attainment is defined when the expected number of days per calendar year, with maximum hourly average concentration greater

than 0.12 ppm, is ≤ 1

1993 (58 FR 13008) EPA decided that revisions to the standards were not warranted at the time.

1997 (62 FR 38856) O 3 8

- h 0.08 Annual fourth

- highest daily maximum 8

- h concentration averaged over 3 years

2008 (73 FR 16483) O 3 8

- h 0.075 Form of the standards remained unchanged relative to the 1997

standard

### Draft

– Do Not Cite or Quote lxxxi June 2012 Table III summarizes the O 3 NAAQS that have been promulgated to date. In each 

### 1

review, the secondary standard has been set to be identical to the primary standard. 

### 2

These reviews are briefly described below. 

### 3

EPA first established primary and secondary NAAQS for photochemical oxidants in 

### 4

1971 . Both primary and secondary standards were set at a level of 0.08 parts per 

### 5

million (ppm), 1

- h avg, total photochemical oxidants, not to be exceeded more than 

### 6

1 hour per year. The standards were based on scientifi c information contained in the 

### 7

1970 AQCD. 

### 8

In 1977, EPA announced the first periodic review of the 1970 AQCD in accordance 

### 9

with Section 109(d)(1) of the Clean Air Act. In 1978, EPA published an AQCD. 

### 10

Based on the 1978 AQCD, EPA published proposed revisions to the original 

### 11

NAAQS in 1978 ( U.S. EPA, 1978b ) and final revisions in 1979 ( U.S. EPA, 1979a )

. 

### 12

The level of the primary and secondary standards was revised from 0.08 to 0.12 ppm; 

### 13

the indicator was revised from photochemical oxidants to O 3 ; and the form of the 

### 14

standards was revised from a deterministic to a statistical form, which defined 

### 15

attainment of the standards as occurring when the expected number of days per 

### 16

calendar year with maximum hou rly average concentration greater than 0.12 ppm is 

### 17

equal to or less than one. 

### 18

In 1982 , EPA announced plans to revise the 1978 AQCD ( U.S. EP A, 1978a ) . In 

### 19

1983, EPA announced that the second periodic review of the primary and secondary 

### 20

standards for O 3 had been initiated ( U.S. EPA, 1983 ) . EPA subsequently published 

### 21

the 1986 O 3 AQCD ( U.S. EPA, 1986 ) and 1989 Staff Paper ( U.S. EPA, 1989 )

. 

### 22

Following publication of the 1986 O 3 AQCD, a number of scientific abstracts and 

### 23

articles were published that appeared to be of sufficient importance concerning 

### 24

potential health and welfare effects of O 3 to warrant preparation of a Supplement to 

### 25

the 1986 O 3 AQCD ( Costa et al., 1992 ) . Under the terms of a court order, on August 

### 26

10, 1992, EPA published a proposed decision ( U.S. EPA, 1992 ) stating that revisions 

### 27

to the existing primary and secondary standards were not appropriate at the time 

### 28

( U.S. EPA, 1992 ) . This notice explained that the proposed decision would complete 

### 29

EPA’s review of information on health and welfare effects of O 3 assembled over a 

### 30

7

- year period and contained in the 1986 O 3 AQCD ( U.S. EPA, 1986 ) and its 

### 31

Supplement to the 1986 O 3 AQCD ( Costa et al., 1992 ) . The proposal also announced 

### 32

EPA’s intention to proceed as rapidly as possible with the next review of the air 

### 33

quality criteria and standards for O 3 in light of emerging evidence of health effects 

### 34

related to 6

- to 8

- hour O 3 exposures. On March 9, 1993, EPA concluded the review 

### 35

by deciding that revisions to the standards were not warranted at that time ( U.S. 

### 36

EPA, 1993 )

. 

### 37

### Draft

– Do Not Cite or Quote lxxxii June 2012 In August 1992, EPA announced plans to initiate the third periodic review of the air 

### 1

quality criteria and O 3 NAAQS ( U.S. EPA, 1992 ) . On the basis of the scientific 

### 2

evidence contained in the 1996 O 3 AQCD and the 1996 Staff Paper ( U.S. EPA, 

### 3

1996e ) , and related technical support documents, linking exposures t o ambient O 3 to 

### 4

adverse health and welfare effects at levels allowed by the then existing standards, 

### 5

EPA proposed to revise the primary and secondary O 3 standards on December 13, 

### 6

1996 ( U.S. EPA, 1996d ) . The EPA proposed to replace the then existing 1

- hour 

### 7

primary and secondary standards with 8

- h avg O 3 standards set at a level of 0.08 ppm 

### 8

(equivalent to 0. 084 ppm using standard rounding conventions). The EPA also 

### 9

proposed, in the alternative, to establish a new distinct secondary standard using a 

### 10

biologically based cumulative seasonal form. The EPA completed the review on July 

### 11

18, 1997 by setting the primar y standard at a level of 0.08 ppm, based on the annual 

### 12

fourth

- highest daily maximum 8

- h avg concentration, averaged over 3 years, and 

### 13

setting the secondary standard identical to the revised primary standard ( U.S. EPA, 

### 14

1997 )

. 

### 15

On May 14, 1999, in response to challenges to EPA’s 1997 decision by industry and 

### 16

others, the U.S. Court of Appeals for the District of Columbia Circuit (D.C. Cir.) 

### 17

remanded the O 3 NAAQS to EPA, finding that Section 109 of the CAA, as 

### 18

interpreted by EPA, effected an unconstitutional delegation of legislative authority. 

### 19

In addition, the D.C. Cir. directed that, in responding to the remand, EPA should 

### 20

consider the potential ben eficial health effects of O 3 pollution in shielding the public 

### 21

from the effects of solar ultraviolet (UV) radiation, as well as adverse health effects. 

### 22

On January 27, 2000, EPA petitioned the U.S. Supreme Court for certiorari on the 

### 23

constitutional issue (a nd two other issues) but did not request review of the D.C. Cir., 

### 24

ruling regarding the potential beneficial health effects of O 3 . On February 27, 2001, 

### 25

the U.S. Supreme Court unanimously reversed the judgment of the D.C. Cir. on the 

### 26

constitutional issue, h olding that Section 109 of the CAA does not delegate 

### 27

legislative power to the EPA in contravention of the Constitution, and remanded the 

### 28

case to the D.C. Cir. to consider challenges to the O 3 NAAQS that had not been 

### 29

addressed by that Court’s earlier decisi ons. On March 26, 2002, the D.C. Cir. issued 

### 30

its final decision, finding the 1997 O 3 NAAQS to be “neither arbitrary nor 

### 31

capricious,” and denied the remaining petitions for review. On November 14, 2001, 

### 32

in response to the D.C. Cir. remand to consider the po tential beneficial health effects 

### 33

of O 3 pollution in shielding the public from effects of solar (UV) radiation, EPA 

### 34

proposed to leave the 1997 8

- h O 3 NAAQS unchanged ( U.S. EPA, 2001 ) . After 

### 35

considering public comment on the proposed decision, EPA published its final 

### 36

response to this remand on January 6, 2003, reaffirming the 8

- h O 3 NAAQS set in 

### 37

1997 ( U.S. EPA, 2003 ) . On April 30, 2004, EPA announced the decision to make the 

### 38

1

- h O 3 NAAQS no longer applicable to areas 1 ye ar after the effective date of the 

### 39

### Draft

– Do Not Cite or Quote lxxxiii June 2012 designation of those areas for the 8

- h NAAQS ( 2004 )

. For most areas, the date that 

### 1

the 1

- h NAAQS no longer applied was June 15, 2005. 

### 2

EPA initiated the next periodic review if the air quality criteria and O 3 standards in 

### 3

September 2000 with a call for information ( U.S. EPA, 2000 ) . The schedule for 

### 4

completion of that rulemaking later became governed by a consent decree resolving a 

### 5

lawsuit filed in March 2003 by a group of plaintiffs representing national 

### 6

environmental and public health organizations. Based on the 2006 O 3 AQCD ( U.S. 

### 7

EPA, 2006b ) published in March 2006, the Staff Paper ( U.S. EPA, 2007b ) and 

### 8

related technical support documents, the proposed decision was published in the 

### 9

Federal Register on July 11, 2007 ( U.S. EPA, 2007a ) . The EPA proposed to revise 

### 10

the level of the primary standard to a level within the range of 0.075 to 0.070 ppm. 

### 11

T wo options were proposed for the secondary standard: (1) replacing the current 

### 12

standard with a cumulative, seasonal standard, expressed as an index of the annual 

### 13

sum of weighted hourly concentrations cumulated over 12 daylight hours during the 

### 14

consecutive 3

- month period within the O 3 season with the maximum index value, set 

### 15

at a level within the range of 7 to 21 ppm

- h; and (2) setting the secondary standard 

### 16

identical to the revised primary standard. The EPA completed the rulemaking with 

### 17

publication of a fin al decision on March 27, 2008 ( U.S. EPA, 2008e ) , revising the 

### 18

level of the 8

- hour primary O 3 standard from 0.08 ppm to 0.075 ppm an d revising the 

### 19

secondary standard to be identical to the primary standard. 

### 20

In May 2008, state, public health, environmental, and industry petitioners filed suit 

### 21

against EPA regarding that final decision. At EPA’s request the consolidated cases 

### 22

were held in abeyance pending EPA’s reconsideration of the 2008 decision. A notice 

### 23

of proposed rulemaking to reconsider the 2008 final decision was issued by the 

### 24

Adm inistrator on January 6, 2010. Three p ublic hearings were held

. T he Agency 

### 25

solicited CASAC review of th e proposed rule on January 25, 2010 and additional 

### 26

CASAC advice on January 26, 2011. On September 2, 2011, the Office of 

### 27

Management and Budget returned the draft final rule on reconsideration to EPA for 

### 28

further consideration. EPA decided to coordinate furt her proceedings on its voluntary 

### 29

rulemaking on reconsideration with the ongoing periodic review, by deferring the 

### 30

completion of its voluntary rulemaking on reconsideration until it completes its 

### 31

statutorily

- required periodic review. In light of that, the l itigation on the 2008 final 

### 32

decision is no longer being held in abeyan ce and is proceeding. The 2008 o zone 

### 33

standards remain in effect. 

### 34

### Draft

– Do Not Cite or Quote lxxxiv June 2012 

### References

CAA. Clean Air Act, as amended by Pub. L. No. 101

- 549, section 108: Air quality criteria and control techniques, § 7408 (1990a). http://www.law.cornell.edu/uscode/text/42/7408 CAA. Clean Air Act, as amended by Pub. L. No. 101

- 549, section 109: National primary and secondary ambient air quality standards, § 7409 (1990b). http://www.epa.gov/air/caa/title1.html#ia CAA. Clean Air Act, section 302: Definitions, § 7602 (2005). http://www.gpo.gov/fdsys/pkg/USCODE

2005

- title42/pdf/USCODE

- 2005

- title42

- chap85

- subchapIII

- sec7602.pdf Costa, DL; Folinsbee, LJ; Raub, JA; Tilton, B; Tingey, DT. (1992). Summary of selected new information on effects of ozone on health and vegetation: Supplement to 1986 air quality criteria for ozone and other

p hotochemical oxidants. (EPA/600/8

- 88/105F). Research Triangle Park, NC: U.S. Environmental Protection Agency. http://cfpub.epa.gov/ncea/isa/recordisplay.cfm?deid=31093 U.S. EPA (U.S. E nvironmental Protection Agency). (1971). National primary and secondary ambient air quality standards. Fed Reg 36: 8186

- 8201.

U.S. EPA (U.S. Environmental Prot ection Agency). (1978a). Air quality criteria for ozone and other photochemical oxidants [EPA Report]. (EPA/600/8

- 78/004). Washington, DC.

U.S. EPA (U.S. Envi ronmental Protection Agency). (1978b). Photochemical oxidants: Proposed revisions to the national ambient air quality standards. Fed Reg 43: 26962

- 26971.

U.S. EPA (U.S. Environmental Protection Agency). (1979a). National primary and secondary ambient air quality standards: Revisions to the national ambient air quality standards for photochemical oxidants. Fed Reg 44: 8202

- 8237. U.S. EPA (U.S. Environmental Prot ection Agency). (1982). Air quality criteria document for ozone and other photochemical oxidants. Fed Reg 47: 11561.

U.S. EPA (U.S. Environmental Protection Agency). (1983). Review of the national ambient air quality standards for ozone. Fed Reg 48: 38009.

U.S. EPA (U.S. Environmenta l Protection Agency). (1986). Air quality criteria for ozone and other photochemical oxidants [EPA Report]. (EPA

- 600/8

- 84

- 020aF

- EPA

- 600/8

- 84

- 020eF). Research Triangle Park, NC. http:// www.ntis.gov/search/product.aspx?ABBR=PB87142949

U.S. EPA (U.S. Environmental Protection Agency). (1989). Review of the national ambient air quality

standards f or ozone: Assessment of scientific and technical information: OAQPS staff report [EPA Report]. (EPA

- 450/2

- 92

- 001). Research Triangle Park, NC. http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey= 2000LOW6.txt

U.S. EPA (U.S. Environmental Protection Agency). (1992). National ambient air quality standards for ozone; Proposed decision. Fed Reg 57: 35542

- 355 57.

U.S. EPA (U.S. Environmental Protection Agency). (1993). National ambient air quality standards for ozone

- Final decision. Fed Reg 58: 13008

- 13019.

U.S. EPA (U.S. Environmental Protection Agency). (1996d). National ambient air quality standards for ozone: Proposed decision. Fed Reg 61: 65716

- 65750.

U.S. EPA (U.S. Environmental Protection Agency). (1996e). Review of national ambient air quality

standards for ozone: Assessment of scientific and technical information: OA QPS staff paper [EPA Report]. (EPA/452/R

- 96/007). Research Triangle Park, NC. http://www.ntis.gov/search/product.aspx?ABBR=PB96203435

U.S. EPA (U.S. Environmental Protection Agency). (1997). National ambient air quality standards for ozone; final rule. Fed Reg 62: 38856

- 38896.

U.S. EPA (U.S. Environmental Protection Agency). (2000). Air quality criteria for ozone and related photochemical oxidants. Fed Reg 65: 57810.

U.S. EPA (U.S. Environmental Protection Agency). (2001). National ambient air quality standards for ozone: Proposed response to remand. Fed Reg 66: 57268

- 57292.

U.S. EPA (U.S. Environmental Protection Agency). (2003). National ambient air quality standards for ozone: Final response to remand. Fed Reg 68: 614

- 645.

U.S. EPA (U.S. Environmental Protection Agency). (2004). Final rule to implement the 8

- hour ozone national ambient air quality standard

- phase 1. Fed Reg 69: 23951

- 24000.

### Draft

– Do Not Cite or Quote lxxxv June 2012 U.S. EPA (U.S. Environmental Protection Agency). (2006b). Air quality criteria for ozone and related photochemical oxidants [EPA Report]. (EPA/600/R

- 05/004AF). Research Triangle Park, NC. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=149923

U.S. EPA (U.S. Environmental Protection Agency). (2007a). N ational ambient air quality standards for ozone. Fed Reg 72: 37818

- 37919.

U.S. EPA (U.S. Environmental Protection Agency). (2007b). Review of the national ambi ent air quality standards for ozone: Policy assessment of scientific and technical information: OAQPS staff paper [EPA Report]. (EPA/452/R

- 07/003). Research Triangle Park, NC. http://www.epa.gov/ttn/naaqs/standards/ozone/data/2007_01_ozone_staff_paper

U.S. EPA (U.S. Environmental Protection Agency). (2008e). National ambien t air quality standards for ozone. Fed Reg 73: 16436

- 16514.