United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued January 18, 2007 Decided March 13, 2007

No. 03-1202

SIERRA CLUB,

PETITIONER

v.

ENVIRONMENTAL PROTECTION AGENCY,

RESPONDENT

BRICK INDUSTRY ASSOCIATION, ET AL.,

INTERVENORS

Consolidated with

06-1013

On Petitions for Review of an Order of the

Environmental Protection Agency

James S. Pew argued the cause and filed the briefs for

petitioner.

Eric G. Hostetler, Attorney, U.S. Department of Justice,

argued the cause for respondent. With him on the brief was

John C. Cruden, Deputy Assistant Attorney. Kerry E. Rodgers,

Attorney, U.S. Environmental Protection Agency, entered an
2

appearance.

Christopher L. Rissetto and Howard L. Gilberg were on the

brief for intervenors the Brick Industry Association, et al. in

support of respondent.

Before: GINSBURG,Chief Judge, TATEL, Circuit Judge, and

WILLIAMS, Senior Circuit Judge.

Opinion for the Court filed PER CURIAM.

Concurring opinion filed by Senior Circuit Judge

WILLIAMS.

PER CURIAM: In this case, the Sierra Club challenges the

Environmental Protection Agency’s air pollution standards for

brick and ceramics kilns. Because most of the standards violate

the Clean Air Act as interpreted by this Court in Cement Kiln

Recycling Coalition v. EPA, 255 F.3d 855 (D.C. Cir. 2001) (per

curiam), and National Lime Ass’n v. EPA, 233 F.3d 625 (D.C.

Cir. 2000), and because the remaining standards violate the

Act’s requirements for “work practice standards,” we vacate the

standards in their entirety and remand for further proceedings

consistent with this opinion.

I.

The Clean Air Act, 42 U.S.C. §§ 7401-7671q, directs the

Environmental Protection Agency to establish emission

standards for “major sources” of hazardous air pollutants listed

in the statute. Id. § 7412(d)(1). In Cement Kiln, we described

the Act as follows:

Until 1990, the Clean Air Act . . . required

the Environmental Protection Agency to set risk-
3

based air pollution standards that would provide

an “ample margin of safety to protect the public

health.” Id. § 7412(b)(1)(B); see also H.R. REP.

NO. 101-490, at 151, 322 (1990). To address

problems with the implementation of risk-based

regulation, Congress amended the Act in 1990 to

require EPA to set the most stringent standards

achievable, 42 U.S.C. § 7412(d)(2), that is,

standards “based on the maximum reduction in

emissions which can be achieved by application

of [the] best available control technology.”

S.REP. NO. 101-228, at 133 (1989), U.S. Code

Cong. & Admin. News at 3385, 3518.

The 1990 amendments included . . . 42

U.S.C. § 7412(d)—which directs EPA to set

standards limiting emissions of listed hazardous

air pollutants (“HAPs”), id. §§ 7412(b), (c)(1)-

(2), from major stationary sources. Section

7412(d)(2) provides that:

Emission standards . . . shall

require the maximum degree of

reduction in emissions of the

hazardous air pollutants subject

to this section . . . that the

Administrator, taking into

consideration the cost of

achieving such emission

reduction, and any non-air

quality health and environmental

impacts and energy requirements,

determines is achievable for new

or existing sources . . . .
4

Supplementing this general guidance, Congress

imposed minimum stringency

requirements—EPA calls them “emission

floors”—which “apply without regard to either

costs or the other factors and methods listed in

section 7412(d)(2).” Nat’l Lime Ass’n v. EPA,

233 F.3d 625, 629 (D.C. Cir. 2000) (“National

Lime II”). For “new sources”— . . . sources on

which construction begins after EPA publishes

emission standards, 42 U.S.C.

§ 7411(a)(2)—“[t]he maximum degree of

reduction in emissions that is deemed achievable

. . . shall not be less stringent than the emission

control that is achieved in practice by the best

controlled similar source . . . .” Id. § 7412(d)(3).

For existing sources, what EPA deems

achievable “shall not be less stringent than[] the

average emission limitation achieved by the best

performing 12 percent of the existing sources

(for which the Administrator has emissions

information) . . . .” Id. As we explained in

National Lime II, EPA implements these

requirements through a two-step process: the

Agency first sets emission floors for each

pollutant and source category and then

determines whether stricter standards, known as

“beyond-the-floor” limits, are achievable in light

of the factors listed in section 7412(d)(2).

233 F.3d at 629.

Cement Kiln, 255 F.3d at 857-58.

In Cement Kiln we considered the Sierra Club’s argument

that EPA’s emission floors for hazardous waste combustors

violated section 7412(d)(3) of the Act, the provision at issue in
5

this case. Id. at 859. For existing sources, EPA had identified

the best-performing 12 percent of sources for which it had

information. Among these sources, EPA then identified the

median source’s emission control technology, which it called the

“maximum achievable control technology”—or “MACT

control”—as the “average” emission limitation of the best

performers. Id.; see 42 U.S.C. § 7412(d)(3)(A). EPA next

identified the worst-performing source using the MACT control

and set the floor at the emission level of that source. 255 F.3d

at 859. For new sources, EPA followed the same approach,

except that instead of using the technology of the median source

as the MACT control, it used the technology of the single bestperforming source. Id.; see 42 U.S.C. § 7412(d)(3). 

The Sierra Club argued that this technology-based approach

violated section 7412(d)(3)’s requirement that floors reflect

emissions actually “achieved” or “achieved in practice” by the

best-performing sources. 255 F.3d at 861. In response, EPA

argued that section 7412(d)(3)’s floor provision “is a gloss” on

section 7412(d)(2), which requires that beyond-the-floor

emission standards be “achievable” by all sources, based on

costs and other factors. Id. According to EPA, section

7412(d)(3) incorporates section 7412(d)(2)’s achievability

requirement, meaning that emission floors must also be

achievable by all sources. Id. We rejected EPA’s interpretation,

finding it to be an impermissible reading of the statute’s

unambiguous language:

Section 7412(d)(3) . . . limits the scope of the

word “achievable” in section 7412(d)(2). While

standards achievable by all sources using the

MACT control might also ultimately reflect what

the statutorily relevant sources achieve in

practice, EPA may not deviate from section

7412(d)(3)’s requirement that floors reflect what
6

the best performers actually achieve by claiming

that floors must be achievable by all sources

using MACT technology.

Id. (citing Chevron U.S.A., Inc. v. Natural Res. Def. Council,

467 U.S. 837, 842-43 (1984) (holding that if Congress has

spoken directly to the disputed issue of statutory construction,

“that is the end of the matter; for the court, as well as the

agency, must give effect to the unambiguously expressed intent

of Congress”)); see also Ne. Md. Waste Disposal Auth. v. EPA,

358 F.3d 936, 955 (D.C. Cir. 2004) (per curiam) (reiterating that

floors based on achievability cannot satisfy the statute’s actual

achievement requirement). EPA chose not to file a petition for

rehearing en banc or to seek Supreme Court review.

Cement Kiln was not the first time this court invalidated an

EPA interpretation of section 7412(d)(3). Six months earlier, in

National Lime II, we considered the Sierra Club’s challenge to

EPA’s setting of “no control” floors—that is, no emission floors

at all—for certain HAPs emitted by cement plants. 233 F.3d at

633-34. Defending its decision, EPA relied on Sierra Club v.

EPA, 167 F.3d 658 (D.C. Cir. 1999) (“Sierra”), in which we

explained that “EPA would be justified in setting the floors at a

level that is a reasonable estimate of the performance of the

‘best controlled similar unit’ under the worst reasonably

foreseeable circumstances.” Id. at 665. Based on Sierra, EPA

argued that because cement plants used no emission control

technology, “no control” floors reasonably estimated variability

among the best performers. National Lime II, 233 F.3d at 633.

We found EPA’s interpretation of the statute untenable:

Nothing in the statute even suggests that EPA

may set emission levels only for those listed

HAPs controlled with technology. To the

contrary, the statute . . . requires EPA to
7

“promulgate regulations establishing emission

standards for each category or subcategory of

major sources . . . of hazardous air pollutants

listed for regulation.” [42 U.S.C.] § 7412(d)(1).

. . .

Contrary to EPA’s argument, nothing in

Sierra relieves it of the clear statutory obligation

to set emission standards for each listed HAP.

Although Sierra permits the Agency to look at

technological controls to set emission standards,

see 167 F.3d at 665, it does not say that EPA

may avoid setting standards for HAPs not

controlled with technology.

Id. at 633-34. Following the panel decision, EPA filed an

unsuccessful petition for rehearing, Nat’l Lime Ass’n v. EPA,

No. 99-1325 (D.C. Cir. Feb. 14, 2001) (order denying

rehearing), but again sought neither en banc nor Supreme Court

review.

With this background in mind, we turn to the facts of this

case. At issue are EPA’s emission standards for brick and

structural clay products (BSCP) kilns and clay ceramics kilns.

Over 500 brick kilns and more than 50 ceramics kilns operate

throughout the United States. BSCPs include brick, clay pipe,

and clay roof tile; ceramics include tile and sanitaryware, such

as toilets and sinks. Production of BSCPs and ceramics involves

processing common clays and shales and forming and firing

shapes. Because transporting clays and shales over long

distances is infeasible, kilns are located close to the mines

supplying the clays and shales used in their products. BSCPs

and ceramics are fired in one of two types of kilns: those that

operate continuously, which include “tunnel” and “roller” kilns;

and those that operate in batch cycles, known as “periodic”
8

kilns. EPA divided brick kilns into three subcategories: large

tunnel brick kilns, small tunnel brick kilns, and periodic brick

kilns. It divided ceramics kilns into four subcategories: large

tunnel ceramics kilns, small tunnel ceramics kilns, roller

ceramics kilns, and periodic ceramics kilns. Reflecting the

different standards set forth in sections 7412(d)(3) and

7412(d)(3)(A), EPA further divided each subcategory into new

and existing kilns.

Each year, brick and ceramics kilns emit over 6,440 tons of

HAPs, including hydrofluoric acid, hydrochloric acid, and

particulate matter containing toxic metals, such as antimony,

arsenic, beryllium, cadmium, chromium, cobalt, lead,

manganese, nickel, and selenium. These HAPs can cause severe

respiratory problems, cancer, neurological and organ damage,

and adverse reproductive effects. National Emission Standards

for Hazardous Air Pollutants for Brick and Structural Clay

Products Manufacturing and Clay Ceramics Manufacturing,

68 Fed. Reg. 26,690, 26,692-94 (May 16, 2003) (to be codified

at 40 C.F.R. pt. 63). 

In 2002, EPA issued a proposed rule setting floors to limit

HAP emissions from new and existing brick and ceramics kilns.

National Emission Standards for Hazardous Air Pollutants for

Brick and Structural Clay Products Manufacturing and Clay

Ceramics Manufacturing, 67 Fed. Reg. 47,894 (proposed July

22, 2002) (to be codified at 40 C.F.R. pt. 63). For the

subcategories in which few or no kilns use air pollution control

devices, EPA proposed floors of “no emissions reductions”—in

other words, no floors at all. Id. at 47,909, 47,912, 47,916-17.

For all remaining subcategories, EPA proposed floors based on

the pollution control devices used by the best-performing kilns,

i.e., those with the lowest emissions. Id. at 47,911, 47,912,

47,917. In their comments on the proposed regulations, industry

members insisted that installing the devices used by the best-
9

performing sources would be technologically and economically

infeasible. For its part, the Sierra Club complained that EPA

had failed to consider non-technology factors—e.g., fuel type,

raw materials, additives and surface coatings, kiln design, and

operator training—that contribute to emissions. U.S. Envtl.

Prot. Agency, National Emission Standards for Hazardous Air

Pollutants for Brick and Structural Clay Products

Manufacturing: Summary of Public Comments and Responses

2-40 (Feb. 28, 2003) (hereinafter “Summary of Public

Comments”). 

In response to these comments, EPA’s final emission

standards set floors for several subcategories based on the

pollution control devices used by the second-best

performers—not, as EPA had proposed, the best

performers—and replaced “no emissions reductions” floors in

other subcategories with a so-called “work practice standard” of

using clean-burning fuels. 68 Fed. Reg. at 26,699-26,701,

26712-13; see 42 U.S.C. § 7412(h) (explaining requirements for

setting work practice standards in lieu of emission standards).

The Sierra Club filed a petition for reconsideration, but EPA

adhered to its standards. National Emission Standards for

Hazardous Air Pollutants for Brick and Structural Clay Products

Manufacturing, 70 Fed. Reg. 69,655, 69,657 (reconsidered Nov.

17, 2005) (to be codified at 40 C.F.R. pt. 63).

The Sierra Club now petitions for review. See 42 U.S.C.

§ 7607(b)(1) (authorizing petitions for review of EPA’s

promulgation of emission standards). The Brick Industry

Association and two ceramics producers intervene in support of

EPA.
10

II.

The Sierra Club argues that EPA’s methodology in setting

floors for brick and ceramics kilns violates the Clean Air Act’s

plain language as interpreted by Cement Kiln and National Lime

II. We agree. See Nat’l Cable & Telecomms. Ass’n v. Brand X

Internet Servs., 545 U.S. 967, 982 (2005) (“A court’s prior

judicial construction of a statute trumps an agency construction

. . . if the prior court decision holds that its construction follows

from the unambiguous terms of the statute.”).

“Achieved,” not “Achievable”

As discussed above, we held in Cement Kiln that “EPA may

not deviate from section 7412(d)(3)’s requirement that floors

reflect what the best performers actually achieve by claiming

that floors must be achievable by all sources using MACT

technology.” 255 F.3d at 861. In setting the floor for existing

large tunnel brick kilns, however, EPA did just that.

Most large tunnel brick kilns that have installed air

pollution control devices use dry lime adsorbers (DLA). Others

use non-DLA technology, including dry lime injection fabric

filters (DIFF), dry lime scrubber/fabric filters (DLS/FF), and wet

scrubbers (WS). In its notice of proposed rulemaking, EPA

concluded that these non-DLA pollution control devices

“represent[ed] the best control[].” 67 Fed Reg. at 47,907.

Because the 94th percentile (the median of the top 12 percent)

of the best-performing large tunnel brick kilns used non-DLA

technology, EPA—as required by Cement Kiln—proposed a

floor based on this technology. Id. at 47,911. But after

receiving “numerous comments from industry representatives”

saying that kilns were unable to retrofit with WS because of a

lack of sewer access to treat wastewater from the device, or with

DIFF or DLS/FF without affecting production, EPA changed
11

course in its final rule. 68 Fed. Reg. at 26,694. Finding that

non-DLA technology would have “potentially significant

impacts on the production process,” id. at 26,695, and contrary

to Cement Kiln’s requirement that floors reflect emission levels

of the best-performing sources, EPA excluded non-DLA

technology from its ranking of best-performing kilns, id. at

26,700. It then set the floor for existing large tunnel brick kilns

based on DLA. Id. 

EPA argues that it has “reasonably construe[d] the term

‘best performing’ . . . to allow it to consider whether retrofitting

kilns with a particular pollution control technology is technically

feasible.” Resp’t’s Br. 27. But EPA cannot circumvent Cement

Kiln’s holding that section 7412(d)(3) requires floors based on

the emission level actually achieved by the best performers

(those with the lowest emission levels), not the emission level

achievable by all sources, simply by redefining “best

performing” to mean those sources with emission levels

achievable by all sources. See 255 F.3d at 861. Moreover,

EPA’s rationales for excluding kilns equipped with non-DLA

technology from its ranking of the best-performing large tunnel

kilns (the infeasibility of retrofitting all kilns with certain nonDLA technology and the negative impact other non-DLA

technology would have on productivity) amount to nothing more

than a concern about ensuring that its floor is achievable by all

kilns in the subcategory—precisely the position we rejected in

Cement Kiln.

III.

EPA’s emission standards run counter to Cement Kiln and

National Lime II in several other respects—all variations on the

Agency’s fundamental failure to set floors at the emission levels

actually achieved by the best-performing sources. 
12

Variability

In Cement Kiln we declared unlawful EPA’s method of

estimating variability among the best performers by lowering

floors to the level of the worst performer using the same

technology. We explained:

[W]e are unpersuaded by EPA’s claim that to

account for the best-performing sources’

operational variability, it had to base the floors

on the worst performers’ emissions. While we

have recognized that a given control can

experience operational variability, the relevant

question here is not whether control technologies

experience variability at all, but whether the

variability experienced by the best-performing

sources can be estimated by relying on emissions

data from the worst-performing sources using the

MACT control. In this case, the evidence EPA

cites to support the MACT approach as a means

of accounting for operational variability fails to

demonstrate the relevant relationship. Some of

the Agency’s citations to the record merely

contain assertions that “[the] approach . . . fully

accounts for normal process variability.” The

actual variability data EPA cites suggest only

that emissions from sources using a given

control vary over a wide range, not that the high

emission levels achieved by sources at one end

of that range reflect levels achieved by sources at

the other end, nor that the best-performing

sources ever experience a wide range of

variability at all.

255 F.3d at 865 (citations omitted). 
13

Here, EPA used the same flawed process to set floors for

new large and small tunnel brick and ceramics kilns, as well as

for existing large tunnel brick kilns. In its rulemaking, EPA

explained that it “used the highest emission level associated with

the[] best performers [i.e., all DLA-controlled kilns] to set the

emission standard because it was [EPA’s] intent to set emission

limits that reflect the performance that the best-controlled

sources continually achieve considering variability.” 68 Fed.

Reg. at 26,700 (justifying technology-based approach for

existing kilns); see also Summary of Public Comments at 2-54

(same, with regard to new kilns). Citing a range of emission

datapoints from a single DLA-equipped kiln, EPA explained

that “[a]ll sources, including the best-controlled sources, have

variability in emissions.” 68 Fed. Reg. at 26,700. Because these

reasons for using the emission level achieved by the worstperforming kilns to predict the variability of the best performers

differ little from the reasons EPA gave in Cement Kiln, this

element of the Agency’s floor-setting methodology is similarly

unlawful.

Defending its approach, EPA points to Mossville

Environmental Action Now v. EPA, 370 F.3d 1232 (D.C. Cir.

2004), in which we held that floors may legitimately account for

variability because “each [source] must meet the [specified]

standard every day and under all operating conditions.” Id. at

1242. In Mossville, however, record evidence demonstrated that

the floor reasonably estimated the actual variability of the bestperforming source. Id. (noting “factual data” that a standard

based on the worst-performing sources “reasonably estimates

the performance of the top performers”). Here, by contrast,

although EPA has some evidence that the best performers

experience variability, it has failed to show that the emission

levels achieved by the worst performers using a given pollution

control device actually predict the range of emission levels

achieved by the best performers using that device. Given
14

Cement Kiln’s holding that EPA may not use emission levels of

the worst performers to estimate variability of the best

performers without a demonstrated relationship between the

two, we conclude that the emission floors for new large and

small tunnel brick and ceramics kilns, as well as for existing

large tunnel brick kilns, violate the Act.

Non-technology Factors

In Cement Kiln, we rejected EPA’s MACT approach to

setting floors given record evidence that factors other than

technology affected emissions. 255 F.3d at 863-65. In doing so,

we noted our conclusion in National Lime II that the MACT

methodology, a purely technology-based approach, would

satisfy the Clean Air Act “if pollution control technology were

the only factor determining emission levels of that HAP.” Id. at

863 (quoting National Lime II, 233 F.3d at 633). We were

unpersuaded by EPA’s twin justifications for refusing to

consider the effect of other factors on emissions, namely that the

effect proved “impossible to reliably quantify,” id. at 865, and

that “floors must be achievable by all sources using MACT

technology,” id. at 864. We explained:

[I]f factors other than MACT technology do

indeed influence a source’s performance, it is not

sufficient that EPA considered sources using

only . . . MACT controls. . . . 

Even accepting the proposition that factors

affecting source performance . . . are difficult to

quantify when defining the MACT control,

nothing in the statute requires EPA to use the

MACT approach. Section 7412(d)(3) requires

only that EPA set floors at the emission level

achieved by the best-performing sources. If EPA
15

cannot meet this requirement using the MACT

methodology, it must devise a different approach

capable of producing floors that satisfy the Clean

Air Act.

Id. at 864-65. 

EPA’s emission standards for existing large tunnel brick

kilns and new large and small tunnel brick and ceramics kilns

suffer from the same defect (in addition to the defects noted

above). In its rulemaking, EPA noted that it had reviewed nontechnology pollution prevention techniques—in particular the

substitution of fuels and clays with lower amounts of hazardous

constituents. It found that fuel type had no appreciable effect on

emissions, that transporting clays over long distances was

impractical, and that changes in either could affect kilns’ ability

to duplicate their existing product lines. 68 Fed. Reg. at 26,699.

Given these findings, EPA set floors based only on pollution

control technology, explaining that “[w]hile we agree that

factors other than [technology] type can affect emissions, we do

not have the data to determine the specific degree of the effect

of factors other than [technology] on emissions, and we believe

that, for the BSCP industry, factors other than [technology] use

are not viable MACT floor . . . control options.” Id. Though

acknowledging that at least one non-technology factor, clay

type, had an appreciable effect on emissions, EPA has

articulated the same justifications it offered in Cement Kiln for

using technology-based floors, i.e., a lack of data to quantify the

effects of non-technology factors and a concern that floors based

on clean clay would be unachievable because of the inability of

kilns to switch clays. Id. These justifications are no more valid

here than they were in Cement Kiln. 

EPA argues that the Clean Air Act’s command that it assess

the emission “control” or “limitation” “achieved” refers to the
16

deliberate steps kiln operators take to reduce emissions rather

than to the “happenstance” of being located near cleaner clay.

Resp’t’s Br. 33-34. Yet we squarely held in National Lime II

that the Clean Air Act requires neither an intentional action nor

a deliberate strategy to reduce emissions. As we explained,

“[t]he Clean Air Act requires the EPA to set MACT floors based

upon the ‘average emission limitation[s] achieved’; it nowhere

suggests that this achievement must be the product of a specific

intent.” 233 F.3d at 640 (citation omitted). EPA’s decision to

base floors exclusively on technology even though nontechnology factors affect emission levels thus violates the Act.

“No Control” Floors

As noted above, in National Lime II we found unlawful

EPA’s “no control” emission floors for categories in which the

best performers used no emission control technology. 233 F.3d

at 633-34. As we explained, EPA has a “clear statutory

obligation to set emission standards for each listed HAP,” which

does not allow it to “avoid setting standards for HAPs not

controlled with technology.” Id. at 634. 

EPA’s failure to set floors for existing small tunnel brick

kilns and existing and new periodic brick kilns violates section

7412(d)(3) for precisely the same reason. EPA set “no

emissions reductions” floors for existing small tunnel brick kilns

because the 94th percentile kiln used no air pollution control

technology and because changes in non-technology factors were

not “appropriate” or “viable.” 67 Fed. Reg. at 47,909

(explaining EPA’s rationale for “no control” floors, which the

Agency later adopted in final rule). EPA also set “no emissions

reductions” floors for all periodic brick kilns, explaining that

they too use no pollution control technology. Id. Other than

again claiming that it has no obligation to set floors unless

sources take some deliberate action to control emissions, EPA
17

has failed to offer any reason for distinguishing what it did here

from what we invalidated in National Lime II.

IV.

This brings us to the one issue in this case controlled by

neither Cement Kiln nor National Lime II, namely EPA’s use of

so-called “work practice” standards instead of emission floors

for the remaining subcategories of kilns. Section 7412(h) of the

Clean Air Act provides that “if it is not feasible in the judgment

of the Administrator to prescribe or enforce an emission

standard . . . , the Administrator may, in lieu thereof, promulgate

a design, equipment, work practice, or operational standard.”

42 U.S.C. § 7412(h)(1). That section further explains that it is

“not feasible” to set an emission standard when “the application

of measurement methodology to a particular class of sources is

not practicable due to technological and economic limitations.”

Id. § 7412(h)(2)(B). 

Invoking section 7412(h), EPA adopted the work practice

standard of using clean-burning fuels for existing ceramics kilns

and new periodic and roller ceramics kilns. 68 Fed. Reg. at

26,712, 26,713. To justify its use of work practice standards,

EPA pointed out that ceramics kilns, like periodic brick kilns,

use no pollution control devices and cannot feasibly substitute

clays. Rather than setting “no control” floors, however, EPA

imposed a clean-burning fuels standard. Id. According to EPA,

setting a more precise floor based on the emission levels

achieved by the use of clean-burning fuels was not feasible

given the absence of data necessary to make this calculation. Id.

at 26,712. 

We agree with the Sierra Club that EPA’s use of work

practice standards instead of emission floors violates section

7412(h). That provision allows EPA to substitute work practice
18

standards for emission floors only if measuring emission levels

is technologically or economically impracticable. Here, EPA

never determined that measuring emissions from ceramics kilns

was impracticable; it determined only that it lacked emissions

data from ceramics kilns. EPA thus had no basis under section

7412(h) for using work practice standards. To be sure, as EPA

points out, because ceramics kilns already use clean-burning

fuels, the work practice standard would have no impact on their

products. For the same reason, of course, it would have no

impact on emissions. 

V.

For the foregoing reasons, we vacate the emission standards

for both brick and ceramics kilns and remand for further

proceedings consistent with this opinion. If the Environmental

Protection Agency disagrees with the Clean Air Act’s

requirements for setting emissions standards, it should take its

concerns to Congress. If EPA disagrees with this court’s

interpretation of the Clean Air Act, it should seek rehearing en

banc or file a petition for a writ of certiorari. In the meantime,

it must obey the Clean Air Act as written by Congress and

interpreted by this court.

So ordered.
WILLIAMS, Senior Circuit Judge, concurring: I agree 

entirely with the court’s opinion and write only to note a 

paradox in the relationship between two key provisions of 

§ 112 of the Clean Air Act. 

Section 112(d)(2) calls for emissions standards that are 

the most stringent that the EPA finds to be “achievable,” 

taking into account a variety of factors including cost. 42 

U.S.C. § 7412(d)(2); see Per Curiam at 3. Section 112(d)(3) 

provides that the standards “shall not be less stringent” than 

the emission controls that have been “achieved in practice.” 

42 U.S.C. § 7412(d)(3); see Per Curiam at 4. The 

“achievable” standards have come to be known as the 

“beyond-the-floor” standards, see id. at 4, 5, meaning, 

obviously, ones more stringent than the “floors” established 

under § 112(d)(3). The language thus embodies an 

assumption that standards based on achievability will be more 

stringent than ones based merely on past achievement. 

What if meeting the “floors” is extremely or even 

prohibitively costly for particular plants because of conditions 

specific to those plants (e.g., adoption of the necessary 

technology requires very costly retrofitting, or the required 

technology cannot, given local inputs whose use is essential, 

achieve the “floor”)? For these plants, it would seem that 

what has been “achieved” under § 112(d)(3) would not be 

“achievable” under § 112(d)(2) in light of the latter’s mandate 

to EPA to consider cost. (Notice that here EPA issued no 

“beyond-the-floor” standards, and petitioner makes no 

complaint on that score.) In other words, as applied to some 

sources, the floor compelled by the statutory language appears 

to be more stringent than “beyond-the-floor.” 

If this were all, we might be talking of a statute whose 

literal words produced a result so “demonstrably at odds with 

the intentions of its drafters” as to justify judicial surgery. See 

United States v. Ron Pair Enterprises, Inc., 489 U.S. 235, 242 
2

(1989) (quoting Griffin v. Oceanic Contractors, Inc., 458 U.S. 

564, 571 (1982)) (internal quotation marks omitted). 

Happily § 112 is not such a statute. Section 112(d)(1) 

authorizes the Administrator to “distinguish among classes, 

types and sizes of sources within a category or subcategory,” 

and the language of subsections 112(d)(2) and (3) pervasively 

refers to standards for sources in each “category or 

subcategory.” The authority to generate subcategories is 

obviously not unqualified; at the least it must be limited by the 

usual ideas of reasonableness. And there is not necessarily 

any guarantee that, even with suitable subcategorization, 

every source will be able to achieve standards that meet a 

lawful application of § 112(d)(3) to reasonably defined 

subcategories. Nonetheless, one legitimate basis for creating 

additional subcategories must be the interest in keeping the 

relation between “achieved” and “achievable” in accord with 

common sense and the reasonable meaning of the statute.