UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX AIR DIVISION

Technical Support Document 

EPA’s Direct Final Rulemaking

for the

California State Implementation Plan

Sacramento Metropolitan Air Quality Management District 

Rule 421 (excluding section 402), Mandatory Episodic Curtailment of Wood 

and Other Solid Fuel Burning

Prepared by: Christine Vineyard

November 2014
2

RULE IDENTIFICATION 

Agency: Sacramento Metropolitan Air Quality Management District 

(SMAQMD)

SIP Approved Rule: There are no previous versions of this rule in the SIP

Superseded Submittals: There are no previous submittals of this rule

Subject of this TSD: Rule 421 – Mandatory Episodic Curtailment of Wood and 

Other Solid Fuel Burning

Amended - September 24, 2009

Submitted - September 21, 2012

Determined Complete - October 11, 2012

RULE SUMMARY 

Rule 421 establishes the following requirements: 

1. During the burning season (November – February), the APCO can declare a voluntary 

or mandatory curtailment of wood burning activity as follows:

 Voluntary Curtailment: This type of curtailment will be declared when the APCO 

determines that the 24-hour average PM2.5 concentration may exceed 25 μg/m3, 

but not likely to exceed 31 μg/m3.

 Stage 1 Mandatory Curtailment: This type of curtailment will be declared when the 

APCO determines that the 24-hour average PM2.5 concentration may exceed 31 

μg/m3, but will not likely to exceed 35 μg/m3. During this type of curtailment only 

U.S. EPA Phase II certified wood burning stoves and pellet-fueled heaters that do 

not emit visible smoke can be used. 

 Stage 2 Mandatory Curtailment: This type of curtailment will be declared when the 

APCO determines that the 24-hour average PM2.5 concentration may exceed 35 

μg/m3. During this type of curtailment all residential wood burning, except for 

limited exemptions as described in the rule, are banned.

2. Public notice of mandatory curtailment periods are made via recorded telephone 

message, on the District website, email to interested parties, notification of television and 

radio stations, or other methods as determined effective by APCO.

3. The rule includes exemptions to curtailment for devices that operate exclusively on 

gaseous fuel, cook stoves, wood burning devices that are the sole source of heat in a 

residence, and fires used as part of religious ceremony. Also, the rule includes a financial 

hardship exemption. The APCO may issue a waiver from the rule if there are compelling 

economic reasons and the waiver will not have adverse impacts on air quality. Submitted 
3

as non-regulatory supplemental material, the Financial Hardship Exemption Decision 

Tree, outlines the criteria for the APCO to grant a waiver.1

We are not acting on Section 402 which includes a penalty provision for first-time 

violators: $50 fine or wood burning awareness course. Future violations are consistent 

with penalty process used in other prohibitory rules. This provision is a part of the 

District’s local regulation, but will be excluded from the Applicable-SIP

EVALUATION CRITERIA - The following criteria were used to evaluate the submitted 

rule. 

1. Enforceability - The Bluebook (Issues Relating to VOC Regulation Cutpoints, 

Deficiencies, and Deviations, EPA, May 25, 1988) and the Little Bluebook 

(Guidance Document for Correcting Common VOC & Other Rule Deficiencies,

EPA Region 9, August 21, 2001) were used to help evaluate compliance with the 

CAA §110(a)(2)(A) requirement for enforceability. 

2. SIP Revisions - CAA §110(l) prohibits EPA from approving any SIP revision that 

would interfere with any applicable requirement concerning attainment and 

reasonable further progress (RFP) or any other applicable requirement of the CAA. 

In addition, CAA §193 prohibits the modification of any SIP-approved control 

requirement in effect before November 15, 1990, in a nonattainment area.

3. Rule Stringency – Effective December 14, 2009, EPA designated SMAQMD as 

nonattainment for the 2006 24-Hour PM2.5 National Ambient Air Quality Standard 

(NAAQS). 40 C.F.R. § 81.305 (2010); 74 FR 58688, 58705-58706 (November 13, 

2009). Consequently, by December 14, 2012, California must submit a revision to 

the State Implementation Plan (SIP) for this nonattainment area that provides for, 

among other things, implementation of all Reasonably Available Control Measures 

(RACM) as expeditiously as practicable, including Reasonably Available Control 

Technology (RACT) for existing sources. CAA § 172(b) & (c)(1), 74 FR at 58689. 

For purposes of implementing the 2006 PM2.5 NAAQS, EPA recommends that 

states evaluate potential RACM/RACT control measures for sources of direct PM2.5

(including condensable PM), SO2, and NOx in the specific nonattainment area, 

consistent with the approach to evaluating RACM/RACT provided in EPA’s 

implementing regulations for the 1997 PM2.5 NAAQS at 40 CFR part 51, subpart Z. 

See Memorandum from Stephen D. Page, Director, EPA Office of Air Quality 

Planning and Standards to Regional Air Directors, Regions I-X, “Implementation 

Guidance for the 2006 24-Hour Fine Particle (PM2.5) National Ambient Air Quality 

Standards (NAAQS).” Accordingly, the SMAQMD will need to adopt as 

RACM/RACT any potential PM2.5, SO2, or NOx control measures that are 

reasonably available considering technological and economic feasibility and that 

would, considered collectively, advance the attainment date by one year or more in 

the SMAQMD nonattainment area. Id. Because Rule 421 regulates direct PM2.5

emissions from residential wood-burning devices, the SMAQMD should consider 

whether reasonably available control measures for these emission sources could, in 

 

1 Letter dated, October 7, 2014, “SMAQMD Rule 421 Supplemental Materials” from Kevin Williams.
4

combination with other reasonably available control measures, advance attainment 

of the 2006 PM2.5 NAAQS in the area by at least one year. As necessary, in 

separate rulemakings, EPA will act on the State’s RACM demonstration for the 

2006 PM2.5 standard based on an evaluation of the control measures submitted as a 

whole and their overall potential to advance the applicable attainment date in 

SMAQMD. 

On March 18, 2002, EPA officially determined that Sacramento County had 

attained the PM-10 NAAQS by the attainment deadline based on PM-10 air quality 

monitoring data recorded during 1998 to 2000 (67 FR 7082). Accordingly, 

SMAQMD is not currently subject to the requirement to implement Best Available 

Control Measures (BACM) for PM-10 and PM-10 precursors in CAA § 189(b) and 

(e). Therefore, we are not evaluating this rule for compliance with BACM 

requirements.

EPA EVALUATION 

1. Enforceability - The rule requirements and applicability are clear, and the 

monitoring, recordkeeping, reporting and other provisions sufficiently ensure that 

affected sources and regulators can evaluate and determine compliance with Rule 

421 consistently. 

2. SIP Revisions – We propose to determine that our approval of the submitted rule 

would comply with CAA §110(l) because the SMAQMD portion of the California 

SIP does not contain any control requirement for wood-burning devices, and our 

approval of Rule 421 into the SIP would neither alter any existing SIP requirement 

nor interfere with the on-going process for ensuring that requirements for RFP and 

attainment of the NAAQS are met. Section 193 of the Act does not apply to our 

proposed action because this is a new rule to the SIP and does not modify any SIPapproved control requirement in effect before November 15, 1990, in a 

nonattainment area.

3. Rule Stringency – We believe the current rule requires all control measures that are 

“reasonably available” considering technologic and economic feasibility, for 

reasons including the following:

 We have compared the control requirements in Rule 421 with analogous rules 

in other local districts and states and believe that Rule 421 is as stringent as or 

more stringent than those other rules.2

 

2 See, e.g. Bay Area Air Quality Management District Rule 6-3 (Adopted July 9, 2008); South 

Coast Air Quality Management District Rule 445 (Adopted March 7, 2008); and San Joaquin Air 

Pollution Control District Rule 4901 (Amended October 16, 2008). Note: provisions regarding 

requirements for the sale, installation, or transfer of residential wood burning devices are detailed 

in SMAQMD Rule 417 (Adopted October 26, 2006), submitted to EPA September 21, 2012. This 

rule will be addressed in a separate, rulemaking.
5

As necessary, in separate rulemakings, EPA will take action on the State’s RACM 

demonstration for PM2.5 and ozone based on an evaluation of the control measures 

submitted as a whole and their overall potential to advance the applicable attainment dates 

in the SMAQMD. See 40 CFR §§ 51.1010, 51.912(d).

RULE DEFICIENCIES 

No deficiencies with Rule 421 were identified that would be sufficient for EPA to propose 

less than full approval.

EPA ACTION

We propose to determine that SMAQMD Rule 421 fulfils the applicable CAA §110 

requirements. Therefore, under section 110(k) of the CAA, EPA staff recommends full 

approval of SMAQMD Rule 421. 

REFERENCES 

1. “Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations,” 

(a.k.a., Bluebook) EPA OAQPS, May 25, 1988 (web citation).

2. “Guidance Document for Correcting Common VOC & Other Rule Deficiencies,” 

(a.k.a., Little Bluebook), EPA Region 9, August 21, 2001 

(http://www.epa.gov/region09/air/sips/littlebluebook2001.pdf).

3. “Memorandum from Stephen D. Page, Director, EPA Office of Air Quality 

Planning and Standards to Regional Air Directors, Regions I-X, “Implementation 

Guidance for the 2006 24-Hour Fine Particle (PM2.5) National Ambient Air 

Quality Standards (NAAQS).

4. “Technical Information Document for Residential Wood Combustion Best 

Available Control Measures”, EPA-450/2-92-002, September 1992.

5. “General Preamble”, Appendix C2--Available Residential Wood Combustion

Control Measures, 57 FR 18072, April 28, 1992.

6. “Strategies for Reducing Residential Wood Smoke”, EPA Document # EPA456/B-09-001, October 2009.

7. Bay Area AQMD Regulation 6, Rule 3 (July 9, 2008).

8. South Coast AQMD Rule 445 (March 7, 2008).

9. San Joaquin Valley Unified AQCD Rule 4901 (October 16, 2008).

10. Letter from Kevin Williams, Sacramento Metropolitan Air Quality Management 

District.

. 

 
6