United States Environmental Protection Agency, Region 9 

Air Division 

Technical Support Document 

for 

EPA’s Notice of Proposed Rulemaking 

for the 

California State Implementation Plan 

South Coast Air Quality Management District’s 

Rule 1111, Reduction of NOx Emissions from Natural Gas-Fired, Fan-Type Central Furnaces 

Prepared by: Idalia Pérez 

June 2010 
South Coast Air Quality Management District (SCAQMD) 

Submitted Rule 

SCAQMD Rule 1111, Reduction of NOx Emissions from Natural Gas-Fired, Fan-Type Central 

Furnaces: 

 Amended: November 6, 2009 

 Submitted: May 17, 2010 

 Determined complete: June 8, 2010 

Previous Rule Submittals 

There are no outstanding submittals of Rule 1111. 

SIP-Approved Rule 

 Adopted: July 8,1983 

 Approved by EPA: May 3, 1984 (49 FR 18830) 

Rule Summary 

Rule 1111 limits NOx emissions from natural gas-fired, fan-type central heating furnaces with a 

rated hear input capacity < 175,000 Btu/hour used in residences and small commercial buildings. 

The Rule also applies to combination heating and cooling units with a cooling rate < 65,000 

Btu/hour. 

Rule Amendments 

Rule 1111 was amended to strengthen the NOx emission limits and expand the applicability to 

include mobile home furnaces. 

The Rule includes a rebate incentive for early compliance and mandates the completion of a 

technology assessment report on the status of manufacturer’s progress towards compliance with 

the new emission limits. 

Other changes were done to the Rule language to improve clarity and enforceability. 

Effects on Emissions 

The staff report indicates that the amendments of Rule 1111 will lead to an estimated reduction 

of between 2.5 to 3.1 tons per day of NOx emissions in 2023. Because of the lifetime of 

residential furnaces, the complete emissions reduction benefits of 6.8 tons per day will not be 

realized until 2043. 

Rule Evaluation 

Generally, SIP rules must be enforceable (see §110(a) of the Clean Air Act, hereafter CAA); must 

require Reasonably Available Control Technology (RACT) for major sources of NOx in 

nonattainment areas (see CAA §182(b)(2) and (f)); must not interfere with applicable requirements, 

including requirements concerning attainment (see CAA §110(l)); and must not relax existing 

requirements in effect prior to enactment of the 1990 CAA amendments (see §193). 
Although the SCAQMD regulates a serious (8-hour) and extreme (1-hour) ozone nonattainment 

area (40 CFR 81), submitted Rule 1111 is not subject to RACT because it is applicable to 

sources that are too small to exceed the major source threshold. 

Guidance and policy documents that we used to define enforceability requirements include the 

following:

• Issues Relating to VOC Regulation, Cutpoints, Deficiencies, and Deviations (the "Blue 

Book"), US EPA, OAQPS (May 25, 1988). 

• Guidance Document for Correcting Common VOC and Other Rule Deficiencies, EPA 

Region IX (August 21, 2001, the “Little Bluebook”).

The Rule was not reviewed to determine its fulfillment of RACT; thus we are not making a 

statement of its merit in this regard. 

Recordkeeping and other compliance provisions in the rule ensure that the requirements are 

adequately enforceable. The elimination of the exemption for mobile homes and the addition of 

more stringent NOx emission limits make the amendments a strengthening of the SIP. Thus, 

approval of the submitted rule does not relax the SIP and satisfies CAA §110(l) and §193. 

Recommendation 

EPA staff recommends approval of SCAQMD submitted Rule 1111 for incorporation into the 

California SIP. 

Attachments 

1. Submitted Rule 1111 (Clean Copy) 

2. Submitted Rule 1111 (Strikeout Copy) 

3. Staff Report 

4. SIP-approved version of Rule 1111