Is Your Commercial Bakery Oven Ready for California Air Quality Compliance?
If you operate a commercial bakery, food manufacturing facility, bread production plant, or other operation using regulated bakery ovens in Southern California, South Coast AQMD Rule 1153 – Commercial Bakery Ovens may affect your facility.
Rule 1153 addresses Volatile Organic Compound (VOC) emissions from commercial bakery ovens. For facilities subject to the rule, demonstrating the required level of VOC emission reduction is an important part of maintaining environmental compliance.
And there is another reason bakery operators should be paying attention in 2026:
South Coast AQMD is continuing to move commercial food-oven regulations toward lower and zero-emission technologies under Rule 1153.1.
That means bakery and food-processing facilities should not wait until the next compliance deadline, equipment replacement or regulatory inspection to evaluate their emissions and testing requirements.
What Does Rule 1153 Cover?
South Coast AQMD Rule 1153 applies to commercial bakery ovens meeting specific heat-input and VOC-emission criteria.
The rule generally applies to bakery ovens with:
Rated heat input capacity of 2 million BTU/hour or more
Average daily VOC emissions of 50 pounds or more
VOC emissions associated with fermentation and baking of yeast-leavened products
Facilities should evaluate their individual equipment, permits, operating conditions and emissions before determining applicability.
What Are the Rule 1153 VOC Requirements?
For applicable existing bakery ovens, Rule 1153 establishes VOC emission-reduction requirements based on the oven’s emissions.
Existing Bakery Ovens
Depending on the applicable emissions category:
70% minimum VOC reduction
For an existing oven with base-year average daily VOC emissions of 50 pounds or more, but less than 100 pounds.
95% minimum VOC reduction
For an existing oven with base-year average daily VOC emissions of 100 pounds or more.
New Bakery Ovens
New bakery ovens subject to Rule 1153 generally require:
95% or greater VOC emission reduction when uncontrolled average daily VOC emissions are 50 pounds or more.
These requirements can make accurate emissions measurement and control-device performance evaluation extremely important.
Why Rule 1153 Compliance Testing Matters
A bakery may believe that its oven is operating normally, but normal production does not automatically mean regulatory compliance.
VOC emissions can be influenced by factors such as:
Yeast percentage
Fermentation time
Product type
Production rate
Oven operating conditions
Exhaust flow
Control-device performance
Changes in equipment configuration
Changes in production processes
A properly planned emissions test can help establish whether the equipment is achieving the required emission-reduction performance.
For facilities subject to source-testing requirements, testing should be planned around the applicable permit conditions, regulatory requirements, approved test methods and operating conditions.
2026 Update: Why Bakery Operators Should Also Watch Rule 1153.1
While Rule 1153 focuses on VOC emissions, Rule 1153.1 addresses NOx emissions from commercial food ovens.
This distinction is extremely important.
In 2026, South Coast AQMD conducted a technology check-in concerning the future zero-NOx requirements under Rule 1153.1.
The agency’s 2026 assessment reported that zero-NOx technology is technically feasible and cost-effective for smaller oven categories. At the same time, the agency recognized that transitioning from natural gas to electricity can create significant fuel-switching and infrastructure costs, particularly for larger ovens.
The 2026 activity included:
February 3, 2026 technology check-in
March 20, 2026 Stationary Source Committee discussion
April 3, 2026 Governing Board update
Continued evaluation of zero-NOx technology and cost-effectiveness
Continued preparation for future zero-emission requirements
Why Does This Matter to Bakery Facilities?
Because today’s VOC compliance project can become part of tomorrow’s broader emissions-management strategy.
Bakery operators should consider both:
VOC compliance under Rule 1153
and
NOx requirements under Rule 1153.1
when planning major oven modifications, burner replacements, electrification projects, new equipment purchases or facility expansions.
What Is Coming Under Rule 1153.1?
Rule 1153.1 establishes Phase I NOx requirements and future zero-emission requirements for certain commercial food ovens.
The zero-emission provisions include categories such as:
Certain bakery ovens rated at or below 3 MMBtu/hr
Certain cooking ovens rated at or below 3 MMBtu/hr
Indirect-fired bakery ovens
Smokehouses
The future compliance structure is based in part on equipment and burner age.
For affected facilities, the transition toward zero-NOx technology can involve:
Equipment evaluation
Electrical capacity assessment
Utility coordination
Permit planning
Equipment replacement or modification
Compliance testing
Engineering analysis
Documentation and reporting
The key message for facility owners: Don’t wait until an equipment deadline forces a rushed decision.
Pros of Rule 1153 Compliance & Emissions Testing
1. Helps Demonstrate Regulatory Compliance
Accurate testing provides documented emissions data that can support compliance demonstrations.
2. Identifies Emissions Problems Early
Testing can reveal problems with oven operation, exhaust systems or VOC control equipment before they become larger compliance concerns.
3. Supports Permit Compliance
Testing and reporting can help facilities maintain documentation associated with applicable permits and regulatory requirements.
4. Supports Better Equipment Decisions
Reliable emissions information can help facility managers determine whether to maintain, modify, upgrade or replace equipment.
5. Improves Environmental Performance
Effective VOC control can contribute to reduced ozone-forming emissions and improved regional air quality.
6. Helps Prepare for Future Regulations
With California continuing to move toward lower-emission and zero-emission technologies, early testing and engineering evaluation can help facilities prepare for future requirements.
Cons & Challenges of Rule 1153 Compliance
Compliance is important, but it can create practical challenges for bakery operators.
1. Testing Costs
Professional source testing requires specialized personnel, equipment, laboratory analysis and reporting.
2. Production Coordination
Testing often needs to occur under representative operating conditions, which requires coordination with production schedules.
3. Potential Control-System Upgrades
If testing identifies insufficient VOC reduction, the facility may need to evaluate control-device modifications or other corrective measures.
4. Operational Disruption
Poorly planned testing can interfere with production schedules.
5. Technical Documentation
Permit conditions, test protocols, operating parameters, calculations and final reports can be complicated.
6. Future Equipment Investment
The broader transition toward low-NOx and zero-NOx commercial food-oven technology may require significant capital planning, particularly where electrical upgrades or equipment replacement are necessary.
At Energy Environmental Solutions, Inc. (EES), we help industrial and commercial facilities approach air-quality compliance through professional testing, engineering support and regulatory documentation.
For bakery and food-processing facilities, EES can help with a compliance strategy that may include:
Rule 1153 Compliance Evaluation
Review the facility’s applicable equipment, operating conditions and regulatory requirements to help determine the appropriate compliance pathway.
VOC Source Testing
Perform emissions testing using applicable regulatory and approved test methodologies.
Test Protocol Development
Develop a testing strategy and protocol based on applicable requirements, permit conditions and facility operating parameters.
Emissions Measurement & Data Analysis
Collect and evaluate emissions data to support an accurate compliance determination.
Control-System Performance Evaluation
Where applicable, evaluate the performance of VOC emission-control equipment.
Compliance Reporting
Prepare technically organized documentation and reports to support regulatory compliance and facility records.
Rule 1153.1 Support
For facilities affected by commercial food-oven NOx requirements, EES can also support:
Environmental compliance is not simply about collecting numbers.
The quality of the testing plan, operating conditions, measurements, calculations and final documentation can all matter.
EES provides a coordinated approach:
PLAN → TEST → ANALYZE → REPORT → SUPPORT COMPLIANCE
Our goal is to help customers obtain accurate, defensible emissions data while minimizing unnecessary operational disruption.
Don’t Wait for a Compliance Problem
If your facility operates commercial bakery ovens in California, now is a good time to review your compliance position.
Ask yourself:
Is my bakery oven subject to Rule 1153?
Do I know my uncontrolled VOC emissions?
Is my VOC control system achieving the required reduction?
When was my last compliance test?
Are my testing records complete?
Does my current permit accurately reflect my equipment?
Could upcoming Rule 1153.1 requirements affect my equipment?
Will future electrification require electrical or utility upgrades?
Should I plan equipment modifications or replacement before a regulatory deadline?
If you cannot confidently answer these questions, a professional compliance review may be worthwhile.
Partner With EES for California Air Quality Compliance
Accurate Testing. Reliable Results. Regulatory Confidence.
Energy Environmental Solutions, Inc. helps facilities navigate complex air-emissions testing and compliance requirements with technical, engineering and testing support.
Protect Your Permit. Protect Your Operations. Prepare for What’s Next.
Rule 1147.2 in California 2026: Latest Updates, Pros, Cons & How EES Helps Industries
Rule 1147.2 — NOx Reductions from Metal Melting and Heating Furnaces is a key South Coast AQMD regulation for facilities operating permitted metal melting, metal heat-treating, metal heating, and metal forging furnaces.
A critical clarification before discussing 2026: Rule 1147.2 is not a statewide California regulation. It is a South Coast AQMD rule applicable within the District’s jurisdiction when the equipment meets the rule’s applicability requirements. The current official rule is identified as Rule 1147.2, adopted April 1, 2022.
As of August 2026, the official South Coast AQMD material reviewed does not show a newly adopted 2026 amendment replacing Rule 1147.2. However, 2026 remains important because South Coast AQMD has an active rulemaking agenda with more than two dozen planned amendments/adoptions across its regulatory program, while the agency continues implementing measures aimed at reducing emissions and improving air quality.
For metal-processing facilities, the practical question is therefore not simply, “Was Rule 1147.2 changed in 2026?” It is:
“Is my furnace currently meeting the applicable Rule 1147.2 limits, testing schedule, permit conditions and monitoring requirements?”
That’s where professional source testing and compliance support become valuable.
Energy Environmental Solutions, Inc. (EES) can help industries with Rule 1147.2 source testing, NOx testing, CO testing, compliance test protocol development, CEMS, RATA, CGA, engineering studies, emissions monitoring and regulatory reporting.
What Is Rule 1147.2?
Rule 1147.2 was created specifically to reduce nitrogen oxide (NOx) and carbon monoxide (CO) emissions from four major categories of combustion equipment:
Metal melting furnaces
Metal heat-treating furnaces
Metal heating furnaces
Metal forging furnaces
The rule applies to an owner or operator of one of these furnaces when the equipment requires a South Coast AQMD permit.
The regulation was developed as part of South Coast AQMD’s broader transition away from the RECLAIM program toward more source-specific emissions controls. South Coast AQMD documents describe Rule 1147.2 as moving metal melting and heating furnace operations from Rule 1147 into a dedicated rule with NOx limits reflecting current BARCT — Best Available Retrofit Control Technology.
That makes Rule 1147.2 particularly relevant to businesses in the metal-processing sector.
Why Does Rule 1147.2 Matter in 2026?
NOx is a major precursor to ozone and particulate pollution. In Southern California, reducing stationary-source NOx remains an important component of regional air-quality planning.
South Coast AQMD’s 2026 outlook identifies extensive rulemaking activity intended to implement the 2016 and 2022 Air Quality Management Plans and the 2024 PM Plan, reduce health risks, and support attainment of state and federal air-quality standards.
That means industrial facilities shouldn’t treat Rule 1147.2 as an old compliance document sitting in a filing cabinet.
And 2026 is especially relevant for facilities managing multiple furnaces because some of the rule’s multi-unit implementation schedule reaches 100% compliance milestones in 2026 and beyond.
Latest Rule 1147.2 Updates for 2026
1. The Current Adopted Rule Is Still the April 1, 2022 Rule
The official South Coast AQMD rulebook identifies Rule 1147.2 as:
Rule 1147.2 — NOx Reductions from Metal Melting and Heating Furnaces Adopted: April 1, 2022
The current official rule remains the primary document facilities should use when evaluating compliance in 2026.
There is an important distinction between current regulatory obligations and future rulemaking activity.
A facility shouldn’t assume that every item appearing on a proposed-rule page is already law.
2. 2026 Is an Important Milestone for Multiple-Furnace Facilities
One of the most relevant provisions for 2026 is the multiple-unit implementation schedule.
For facilities with two or more applicable units, Rule 1147.2 provides a phased approach based on the percentage of total rated heat-input capacity represented by units covered by the implementation schedule.
The rule specifies a January 1, 2026 milestone requiring:
100% of applicable rated heat-input capacity for facilities with 2–9 units
67% for facilities with 10–19 units
The schedule continues to January 1, 2028, when 100% applies to the 20-or-more-unit category under the specified schedule.
Why is this important?
A company operating one furnace may have a relatively straightforward compliance program.
A company operating 10, 15 or 20 furnaces has a much more complicated compliance calendar.
For those facilities, 2026 is not simply another year on the calendar—it can represent a significant implementation milestone.
3. Rule 1147.2 Has Different Limits for Different Furnaces
One of the biggest mistakes a facility can make is assuming there is one universal NOx limit for every furnace.
There isn’t.
For existing units below 40 MMBtu/hr, Table 1 establishes different NOx limits depending on furnace type and operating temperature.
Existing Furnace
NOx Limit
CO Limit
Metal Melting
40 ppm
1,000 ppm
Metal Heat Treating / Heating / Forging ≤1,200°F
40 ppm
—
Metal Heat Treating / Heating / Forging >1,200°F
50 ppm
—
Radiant-Tube Burners
50 ppm
—
Units ≥40 MMBtu/hr
15 ppm
—
The applicable ppm limits are corrected to 3% oxygen on a dry basis, with an 8-hour rolling average applying where specified for units equipped with certified NOx CEMS.
That means compliance testing has to be designed around the actual furnace configuration.
4. New Units Face Different Requirements
Rule 1147.2 also establishes a separate Table 3 for new units.
For example:
Metal melting furnaces below 40 MMBtu/hr: 40 ppm NOx
Metal heat treating/heating/forging ≤1,200°F: 30 ppm NOx
Metal heat treating/heating/forging >1,200°F: 40 ppm NOx
Radiant-tube burners: 40 ppm NOx
Units ≥40 MMBtu/hr: 15 ppm NOx
The rule specifies the applicable oxygen correction and averaging provisions.
This is an important consideration when a facility is replacing an old furnace.
Replacing equipment does not necessarily mean you can simply carry the old compliance assumptions into the new installation.
5. Burner Age Can Affect Implementation
For certain units below 40 MMBtu/hr, Rule 1147.2 uses burner age as part of its implementation schedule.
For applicable existing units, facilities need to determine burner age using documentation such as:
Burner manufacturer invoices
Previous permit applications
Manufacturer identification/rating plates
Other substantiated written information approved by the Executive Officer
Where burner age cannot be determined through the specified methods, the rule provides a default treatment.
This makes equipment records extremely important.
Think of burner documentation as part of your compliance evidence.
If you don’t know when the burner was installed, you may have difficulty determining which implementation pathway applies.
6. Source Testing Is a Core Requirement
Rule 1147.2 contains specific source-testing requirements.
For units subject to the applicable concentration limits:
Units below 10 MMBtu/hr
A source test is required no later than 60 calendar months from the previous source test.
Units ≥10 MMBtu/hr
The testing interval depends on annual heat input:
≤23 billion Btu/year: up to 60 months
>23 billion Btu/year: up to 36 months
These requirements are based on the rule’s specified testing provisions.
This means the test frequency isn’t necessarily determined by furnace size alone.
Annual heat input can matter.
7. New Furnaces Have an Initial Testing Requirement
For new units, Rule 1147.2 requires an initial source test no later than 18 months after the Permit to Construct is issued, unless the Executive Officer approves an extension in writing.
For existing units, the rule establishes its own initial testing provisions and allows certain previously conducted South Coast AQMD-approved source tests to be used when the specified conditions are satisfied.
This creates an important project-management requirement:
Environmental compliance should be included in the equipment installation schedule from the beginning.
Don’t wait until the furnace is commissioned and production is underway to start thinking about source testing.
8. A Test Protocol Must Be Submitted Before Testing
Rule 1147.2 requires the source-test protocol to be submitted to the Executive Officer for approval at least 90 days before the scheduled source test.
The rule also specifies when the actual test must occur relative to protocol approval.
This is one of the strongest reasons to work with an experienced source-testing company.
A compliance test is not simply:
“Bring the analyzer → measure emissions → issue a report.”
Rule 1147.2 specifies approved source-testing procedures, including applicable South Coast AQMD methods and EPA Method 19, with alternative methods requiring the appropriate advance approvals.
The rule specifically references methods including:
South Coast AQMD Method 100.1
South Coast AQMD Method 7.1
South Coast AQMD Method 10.1
EPA Method 19
It also requires compliance source testing to use a South Coast AQMD-approved contractor under the Laboratory Approval Program for the applicable procedures.
That makes contractor selection a compliance issue—not merely a purchasing decision.
10. Source-Test Reports Have a 60-Day Deadline
After testing, Rule 1147.2 requires source-test reports to be submitted to the Executive Officer within 60 days of completion of the source test.
This creates three separate deadlines that facility managers should track:
Protocol submission → Test date → Report submission
A facility can conduct a technically successful test and still create a compliance problem if the required documentation isn’t handled correctly.
11. Large Furnaces May Require CEMS
For units with a rated heat-input capacity of 40 MMBtu/hr or greater, Rule 1147.2 includes CEMS requirements for measuring NOx and oxygen under specified facility circumstances.
The rule references applicable requirements under South Coast AQMD Rules 218.2 and 218.3, and Rule 2012 for certain RECLAIM facilities.
This means large-furnace compliance may involve much more than periodic stack testing.
Facilities may need to manage:
CEMS → Certification → QA/QC → RATA → Monitoring → Data validation
That is where specialized environmental testing expertise becomes especially valuable.
Pros of Rule 1147.2
1. Lower NOx Emissions
The primary benefit is reduced NOx emissions from metal-processing furnaces.
Lower NOx supports regional efforts to improve ozone and particulate pollution.
2. Better Combustion Performance
Testing can identify combustion problems involving:
Burner settings
Air/fuel ratio
Excess oxygen
Burner deterioration
Furnace operation
Control systems
3. More Transparent Compliance
Measured emissions data provide a stronger compliance record than relying solely on theoretical calculations.
4. Encourages Cleaner Technology
The regulation can encourage facilities to consider:
Low-NOx burners
Improved combustion controls
Burner modernization
Better monitoring
Furnace upgrades
5. Supports Long-Term Planning
A structured testing program gives facility managers better information about equipment performance.
6. Helps Reduce Community Exposure
Metal-processing facilities can be located near industrial communities. Reducing combustion-related pollutants can support broader air-quality objectives.
Cons and Challenges of Rule 1147.2
1. Testing Costs
Professional source testing requires specialized personnel, equipment, calibration, field measurements, data analysis and reporting.
2. Production Disruption
Testing must be coordinated with furnace operations and production schedules.
3. Equipment Upgrades Can Be Expensive
Older burners may not easily achieve newer emission limits without modification or replacement.
4. Multiple Units Increase Compliance Complexity
Facilities with many furnaces may have different:
Burner ages
Heat-input ratings
Operating temperatures
Emission limits
Test frequencies
Permit conditions
5. CEMS Adds Another Layer
Large units may have continuing CEMS-related responsibilities involving certification, maintenance and performance testing.
6. Documentation Is Critical
Permit records, burner-age documentation, source-test reports and monitoring records need to remain organized.
What Industries Should Pay Attention to Rule 1147.2?
Potentially affected operations include facilities involved in:
Metal Casting
Foundries
Metal Forging
Heat Treating
Metal Heating
Aluminum Processing
Steel Processing
Iron Processing
Nonferrous Metal Manufacturing
Industrial Furnace Operations
Metal Fabrication
The exact applicability depends on the equipment and permit.
Rule 1147.2 Compliance: What Should a Facility Check?
A facility manager should review the following:
Is the furnace subject to Rule 1147.2?
What type of furnace is it?
What is its rated heat-input capacity?
What is the burner age?
What is the applicable NOx limit?
Does a CO limit apply?
Is the unit a new or existing unit?
Is the facility RECLAIM, former RECLAIM or non-RECLAIM?
When was the last source test?
When is the next test due?
Is the source-test protocol approved?
Is CEMS required?
Are RATA/CGA requirements applicable?
Are the required permits current?
Are source-test reports submitted on time?
Are records complete?
How EES Helps With Rule 1147.2 Compliance
Energy Environmental Solutions, Inc. (EES) provides environmental testing and engineering support to industrial facilities.
Rule 1147.2 Source Testing
EES can help facilities perform compliance source testing for applicable metal-processing furnaces.
NOx Testing
Accurate NOx measurement is fundamental to demonstrating compliance with Rule 1147.2.
CO Testing
Where applicable, EES can support CO emissions testing alongside NOx measurements.
For large furnaces subject to CEMS requirements, EES can support emissions monitoring programs.
RATA & CGA
EES can assist facilities with applicable Relative Accuracy Test Audits (RATA) and Cylinder Gas Audits (CGA).
Engineering Studies
EES can evaluate combustion performance and help facilities understand potential compliance strategies.
Regulatory Reporting
After testing, EES can assist with technical documentation and reporting.
Rule 1147.2 Testing Process
A professional compliance project can be organized into the following stages:
1. Permit Review
Review the current South Coast AQMD permit and equipment information.
2. Applicability Review
Determine exactly how Rule 1147.2 applies to the furnace.
3. Limit Identification
Determine the applicable NOx and CO limits.
4. Testing Schedule
Calculate when the next source test is due.
5. Protocol Development
Develop and submit the source-test protocol.
6. Field Testing
Conduct the required emissions measurements under appropriate operating conditions.
7. QA/QC
Review calibration, sampling and analytical data.
8. Emissions Calculations
Calculate concentrations and applicable emission rates.
9. Reporting
Prepare and submit the source-test report.
10. Follow-Up
If results indicate noncompliance, evaluate appropriate corrective actions.
Why Proactive Rule 1147.2 Testing Is Important in 2026
South Coast AQMD’s 2026 regulatory agenda demonstrates that the District continues to actively develop and implement air-quality controls. The agency says its 2026 rule calendar contains more than two dozen planned rule amendments and adoptions aimed at implementing air-quality plans, reducing health risks and improving compliance clarity.
That doesn’t mean Rule 1147.2 itself was amended in 2026.
It means the regulatory environment surrounding industrial emissions continues to evolve.
A facility that waits until an inspection, permit renewal or failed test to examine its furnace emissions may have fewer options than a facility that monitors performance proactively.
Rule 1147.2: 2026 Pros vs. Cons
Pros
Cons
Reduces NOx emissions
Source testing costs
Supports cleaner air
Production scheduling challenges
Encourages modern burners
Potential equipment upgrades
Provides measurable compliance data
Complex requirements for multiple furnaces
Helps identify combustion problems
CEMS obligations for certain large units
Improves regulatory readiness
Detailed documentation required
Supports long-term environmental planning
Testing must follow approved methods
The 2026 Takeaway
Rule 1147.2 remains an important compliance requirement for applicable metal-processing furnaces in the South Coast AQMD jurisdiction.
The current adopted rule dates to April 1, 2022, and the official material reviewed does not show a replacement 2026 amendment. At the same time, 2026 includes important implementation and regulatory-planning milestones, particularly for facilities with multiple furnaces.
For facility managers, the smartest approach is not to wait for a regulatory surprise.
Know your furnace. Know your burner age. Know your NOx limit. Know your testing frequency. Know your permit. Know your CEMS obligations.
And most importantly:
Know whether your emissions data can demonstrate compliance.
Rule 1147.1 in California 2026: Latest Updates, Pros, Cons & How EES Helps Aggregate-Drying Facilities
Rule 1147.1 — NOx Reductions from Aggregate Dryers is an important South Coast AQMD regulation affecting certain aggregate-drying operations in Southern California. The rule establishes NOx and CO emission limits, source-testing requirements, monitoring provisions, recordkeeping, and compliance obligations for applicable aggregate dryers.
For 2026, there is an important distinction to make: Rule 1147.1 is not a statewide California regulation. It is a South Coast AQMD rule that applies within the District’s jurisdiction when the equipment meets the rule’s applicability requirements. South Coast AQMD’s current Regulation XI rulebook identifies Rule 1147.1 as “NOx Reductions from Aggregate Dryers,” adopted August 6, 2021.
At the same time, South Coast AQMD’s current proposed-rules pages continue to list Proposed Rule 1147.1 among rules in the proposal process. The dedicated proposal page, however, contains rulemaking documents dating primarily from 2020–2021. Therefore, businesses should not interpret that listing alone as evidence that a new Rule 1147.1 amendment was adopted in 2026.
For aggregate producers, asphalt and construction-material facilities, and other operations using regulated dryers, the practical message is simple:
Know your applicable NOx limit, know your testing deadline, and verify that your aggregate dryer can demonstrate compliance.
Energy Environmental Solutions, Inc. (EES) can help facilities with Rule 1147.1 source testing, NOx testing, CO testing, compliance test protocol development, emissions measurements, CEMS/RATA support, engineering studies, QA/QC and regulatory reporting.
What Is Rule 1147.1?
Rule 1147.1 was adopted by the South Coast AQMD Governing Board on August 6, 2021. It specifically addresses NOx reductions from aggregate dryers and was created as part of South Coast AQMD’s broader strategy to transition NOx sources away from the RECLAIM trading program toward more direct, source-specific controls.
The rule applies to qualifying gaseous-fuel-fired aggregate dryers with more than 1 pound per day of NOx emissions and a rated heat-input capacity greater than 2 million Btu/hour, subject to the rule’s detailed applicability provisions and exemptions.
Aggregate dryers are used to remove moisture from materials such as sand, gravel, crushed stone and other aggregate products. Because the drying process commonly involves high-temperature combustion, the burners can generate NOx.
And here’s the important part:
The larger the combustion system and the higher its emissions, the more important compliance testing becomes.
Why Does Rule 1147.1 Matter in 2026?
NOx is a major air pollutant involved in the formation of ground-level ozone and particulate matter. Southern California has historically faced significant challenges meeting federal and state air-quality standards, so stationary combustion sources remain an important part of regional emission-reduction strategies.
South Coast AQMD specifically developed Rule 1147.1 to establish NOx and CO requirements for aggregate dryers at non-RECLAIM, RECLAIM and former-RECLAIM facilities, together with monitoring, reporting and recordkeeping provisions.
The District’s planning documents estimate that Rule 1147.1 contributes additional NOx reductions as part of the transition from RECLAIM to command-and-control requirements. One South Coast AQMD emissions-inventory document identifies an estimated 0.01 tons/day of NOx reduction by 2030 attributable to Rule 1147.1, with implementation beginning in 2025 and reductions continuing toward 2057.
So while Rule 1147.1 is not a brand-new 2026 regulation, its compliance requirements remain relevant.
Latest 2026 Rule 1147.1 Update: What Facilities Should Know
1. The Current Adopted Rule Is Still Dated August 6, 2021
South Coast AQMD’s current official Regulation XI listing identifies:
Rule 1147.1 — NOx Reductions from Aggregate Dryers Adopted: August 6, 2021
Unlike several other South Coast AQMD rules that received amendments in 2025 or 2026, the current rulebook does not identify a 2026 amendment to Rule 1147.1.
That is an important SEO and compliance point because online articles sometimes describe old proposed-rule documents as if they were new 2026 regulations.
For 2026, facilities should work from:
The currently adopted Rule 1147.1 + their current South Coast AQMD permit + any applicable compliance conditions.
2. Proposed Rule 1147.1 Still Appears on South Coast AQMD’s Proposal Page
There is an unusual point worth highlighting.
South Coast AQMD’s current Active Proposed Rules page lists Proposed Rule 1147.1.
However, the dedicated Rule 1147.1 proposal page presents the original rulemaking materials, including the August 6, 2021 Notice of Public Hearing, July 2021 draft language and 2021 staff documents.
Therefore, companies should be careful when reading search results about “new Rule 1147.1 updates.”
The safest interpretation in 2026 is:
Rule 1147.1 remains an adopted South Coast AQMD rule, while the District’s website also retains/list its proposed-rule project materials. There is no verified evidence in the current official rulebook that a new 2026 amendment has replaced the adopted August 2021 rule.
This distinction is particularly important when preparing a compliance test.
3. NOx and CO Limits Remain Central
Rule 1147.1 establishes a 30 ppm NOx limit and 1,000 ppm CO limit, corrected to 3% oxygen on a dry basis, for the applicable gaseous-fuel-fired aggregate dryers under the rule’s relevant provisions.
The rule also established interim requirements for certain facilities during implementation.
The 2021 adoption materials identify:
Requirement
Rule 1147.1 Provision
Primary NOx limit
30 ppm
CO limit
1,000 ppm
Oxygen correction
3% O₂, dry
Applicability threshold
>1 lb/day NOx
Rated heat-input threshold
>2 MMBtu/hr
Source testing
Required for applicable units
Large dryers ≥40 MMBtu/hr
Annual testing
The precise applicability and compliance pathway should always be confirmed against the current rule and permit.
4. Source Testing Frequency Depends on Dryer Size
One of the most important Rule 1147.1 requirements for facility managers is the periodic source-testing schedule.
The current rule provides different testing frequencies based on the aggregate dryer’s rated heat-input capacity.
Aggregate dryer below 10 MMBtu/hr
Source testing is required every 5 calendar years, with the rule restricting how early the subsequent test can occur.
Aggregate dryer ≥10 and <40 MMBtu/hr
Source testing is required every 3 calendar years, again subject to the minimum interval specified by the rule.
Aggregate dryer ≥40 MMBtu/hr
Source testing is required every calendar year.
For a large dryer that has not operated for at least six consecutive months, the rule also provides a provision allowing the source test to occur within 90 days after operations resume, subject to the rule’s conditions and fuel-use documentation.
Why This Matters for 2026
Imagine an aggregate dryer operating at 45 MMBtu/hr.
Its operator cannot treat compliance testing as something to think about every three or five years.
The applicable rule calls for annual source testing.
Now consider a facility operating several dryers of different sizes. The testing calendar can become complicated very quickly.
That is why environmental managers should maintain a centralized compliance schedule containing:
Equipment identification
Burner age
Rated heat input
Applicable NOx limit
Applicable CO limit
Last source-test date
Next source-test deadline
Permit conditions
Protocol approval
Test report submission date
Maintenance records
Missing a testing deadline can turn a technical compliance requirement into an operational problem.
5. Source-Test Reports Must Be Submitted
Rule 1147.1 requires source-test reports to be submitted to the Executive Officer within 60 days of completion of the test.
That means the project does not end when the field testing is complete.
The complete compliance cycle is:
Plan → Protocol → Test → QA/QC → Calculations → Report → Submission → Recordkeeping
A technically excellent field test can still create headaches if the final report is incomplete, inaccurate or submitted late.
6. Five-Year Recordkeeping Requirement
Rule 1147.1 requires source-test records to be maintained for five years and made available to South Coast AQMD personnel upon request.
This is especially important for companies with multiple facilities or multiple aggregate dryers.
Environmental records should not be scattered across emails, maintenance folders and individual computers.
A better approach is to maintain a centralized compliance file for every regulated unit.
7. Existing CEMS and Monitoring Systems Matter
Rule 1147.1 does not simply require every aggregate dryer to install a brand-new CEMS.
However, qualifying facilities with existing continuous in-stack emissions monitoring systems or equivalent verification systems must retain and operate them according to the applicable requirements.
The rule also allows certain other required testing or monitoring activities to satisfy a source-test requirement under specified conditions.
For example, qualifying:
Title V periodic monitoring/testing, or
RATA associated with CEMS
may be used to satisfy one instance of periodic source testing when the requirements of the rule are met.
This can potentially reduce duplicate testing—but only when the regulatory conditions are satisfied.
Rule 1147.1 Compliance: Pros
1. Reduces NOx Emissions
The biggest environmental advantage is straightforward: lower NOx emissions from aggregate-drying operations.
NOx reductions support South Coast AQMD’s broader efforts to improve regional air quality.
2. Encourages Modern Combustion Technology
Older burners can have substantially different emissions performance from newer low-NOx systems.
Rule 1147.1 creates an incentive for facilities to evaluate burner technology and combustion performance.
3. Provides Measurable Compliance
Instead of relying entirely on equipment specifications, source testing gives the facility actual emissions data.
4. Identifies Equipment Problems
Testing can uncover issues involving:
Burner performance
Combustion-air ratios
Fuel/air control
Temperature
Draft
Excess oxygen
Maintenance
Instrumentation
5. Improves Regulatory Documentation
A well-prepared test report provides evidence that the facility is monitoring its environmental performance.
6. Supports Long-Term Air-Quality Planning
South Coast AQMD’s Rule 1147.1 strategy is part of the District’s broader transition from RECLAIM to direct emissions limits.
Rule 1147.1 Compliance: Cons & Challenges
1. Source Testing Costs Money
Qualified source testing requires trained personnel, specialized instruments, calibration, field work, calculations and reporting.
2. Production Scheduling Can Be Difficult
Aggregate facilities cannot always stop or modify production simply to accommodate a test.
Testing must often occur under representative operating conditions.
3. Burner Replacement Can Be Expensive
Facilities with older burners may need to evaluate replacement or upgrades to maintain compliance.
4. Multiple Dryers Increase Complexity
A facility operating several aggregate dryers may have different:
Heat-input ratings
Burner ages
Permit conditions
Testing frequencies
Compliance deadlines
5. Compliance Data Must Be Defensible
Incorrect oxygen correction, sampling problems, calibration issues or unsuitable operating conditions can compromise a test.
6. Regulatory Interpretation Can Be Complex
Rule 1147.1 interacts with permits, monitoring requirements and the broader South Coast AQMD regulatory structure.
That is why facilities should not rely solely on a generic internet summary.
What Does an Aggregate Dryer Test Measure?
A Rule 1147.1 compliance test can involve measurement of NOx and CO, along with supporting measurements necessary to establish compliance under the applicable test method and permit.
Depending on the test protocol, testing may involve:
NOx concentration
CO concentration
Oxygen
Carbon dioxide
Stack gas conditions
Gas flow
Moisture
Fuel usage
Production rate
Dryer operating temperature
Burner operating conditions
The data are then evaluated against the applicable regulatory limit.
The goal is not simply to produce numbers.
The goal is to produce defensible compliance evidence.
Why Compliance Test Protocol Development Matters
Before testing begins, facilities should determine exactly how the test will be performed.
A compliance test protocol can identify:
Applicable regulations
Permit conditions
Emission limits
Sampling locations
Test methods
Number of test runs
Operating conditions
QA/QC requirements
Calculations
Reporting requirements
Rule 1147.1 requires applicable source testing and approved testing procedures under its compliance provisions.
A poorly planned test can create unnecessary risk.
Protocol first. Testing second.
How EES Helps Industries With Rule 1147.1
Energy Environmental Solutions, Inc. (EES) provides environmental testing and compliance support for industrial facilities.
Rule 1147.1 Source Testing
EES can support compliance testing for applicable aggregate dryers, including NOx and CO measurements.
NOx Testing
Accurate NOx measurement is at the center of Rule 1147.1 compliance.
CO Testing
The rule also establishes CO requirements, making reliable CO measurement important.
Where applicable, EES can support continuous emissions monitoring and associated performance testing.
Engineering Studies
EES can help facilities evaluate combustion equipment, emissions trends and potential control strategies.
Regulatory Reporting
EES can assist with technical documentation and reporting following source testing.
Industries That May Need Rule 1147.1 Support
Potentially affected operations can include facilities involved in:
Aggregate production
Sand and gravel processing
Crushed stone production
Construction materials
Asphalt-related material production
Mineral processing
Aggregate drying
Other operations using qualifying aggregate dryers
Applicability must be confirmed against the actual equipment and permit.
Rule 1147.1 vs. Rule 1147
These rules are easy to confuse.
Rule
Primary Focus
Rule 1147
NOx reductions from miscellaneous combustion sources
Rule 1147.1
NOx reductions from aggregate dryers
Rule 1147.2
NOx reductions from metal melting and heating furnaces
South Coast AQMD adopted Rule 1147.1 specifically to separate aggregate dryers from the broader miscellaneous-source framework.
This distinction matters when determining the applicable emission limits and testing requirements.
2026 Rule 1147.1 Compliance Checklist
If your facility operates an aggregate dryer in the South Coast AQMD jurisdiction, review:
Is the dryer subject to Rule 1147.1?
What is its rated heat-input capacity?
Is its NOx emission level above the applicability threshold?
What NOx limit applies?
What CO limit applies?
When was the burner installed?
When was the last source test?
When is the next test due?
Is the testing contractor appropriately qualified/approved?
Is the test protocol ready?
Are operating conditions representative?
Are calibration records current?
Are CEMS/RATA requirements applicable?
Are source-test reports submitted within the required timeframe?
Are five years of records available?
The 2026 Takeaway for Aggregate Facilities
The biggest misunderstanding about Rule 1147.1 is thinking:
“It is a 2021 rule, so it isn’t a 2026 issue.”
That’s not how environmental compliance works.
A rule can remain unchanged while its testing deadlines, permit conditions and operational obligations continue year after year.
For applicable aggregate dryers, Rule 1147.1 establishes a structured framework around NOx and CO emissions, periodic source testing, monitoring, reporting and recordkeeping. South Coast AQMD’s current rulebook continues to identify the adopted rule, while the District’s current proposal pages still reference Proposed Rule 1147.1 materials.
Don’t wait for the next compliance deadline.
If your aggregate dryer is approaching its source-test date, now is the time to verify:
Your permit. Your emission limits. Your testing frequency. Your protocol. Your equipment condition. Your records.
Need Rule 1147.1 Testing in California?
Energy Environmental Solutions, Inc. (EES) helps industrial facilities with:
Rule 1147.1 Source Testing | Aggregate Dryer Testing | NOx Testing | CO Testing | Compliance Test Protocol Development | Source Testing | Stack Testing | CEMS | RATA | CGA | Engineering Studies | QA/QC | Regulatory Reporting
Measure Emissions. Verify Compliance. Protect Your Operations.
Rule 1147 in California 2026: Latest Updates, Pros, Cons & How EES Helps Industries
Rule 1147 — NOx Reductions from Miscellaneous Sources is an important South Coast AQMD regulation for certain fuel-fired combustion equipment in Southern California. It is designed to reduce nitrogen oxide (NOx) emissions while limiting carbon monoxide (CO) from permitted gaseous- and liquid-fuel-fired equipment that is not covered by another applicable Regulation XI rule.
Important: Rule 1147 is not a statewide California rule. It applies within the South Coast AQMD jurisdiction to equipment meeting the rule’s applicability requirements. Other California air districts have their own rules and permit requirements.
For industrial facilities operating spray-booth heaters, ovens, dryers, furnaces, thermal oxidizers, afterburners, vapor incinerators, tenter-frame dryers, process heaters and other miscellaneous combustion equipment, understanding the current Rule 1147 requirements can be critical to avoiding compliance problems.
Energy Environmental Solutions, Inc. (EES) helps facilities with Rule 1147 source testing, NOx testing, CO testing, compliance test protocol development, emissions testing, CEMS/RATA/CGA, engineering studies and regulatory reporting.
What Is South Coast AQMD Rule 1147?
Rule 1147 was adopted in 2008 and most recently amended on May 6, 2022. The current South Coast AQMD rulebook identifies it as Rule 1147 — NOx Reductions from Miscellaneous Sources.
The rule applies to certain gaseous- and/or liquid-fuel-fired combustion equipment requiring a South Coast AQMD permit, when another Regulation XI rule does not already apply to the unit.
Covered equipment can include categories such as:
Thermal oxidizers
Catalytic oxidizers
Afterburners
Vapor incinerators
Ovens
Dryers
Dehydrators
Heaters
Furnaces
Kilns
Calciners
Cookers
Roasters
Tenter-frame dryers
Fabric and carpet dryers
Remediation units
Certain liquid-fuel-fired equipment
The exact applicability depends on the equipment, fuel, rated heat-input capacity, permit status and other provisions of the rule.
Why Does Rule 1147 Matter in 2026?
The environmental reason is straightforward: NOx contributes to ozone and particulate pollution, making NOx reductions an important component of regional air-quality planning.
South Coast AQMD’s Rule 1147 technology assessment explains that the rule’s NOx reductions are an important part of the region’s attainment strategy for federal and state ambient air-quality standards, including standards for ozone, PM2.5 and PM10.
And the need for effective air-quality controls remains highly relevant in 2026. South Coast AQMD’s current 2026 news and regulatory activity includes ozone advisories, particulate-related actions, toxic-air-contaminant rulemaking and additional emissions-control initiatives.
The compliance message for industry:
NOx compliance is not simply about installing a burner or combustion system. Facilities need to demonstrate that applicable equipment actually operates within its required emissions limits.
Latest Rule 1147 Updates for 2026
1. The Current Rule Remains the May 6, 2022 Version
As of August 2026, South Coast AQMD’s current Regulation XI listing identifies Rule 1147 as amended May 6, 2022. There is no indication on the current official rule listing of a newer 2026 amendment to Rule 1147 itself.
That distinction is important.
“Latest 2026 update” does not mean Rule 1147 itself was amended in 2026. Instead, facilities need to consider the current Rule 1147 requirements alongside their current permits and other 2026 regulatory developments.
2. Source Testing Remains a Major Compliance Requirement
For units subject to Rule 1147 with NOx emissions of at least 1 pound per day, the rule requires source testing to demonstrate compliance with applicable NOx and CO limits in the rule or permit.
The testing frequency depends on the equipment’s Rated Heat Input Capacity:
Rated Heat Input Capacity
Source-Test Frequency
< 10 MMBtu/hr
Every 5 calendar years
≥ 10 and < 40 MMBtu/hr
Every 3 calendar years
≥ 40 MMBtu/hr
Every calendar year
≥40 MMBtu/hr with ≥6 months shutdown
Test within 90 days after resumed operation, subject to the rule’s conditions
These intervals are specified in Rule 1147 paragraph (h)(12).
This is one of the most important points for facility managers:
Your source-test due date can depend directly on the equipment’s rated heat-input capacity and NOx emissions.
3. Rule 1147 Requires an Approved Test Protocol
Source testing isn’t simply a matter of sending a technician to the facility and taking measurements.
Rule 1147 requires the operator to submit a source-test protocol to the Executive Officer for approval no later than 90 days before the scheduled source test, subject to the rule’s timing provisions.
For subsequent compliance determinations, protocol resubmission may not be necessary when an approved protocol already exists, provided the unit has not been modified in a way requiring a permit modification and the applicable limits have not become more stringent.
Why does this matter?
Because an improperly planned test can create unnecessary delays, additional costs and potentially unusable compliance data.
Test planning should happen before the test day—not after.
4. Independent Testing Is Required
Rule 1147 requires compliance determinations to be conducted by an independent contractor approved by the Executive Officer under the Laboratory Approval Program for the applicable test methods.
That means facilities should verify that their selected testing company has the appropriate qualifications and approvals for the methods being used.
This is particularly important when a facility is approaching a regulatory deadline.
5. Recordkeeping Still Matters
Rule 1147 requires source-test reports and maintenance records to be maintained for at least five years and made available to South Coast AQMD personnel upon request.
This means compliance doesn’t end when the testing crew leaves the site.
Your facility should maintain:
Source-test reports
Maintenance records
Rated heat-input information
Fuel records where applicable
CEMS records where applicable
Compliance documentation
Approved testing protocols
Equipment modification records
Good documentation can be as important as good testing.
What Emission Limits Does Rule 1147 Establish?
Rule 1147 contains different NOx and CO limits depending on the equipment category, fuel type, process temperature and whether the unit is an in-use unit or subject to the newer Table 2 requirements.
For example, Table 1 includes different limits for equipment such as thermal oxidizers, ovens, heaters, dryers and other combustion equipment.
For certain gaseous-fuel-fired thermal oxidizers, catalytic oxidizers, afterburners and vapor incinerators, the Table 1 NOx limit is 60 ppmv or 0.073 lb/MMBtu, with a CO limit of 1,000 ppmv.
Table 2 establishes more stringent requirements for applicable equipment.
For example, gaseous-fuel-fired thermal oxidizers, catalytic oxidizers, afterburners and vapor incinerators are listed at 20 ppmv or 0.024 lb/MMBtu NOx under Table 2.
Do not assume these numbers automatically apply to your equipment. The applicable limit must be determined from the rule, equipment category, permit and compliance schedule.
A Key 2026 Compliance Option: Less Than 1 Pound of NOx Per Day
Rule 1147 provides an alternative pathway for certain units.
An owner or operator may elect to comply by demonstrating NOx emissions below 1 pound per day averaged over a calendar month, or by meeting an existing permit limit below 1 pound per day, whichever is applicable under the rule.
However, if the facility fails to demonstrate compliance with that option, additional permit and compliance requirements can be triggered.
This makes accurate emissions calculations and recordkeeping particularly important.
Pros of Rule 1147 Compliance
1. Lower NOx Emissions
The primary environmental benefit is reduced NOx emissions from miscellaneous combustion sources.
Lower NOx contributes to regional efforts to address ozone and particulate pollution. South Coast AQMD describes Rule 1147’s NOx reductions as an important component of its attainment strategy.
2. Better Combustion Performance
Testing can reveal problems involving burners, combustion-air systems, controls or operating conditions.
A failed or borderline test can therefore become an opportunity to identify equipment problems.
3. More Reliable Compliance Data
Professional source testing provides measured emissions data instead of relying exclusively on theoretical calculations or equipment specifications.
4. Better Maintenance Decisions
Testing results can help environmental and maintenance teams identify whether combustion equipment needs adjustment, repair or modernization.
5. Improved Regulatory Readiness
Maintaining current testing and maintenance records can make inspections and compliance reviews easier.
Cons and Challenges of Rule 1147
1. Testing Costs
Source testing requires specialized equipment, qualified personnel, laboratory or analytical resources and technical reporting.
2. Production Disruption
Testing may need to occur under specific operating conditions, which can require coordination with production schedules.
3. Protocol Approval Takes Planning
The requirement for an approved test protocol means facilities need to start preparing well before the actual test date.
4. Equipment Modifications Can Change Requirements
Changes to burners, combustion systems, fuel systems or operating conditions may affect the compliance pathway.
5. Multiple Equipment Categories
Rule 1147 covers a wide variety of equipment, so the correct testing approach is not identical for every unit.
6. Testing at the Wrong Operating Condition Can Create Problems
Rule 1147 specifies operating conditions for compliance determinations, including testing at the maximum heat-input range at which the unit normally operates and additional conditions for specified equipment categories.
What Equipment Should California Facilities Review?
If your facility is located in the South Coast AQMD jurisdiction, review Rule 1147 applicability if you operate permitted fuel-fired equipment such as:
The actual applicability must be confirmed against the current rule and permit.
How EES Helps With Rule 1147 Compliance
Energy Environmental Solutions, Inc. (EES) provides technical testing and environmental compliance support for industrial facilities.
Rule 1147 Source Testing
EES can assist with testing programs designed to demonstrate applicable NOx and CO emission compliance.
Compliance Test Protocol Development
EES helps develop testing protocols covering:
Sampling locations
Applicable test methods
Operating conditions
Test runs
QA/QC
Calculations
Reporting requirements
NOx Testing
Accurate NOx measurements are central to Rule 1147 compliance.
CO Testing
Rule 1147 also establishes CO requirements for applicable equipment, making CO testing an important part of many compliance demonstrations.
CEMS / RATA / CGA
For facilities using continuous emissions monitoring systems, EES can support applicable CEMS, RATA and CGA requirements.
Rule 1147 also provides circumstances in which qualifying periodic monitoring or CEMS relative-accuracy testing may be used as part of the source-testing compliance schedule.
Engineering Studies
EES can help facilities evaluate combustion-system performance, emissions trends and potential compliance strategies.
Regulatory Reporting
Testing isn’t complete until the data have been properly evaluated and documented.
EES can help prepare organized technical reports and supporting documentation.
Rule 1147 Compliance Testing Process
A professional compliance project generally follows this sequence:
1. Review the Permit Determine the applicable permit limits and conditions.
2. Confirm Rule Applicability Determine whether Rule 1147 applies to the unit.
3. Determine Testing Frequency Review NOx emissions and rated heat-input capacity.
4. Develop the Test Protocol Select appropriate methods and operating conditions.
5. Submit for Approval Follow South Coast AQMD protocol-approval requirements.
6. Conduct Field Testing Perform NOx, CO and supporting measurements.
7. QA/QC Review Review calibration, field data and calculations.
8. Calculate Emissions Determine compliance with the applicable limit.
9. Prepare the Report Document the test conditions, methods, results and conclusions.
10. Maintain Records Retain required documentation for the applicable period.
Why Proactive Rule 1147 Testing Makes Sense in 2026
South Coast AQMD states that its compliance staff conduct regular inspections to ensure equipment and processes are operating in compliance with applicable clean-air rules.
The agency also explains that failure to correct a Notice to Comply can lead to a Notice of Violation and penalties, while continuing violations can result in daily penalties.
That is why waiting until an inspector identifies a problem is a risky compliance strategy.
A better approach:
Know your limit. Know your test date. Know your operating conditions. Know your documentation.
Rule 1147 Compliance Checklist for 2026
Before your next test, review:
Is the unit subject to Rule 1147?
Is the current permit available?
What NOx limit applies?
What CO limit applies?
What is the unit’s rated heat-input capacity?
Is NOx ≥1 lb/day?
When was the last approved source test?
Is the next test due?
Has the test protocol been approved?
Has the equipment been modified?
Are operating conditions representative?
Are maintenance records current?
Are required fuel meters installed and maintained?
Are five years of required records available?
Is the testing contractor appropriately approved?
2026 Bottom Line
Rule 1147 remains an important South Coast AQMD NOx-compliance requirement in 2026. Although the rule itself was last amended on May 6, 2022, its current requirements continue to govern applicable miscellaneous combustion equipment, including specific source-testing frequencies, test protocols, NOx/CO limits and recordkeeping requirements.
For facilities with applicable equipment, the biggest mistake is assuming that “the equipment has always passed” means the next test can be treated casually.
Thermal Oxidizer Testing in California (2026): Latest Updates, Pros, Cons & How EES Helps Industries Stay Compliant
California continues to maintain some of the nation’s most demanding requirements for controlling VOC and toxic air contaminant emissions from industrial operations. For facilities using thermal oxidizers, regenerative thermal oxidizers (RTOs), catalytic oxidizers, afterburners, or related combustion-control equipment, performance testing can be an important part of demonstrating that the control device is actually achieving the required emissions-control performance.
A key 2026 development is that South Coast AQMD is actively evaluating control technologies and emissions requirements across several industrial sectors. Its March 2026 staff report for aerospace coating operations, for example, discusses thermal oxidizers as VOC and toxic-air-contaminant controls and notes that they can achieve destruction efficiencies above 98% in appropriate applications. At the same time, the report highlights an important challenge: thermal oxidation of certain compounds can create secondary pollutants such as HCl and HF, potentially requiring additional control equipment.
For industrial facilities, this means thermal oxidizer testing should not be viewed simply as a one-time emissions test. Temperature, residence time, combustion conditions, VOC destruction efficiency, NOx, CO, and potentially other pollutants all need to be considered according to the applicable permit and Air District requirements.
Energy Environmental Solutions, Inc. (EES) helps California industries with Thermal Oxidizer Testing, VOC Testing, Source & Stack Testing, NOx and CO Testing, Compliance Test Protocol Development, CEMS/RATA/CGA, Engineering Studies, and Regulatory Reporting.
What Is Thermal Oxidizer Testing?
A thermal oxidizer destroys VOCs and other combustible pollutants by oxidizing them at elevated temperatures.
Testing can be used to determine whether the equipment is achieving the required destruction or removal efficiency (DRE) and whether emissions from the control device comply with applicable permit or regulatory limits.
Depending on the facility and permit, testing may evaluate:
VOC destruction efficiency
VOC concentration
NOx emissions
CO emissions
CO₂
O₂
Flow rate
Temperature
Residence time
Combustion conditions
Particulate matter
Toxic air contaminants, where applicable
The exact testing requirements are facility- and permit-specific. There is no single California-wide thermal-oxidizer test that automatically applies to every facility.
Latest California Thermal Oxidizer Updates for 2026
1. South Coast AQMD Is Actively Evaluating Thermal Oxidizers
One of the clearest 2026 regulatory developments comes from South Coast AQMD’s work on Proposed Amended Rule 1124, covering aerospace assembly and component manufacturing operations.
The March 2026 staff report evaluates thermal oxidizers as a potential control technology for VOC and toxic-air-contaminant emissions. South Coast AQMD states that thermal oxidizers can achieve destruction efficiencies exceeding 98% under suitable operating conditions.
However, the agency also identifies limitations for some compounds. For example, thermal oxidation of chlorinated and fluorinated compounds can generate acidic byproducts such as hydrochloric acid and hydrofluoric acid, potentially requiring scrubbers and additional controls.
What this means for industry: choosing a thermal oxidizer is not simply about achieving a high VOC destruction percentage. Facilities must also evaluate the pollutants created by the combustion process.
2. 2026 Rulemaking Continues Across California’s Industrial Air Sector
South Coast AQMD’s 2026 regulatory agenda includes numerous proposed amendments and new rules addressing particulate matter, toxic air contaminants, monitoring, New Source Review, and other air-quality requirements.
This broader regulatory activity matters to facilities operating thermal oxidizers because a control device may address one pollutant while creating or affecting another.
For example, South Coast AQMD’s emissions-reporting guidance for thermal oxidation notes that when VOC vapors are destroyed through thermal oxidation, NOx, SOx, CO, PM, and toxic air contaminants may also be generated. The agency encourages operators to use site-specific test results where available for emissions calculations.
That makes comprehensive testing increasingly valuable.
3. Source Testing Can Be a Permit Requirement
Thermal oxidizer testing requirements are often written directly into individual facility permits.
For example, a Bay Area Air Quality Management District permit requires a thermal oxidizer to be source tested annually for VOC control efficiency as well as NOx and CO emissions, with results reported to the District. The permit also specifies continuous temperature monitoring and recordkeeping requirements.
This demonstrates an important point:
Thermal oxidizer testing frequency and pollutants are determined by the applicable permit and regulatory requirements.
Some facilities may require annual testing; others may have different schedules or testing triggers.
4. California Facilities Continue Using Performance Testing to Demonstrate Control Efficiency
South Coast AQMD Hearing Board documents also show real-world applications of thermal oxidizers.
In a 2025 case involving a petroleum facility, a portable thermal oxidizer was allowed temporarily to replace an afterburner, subject to conditions including a minimum overall VOC control efficiency of 99% and a performance test shortly after startup to demonstrate compliance.
Although that order was issued in 2025, it remains a useful example of how regulators can use performance testing to verify control-device performance during temporary or modified operating conditions.
Why Is Thermal Oxidizer Testing Important?
A thermal oxidizer may look like a simple solution:
VOC-containing gas → high-temperature combustion → cleaner exhaust
But real-world performance depends on several variables.
If the temperature is too low, residence time is inadequate, mixing is poor, or the system is overloaded, destruction efficiency can decline.
Testing helps answer the critical question:
Is the thermal oxidizer actually performing as required under real operating conditions?
Key Parameters That Can Affect Performance
Temperature
Thermal oxidation requires sufficient temperature to initiate and maintain the oxidation reaction.
Temperature requirements vary depending on the equipment, pollutants, permit, and process.
Residence Time
The contaminated gas needs enough time inside the combustion chamber for the oxidation reaction to occur effectively.
Turbulence & Mixing
Good mixing of combustion air and contaminated gas is essential for consistent oxidation.
South Coast AQMD specifically identifies temperature, residence time, and turbulence/mixing as important design factors for thermal oxidizers.
VOC Loading
An oxidizer operating with a highly variable VOC concentration may behave differently from one receiving a stable waste stream.
Testing under representative operating conditions is therefore critical.
Pros of Thermal Oxidizer Testing
1. Demonstrates Compliance
Testing can provide documented evidence that the control device is meeting applicable permit requirements.
2. Verifies VOC Destruction Efficiency
Testing can determine whether the thermal oxidizer is achieving its required VOC control efficiency.
3. Identifies Performance Problems
Testing can reveal declining control efficiency, combustion problems, unusual emissions, or operational conditions requiring investigation.
4. Supports Permit Compliance
Reliable source-test results can support permit renewals, modifications, inspections, and regulatory reporting.
5. Improves Environmental Performance
Properly operated thermal oxidizers can substantially reduce VOC emissions and associated air-quality impacts.
6. Provides Better Emissions Data
Site-specific testing can provide more defensible information than relying exclusively on generic emission factors.
Cons & Challenges of Thermal Oxidizer Testing
Thermal oxidizer testing also comes with challenges.
Testing Costs
Professional source testing requires specialized equipment, trained personnel, laboratory analysis where applicable, and technical reporting.
Production Scheduling
Testing may need to be performed during specific operating conditions, making coordination with production important.
Complex Testing Requirements
VOC destruction efficiency testing can require simultaneous inlet and outlet measurements, operating-condition documentation, and carefully designed sampling procedures.
Secondary Pollutants
Thermal oxidation can produce NOx, CO, SOx, PM, and potentially toxic or acidic combustion byproducts, depending on the waste stream. South Coast AQMD specifically highlights these considerations in its emissions-reporting guidance.
Equipment Maintenance
Burners, combustion chambers, temperature sensors, controls, fans, dampers, and related equipment need appropriate maintenance to maintain performance.
Regulatory Changes
California’s air-quality regulations continue evolving, making it important for facilities to verify current requirements rather than relying on an old test protocol.
Thermal Oxidizer Testing: What May Be Tested?
A facility’s testing program may include:
Parameter
Why It May Be Tested
VOC
Determine emissions and/or destruction efficiency
NOx
Evaluate combustion-related emissions
CO
Identify incomplete combustion
CO₂
Support combustion and emissions calculations
O₂
Support emissions calculations and combustion evaluation
Flow Rate
Determine mass emissions
Temperature
Verify operating conditions
PM
Evaluate particulate emissions where applicable
Toxic Air Contaminants
Evaluate pollutants specific to the process
Inlet/Outlet VOC
Calculate control efficiency
The exact parameters should always be determined from the facility permit, applicable Air District rules, approved test protocol, and regulatory requirements.
How Energy Environmental Solutions, Inc. Helps Industries
Energy Environmental Solutions, Inc. (EES) provides comprehensive testing and engineering support for facilities using thermal oxidizers and other air pollution control devices.
Thermal Oxidizer Performance Testing
EES can help facilities evaluate thermal oxidizer performance through appropriate source-testing programs.
VOC Destruction Efficiency Testing
We can support testing programs designed to determine VOC inlet and outlet concentrations and control efficiency, where required.
NOx & CO Testing
Because combustion can create secondary pollutants, EES can support testing for NOx and CO where required by permits or regulations.
Source & Stack Testing
Our team provides source and stack testing using applicable EPA, CARB, and local Air District methods.
Compliance Test Protocol Development
Before testing begins, a well-developed protocol can define:
Sampling locations
Test methods
Operating conditions
Number of runs
QA/QC requirements
Analytical procedures
Calculations
Reporting requirements
CEMS, RATA & CGA
EES also supports:
CEMS Certification
RATA
CGA
QA/QC programs
Monitoring support
Engineering Studies
Engineering evaluations can help facilities understand equipment performance and identify potential emissions-control improvements.
Regulatory Reporting
After testing, EES can provide technical reports containing emissions calculations, field information, QA/QC documentation, and test results suitable for regulatory review.
Industries That May Use Thermal Oxidizers
Thermal oxidizers are used across many industrial applications, including:
Chemical Manufacturing
Aerospace Manufacturing
Petroleum & Refining
Pharmaceutical Manufacturing
Printing Operations
Coating Operations
Food Processing
Industrial Manufacturing
Waste Treatment
Landfill Gas Control
Solvent-Using Operations
Fuel Processing
Composite Manufacturing
The applicable testing requirements vary significantly by industry and facility.
Why Choose EES for Thermal Oxidizer Testing?
When a thermal oxidizer is part of your compliance strategy, the question isn’t simply “Can it burn VOCs?”
The real questions are:
Is it achieving the required control efficiency?
Are operating conditions documented?
Are secondary emissions being evaluated?
Is the testing performed according to the applicable protocol?
Is the final report defensible during an inspection?
EES helps facilities address these questions through:
✔ Experienced environmental professionals
✔ California regulatory expertise
✔ Source & stack testing
✔ VOC testing
✔ Thermal oxidizer performance testing
✔ NOx & CO testing
✔ Compliance test protocols
✔ CEMS/RATA/CGA support
✔ Engineering studies
✔ QA/QC documentation
✔ Inspection-ready reporting
✔ Responsive technical support
Don’t Wait Until Your Thermal Oxidizer Fails a Test
A thermal oxidizer is a control device, not a guarantee of compliance.
Its performance depends on equipment condition, operating parameters, waste-stream characteristics, combustion conditions, monitoring, and maintenance.
With California continuing to develop and amend air-quality requirements in 2026, proactive testing and compliance planning can help industrial facilities identify potential issues before they become larger regulatory problems. South Coast AQMD’s current rulemaking activity and facility-specific permit requirements demonstrate why companies should review their testing obligations regularly.
Need Thermal Oxidizer Testing in California?
Energy Environmental Solutions, Inc. can help with:
