The New SCAQMD CEMS Rules Are Here


SCAQMD Code took effect on January 1, 2022

SCAQMD New CEMS Rules 218.2 and 218.3 Overview​

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South Coast Air Quality Management District (SCAQMD) has amended CEMS Rule 218 Continuous Emissions Monitoring and adopted new Rule 218.2 Continuous Emission Monitoring System: General Provisions and Rule 218.3 Continuous Emission Monitoring System: Performance Specifications.
ow they may impact your current compliance plan. We provide an overview of what air compliance consists of, an overview of navigating the PADEP “Phase I, II and III” process, and best practices and innovative tools to help streamline compliance. A solid approach with the right plan and correct tools will reduce risk and help ensure compliance.

SCAQMD CEMS Rules 218.2 and 218.3 Update

South Coast Air Quality Management District (SCAQMD) has amended CEMS Rule 218 Continuous Emissions Monitoring and adopted new Rule 218.2 CEMS: General Provisions and Rule 218.3 CEMS: Performance Specifications.

The amended Rule 218 and the new Rules 218.2 and 218.3 provide specifications for both former RECLAIM CEMS that are previously certified according to the RECLAIM program, as well as non-RECLAIM CEMS that are previously certified according to Rules 218 and 218.1.

To learn more about the revised CEMS Code (2021), and for the most up-to-date content, view the full Rule 218.2 CEMS: General Provisions and Rule 218.3 CEMS: Performance Specifications.

Major changes from Rules 218 to 218.2

1. Changes to the CEMS Failure Provisions

Rule 218.2 will allow an additional 96 hours if the emission source is not operating and will no longer require an interim variance for the additional 96 hours.

2. Changes in the Reporting Requirements

RATA report submission must be submitted within 60 days after completion of the test. This requirement is consistent with Rule 2012.

3. Changes in the Provisional Data Validation

Upon completion of a successful calibration error test and prior to the approval of final CEMS certification or recertification, all emissions data shall be considered valid quality-assured data beginning at the hour of the passed calibration error test. The calibration error test must be passed prior to any of the certification tests, but no more than 14 days prior to all of the required certification tests. If the certification tests are not approved the data shall be retroactively considered invalid until the hour of the next completion of the certification tests.

4. Allowance for CEMS Shut Downs

Rule 218.2 conditionally allows a CEMS shutdown if an emission unit is down for a minimum of 168 consecutive hours. There are also options to demonstrate a unit is not operating. After zero emissions have been recorded for a minimum of 4 hours after a unit shutdown period and proper notification and reporting has been performed. You must resume CEMS operation for a minimum of 4 hours prior to the unit resuming operations and a calibration error test must be passed before any emissions are detected.

Major changes from Rules 218.1 to 218.3

1. Changes to Span Range Requirements

Approving a span range if both requirements cannot be concurrently satisfied is included in Rule 218.3, as well as approving a span range with the upper span value at up to 10 ppm for a unit with emission limit less than 5 ppm. Exempting a top span range of a multiple span range analyzer is also included in Rule 218.3.

2. Changes to Data Acquisition and Handling System Requirements

Recording all status codes for emissions data is specified in Table 2 of Rule 218.3.

3. Changes to RATA Requirements and de minimis Standards

If the number of tests exceeds nine sets, data may be discarded if it is identified as an outlier according the SCAQMD Technical Guidance Document R-004, or for valid reasons which must be substantiated.

Revised previous language that stated, “once every 12 months, no later than the end of the calendar quarter in which the date of the original certification test was performed”. Rule 218.3 now states “within 12 months of the end of the month the previous relative accuracy test was performed”.

4. New Quality Assurance Checks

There are some restructured rule languages related to response check, cyclonic flow check, and linearity error, but no change to the requirements. A NOx converter efficiency check and a sample bias check are included as additional required checks as part of Rule 218.3.

VIM Technologies Can Help

VIM Technologies stands ready to help affected sources navigate the new SCAQMD CEMS Rules requirements. VIM’s state-of-the-art DAS is fully equipped to comply with the new monitoring, recordkeeping requirements.  In addition, VIM’s COMPAS group has over 125 years of combined CEMS and regulatory experience, including specific SCAQMD expertise, that can help with your Monitoring Plan, QA/QC Plan, Reporting & Regulatory SupportCEMS Program AuditsRegulatory Training, and DAHS Tune-ups.

If the newly adapted (March 5, 2021) SCAQMD CEMS Rules 218.2 and 218.3 impact your facility and you want to learn more, complete the form below to request a complimentary webinar overview.


VIM Technologies experts are standing by to prepare an action plan to help you and your organization be ready for the CEMS update.

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