Operating Monitoring Assessment – Air
The Environment Agency (EA) quietly scores how credible your emissions monitoring is — not how high or low your emissions are. That score is the Operator Monitoring Assessment (OMA). Strong OMA = less regulatory pressure; weak OMA = more scrutiny. This guide explains OMA in minutes and shows practical steps to improve your score fast. GOV.UK
Original EA guidance:
- OMA overview page (GOV.UK): “Operator monitoring assessment: environmental permits.” GOV.UK
- Full OMA (Air) PDF: “Guidance on undertaking an Operator Monitoring Assessment.”
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/651005/LIT_5230.pdf GOV.UK
Who this is for
Any EPR‑regulated installation with emissions monitoring requirements — power and heat, chemicals, waste and resources, food and drink, minerals, metals, pharmaceuticals, data centres with engines/boilers, and more. If your permit expects stack testing and/or CEMS, then OMA applies. GOV.UK
What OMA actually measures (in plain English)
OMA is the EA’s structured audit of how you manage monitoring, covering four areas:
- Management of monitoring (procedures, roles, planning, training, data use)
- Periodic stack testing (sampling points, methods, accreditation)
- Continuous emissions monitoring systems (CEMS) (location, certification, calibration, reliability)
- Quality assurance (proficiency testing, audits, reporting)
OMA scores each element 1–5 (1=poor, 3=acceptable, 5=excellent) and rolls these into section and overall percentages. It is used to gauge confidence in your monitoring — and to target improvements. GOV.UK+1
Key point: OMA assesses monitoring quality, not your actual emissions levels. Even low‑emission sites can score poorly if monitoring arrangements are weak. GOV.UK
Why OMA matters even more through 2025–26
- Data‑led regulation: EA guidance places strong emphasis on certified kit, validated data, and EN 14181 quality assurance for CEMS (QAL2/QAL3/AST). Weak QA means weak confidence — and closer oversight. GOV.UK
- Standards and siting: Using the wrong sampling location or poorly mixed gas streams undermines representativeness; the EA points operators to EN 15259 measurement location requirements. GOV.UK
- Certification and competence: MCERTS underpins instruments, organisations, and personnel — a recurring OMA theme. GOV.UK
- Policy context: England’s legally binding PM₂.₅ targets (with 2028 interim milestones and 2040 endpoints) keep air monitoring under sustained focus, reinforcing the need for credible, auditable data. uk-air.defra.gov.uk+1
The four drivers of your OMA score (and what “good” looks like)
- Procedures you actually use
- Controlled, current SOPs for CEMS, calibrations (QAL2/QAL3/AST), periodic testing, and data checks.
- Site‑specific protocols (SSPs) prepared and reviewed before stack testing. GOV.UK+1
- Equipment and locations that meet standards
- CEMS and DAHS are MCERTS‑certified for relevant measurands and ranges.
- Sampling planes/ports designed to EN 15259 for representative measurement. GOV.UK+1
- Competence and accreditation
- MCERTS‑certified organisations and personnel for manual stack testing; appropriate UKAS/MCERTS scopes for methods used. GOV.UK
- Data that you review and act on
- Valid data capture ≥95–98% (as applicable), trend reviews, control charts for drift, and documented decisions based on data. GOV.UK
10‑minute OMA readiness check (quick wins for busy teams)
- Findable procedures: Can you retrieve the latest SOPs for CEMS calibration and stack testing within 60 seconds? GOV.UK+1
- SSP before testing: Is a site‑specific protocol drafted, reviewed, and shared before each periodic monitoring event? GOV.UK
- Right sampling point: Do your stack ports and platforms demonstrably meet EN 15259 (evidence on file)? GOV.UK
- MCERTS proof: Are your testing organisation, lead personnel, CEMS, and (where relevant) DAHS all MCERTS‑certified for the required ranges? GOV.UK
- QAL routines: Can you show QAL2 reports, QAL3 control charts, and the latest AST — plus what actions followed? GOV.UK
- Data availability: Do you track valid data capture and downtime with reasons and corrective actions? GOV.UK
- Management review: Are trends and exceedance “near‑misses” reviewed at management meetings with notes and owners? GOV.UK
- On‑time returns: Were all permit returns submitted on time and in the correct format this year? GOV.UK
If you can’t quickly evidence any of the above, those are high‑leverage OMA improvements.
How to use OMA inside your business (beyond “passing the audit”)
- Prioritise investment: Use OMA findings to justify CEMS upgrades, port modifications, or contractor changes. GOV.UK+1
- Lower regulatory burden: Strong OMA increases EA confidence and typically reduces intervention. GOV.UK
- Strengthen ESG: OMA evidence shows monitoring integrity — valuable for lenders, insurers, and corporate reporting.
- Prevent cost and disruption: QA routines (especially QAL3 drift control) prevent data loss and emergency retests. GOV.UK
Where Alkali fits (support mapped directly to OMA)
See our services: https://alkaliconsultants.com/services/
- OMA pre‑assessments (full or targeted) — Gap‑analysis against the EA scoring framework, with a prioritised action plan. GOV.UK
- CEMS assurance — Location reviews (EN 15259), MCERTS range checks, QAL2/QAL3/AST preparation, drift/control‑chart set‑up, data verification. GOV.UK+2GOV.UK+2
- Stack testing management — Contractor selection and oversight, SSP development, witnessing, and report QA against EA/MCERTS expectations. GOV.UK+1
- Permit‑aligned procedures and training — SOPs, roles/deputies, monitoring schedules, and non‑technical training for site teams. GOV.UK
FAQs
Is OMA only about emissions to air?
OMA as a framework covers operator self‑monitoring under the EPR. This article focuses on OMA (Air), which applies to stack emissions; the EA provides separate guidance for the overall OMA process. GOV.UK+1
Does OMA judge my emissions levels?
No. It evaluates how credible your monitoring is — procedures, methods, siting, accreditation, calibration, data handling, and QA. GOV.UK
What standards does the EA expect me to follow?
For CEMS QA, follow EN 14181 (including QAL2/QAL3/AST). For sampling locations, follow EN 15259. Use MCERTS‑certified equipment, organisations, and personnel where available. GOV.UK+2GOV.UK+2
Why is this important in 2025–26?
Because the policy backdrop keeps attention on reliable air monitoring. England has legally binding PM₂.₅ targets with 2028 interim milestones and 2040 endpoints; credible monitoring underpins compliance and enforcement. uk-air.defra.gov.uk+1
Sources and further reading
- EA — Operator monitoring assessment: environmental permits (overview). GOV.UK
- EA — OMA (Air) full PDF. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/651005/LIT_5230.pdf GOV.UK
- EA — Monitoring stack emissions: quality assurance of CEMS (EN 14181, QAL2/QAL3/AST). GOV.UK
- EA — Monitoring stack emissions: measurement locations (EN 15259). GOV.UK
- EA — MCERTS: monitoring emissions to air, land and water (scheme overview). GOV.UK
- DEFRA — PM₂.₅ targets (interim guidance) and legislation (2040 endpoints, 2028 milestones). uk-air.defra.gov.uk+1
