Air quality assessment authors and IAQM competence

Nobody needs a licence to write an air quality assessment for a planning application. There is no equivalent of the ecologist's protected species licence and no statutory competent person regime. What exists instead is a set of published methods, a professional institute whose guidance everyone cites, and a council environmental health officer who will read the report closely and knows exactly which shortcut was taken.

For a developer scoping the evidence base on a major application, the useful question is not who is allowed to write it. It is whose assessment will survive review without a request for further information at week ten.

What the assessment is being judged against

Air quality sits in planning through two doors. The first is the local air quality management regime under Part IV of the Environment Act 1995, which requires councils to review air quality and to declare an air quality management area where objectives are not met, then to produce an action plan. The second is national planning policy and guidance, which asks whether a proposal would give rise to unacceptable levels of pollution and whether it takes opportunities to improve air quality.

Neither door sets a numerical planning threshold. The assessment therefore has to do three things: characterise the baseline, predict the change the development causes, and describe that change in terms a decision maker can weigh.

That last step is where inexperienced authors falter. A table of concentrations is not a conclusion. The reviewing officer wants to know the magnitude of change at each receptor, expressed against the relevant objective, and what that means for the planning balance.

IAQM grades and what they signal

The Institute of Air Quality Management publishes the guidance the sector runs on, covering land use planning and development control, construction dust, and odour. Its membership grades appear on report title pages as shorthand for experience.

Chartered status is held separately, through the parent body, as Chartered Scientist or Chartered Environmentalist. A senior assessor may therefore sign as MIAQM CEnv, and both parts of that mean something different.

None of it is compulsory. All of it affects how quickly a council accepts the work.

Environmental health teams are small and their reviewers tend to specialise. In an authority with a declared management area on a busy corridor, the officer will have read dozens of assessments on the same roads and will know the local monitoring data by heart. An assessment that misstates the position of a diffusion tube, or quotes a background figure from the wrong year, loses credibility on page four and never recovers it.

The parts of the report that get challenged

Baseline characterisation comes first. A weak assessment lifts background maps from the national dataset and stops. A strong one uses the background maps, then adds the council's own monitoring from its annual status report, including diffusion tube locations and any continuous analyser, and explains where the site sits relative to each.

Model verification comes second, and it is the single most common reason an assessment is sent back. Where dispersion modelling has been carried out, the modelled concentrations at monitoring locations must be compared with measured values and an adjustment derived. An assessment that reports raw model output as though it were measurement will not be accepted by an environmental health officer who verifies models for a living.

Receptor selection comes third. Receptors should sit at the locations and heights where relevant exposure occurs, which means facade positions at residential properties and at schools rather than a convenient point in a car park.

Emissions assumptions come fourth. Traffic data should come from the transport work rather than from a separate estimate, so the transport assessment and the air quality work do not contradict each other on flows. If they do, an objector will find it.

Where competence is legally required, and where it is not

Air quality assessment sits in the professional recommended category rather than the professional required one. Councils usually expect a suitably qualified author, and professional review is strongly advised, though no statute reserves the work.

Two related situations do change that. Where the scheme is EIA development and air quality is a scoped in topic, the Environmental Statement must be prepared by competent experts under the EIA Regulations 2017, which brings the air quality chapter into a formal competence requirement. And where an environmental permit is needed for combustion plant, the permit application runs under a separate regime with its own technical expectations.

For everything else, competence is demonstrated rather than certified. Ask for two recent assessments on comparable schemes, look at the verification section of each, and note whether the author has appeared at an inquiry.

Professional indemnity cover is the other question worth asking, and it is asked far too rarely. An air quality assessment supports a decision that fixes ventilation strategy, window openings and sometimes the layout of an entire block. If the assessment is wrong, the remedy is expensive and it lands during construction. A sole practitioner without cover appropriate to the scheme value is a risk the developer carries rather than the consultant.

Briefing the work so it holds together

Give the assessor the transport outputs, the energy strategy including any combustion plant, the site layout with receptor positions, and the construction programme. Missing the energy strategy is the common gap, because a combined heat and power unit or a biomass boiler changes the assessment entirely and tends to arrive late in design.

Timing matters as much as content. An assessment produced after the layout is fixed can only report the position, whereas one produced while the massing is still fluid can move a habitable room off a polluted facade at no cost. On schemes beside a busy road, commission the air quality input at the same point as the acoustic input and let the two disciplines argue about window openings before the drawings are issued.

Ask for four things in the deliverable:

• a clear statement of which guidance version and which model were used
• a verification section with the adjustment factor and the monitoring data behind it
• an emissions mitigation package expressed as commitments that can become planning conditions
• a construction dust assessment with mitigation set out in a form that can be carried into a construction management plan

That last point saves duplication later, because the dust mitigation belongs in the construction management plan and it is easier to write once.

Illustrative example: a scheme of 120 flats on a main road inside an air quality management area. Background maps show concentrations close to the annual objective. The assessor verifies the model against three council diffusion tubes on the same road, adjusts, and reports facade concentrations at the proposed windows. The design responds by moving habitable rooms away from the road frontage and specifying mechanical ventilation with filtration on the affected elevations. The report then lists those as commitments. This example is illustrative.

PlanScope drafts an air quality assessment structured to UK planning policy, with the policy framework, receptor tables and mitigation sections laid out and site specific facts flagged for confirmation. The modelling, the verification and the professional judgement stay with the assessor. The professional directory is the route to arrange that review before submission.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.