An air quality assessment considers whether a proposed development could affect local air quality or expose future occupants to unacceptable pollution levels. It provides the planning authority with evidence about existing conditions, predicted impacts and any mitigation needed.The appropriate assessment can range from a desk-based Baseline Air Quality Assessment to a detailed Standard or Impact Air Quality Assessment involving dispersion modelling.

A Baseline Air Quality Assessment is a desk-based screening assessment. It reviews existing monitoring data, Defra background concentrations, local policy and the surrounding environment. It does not include dispersion modelling.A Standard Air Quality Assessment includes dispersion modelling to predict pollutant concentrations across the proposed development. It is commonly used to assess whether future occupants would experience acceptable air quality.An Impact Air Quality Assessment provides the most detailed assessment. In addition to assessing conditions within the development, it considers how development-generated emissions—particularly changes in traffic—could affect existing sensitive receptors in the surrounding area.Terminology can differ between planning authorities, so the required scope is more important than the name of the assessment.

The correct assessment depends on the development’s location, scale, proposed use, traffic generation and proximity to pollution sources.Smaller developments with limited emissions may only require a Baseline Air Quality Assessment. Dispersion modelling may be needed where sensitive uses are proposed near busy roads, pollutant concentrations are elevated or the development is within an Air Quality Management Area. An Impact Air Quality Assessment may be required where the proposal is expected to generate significant traffic or affect existing receptors.We can review your project details and advise which level is proportionate before providing a quotation.

No. A Baseline Air Quality Assessment uses existing monitoring data, Defra background concentrations and site information, without dispersion modelling.Modelling is generally required where desk-based evidence cannot adequately demonstrate that air quality will be acceptable, or where the development could have a material effect on surrounding pollutant concentrations. Standard and Impact Air Quality Assessments therefore include dispersion modelling.

The scope varies according to the level of assessment, but a report may include:Review of the development and surrounding areaNational and local planning-policy reviewAir Quality Management Area informationLocal authority monitoring dataDefra background concentrationsAssessment of NO₂, PM₁₀ and PM₂.₅Identification of pollution sources and sensitive receptorsScreening of traffic and operational emissionsDispersion modelling, where requiredConstruction dust assessment, where relevantAir Quality Neutral Assessment, where applicableMitigation recommendationsClear conclusions for the planning authorityThe fee proposal will confirm exactly what is included for your project.

Identifying a potential issue does not automatically mean that planning permission cannot be obtained. The assessment will explain the significance of the risk and recommend proportionate measures to address it.Mitigation could include changes to the site layout, positioning sensitive rooms away from pollution sources, ventilation measures, low-emission heating, electric-vehicle infrastructure, travel-plan measures or an emission mitigation assessment. Where appropriate, we can also discuss the findings with the planning authority.

To get started, we normally require:The site addressA description of the proposed developmentAny air quality comments from the planning authorityTraffic or transport information, where availableDetails of proposed parking and heating systems, where applicableIf some information is not yet available, we can identify what is essential during our initial review. Once all necessary information has been received, we normally aim to complete the assessment within two working days.