STAIR air quality screening helps a project team identify road-traffic impacts that need further ecological assessment. Its value depends on a clear handover between the transport, air-quality and ecology specialists.
What STAIR air quality screening does
Natural England commissioned AECOM to develop the Screening Tool for Air Quality Impacts from Roads. IAQM hosts the tool through the IES website. The September 2026 release is version 1.2, with a supporting technical development report.
The accompanying explanation addresses a limitation of the commonly used 1,000 annual average daily traffic proxy. It was developed for nitrogen oxides, rather than validated for all nitrogen-deposition and ammonia effects. STAIR provides a more ecologically relevant way to identify roads needing further assessment.
However, screening in a road does not itself establish likely significant effects or adverse effects on site integrity. The publisher also makes clear that this development changes neither environmental standards nor legal requirements. Keep the screening result distinct from the ecological conclusion.
Check applicability before assembling the inputs
The technical report describes screening against Natural England’s 1% criterion for nitrogen oxides, ammonia and nitrogen deposition. It limits use to ecological sites within 200 metres of the assessed road. Ask the specialists to confirm applicability and the relevant assessment route before using a result.
Also keep the tool version separate from the report version. Record both with the saved assessment files. A reference to “the latest spreadsheet” is difficult to audit when a reviewer receives a different release.
Use Natural England’s standing advice alongside the technical report. Confirm which ecological sites and features require consideration, then record any scope agreed with the relevant authority.
Coordinate three specialist handovers
The following is an original briefing sequence. It does not reproduce the tool’s calculation method or replace its instructions.
| Handover | Information to reconcile | Review hold point |
|---|---|---|
| Transport → air quality | Road-link identifiers, scenario years, traffic change and the sources supporting the selected inputs. | Confirm that the input set describes the current proposal. |
| Ecology → air quality | Site boundaries, relevant habitat features, receptor locations and specialist advice on assessment criteria. | Agree the receptor schedule and scope. |
| Air quality → ecology and planning | Versioned screening outputs, assumptions, limitations and roads needing further consideration. | Record the assessment response and its author. |
First, match road identifiers between the transport drawings and assessment files. Next, check that the scenario labels mean the same thing to each author. Where information is provisional, identify the owner and expected resolution date.
Then ask the specialists to reconcile the receptor schedule. A single map should not quietly stand in for the ecological evidence supporting it. Keep a record of the boundary source and the relevant features being considered.
Our traffic-input coordination guide covers the wider information handover. Use it with the agreed air quality assessment scope and appropriate ecological baseline evidence.
Make changes traceable
A screening result belongs to a particular input set. Therefore, when the proposal changes, describe the change before reusing an earlier conclusion. Ask the responsible specialists whether the road network, scenarios, receptors or assessment approach need review.
A fictional design change
A revised access redistributes traffic between two road links. The coordinator retains the previous input file, issues the revised transport information and asks the air-quality specialist to review the screening. The ecologist then receives the revised outputs and records the implications for their advice. This example illustrates document control, not a prediction of ecological effects.
Finally, close the action only when the report and its supporting files agree. If a question remains open, show it in the issue register. This helps a reviewer distinguish an agreed conclusion from work still in progress.
Common questions
Is STAIR a new legal threshold?
The publisher describes it as a screening tool and states that environmental standards and legal requirements have not changed. Apply it within the appropriate specialist assessment route.
Does screening in mean a project is unacceptable?
No. It identifies a need for further consideration. The relevant assessment, mitigation and ecological judgement determine the next steps.
Should a coordinator run the tool instead of an air-quality specialist?
Agree responsibilities through the appointment. This guide helps coordinate reliable inputs; it does not train a reader to select methods or interpret ecological effects.
References and scope
- IES / IAQM. Natural England’s Standing Advice and Screening Tool for Air Quality Impacts from Roads. Tool v1.2 released September 2026; explanatory scope and limitations checked 2 November 2026.
- AECOM for Natural England. STAIR Technical Development Report, September 2026. Development note v1.0; distinct from tool v1.2.
- Natural England. Air pollution and development: advice for local authorities. Current online standing advice, accessed 2 November 2026.
England advice context. Project scope and competent-authority requirements need specialist confirmation. No spreadsheet or macros were executed in preparing this coordination article.
Connect the transport and ecological evidence
Discuss the assessment brief with ACP. Provide the proposal, traffic information, relevant site boundaries and any authority correspondence.