Air Quality Assessment and Ventilation Strategy — Condition Discharge, Dalling Road, Hammersmith
We prepared a screening-level Air Quality Assessment and a Ventilation Strategy for 186 Dalling Road, London W6 0EU, to discharge Condition 9 of planning permission 2025/02481/FUL, on behalf of Athena Young of John Rich Architects. The site sits inside the borough-wide Hammersmith & Fulham Air Quality Management Area, yet measured and modelled concentrations fall well below the national objectives: indicative monitoring at Brackenbury Primary School, 159 metres north, recorded an annual mean nitrogen dioxide concentration of 28.2 µg/m³ in 2024 against the 40 µg/m³ objective, and London Atmospheric Emissions Inventory concentrations interpolated to the 2027 opening year indicate 19.6 µg/m³ at the site. That evidence supported a proportionate ventilation specification rather than a defensive one, with every intake and extract termination fixed on the approved drawings.
Air Quality Assessment and Ventilation Strategy Discharging Condition 9 for a Change of Use at Dalling Road, Hammersmith
Location: 186 Dalling Road, London, W6 0EU | Client: Athena Young, John Rich Architects | Services: Air Quality Assessment; Ventilation Strategy
An AQMA Designation Is a Starting Point, Not a Verdict
The site lies within the Hammersmith and Fulham Air Quality Management Area, declared on 3 November 2000 across the whole borough for the annual mean nitrogen dioxide and 24-hour mean PM10 objectives. A borough-wide AQMA tells you very little about a specific address. It is a policy boundary drawn around an authority that could not demonstrate compliance everywhere; it is not a measurement at the site.
We were appointed by Athena Young of John Rich Architects to prepare a Ventilation Strategy Report, together with the screening-level air quality assessment on which it rests, for the change of use of the basement and ground floor of 186 Dalling Road, London W6 0EU, from Class E(c)(ii) to Class C3, and the conversion of the building into a four-storey single family dwellinghouse. Full planning permission was granted by the London Borough of Hammersmith & Fulham on 10 November 2025 under reference 2025/02481/FUL. Condition 9 of that permission requires the Ventilation Strategy Report to be submitted to and approved in writing by the Local Planning Authority before above-ground works commence.
The Monitoring Data
The assessment went to the monitoring data rather than to the designation. The nearest indicative monitoring, at Brackenbury Primary School 159 metres north on Dalling Road, recorded an annual mean nitrogen dioxide concentration of 28.2 µg/m³ in 2024 against the 40 µg/m³ objective. London Atmospheric Emissions Inventory concentrations interpolated to the 2027 opening year indicate 19.6 µg/m³ nitrogen dioxide at the site. Both figures sit below the objective by a margin of at least 29%.
We reviewed the borough's latest Annual Status Report and its Air Quality Action Plan alongside the Defra background maps, so that the site figures could be read against the borough trend rather than as isolated numbers.
What That Means for the Ventilation Specification
Where concentrations are demonstrably below the objectives, the proportionate response is a ventilation strategy that secures good indoor air quality and protects the occupants from local sources — traffic on Dalling Road, and cooking and combustion within the building — rather than one designed around a pollution problem the data does not support.
The strategy sets out intake and extract termination positions for each habitable room, specified on the approved elevations and floor plans so that the contractor and the Local Planning Authority can see exactly where each termination sits. Intakes are located away from the highway frontage and from the extract terminations of adjoining premises. Ventilation rates follow Approved Document F for the dwelling as consented, and the filtration tier is set to match the screened concentrations rather than defaulting to the highest specification available.
The report also confirms the overheating and energy positions, so that the ventilation strategy is not read in isolation from the building's wider servicing design.
The Screening Assessment
The development's own impacts were screened against the EPUK/IAQM criteria (January 2017). The scheme introduces one dwelling on a site with no car parking provision, and falls below every indicative screening criterion — for traffic generation, for car park size and for combustion plant. No dispersion modelling was required, and none was undertaken. Construction dust was addressed by reference to the IAQM guidance and the standard mitigation appropriate to a conversion of this scale.
Outcome
The measures set out in the report address each limb of Condition 9. Subject to their implementation, and to the post-installation compliance report required by Condition 10, the development is acceptable in air quality terms. The work shows the value of screening a site properly before specifying mitigation: an AQMA address does not automatically require an elevated filtration specification, and the evidence base is what determines the answer.