Air quality

We have undertaken an Air Quality assessment to understand what the likely impacts would be of pedestrianising Oxford Street west in accordance with our proposals. This work is being supported by external independent consultants who have undertaken modelling work for us. The assessment covers key air pollutants, Nitrogen Dioxide (NO₂), Particulate Matter (PM_2.5 and PM₁₀) at 85 selected sensitive locations such as homes, schools, hospitals and local community buildings and spaces within the study area. Carbon Dioxide (CO₂) emissions have been calculated based on total road traffic volumes.

The work has used outputs from the traffic modelling to ensure consistency and accuracy of our model predictions. We have also been undertaking monitoring of existing Air Quality levels in and around Oxford Street west to underpin the assessments.

NO₂ and Particulate Matter are pollutants which cause the greatest concern to public health. These impacts occur from emissions from road vehicles and traffic flow rates, fleet composition and vehicle speeds which all affect the levels of air pollution. NO₂, PM₁₀ and PM_2.5 are measured in micrograms per cubic meter of air (μg/m3). The Air Quality Standards Regulations 2010 set out the legal limits (called ‘limit values’) for concentrations of pollutants in outdoor air. In addition, the World Health Organisation and the Mayor of London have also set out recommendations for targets pollutants concentrations which are lower than the legal limits.

How have the air quality impacts been determined?

The air quality modelling is based on traffic speed and flow data from the traffic reassignment model used to understand traffic flow changes on London’s road Network. The outputs from the traffic model are fed into the air models which allows us to understand what the forecasted changes are in air quality associated with the proposed scheme are likely to be.

The assessments consider the following scenarios:

• Baseline Situation: the current standards of air quality for Oxford Street and Central London
• Future Situation without Oxford Street West Proposals: the current baseline situation but with other developments that have planning permission and other road improvements planned for implementation up to 2026
• Future Situation with Oxford Street West Proposals: the Oxford Street proposals and other committed developments that have planning permission and road improvements planned for implementation up to 2026
  
  

What are the potential impacts, what does this mean for me?

Current Baseline situation

In 2024, annual average NO₂ levels on Oxford Street west and at the majority of locations within the study area were below the limit value of 40 micrograms per cubic metre (µg/m³) at ³). However three locations on Piccadilly (London Park School and nearby residential buildings on the first and second floors), are above the limit value. The highest level was recorded 49.1 µg/m³ at London Park school, which aligns with recent monitoring nearby which recorded levels above 50 µg/m³.

In 2024, concentrations of both PM₁₀ (larger particles) and PM_2.5 (finer particles) across the study areas including Oxford Street west, are well below the limit values 40 µg/m³ and 20 µg/m³ respectively. However, current PM_2.5 levels are close to or above the 2028 interim air quality target of 12 µg/m³ and exceed the Mayor of London’s target of 10 µg/m³.

The total baseline CO₂ emissions in 2024 from all modelled roads in the study area are 24,390 tonnes per year.

Key findings from the Future Situation Without the Scheme

NO₂ concentrations decrease from the baseline situation due to tighter vehicle legislation, local road improvement schemes, broader Mayoral and local policies such as ULEZ, cleaner vehicles and increased uptake of electric vehicles. These initiatives will continue to improve concentrations, and the downward trend is expected to continue which will improve air quality levels over time.

In 2026, locations on Oxford Street west and at the majority of locations within the study area are below the limit value NO₂ limit of 40 µg/m³. However, two locations on Piccadilly (London Park School and a first-floor residential building) are forecast to be above the limit value NO₂ limit of 40 µg/m³. The highest level remains at London Park School, with a forecast concentration of 42.6 µg/m³. However, the NO ₂ levels across the entire study area without the scheme are lower than the current 2024 baseline.

The map below shows the changes in NO₂ concentration levels for the “without scheme” scenario compared to the “with scheme” scenario at selected receptors across the study area.

Across the study area including Oxford Street west, concentrations of both PM₁₀ and PM_2.5 are still below the limit values 40 µg/m³ and 20 µg/m³ respectively. However, as with the baseline, PM_2.5 levels across the study area remain close to or are just above the 2028 interim target of 12 µg/m³ in 2026. Only two first-floor residential locations on Grosvenor Street and New Bond Street are forecast to meet the mayoral target of 10 µg/m³. All other locations including Oxford Street west are above this target but are under the limit values.

Total CO₂ emissions in 2026 from all modelled roads in the study area without the scheme are 21,984 tonnes per year. Between 2024 and 2026, across the entire modelled road network in the study area, road traffic related CO₂ emissions naturally go down due to improvements in the fleet (by 10%).

(Changes in NO2 concentrations with and without the scheme)

Key findings from the Future Situation with the Scheme

Our modelling shows that at the majority of locations in the Oxford Street West area, pedestrianisation would have no material effect on air quality. In fact, several locations in the area are predicted to benefit from improved NO₂ levels.

With the scheme in place, locations on Oxford Street west and at the majority of locations within the study area are still below the limit value NO₂ limit of 40 µg/m³. The same two locations on Piccadilly (London Park School and a first-floor residential building) are still forecast to be above the limit values.

However, with the scheme in place and when compared to the 2026 without scheme scenario, there are imperceptible increases of NO₂ levels at locations across the study area. There are slight increases at the London Park School and the first-floor residential building where there is a forecast increase of 0.4 µg/m³ and 0.5 µg/m³ respectively. There are also slight increases at ground-floor homes on Brook Street and Upper Brook Street.

In summary, the NO₂ levels across the study area with the Oxford Street west scheme in place are:

• 43 locations are expected to see an increase in NO₂ of 0.1 µg/m³. This is considered to be imperceptible
• 24 locations are expected to see a decrease in NO₂ of more than 0.1 µg/m³. This is considered to be imperceptible
• The largest increase (2.1 µg/m³) is at a ground-floor residence on Upper Brook Street
• The largest decrease (3.5 µg/m³) at a first-floor residence on Oxford Street west
• 6 locations are predicted to benefit from improved NO₂ levels, 4 of which are within the scheme area

The map below shows the future NO₂ concentration levels with the scheme at selected receptors across the study area.

With the scheme in place, concentrations of both PM₁₀ and PM_2.5 still fall below the limit values 40 µg/m³ and 20 µg/m³ respectively across the study area including Oxford Street West. However, as with the 2026 without scheme scenario, PM_2.5 levels remain close to or just above the 2028 interim target of 12 µg/m³. Only one first-floor residence on New Bond Street is forecast to meet the mayoral target of 10 µg/m³. The highest modelled annual average levels are: PM₁₀: 25.0 µg/m³ and PM_2.5: 13.2 µg/m³ which occur on Park Lane however these forecasts are still below the limit values.

Total CO₂ emissions in 2026 from all modelled roads in the study area with the scheme are 21,553 tonnes per year. There is a slight reduction of 2% in CO₂ emissions associated with the scheme when compared to 2026 without the scheme, due to a small overall reduction in vehicle kilometres travelled.

(Future NO₂ concentration levels with the scheme)

Summary

While air quality modelling shows exceedances of the NO₂ annual limit value (40 µg/m³) at locations on Piccadilly, including London Park School, recent monitoring data across central London indicates a clear downward trend in pollution levels.

From 2022 onwards, all automatic and the majority of non-automatic air quality monitoring sites have recorded consistent reductions in NO₂ concentrations, with all automatic sites meeting legal limits in 2024. This improvement is driven by:

• Stricter vehicle emissions standards through the implementation of the Ultra Low Emission Zone (ULEZ)
• Increased uptake of electric vehicles
• Emissions-based parking charges
• Cleaner public and council fleets

Overall, our modelling shows that at all locations along Oxford Street west are forecast to experience reductions in annual mean NO₂ concentrations. Changes in PM₁₀ and PM_2.5 levels due to the scheme are considered negligible at all locations including Oxford Street west.

For the majority of the locations across the study area, there is a high number of imperceptible changes in air quality levels when comparing with the scheme to the without scheme scenario. The greatest improvements in air quality are experienced between the 2024 baseline scenario and the two 2026 scenarios. This is due to the continued improvements listed above. The table below provides a more detailed breakdown of the level of change.

Breakdown of changes in NO2 concentrations with the scheme compared to without the scheme in 2026.

Given these trends and ongoing policy measures, it is reasonable to expect that NO₂ levels at currently exceeding sites will continue to decline, supporting an overall improvement in air quality levels across the study area.

Additional information on the environmental impacts of our proposals is available here.