Roadside NO2 Projection Factors

The table below provides the year adjustment factors for roadside NO2 concentrations, with different factors for London (Central, Inner and Outer) and the rest of the UK. The factors have been calculated as the average of modelled concentrations across approximately 1,900 road links in London, and 7,000 links elsewhere, taking into account the changes in traffic activity, and emission factors for NOx and primary NO2 (f-NO2).

See para 7.70 of Technical Guidance LAQM.TG(16) for more information.

Projecting Annual Mean Roadside NO2 Concentrations to Future Years
Year Adjustment Factor to be Applied Worked Example
Central London (Without ULEZ) Central London (With ULEZ) Inner London Outer London HDV <10% Rest of UK HDV >10% Rest of UK
2013 1.000 1.000 1.000 1.000 1.000 1.000

The measured NO2 concentration at a roadside site in Outer London in 2015 is 44.5µg/m3. The projected concentration for 2017 would be: 44.5 x (0.806/0.904) = 39.7µg/m3

Roadside locations are typically within 1 to 5 metres of the kerbside, but may extend up to 15 metres depending upon the road configuration and traffic flow.

2014 0.929 0.929 0.940 0.952 0.961 0.944
2015 0.858 0.858 0.880 0.904 0.922 0.888
2016 0.813 0.813 0.831 0.855 0.874 0.838
2017 0.769 0.769 0.783 0.806 0.826 0.788
2018 0.725 0.725 0.734 0.757 0.778 0.738
2019 0.680 0.680 0.685 0.708 0.730 0.688
2020 0.636 0.464 0.636 0.659 0.682 0.638
2021 0.603 0.455 0.605 0.629 0.658 0.615
2022 0.569 0.445 0.573 0.599 0.633 0.591
2023 0.536 0.435 0.542 0.569 0.609 0.567
2024 0.503 0.426 0.511 0.540 0.584 0.543
2025 0.470 0.416 0.479 0.510 0.560 0.519
2026 0.460 0.411 0.469 0.500 0.550 0.512
2027 0.450 0.406 0.458 0.489 0.541 0.504
2028 0.440 0.401 0.448 0.479 0.532 0.496
2029 0.430 0.396 0.437 0.468 0.522 0.488
2030 0.420 0.391 0.427 0.458 0.513 0.481

HDV emission projections for NO2 are expected to decline at a different rate to other vehicle types, i.e. cars and vans.

The column "HDV >10% Elsewhere UK” is appropriate for roads outside London where HDVs contribute greater than 10% of the total traffic flow. It is expected that the majority of roads that fall into this category will be motorways or trunk roads.

For roads outside of London that have less than 10% HDVs (including any motorways or trunk roads with less than 10% HDVs), it is recommended that the “HDV =<10% Elsewhere UK” factors are used, which represent the anticipated changes in ambient NO2 concentrations along these roads, where cars  and vans  have a greater  influence on future emission projections.

For roads outside of London where traffic fleet break down information is not known and it is not possible to undertake a bespoke traffic survey within the required timescales, it is recommended that a precautionary approach be taken whereby the “HDV =<10% Elsewhere UK” projection factors are used.

Two sets of projection factors are provided for Central London – one including and another excluding the impacts associated with the Ultra Low Emission Zone (ULEZ) from 2020 onwards. Users must decide which is most representative of the particular scenario of interest, and then apply the relevant projection factor accordingly.

This table is expected to be updated from time to time, so has been removed from LAQM.TG(16) to enable these amends to take place.

For further support, please contact the LAQM Helpdesk.