An empirical approach for the prediction of annual mean nitrogen dioxide concentrations in London

An empirical statistical approach for predicting annual mean NO₂ concentrations in London using readily available data, providing a practical alternative to dispersion modelling.

An empirical approach for the prediction of annual mean nitrogen dioxide concentrations in London

D.C. Carslaw, S.D. Beevers, G. Fuller

Atmospheric Environment, 2001

Techniques are presented for the prediction of current and future annual mean NO₂ concentrations in London using hourly average NOx (NO + NO₂) and NO₂ monitoring data. The approach defines site-specific relationships between the annual mean NOx and NO₂ concentrations at background and roadside sites across London. By applying NOx frequency distributions derived from monitoring data, it is possible to investigate the effect of different NOx emission reduction strategies on predicted NO₂ concentrations. The non-linear nature of the NOx–NO₂ relationship means that the reductions in NOx required to meet the UK annual mean NO₂ air quality objective of 40 μg m^-3 vary considerably between sites. Application of the approach suggests that meeting the objective in central London will be particularly challenging, requiring NOx concentrations as low as 30 ppb, compared with values of 36–40 ppb for outer London.

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