Recommendation 17

Government uses national and local modelling, together with two national networks of monitoring stations, to direct its actions on air quality, with directions to local authorities issued primarily on the basis of a national model identifying areas of likely exceedance of air quality targets.19 The national network consists of around 430 unique monitoring stations across two separate networks; the UK Urban NO2 Network, established in 2020, and the older Automatic Urban and Rural Network.20 The Joint Air Quality Unit estimates that the overall uncertainty in the national model is around +/- 30%, as it was in 2017, although it has found that the model results are now more closely aligned to the results produced by the more detailed local models.21 The NAO reported that some local authorities that had been directed to act by government are concerned that this could create an unfair situation whereby other local areas might be experiencing high levels of NO2 pollution but not be required to take action because the national model had not projected a breach of local concentration limits.22