The government agrees with the Committee’s recommendation. Recommendation implemented. The government is satisfied that the best available evidence that meets the stringent requirements for assessing compliance with the annual mean Nitrogen Dioxide (NO2) limit value under the Air Quality Standards Regulations (2010) (AQSR) has been used to identify areas in exceedance and bring them into the programme. An uncertainty of around +/-30% is not unusual for a model of this scale and complexity, and assessments have demonstrated that the national model meets the uncertainty requirements for assessing compliance under the AQSR. The government continues to work with external experts to identify and implement further targeted improvements to the national model to ensure it uses the best available evidence and reflects the impact of local measures. The government has also set up a new monitoring network which has greatly increased the number of locations where compliance with NO2 limits is assessed using measurements. This network is achieving lower levels of uncertainty (<15%) and has more than tripled the number of roadside measurements used in the NO2 compliance assessment. Since both modelled and measured values contain uncertainties, the government cannot definitively guarantee that all areas of exceedance have been identified. Where local authorities’ air quality monitoring identifies a potential NO2 breach, they can share this evidence with the Joint Air Quality Unit. Whether a locally identified breach should be tackled through the NO2 programme or through the Local Air Quality Management (LAQM) regime will depend on whether the monitoring data meets the specific siting and data quality requirements of the AQSR.