4) A clean air zone defines an area where targeted action is taken to improve air quality and resources are prioritised and coordinated in order to shape the urban environment in a way that delivers improved health benefits and supports economic growth.5) Clean air zones have been introduced with a specific focus on tackling NO2 concentrations in areas that are breaching legal limits. The UK are compliant with other limit levels of other exhaust pollutants, but clean air zones will also help to reduce public exposure to pollutants such as particulate matter. Previous versions of this document have referred to a ‘non-charging’ clean air zone where targeted measures can be put in place to tackle air pollution. A local authority could still choose to implement such a non-charging zone, and the measures and approaches described in Annex B could be considered in such a case. However, for the avoidance of confusion, for the purpose of this document, a clean air zone refers specifically to a charging clean air zone. This is an area where a local authority applies charges using powers under the Transport Act to deliver NO2 reductions. The previous version of this document referred to non-charging clean air zones along with a number of activities local authorities could take in such zones. As the term clean air zone has since come to refer specifically to a charging scheme version 3.0 of this document has removed the concept of a non charging clean air zone. Other measures local authorities can take, whether as part of/alongside a clean air zone; developed as a result of a local NO2 plan; or independently of a clean air zone are described in Annex B.6) The NO2 Plan explains that “It is for local authorities to develop innovative local plans that will achieve statutory NO2 limit values within the shortest possible time…the UK government has identified clean air zones that include charging as the measure it is able to model nationally which will achieve statutory NO2 limit values in towns and cities in the shortest possible time. Given the potential impacts on individuals and businesses, when considering between equally effective alternatives to deliver compliance, the UK government believes that if a local authority can identify measures other than charging zones that are at least as effective at reducing NO2, those measures should be preferred as long as the local authority can demonstrate that this will deliver compliance as quickly as a charging clean air zone.