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Air pollution is a significant public health concern.  High levels of nitrogen dioxide can cause respiratory irritation to even the fittest of individuals, but can be worse for those with existing respiratory problems such as asthma or chronic obstructive pulmonary disease. The main source of nitrogen dioxide (NO2) emissions is from local road traffic.

To address this, the UK government undertook national modelling and published the UK plan for tackling roadside nitrogen dioxide concentrations in July 2017. This identified 28 local authorities as having predicted exceedances of the statutory annual mean EU limit value for nitrogen dioxide (NO2) within their areas. These authorities were directed by the Secretary of State to develop a plan to acheive air quality improvements and to bring about compliance with legal limits in the shortest possible time. Guildford, Rushmoor and Surrey Heath borough councils were named due to a predicted exceedance along the A331, Blackwater Valley Relief Road. Working with Hampshire and Surrey County Councils, The Blackwater Valley group investigated the A331 and the adjoining road network to identify the scale of the potential problem.

The results of detailed, local transport and air quality modelling has shown that, in the absence of any additional measures, a 1.8km section of the A331 will not be compliant with the annual mean NO2 EU limit value until at least 2022.

Following a detailed options appraisal process, it was determined that a speed restriction of 50mph, along this section of the A331, between a point just south of the Coleford Bridge Junction and the Frimley Road junction, is likely to bring about compliance by 2021.

This section of the A331 only runs through Rushmoor and Surrey Heath borough council areas, so Guildford Borough Council were not required to proceed further. In March 2019, Rushmoor and Surrey Heath Borough Councils and Hampshire and Surrey Country Councils, were further directed by the Secretary of State to implement the speed limit restriction and provide a full Business Case to Government by 17 May 2019 at the latest.

The total cost of delivering this plan will be £283,915. Hampshire County Council as Highway Authority will deliver the speed restriction and have secured Central Government funding of £101,094 for its implementation. Rushmoor Borough Council, on behalf of the Blackwater Valley Group, will monitor and evaluate the implementation of the speed restriction measure over a period of four and half years at a cost of £196,445 also provided by Central Government funding.

The speed restriction was implemented in June 2019. It will be decommissioned once compliance with the annual mean NO2 EU limit value can be demonstrated.

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