Dorset Heathlands Air Quality Mitigation

Protecting Dorset Heathland from Airborne Nitrogen-Based Pollutants

Overview

The Dorset Heathlands are designated as Site of Special Scientific Interest (SSSI), RAMSAR, Special Area of Conservation (SAC) and Special Protection Area (SPA) which means that they are nationally and internationally important site for numerous wildlife species.  

The focus of Air Quality Mitigation is to mitigate against the adverse effect of nitrogen-based airborne pollutants upon the Dorset Heathlands. These pollutants are deposited on heathland soils causing nutrient enrichment, this encourages invasive or nutrient loving plants to outcompete the heathland flora that prefer low nutrient soils. If the Ammonia and Nitrogen Dioxide levels in the air are too high, then they can also have direct toxic effects on heathland plant communities.  

The Dorset Heathlands Interim Air Quality Strategy was prepared jointly between BCP Council and Dorset Council with advice from Natural England. The strategy sets out the approach to address sources of airborne nitrogen-based pollution generated in the vicinity of the Dorset Heathlands.  

Vehicle emissions can cause nutrient deposition and direct toxicity effects on areas within 200 metres of roads.  The Air Quality Strategy found that additional vehicle trips generated by new development are likely to have an adverse effect upon the integrity of Dorset Heathlands designated sites. 

Legal Context

Under Article 6(2) of the Habitats Regulations, member states must prevent the deterioration of designated sites. Local plans and planning permissions must conclude no significant adverse effects on these sites through a habitats regulations assessment (Article 6(3) of the Habitats Directive). 

Heathland Decline

Over the past 100 years, population growth and changes in human activity have dramatically reduced heathlands. The Wildlife and Countryside Act 1981 provided legal protection to these areas, including Dorset’s heathlands. 

Planning Framework

The National Planning Policy Framework and Planning Practice Guidance outline procedures for approving development proposals.

Dorset Heathlands Interim Air Quality Strategy

The Dorset Heathlands Interim Air Quality Strategy states that where there is evidence of air pollution affecting the heathlands, then opportunities for remediation or mitigation should be taken through additional or increased management practices.  

There are two approaches in the strategy: 

Category 1 measures to mitigate the direct impact of development.  

Mitigation measures and initiatives will initially focus on heathlands within 200m of A and B roads, prioritising the heaths identified by air quality monitoring as being most at risk. Types of measures could include focussed grazing or stripping back of nutrient enriched soil and vegetation. This management will help facilitate native heathland species to recover. 

Category 2 measures to improve air quality across the whole of the Dorset Heathlands.  

Category 2 measures will aim to address air pollution across the entire heathland site (beyond 200 metres from a road) and are essential in ensuring that Category 1 measures are not undermined. These projects will be carried out at locations around the heathland area and focus on Ammonia emissions from agriculture.  

Support for Project Applications

We are looking to support project applications to mitigate air quality impacts. Examples include: 

• enhancing land management to support native heathland species recovery
• incorporating mitigation measures in major developments near heathland
• designing agricultural buildings to reduce pollution
• changing agricultural land use to lower nitrogen inputs

Avon Heath and Matcham’s View 

To mitigate nitrogen deposition from road traffic emissions from A338 and A31 work was carried out to enhance strategic areas of heathland restoration where there had recently been forestry plantation and overgrown scrub. Remaining invasive scrub was removed, and nutrient enriched soil was scraped away to create important bare ground habitat.

Upton Heath 

Air Quality monitoring identified Upton Heath as being at high risk from traffic pollution.  

Mitigation measures focused on areas of the heath next to the A35 showing evidence of nutrient enrichment from traffic emissions, trees and scrub were removed and nutrient rich soils scraped to create bare ground habitats. 

Funding and Governance

• Community Infrastructure Levy funding for air quality mitigation is overseen by a steering group from Dorset and BCP Councils, Natural England, and the Dorset Heaths Partnership.
• Final approval lies with Senior Officers based on funding levels.
• Mitigation must be secured for the life of the development using standard management agreements.

How to Apply or Enquire

For an informal conversation about your land or to propose a potential project, contact the Air Quality Mitigation Officer.