AIR QUALITY MITIGATION SCHEMES
While many projects have a negligible or insignificant effect on local air quality, they may still introduce new sources of dust, road traffic or combustion emissions and thus increase pollutant levels. To counterbalance or offset this increase, a growing number of local authorities have begun to request air quality mitigation schemes. There are a number of ways that air quality mitigation schemes can be established, depending on the local authority and the pollutant source under consideration.
Most local authorities now require assessments of dust emissions during construction and demolition phases of projects to be completed in accordance with either the Institute of Air Quality Management (IAQM) guidance document "Assessment of Dust from Demolition and Construction" or the Greater London Authority guidance document “The Control of Dust and Emissions During Construction and Demolition Supplementary Planning Guidance”. Both documents provide a mechanism by which appropriate mitigation techniques can be established for various stages of the construction phase of a project. These techniques are usually those that would normally be used by contractors in any instance.
Reducing exposure of new residents to poor air quality
Consideration of local air quality at the design stage of any project can ensure exposure of future residents to unacceptable levels of pollutants is avoided. IAQM guidance suggests the use of buffer zones where particularly sensitive members of the population are expected to be present e.g. in areas where pollution concentrations are high, school buildings should generally be sited a minimum of 100m from busy roads.
Where new dwellings are proposed within areas of poor air quality, it MAY be possible to use design and ventilation arrangements to reduce the impact of the external environment on occupants to acceptable levels. In this case, ventilation systems can be used which draw “clean” air into developments from a location away from sources of air pollution e.g. roof level or filtration systems can be put in place within the ventilation system.
Local authority guidance
Some local authorities have produced their own Planning Advisory Notes (PAN) or Supplementary Planning Documents (SPD), which allocate particular mitigation measures to developments based on size, location and/or impact.
Road traffic and combustion emissions mitigation
IAQM guidance “Land-Use Planning & Development Control: Planning For Air Quality” provides principles of good practice that should be applied to all developments during their operational phase to reduce emissions associated with developments. These include:
- The provision of 1 electric vehicle charging point per 1000 m2 of commercial floor space
- The provision of at least 1 Electric Vehicle (EV) “rapid charge” point per 10 residential units in communal residential parking
- Where on-site parking is provided for residential units, EV charging points for each parking space should be made
- A detailed travel plan that sets out measures to encourage sustainable modes of transport
- All gas-fired boilers to meet a minimum standard of <40 mgNOx/kWh
- All gas-fired CHP plant to meet a minimum emissions standard
The IAQM guidance also describes the use of financial contributions to offset emissions based on quantification of the emissions associated with a development. In this case, the damage cost approach used by Defra can be used, whereby calculated emissions are multiplied by the damage cost of each pollutant to determine the air pollution damage costs associated with the development. The table below shows an example of the damage costs of particulate matter and oxides of nitrogen per tonne, as published by Defra:
AIR QUALITY DAMAGE COSTS PER TONE (2015 PRICES)
|POLLUTANT||COST PER TONNE|
|Particulate Matter (PM)||Transport average (central estimate)||£58,125|
|Oxides of nitrogen (NOx)||Transport average (central estimate)||£21,044|
Financial contributions may be used by local authorities for installation of electric charging points in public car parks and to fund air quality action plan objectives.
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