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Poor Air Quality can impact people's health. An Air Quality Assessment seeks to establish whether a proposed development is suitable in a given area. Is the air quality good enough for people to live there? Will it make the air quality in the area worse?
A relatively new concept in Air Quality Assessment is Air Quality Neutrality. In presenting a proposal for a new development is required to prove that it will not worsen air quality. A car free development, running on electric heating in a central urban location, may easily meet these criteria. However, for sub-urban developments things can be more difficult.
Detailed Air Quality Assessment
Air Quality Assessment Screening Thresholds
There are obvious
developments that are associated with air quality impacts these might
include coal fired power plants, oil refineries, waste incinerators (EfW).
There is often air quality impacts associated with the construction
phase of most projects, traffic dust and smoke from poorly maintained
plant can be a problem.
There are direct and indirect emissions to be considered, a factory that make
plastic milk bottles for example might
have direct emissions (impacts) from the heating of plastics etc, and
indirect emissions from the power station where is sources the energy to
heat the plastics.Steam is a visually polluting emission that many find of
concern, when in most cases steam contains little more than water vapour.
An air quality impact assessment may contain:
- Impact Prediction
- Monitoring
NOx emissions are also carefully considered within larger urban areas. The introduction of large number of condensing boilers (which a produce higher levels of NOx) within new build schemes are typically frowned upon. Combined heat and power is a good alternative, although plant will need to carefully specified to ensure minimised NOx emissions.
Most people in Europe spend 90% of their time indoors so indoor air quality is very important. Indoor Air quality has a major influence on health and comfort of building occupants. Indoor air quality can be lowered via the presence of a great many gaseous and particulate elements which lower air quality and have harmful effects on occupants.
There are a great many sources to be considered when assessing air
quality indoors. In fact just about everything that an occupant
does in abuilding including breathing has the potential to lower the air
quality if the air volume is not sufficiently ventilated.
Offices and Homes alike use a large variety of cleaning products,
cosmetic products and many home have boilers or log burners which have
the potential to introduce combustion by products in to the indoor air
volume.
When SWEL undertake indoor air quality monitoring we typically monitor
for around 40 "determinants", that is to say different chemicals that
may point out significant sources of pollutants. We can then match these
determinants (Para-dichlorobenzene for example) to a common house hold
source (Moth Balls). Although this compound is also used in in
disinfectants and deodorants!
Quite often the identification of an unpleasant odour by the buildings occupants is the trigger for a indoor air quality assessment being undertaken, and in these instances it is important to characterise the odour and start looking in the right direction. Hidden mold can often cause odours, and this is fairly easy to find without undertaking any monitoring.
However with other odours such as solvents it is extremely useful to undertake air quality monitoring so as to narrow down a potentially long list of sources.
Although VOCs in paints and other surface coatings are being phased out they represent some of the most polluting substances that are used in the home and work place. A classic example of this is painting a nursery prior to the birth of child. Gloss paints, and spirit based varnishes are significant.
Samples can be collected using a TD tube packed with
sorbent, in which one end of the tube is fitted with an open mesh diffusion cap
for VOC collection. The tubes are sent with brass caps; when sampling is
required the cap is removed from the sample end (the side of the tube marked
with a groove) and replaced with the diffusion cap. The diffusion/gauze
cap is used to provide a regulating barrier to diffusion. Passive sorbent
tubes can be deployed for two weeks or less depending on the specific project
and limit of detection requirements. The diffusion sampler is replaced
with the original brass cap when sampling is complete. Each tube has a
unique reference to allow simple identification of the sample. The
laboratory reports time weighted average concentrations in µg/m3 for
those VOCs with published uptake rates. For those without, the laboratory
reports contaminants as ng/tube.
I’ve asked my colleagues to provide costs for our UST – it
will include the key indicator compounds for petroleum hydrocarbons – BTEX, Nap,
TPH C6-12 etc.
The IAQM Guide for Planning Applications gives details of two "levels" of Air Quality Impact Assessment:
This would involve the detailing of Good Design as below, and a qualitative assessment of Air Quality Impacts. If the development were small for example and the Baseline Air Quality was good, then the impact could well be low.
As well as the detailing of Good Design this would include a quantitative assessment. A quantitate assessment would likely involve extensive data collection and then modeling of the site using Aermod or similar modeling program (we use Aermod). In this way a quantitative assessment is made.
There a number of suggestion for design and specification that are included with the IAQM Guide:
No “Street Canyon” it created. There are large gaps between buildings. This will allow air to circulate and disperse street level air pollution.
“Delivering sustainable development should be the key theme of any application”. This is a wide ranging statement, there are various sustainable features incorporated in the developments design.
There are no habitable rooms. Any vents of chimney stacks will be sited towards the central access road so as to maximise distances of point source emissions from dwelling. Chimneys may be installed pending relevant permissions but are not sought as part of this planning application. Vents would serve for building ventilation (HVAC); these will be directed towards the site interior, for above stated reasons.
Charging points to the ratio of 1 for 1000m2 is required. The floor area of each unit is 225m2. e.g. The development of 20 units. Total floor area is 4500m2. 4 charging points are required.
Owing the general planning use type it is not thought practical to prepare a Green Travel Plan. For example TRICS data or similar would not be detailed enough to form targets, and as such any such report would be largely subjective in nature, as no clear targets could be defined.
All gas-fired boilers to meet a minimum standard of <40 mgNOx /kWh.
London does receive a lot of attention with regards to Poor Air Quality, however there are many other places in the UK that suffer from poor Air Quality.
There is ample evidence of the adverse health effects caused by air pollution (WHO, 2006). In response to these health impacts, the Air Quality Strategy (AQS) for England, Scotland, Wales and Northern Ireland (Defra, 2008) sets out the UK’s way forward on air quality issues, details objectives to be achieved, and proposes measures to help reach them. These UK objectives largely reflect EU Limit Values (EC, 2008). The GLA and the London boroughs and district councils outside the capital have responsibilities for the management of air quality and must work towards the attainment of AQS objectives.
This study has found that in 2013 there was still significant exposure of the London population to levels of NO2 above the EU limit value and that this exposure is predicted to decline significantly (96%) by 2020. However, current modeling results show that in 2020 there will still be more than 72,000 people living in locations with average NO2 above the EU limit value.
Here are some thresholds that would indicate as to whether you development requires an Air Quality Assessment. These thresholds are used to describe "Major Developments", which would then trigger the requirement for an Air Quality Assessment, some other thresholds are sometimes used, stemming from industry specific guidance.
As of November 2021 The London Mayor's Office Released guidance on Air Quality Neutrality Assessment, this a quite a simple matter for minor developments but for major developments it involves quite a lot of work.
Air Quality Impact Assessment Horsham, West Sussex |
The Housing Association were concerned that dust and gaseous emissions from the proposed demolition and construction activities would impact on their residents health. |
Air Quality Assessment - Norfolk |
The assessment of risks in this instance relied on secondary data collected, and used as a baseline. With impacts considered throughout the construction and operational phases of the development. |
Air Quality Assessment - Brent, London (NW6) |
A resident approached Southwest Environmental Limited with concerns over the quality of air within their living space. It was thought that air quality might be lowered owing to the neighboring property uses. |