Greening an Urban Canyon to reduce exposures to … an Urban Canyon to reduce exposures to ... noise...
Transcript of Greening an Urban Canyon to reduce exposures to … an Urban Canyon to reduce exposures to ... noise...
Richard White
Wider Determinants Specialist
City of Wolverhampton Council
Patrick Saunders
Professor of Public Health
University of Staffordshire
Greening an Urban Canyon to reduce exposures to
harmful pollutants
Case studies from the West Midlands
West Midlands Air Quality
• Exposures to harmful pollutants
attributed to between 6 and 8% of
premature deaths per year across
West Midlands
• Road traffic is the overwhelming
cause
• Between a quarter and a third of
West Midlands families live close to
busy roads (10,000 car vehicle
movements per day).
• Not just caused by motorway
network but too much traffic on
smaller roads that cannot cope
• Some local centre roads designated
as A-Roads carrying too much
through-traffic
• Six of seven WM authorities have
declared Air Quality Management
Areas (AQMA).
Sandwell NO2 exceedance areas
(measured)
Bearwood Road, Smethwick, Sandwell
• Heavily trafficked commercial
thoroughfare (with approximately
11,000-13,000 vehicle movements per
day).
• High levels of traffic related air
pollution, primarily via direct vehicular
exhaust emissions of NO2 and PM.
• Urban street canyon - road cuts
through dense area of buildings,
higher than width of the street.
• Air movement restricted, increased
residence time of pollution, increased
concentration levels and exposure
periods.
• Attracts large numbers of shoppers
and commuters. Primary school &
living accommodation on the upper
floors of commercial premises.
The toxic street environment: a perfect storm of numerous health harms
Canyon Effects
• Air recirculation and
“downdraft” effect
• Accumulation of emissions -
low wind speed
• Increased “residence time”
of pollutants – time to sink to
pavement level
• NO2 concentrations could be
considerably higher at road
level
• Concentrations of NO2 are repeatedly above the annual mean objective by a
large margin.
• The annual mean objective for NO2 is 40µg m3 for the protection of human
health. No local PM data but this is also assumed to be high and no safe limit.
Options
Titanium oxide surfaces, activated
carbon surfaces and vegetation
Vegetation chosen as plants have good
deposition qualities:
• Metabolic uptake
• Leaf surface “stickiness”
• Large surface area
• Aerodynamic properties
Other benefits include:
Reduced surface temperatures, reduced
noise pollution, biodiversity, amenity,
aesthetics
National interest
Birmingham New Street Station
The Floral Trail – a living wall of 324m, with plants chosen specifically for their
ecological biodiversity and wildlife value. The plants are mainly evergreen to ensure
year-round planting and colour as well as being suitable for the site's southerly
aspect. The living wall was unveiled as part of the station redevelopment.
On a public street, it creates a powerful impression for visitors and passers-by,
and is a visible expression of Aston University’s commitment to sustainability,
recognised by a Platinum EcoCampus award.
Aston University
Study
• Challenge of applying conventional control
measures (i.e. removal of people from
exceedances!)
• Council & PHE worked with the
Universities of Birmingham and
Staffordshire to explore greening street
canyons to both reduce pollution and to
enhance urban environments.
• Air dispersion modelling exercise
undertaken.
• Model demonstrated real potential for
reducing pollution levels and improving the
urban environment.
• Street level reductions of 40% of NO2 and
60% of PMs could be achieved*. *Pugh TAM, MacKenzie AR, Whyatt JD, Hewitt NC.
Effectiveness of Green Infrastructure for Improvement of
Air Quality in Urban Street Canyons. Environmental
Science and Technology 2012. 46: 7692-99.
Greening Strategy
• Funding set aside for streetscape
improvements, including the
installation of green walls at a
number of predetermined
locations.
• Led by planning department &
initially focused on aesthetics.
• Ivy walls were chosen. They are a
type of green wall. Pre-grown ivy
can be installed directly onto
existing structures; they are quick
growing, robust and can cover
large areas.
• However, limitations in site
availability, resource and
maintenance were found.
• So, focused on main receptors.
Bearwood Infant School • Around 34m length of boundary
fencing facing Bearwood Road.
• Chosen for the first trial of ivy walls
as children are vulnerable to the
effects of air pollution
• Playground stands immediately
alongside a busy stretch of
Bearwood Road.
• Backed up by a publicity campaign
and school working with parents to
prevent idling.
• Around 30m added in second phase
“We are delighted with the ivy panels,
which provide the school with much-
needed additional greenery and create
an attractive backdrop to the
playground”.
Debbie Haywood, Head teacher at
Bearwood School
Make your place greener. If you’re in an urban
environment, think about how to bring nature into
the place.
“The balance of evidence indicates conclusively
that knowing and experiencing nature makes us
generally happier, healthier people.
(Russel, Roly; et al. Annual Review of
Environment and Resources, 2013, Vol. 38)
Further sites
• Another six potential hotspot areas were identified and green walls were installed
at three of these sites. Prominent site (above) located near to bus station.
• Over 120m2 installed in total.
• Ivy is effective at removing air pollution and being evergreen, it works all year
round.
• The manufacturer claims that annually 23m2 of ivy wall will absorb the equivalent
carbon emissions as an average city tree. These installations are the total
equivalent of between five and seven fully grown trees, but only take up a fraction
of the area in comparison and are more visually striking and prominent.
• Better option than trees here as danger of forming a roof to the canyon making
trapped pollution worse.
“The first use of instant ivy
hedging in Bearwood was around
a decade ago, on Lightwoods
Hill, and it has proved to be a
successful product. We know we
have air quality problems
associated with the level of traffic
on Bearwood Road and we
believe the best solution is to
combine greening initiatives such
as these ivy walls with taking
steps to challenge people who
run the most polluting vehicles”.
Councillor Steve Eling, Deputy
Leader of Sandwell Council
and Councillor for Abbey ward
Black Country Air Quality SPD Planning Guidance to allow local authorities to
give weight to mitigation measures in
development proposals which include:
• Increasing the distance between the
development facade and the pollution
source;
• Implementing Low Emission Strategies;
• The design of schemes to place residential
units at the rear of the development or on
higher floors;
• Design of schemes to avoid the creation
of canyons, allowing a greater degree of
pollutant dispersal;
• Additional measures that may be required
by either planning condition or planning
obligation to make the development
acceptable - Any other measures within
an Air Quality Action Plan or Low
Emission Strategy relevant to the
development.
Future considerations • VW fraud shows market-led EURO standards not
bringing about improvements in emissions.
• DEFRA are providing a framework through
proposed Clean Air Zones to enable LA’s to apply
access control measures.
• Risk that local bus fleets outside proposed
Birmingham Clean Air Zone will be broadly similar
by 2020 and vehicle fleet turnover projections will
not be as optimistic as expected!
• Centro developing a plan to reduce fleet emissions
– WM authorities have supplied information on
NO2 hotspots in relation to bus routes to assist
with the prioritisation of any future work
programme undertaken to reduce emissions.
• Given the introduction of PM2.5 as a public health
concern to be addressed through the PHOF &
impact of an increasing number of private car
owners using diesel vehicles, further interventions
need to be planned:
• Raising air pollution awareness, encouraging
private car users to use alternative routes,
make more local trips by walking or cycling,
organising street festivals and street markets.
Summary
• Greening is effective in urban street canyons and all
urban settings if space can be found.
• Low-cost solution for spatially-restrained locations.
• Can piggy-back onto planning/streetscape proposals.
• Can be linked to awareness raising, particularly sensitive
receptors (i.e. schools) – its about starting the
conversation and encouraging local action.
• Has to be part of a wider strategy on air pollution.
• Look at effects of local road traffic.
• Take advantage of media interest & future opportunities.
He certainly agrees…
Sir David Attenborough on his 90th birthday, presenter,
environmentalist, conservationist and national treasure!
Thanks for Listening!