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!

richard.white@wolverhampton.gov.uk

carolan57@icloud.com