Discussion meeting: Mitigating operational impacts

1. Mitigating operational
impacts of developments
Stephen Inch
Senior Policy and Programme Officer (Air Quality)
March 2019

2. • New developments, transport schemes, energy projects and industries can all
increase the exposure to air pollution by:
 Increasing or creating new emissions of pollutants.
 Increasing concentrations of pollutants arising through the design or
layout of the project.
 Increasing exposure to pollution by putting people where the pollution is,
or putting pollution where the people are.
• Conversely they can help improve air quality by:
 Reducing emissions of pollutants
 Reducing accumulation of pollutants and exposure by design and layout
 To be effective in the long term other improvements in existing air quality
need to be supported by new developments.
Why designing out pollution matters?

3. What is mitigation for?
The cynical view:
“Mitigation” allows decision
makers to approve a project
that is desirable for other
reasons.
“Mitigation” delivers the result
the client asked for; a scheme
that ticks the air quality box.
If all else fails a mitigation
payment can be made to
achieve the “right” outcome.
The positive view:
Well designed mitigation can
ensure that desirable projects avoid
causing harm, or minimise the harm
caused.
Well designed mitigation measures
can help the client understand how
to get the best result for their
project.
Well targeted off site measures or
payments can be used sometimes
to offset harms or even deliver
greater benefits elsewhere.

4. Moving towards positive mitigation
• Poor mitigation solutions arise from many
sources:
 Timing,
 Communication/integration issues,
 Asking the wrong questions,
 Seeking easy answers,
 Framing the problem rather than the
solution
• Qualities of good mitigation:
 Necessary: other options have been
eliminated,
 Focussed on the correct problem,
 Genuinely additional,
 Quantified/quantifiable,
 Deliverable/designed in

5. Hard questions
 What is the proper role of concentration limits and other standards in
decision making and design? How do we move beyond a simplistic
39.9 is fine, 40.1 is no go approach?
 How does an improving Air Quality context fit in? Can we avoid using
external improvements as headroom?
 How do we drive better outcomes for all developments, not just those
in areas of exceedance?
 Should “mitigation” apply to well understood impacts or only to risks?

6. Prevent
Reduce
MitigateCan
more be
done on
site?
Are there
relevant
things to
do offsite?
Prevention or reduction measures fall broadly into two categories:
• Eliminating or reducing the impact of sources
• Designing out places of exposure or features that tend towards
accumulation rather than dispersal of pollutants
• As these can be designed into the project they should be, and
the effect of them quantified
Offsite measures can help solve the problem,
especially where:
The relevant source is related to local traffic, or
traffic management, or
Where the development is increasing emissions
offsite (e.g. from an energy centre)
Fitting mitigation into the design process

7. NO2 Filter
Why is this a bad solution?
• It doesn’t reduce exposure very
much
• Sealed windows are not a good
design feature
• It does nothing to reduce
exposure outside the building,
or address concentrations.
• It is expensive, high
maintenance and liable to
break.
• Background ventilation required
unless MVHR is used, and may
still be installed even then.
Learning from bad solutions 1

8. This looks more promising – there is a buffer zone

9. Why is this a bad solution?
• It increases outdoor
exposure for the most
vulnerable residents.
• It’s focussed on maintaining
pre-determined design
features (the interior access
road).
• No communication between
parts of the design and
assessment team.
• Not addressing the
problem, or using the
opportunities on site.
Learning from bad solutions 2

10. Can management measures work? Silvertown Tunnel
Purpose of the project:
- Increase the resilience of the existing
river crossing at Blackwall
- Increased cross river public transport
Identified risk:
 Induced traffic from new road capacity
Solution:
• Charging scheme to deter traffic, applied
to both tunnels
Monitoring and enforcement:
 Direct and proxy measurements
 Formal external oversight
 Mechanisms for change
 Surety of control and access to control
mechanisms

11. London – developing new approaches

12. London Plan approach
• Strategic level prevention and reduction:
o Air Quality Positive: exploiting
opportunities to improve air quality at
the masterplan scale.
o Healthy streets: 10 “Healthy Streets
indicators” aimed at making streets
more about people than cars.
o Alignment of public transport, energy
and spatial policies.
• Local level prevention and reduction:
• Air Quality Neutral: maximum
pollution outputs by use class and
size
• Maximum parking standards
• Charging infrastructure for EVs
• Construction impacts

13. Revising the role of assessments
Current practice
Architects design
Impact Assessment
All fine Mitigation
New London Plan
Baseline modelling
Design constraints
Design
Negative impacts Zero/positive impacts
Impact Assessment/modelling
Energy
Transport
Existing Air Quality
Public Realm
Sealed windows
Some trees
Travel Plan

14. Schools audits programme
• Undertaken in 2017/18 the Mayors
schools audits program used a detail
driven approach to reducing exposure at
the 50 most polluted schools in London.
• The Audits focussed on understanding
the context, the fabric and the way the
schools are accessed and used
• The final output was a list of prioritised
measures to reduce exposure
• While not directly applicable to unbuilt
new developments there are some
potential lessons for identifying
mitigation measures in development
scenarios.

15. Step 1: Context
Following on from a desk study of
existing pollutant concentrations the local
context was examined. Key questions:
- What is changing in the area (positive
and negative)
- Where are the key cycle, walking,
public and private transport routes,
and how good are they?
- Where are people going to and
coming from?
- Are there other features such as road
calming, bus stops, delivery parking
etc?

16. Step 2: Site in detail
Looking within the site and the
immediate surroundings. Key
Questions:
- How are the internal and external
spaces laid out?
- What are the on site and likely
sources of pollution?
- How is the building ventilated?
- Where are the access and exist
points?
- How does the site relate to its
immediate and wider environment?

17. Recommending measures

18. • No one size fits all solutions, although one size
can fit many
• Understanding how the site fits it’s context how it
is used and what drives behaviour helps identify
which are the best measures
• Details matter: moving beyond desk studies lead
to more sophisticated outcomes.
• Considered properly combinations of measures
can be effective just throwing everything at the
situation isn’t always best
• 50 highways measures, 31 on site measures and
19 behavioural measures were identified during
the audits. The majority of these could be adapted
or directly applied to new sites.
Key lessons from the audit program

19. Conclusions
 Bad mitigation is easy.
 Good mitigation is hard to do, but can often be avoided by early
intervention/assessment.
 Generic approaches to mitigation need re-thinking, more detailed
site assessment could be beneficial.
 The need to mitigate at all can be reduced by more robust
strategic and local design approaches.
 Timing matters.
 Information sharing and collaboration matters.

20. stephen.inch@london.gov.uk
@ldn_environment
www.london.gov.uk/environment-newsletter