Using the IAQM guidance on assessing air quality impacts on nature conservation sites in practice

Mark Broomfield

1. © Ricardo plc 2020
Institute for Air Quality Management
Dispersion Model Users Group
Using the IAQM guidance on
assessing air quality impacts on
nature conservation sites in practice
24 February 2021

2. 224 February 2021Dispersion Model Users Group© Ricardo plc 2021
Using the IAQM guidance on assessing air quality
impacts on nature conservation sites in practice
•Legal developments, policy shifts, updated
guidance
•Demonstrate how we’ve used leading-edge
modelling techniques to assess local authority
development plans
–Turning HRA on its head
–The advantages of high spatial resolution
–Integrating model results with habitat mapping
–Communicating the findings
Overview
Holman et al (2020). A guide to the assessment of air quality impacts on designated nature conservation sites –version 1.1, Institute of Air Quality
Management, London.

3. 324 February 2021Dispersion Model Users Group© Ricardo plc 2021
Established approach to HRA
HRA process and principles
STAGE 1 –
Screening for
‘Likely Significant Effects’
(LSE)
No
LSE
LSE
No further assessment
required
STAGE 2 –
Appropriate Assessment
to determine ‘adverse effects
on site integrity’
No
adverse
effect
No further assessment
required
Adverse effect
For plan to
progress:
STAGE 4 –
IROPI*
derogation
with
compensation
For plan to
progress:
STAGE 3 –
Assess
Alternatives
No alternative
*Imperative Reasons of Overriding Public Interest
Increasing detailIntense detail

4. 424 February 2021Dispersion Model Users Group© Ricardo plc 2021
IAQM guidance
HRA process and principles

5. 524 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Regional modelling of South Hampshire housing strategy

6. 624 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Designated habitat sites: SPAs / Ramsar sites

7. 724 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Designated habitat sites: SACs

8. 824 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Designated habitat sites: SSSIs

9. 924 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Workflow:
–Input:trafficflowinformationfromatransportmodel(AADT,speed,fleetinfo).
–RapidEmsmodule: calculateslink-specificemissionsfactorsbasedonCOPERT
(forNOx,PM
10,PM
2.5)andEMEP/EEA(forNH
3).
–RapidRoadmodule: usesconvolutionalgorithmswithAERMODdispersionalgorithmsto
predictairborneconcentrations.
–Modelverification(referenceyear):combinespredictedconcentrationswithDefra
backgroundmapsandmeasureddatatodeterminelinearadjustmentfactors.
•173 measurement points for NOx/NO
2: adjustment factor = 1.31
•Limited / no measured data available for NH
3:
Used greater of PM and NOx adjustment factor = 3.90
–Model prediction for future years: apply the same adjustment factors. Where available,
background pollutant information provided by Defra’s background maps (for NOx, NO
2,
PM
10, PM
2.5).
–Output: high resolution and suitable for processing in GIS software.

10. 1024 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Modelled concentrations at c.5 metre resolution across the full South Hampshire area: Do Minimum

11. 1124 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Modelled concentrations at c.5 metre resolution across the full South Hampshire area: Do something

12. 1224 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Then we can use this information to focus in on individual authority development plans
in the context of this potential in-combination effect
•Example: Chichester & Langstone Harbour SPA Stage 1: Screening
•Havant Borough Local Plan 2036
Pollutant
Deposition
type
Minimum CL
Maximum modelled
contribution
% of CL
Nutrient nitrogen
deposition (kgN/ha-year)
Forest 8 0.312
3.9%
Grassland 8 0.197 2.5%
Acid deposition (kEq/ha-
year)
Forest 1.123 0.0222 2.0%
Grassland 1.123 0.014 1.2%
Airborne NOx (µg/m
3
) n/a 30 0.47
1.6%
Airborne NH
3(µg/m
3
) n/a 3 0.034
1.1%

13. 1324 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Then we can use this information to focus in on individual authority development plans
in the context of this potential in-combination effect
•Example: Chichester & Langstone Harbour SPAStage 2: Appropriate Assessment

14. 1424 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution: habitat mapping
•Then we can use this information to focus in on individual authority development plans
in the context of this potential in-combination effect
•Example: Chichester & Langstone Harbour SPAStage 2: Appropriate Assessment
–Background concentrations/deposition
–Qualifying features
–Habitat maps
–Areas below mean
high water
–Habitat surveys

15. 1524 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution: habitat mapping
•Then we can use this information to focus in on individual authority development plans
in the context of this potential in-combination effect
•Example: Chichester & Langstone Harbour SPAStage 2: Appropriate Assessment
–Background concentrations/deposition
–Qualifying features
–Habitat maps
–Areas below mean
high water
–Habitat surveys

16. 1624 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Then we can use this information to focus in on individual authority development plans
in the context of this potential in-combination effect
•Example: River Itchen SAC Stage 1: Screening
•Fareham Borough Local Plan 2021 –2037
Pollutant
Deposition
type
Minimum CL
Plan alone
Maximum
modelled
contribution
% of CL
In combination
Maximum
modelled
contribution
% of
CL
Nutrient nitrogen
deposition (kgN/ha-year)
Forest 15 0.243
1.62% 17.1 114%
Grassland 15 0.159 1.06% 11.4 75.8%
Acid deposition (kEq/ha-year)
Forest Not sensitive N/A N/A N/A N/A
Grassland Not sensitive N/A N/A N/A N/A
Airborne NOx (µg/m
3
) n/a 30 0.142 0.47% 3.02
10.1%
Airborne NH
3(µg/m
3
) n/a 3 0.029 0.96% 2.25
75.0%

17. 1724 February 2021Dispersion Model Users Group© Ricardo plc 2021
The advantage of high spatial resolution
•Then we can use this information to focus in on individual authority development plans
in the context of this potential in-combination effect
•Example: River Itchen SAC Stage 2: Appropriate Assessment
–Background concentrations/deposition
–Qualifying features
–Comparison with neighbouring authority

18. 1824 February 2021Dispersion Model Users Group© Ricardo plc 2021
Consultation with Statutory Nature Conservation Organisations
•Series of meetings
–SNCO
–LA strategic planners
–LA ecologist
•Outline approach
•Prepare detailed “key issues”
document
•Enables focus on areas of
potential impact
•Go through ecological evidence
in detail
–Identify any additional data resources
e.g. wildlife groups
–Draw on experience of NE and LA officers
–Discuss mitigation if needed
•No surprises in final HRA

19. 1924 February 2021Dispersion Model Users Group© Ricardo plc 2021
Key issues from IAQM guidance
•Recent case law
–Wealden judgment: affects in-combination assessment and use of screening criteria
–“People over Wind” judgment: affects consideration of mitigation at screening stage
–Joined Cases C-293/17 and C-294/17: “ a reduction in emissions can only be taken into
account in an appropriate assessment if the expected benefits are certain at the time of
the assessment.”
•“certain” means “no reasonable scientific doubt”
•General principles
–Suitably qualified, experienced and competent
assessors should carry out the assessment
–A precautionary approach is required
•A degree of pragmatism needed because
absolute scientific certainty is rare
–The assessment should be appropriate to the risk
–The assessment should be undertaken with an ecologist
•An air quality specialist should not make judgements on whether there is a likely
significant effect or an adverse effect on the integrity of a site.
–Always consult with the regulator

20. 2024 February 2021Dispersion Model Users Group© Ricardo plc 2021
Thank you for your attention
Dr Mark Broomfield
[email protected]
•Acknowledgments
–Jade Ellis and David Hayward, Havant Borough Council
–Gayle Wootton and Nick Cutler, Fareham Borough Council
–Colleagues and associates
•Dr Thomas Adams
•Charlotte Day
•Tom Priestley
•Richard Andrews (Andrews Wildlife Consultants Ltd)