IAQM AGM: Air quality - past, present and future

1. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
PM2.5 – Meeting the WHO guideline value
Dr Claire Holman
Brook Cottage Consultants Ltd.
Claireholman@brookcottage.info

2. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Contents
1. WHO PM2.5 Guidelines
2. Commitments
3. Is it achievable?
4. Summary
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3. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
WHO Guideline
Should there be a mandatory
PM2.5 limit value
of 10 µg/m3?

4. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Purpose of WHO Guidelines
• To provide a uniform scientific basis for understanding the effects of air
pollution on human health
• Guidelines can be a basis for the development of local or national air quality
standards for the management of air quality
• Key issues that need to be considered to move from guidelines to air quality
standards and management:
• Technical
• Political
• Economic and
• Social considerations.

5. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
2005 WHO Global Update
“The annual average guideline value of 10 μg/m3 for PM2.5 was
chosen to represent the lower end of the range over which
significant effects on survival have been observed in the
American Cancer Society (ACS) Study”
• Large uncertainty in the evidence
• epidemiological evidence is largely based on studies using PM10 as the
exposure indicator

6. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
2013 WHO Review of evidence of health aspects of air pollution -
REVIHAAP
• Confirmed and strengthened conclusions of the 2005
WHO AQG on the causal link between PM2.5 and
adverse health outcomes
• The evidence base for the association between PM
and health effects has become much larger and
broader.
• It is important to update the current WHO guidelines
for PM.
• Recent long-term studies show associations between
PM and mortality at levels well below the current
annual WHO air quality guideline level for PM2.5, which
is 10 µg/m3.

7. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
REVIHAAP – PM2.5 Exposure
• Population exposure dominated by indoor exposure to PM of ambient origin and commuting
• On average, outdoor air responsible for 40–70% of the total population exposure
• Ambient PM2.5 policies affect 60–80% of the urban population exposure:
• ambient origin that penetrates indoors
• part of commuting exposure influenced by ambient air policies
• plus exposure during the time spent in outdoor environments.
• Reducing ambient PM2.5 by 10 µg/m3 reduces the average population exposure concentration
by 5–8 µg/m3 because, on average
• The average PM2.5 infiltration into buildings decreases as new, sealed and air-conditioned
buildings replace the older building stock

8. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
New WHOAQGs?
• Air quality guidelines currently being revised
• Possibility that there will be new guidelines published in 2020
• May include short term PM2.5 guidelines
• Long term PM2.5 guidelines more stringent?

9. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
London committed to WHO PM2.5 guideline
9
The Mayor will set new concentration targets
for PM2.5 with the aim of meeting WHO
guidelines by 2030
May 2018

10. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Clean Air Strategy

11. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Michael Gove
“We have got to ensure our Environment Bill includes a
legally binding commitment on particulate matter so
that no part of the country exceeds the levels
recommended by the WHO”
16 July 2019
Gove appointed Chancellor of the Duchy of Lancaster
- 8 days later

12. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
1st Reading in HoC – 15 October
2nd Reading in HoC – 28 October
12
Environment Bill 2019

13. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Annual Mean PM2.5
13 Source: Clean Air Strategy, 2019

14. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Annual Mean PM2.5
• 14
14 Source: Clean Air Strategy, 2019

15. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Can 10 µg/m3 be achieved by 2030? - Defra Analysis
• Two models used (Imperial College IAM and King College CMAQ/ADMS) –
different assumptions, spatial resolution and methodologies. Do not take
account of technological innovation, Road to Zero strategy, climate change
policies or behaviour change. Assumes all EU member states meet NECD
emission limits
• Details differ e.g. importance of different sources
• Significant uncertainty in predicting future PM2.5 concentrations
• But similar conclusions – population exposure will be significantly lower in
2030 than now.
• Meeting NEDC emission limits will give a health benefit of £6.8 billion/year
(excluded NHS and social care costs)

16. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Can 10 µg/m3 be achieved by 2030?
ApSimon et al., 2019. PM2.5 exposure and reduction towards achievement of WHO Standards.
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Red 10-11 µg/m3
Brown > 11 µg/m3

17. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
ApSimon et al., 2019. PM2.5 exposure and reduction towards achievement of WHO Standards.
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Yellow 3-5 µg/m3 Yellow 1-1.25 µg/m3
Brown > 2 µg/m3
Yellow 3-5 µg/m3
Orange 5-7.5 µg/m3
Yellow 0.3-0.5 µg/m3
Brown >1.0 µg/m3
PM2.5 Contributions fromA) natural sources; B) imported C) UK primary D) UK
Secondary (2016)

18. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
ApSimon et al., 2019. PM2.5 exposure and reduction towards achievement of WHO Standards.

19. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
ApSimon et al., 2019. PM2.5 exposure and reduction towards achievement of WHO Standards.

20. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Kings College London Study – London >10 µg/m3
Kitwiroon, Beevers & Williams, 2019. The WHO Air Quality guidelines for PM2.5 CMAQ Modelling of future scenarios

21. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
PM2.5 WHO guideline analysis
• KCL London analysis @ 20m in urban areas for 2030 business as usual
(BAU) areas exceeding10 µg/m3:
• 25% of London
• 10% of Bristol/Cardiff
• 2% Leeds, Liverpool/Manchester
• <1% Edinburgh/Glasgow
• 2030 BAU+CAS measures areas exceeding10 µg/m3:
• ~2% London
• <1% other cities

22. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Defra’s Conclusion
“On the basis of scientific modelling, which has
not considered full economic viability and practical
deliverability, we believe that, whilst challenging, it
would be technically feasible to meet the WHO
guideline level for PM2.5 across the UK in the
future. Substantive further analysis is needed to
understand what would be an appropriate
timescale and means, and we will work with a
broad range of experts, factoring in economic,
social and technological feasibility to do this.”

23. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
AQEG Views on future PM2.5 targets
• Any target that drives reductions in exposure both
above and below 10 µg/m3 will give health benefits
• A threshold-based target is crude, BUT is a useful
basis for driving progress.
• Limited use for driving continuous improvement for
areas that achieve the target and may drive
unintended negative behaviours such as ‘polluting
up to’ the limit value.
• To motivate continuous improvement for areas below
10 µg/m3, a population-weighted mean concentration
metric should be considered.

24. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Mayor of London
• London is capable of meeting WHO
limits for PM2.5 by 2030
• But needs without additional measures
• The UK Government should follow in
London’s footsteps and adopt the
WHO guideline limit for PM2.5 by 2030
as a legally-binding target

25. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Summary – mixed bag
• PM2.5 - 10 µg/m3 by 2030 achievable
• Need reductions in:
• Imported PM
• Primary UK emissions including road traffic and woodburning
• Problem greatest in London
• Mayor needs additional measures
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26. Brook Cottage Consultants Ltd.: Experts in Air Quality Management
Any questions?