The document summarizes the conclusions of the WHO REVIHAAP project which reviewed evidence on the health effects of air pollution. The project found that new studies since 2005 have strengthened the evidence that particulate matter (PM), ozone and nitrogen dioxide negatively impact health and mortality at levels commonly found in Europe. This supports the WHO Air Quality Guidelines but suggests effects may occur at even lower concentrations. The project also found new evidence that long term exposure to PM is associated with various health outcomes. Overall, the conclusions provide scientific support for actions to improve air quality and reduce the health burden of air pollution in Europe.

1. Recent developments in
Air quality and health –
Summary of conclusions from
WHO project REVIHAAP
Marie-Eve Héroux
Technical Officer, Air Quality & Noise
European Centre for Environment and Health
WHO Regional Office for Europe

2. Air Science Policy Event
15 April 2013, Dublin
Presentation outline
• WHO projects REVIHAAP and HRAPIE
• Context, process, progress, timeline
• Results from evidence review
• Main conclusions from REVIHAAP

3. Air Science Policy Event
15 April 2013, Dublin
Context for REVIHAAP and HRAPIE work

4. Air Science Policy Event
15 April 2013, Dublin
Review of evidence on health aspects of
air pollution for guidance of EU policy
OBJECTIVE:
To provide the European Commission and its
stakeholders with scientific evidence- based advice on
health aspects of air pollution in support of the
comprehensive review of air quality legislation due in
2013.
*While some of the questions directly address policies, the
recommendations from the projects are based solely on scientific
conclusions on health aspects of air pollution, and do not consider
other issues which are relevant for policy formulation.

5. Air Science Policy Event
15 April 2013, Dublin
WHO projects
- Jointly financed WHO/EC
- Coordinated by WHO-ECEH
- Provide answers to 26 key questions posed by the EC
REVIHAAP
(24 questions)
Review of
evidence
review on
health
aspects of
air
pollution
Oct 2011
– April
2013
(18
months)
HRAPIE
(2 questions, building on
REVIHAAP work)
Identification
of
concentration
-response
functions for
key pollutants
and health
outcomes
Survey on
newly
emerging
issues on
risks to
health from
air
pollution
Sept
2012 –
Sept
2013
(12
months)

6. Air Science Policy Event
15 April 2013, Dublin
REVIHAAP: Process and progress
Scientific Advisory Committee
• 8 experts
• Offer guidance and oversight of project
• SAC meetings December 2011 & June 2012
Review of evidence and development of answers
• 29 experts authors
• Across various relevant disciplines
• Represent wide range of countries and institutions
• Work together in small groups
• 32 experts external reviewers
• Comment on completeness, validity and clarity
• WHO Expert meetings August 2012 & January 2013
Publications:
• REVIHAAP First results published January 2013
• Full technical report available April 2013

7. Air Science Policy Event
15 April 2013, Dublin
REVIHAAP Key questions
• PM, ozone, NO2, SO2, metals (As, Cd, Hg, Pb, Ni), PAHs
• New findings regarding health effects
• Concentration-response functions and thresholds
• Air pollution constituents and sources
• Integration of evidence and policy implications
• WHO air quality guidelines
• EU policies
• Critical data gaps

8. Air Science Policy Event
15 April 2013, Dublin
Evidence on health effects of PM (1/2)
• The scientific conclusions of the 2005 WHO Guidelines about the
evidence for a causal link between PM2.5 and adverse health
outcomes in humans have been confirmed and strengthened and,
thus, clearly remain valid
• New studies on short- and long-term effects
• Studies linking long-term exposure to PM2.5 to several new
health outcomes (e.g. atherosclerosis, adverse birth outcomes,
childhood respiratory disease, neurodevelopment and cognitive
function, diabetes)
• Associations between long-term exposure to PM2.5 and mortality
at levels below the current annual WHO AQG
• Effects of long-term exposure greater than those of short-term

9. Air Science Policy Event
15 April 2013, Dublin
Evidence on health effects of PM (2/2)
• Both short-term (such as 24-hour average) and long-term (annual
means) exposure to PM2.5 affect health
• Maintaining independent short-term and long-term limit values for
ambient PM10 in addition to PM2.5 to protect against the health
effects of both fine and coarse particles is well supported
• In the absence of a threshold and in light of linear or supra-linear
risk functions, public health benefits will result from any reduction of
PM2.5 concentrations, whether or not the current levels are above or
below the limit values

10. Air Science Policy Event
15 April 2013, Dublin
Evidence on PM sources, fractions and
components
• Three important components – black carbon, secondary
organic aerosols, and secondary inorganic aerosols – for which
there is substantial exposure and health research finding
associations and effects
– may provide valuable metrics for the effects of mixtures of
pollutants from a variety of sources
• Short-term exposures to coarse particles (including crustal
material) are associated with adverse respiratory and
cardiovascular health effects, including premature mortality
• Increasing, though as yet limited, epidemiological evidence on
the association between short-term exposures to ultrafine
(<0.1 µm) particles and cardio-respiratory health, as well as the
central nervous system

11. Air Science Policy Event
15 April 2013, Dublin
Evidence on health effects of ozone
• New evidence for an effect of long-term exposure to ozone on:
– mortality, especially among persons with potentially predisposing
conditions (COPD, diabetes, congestive heart failure, and
myocardial infarction)
• asthma incidence, asthma severity, hospital care for asthma and
lung function growth
• Adverse effects of exposure to daily ozone concentrations (maximum
daily 1-hr or 8-hr mean) on:
• all-cause, cardiovascular and respiratory mortality
• respiratory and cardiovascular hospital admissions, after
adjustment for the effects of particles (PM10)
• The evidence for a threshold for short-term exposure not consistent,
but likely to lie below 45 ppb (90 µg/m3) (max 1-hr)

12. Air Science Policy Event
15 April 2013, Dublin
Evidence on health effects of NO2
• New studies document associations between day-to-day variations in
NO2 and variations in mortality, hospital admissions, and respiratory
symptoms.
• New studies showing associations between long-term exposure to
NO2 and mortality and morbidity.
• Both short- and long-term studies found these adverse associations
at concentrations at or below the current EU LV (= WHO AQG).
• The associations between NO2 and short-term health effects in many
studies remain after adjustment for other pollutants (including PM10,
PM2.5, black smoke).
• … it is reasonable to infer that NO2 has some direct effects.
• No health evidence to suggest changing the averaging time for
the short-term EU limit value (1-hour).

13. Air Science Policy Event
15 April 2013, Dublin
Evidence of health risks from proximity to
roads
• Elevated health risks associated with living in close proximity to
roads is unlikely to be explained by PM2.5 mass.
• Current evidence does not allow discernment of the pollutants
or pollutant combinations that are related to different health
outcomes, although association with tail pipe primary PM is
increasingly identified.
• Toxicological research indicates that non-exhaust pollutants
could be responsible for some of the observed health effects.

14. Air Science Policy Event
15 April 2013, Dublin
REVIHAAP Main conclusions
• Considerable amount of new scientific information on health effects
of PM, ozone and NO2 has been published in the recent years
– Evidence has strengthened
– Effects observed at levels commonly present in Europe
– Supports the scientific conclusions of the WHO Air Quality
Guidelines, last updated in 2005
– Indicates that the effects can occur at air pollution
concentrations lower than those serving to establish the 2005
Guidelines
• Provides scientific arguments for the decisive actions to improve air
quality and reduce the burden of disease associated with air
pollution in Europe.