Transcript Diapositiva 1

Health Effects of Nitrogen
Dioxide and the EU policy
Francesco Forastiere
Roma, 16 October 2012
Policy makers for environmental
issues
•
•
•
•
Local councils
Regional environmental authorities
Ministry of Environment and Industry
EU DG Environment
• Regional and national Health Authorities
Types of policy makers
•
•
•
•
•
•
•
•
Informed/uninformed
Honest / not honest
Conflicts of interests / no conflicts
Equality / inequality
Environmental sustainability Yes/ No
Long-term planner / short-term planner
Ability to manage stakeholders Yes/ No
Take a decision or wait for the next term
What kind of work we do?
• Provide a single effect estimate (one point
with bars)
• Provide a pooled effect estimate (one BIG
point with bars)
• Provide a narrative synthesis of the
evidence (with/without uncertainty)
• Provide health impact assessment
• Provide integrated environmental and health
impact assessment
What is the most relevant evidence?
Evidence
• Causality
• Latency period
• Dose-response
• Threshold
• What if ...
• Impact assessment
Qualitative / quantitative
• Qualitative
• Qualitative
• Quantitative
• Quantitative
• Qualitative
• Quantitative
The Nitrogen dioxide case
Description of the problem
• Nitrogen dioxide is one the classical outdoor air
pollutants
• A wide range of effects on health have been found by
epidemiological studies to be associated with NO2
• WHO has recommended both short- and long-term
• guidelines which have been translated into standards
• The annual average Limit Value (40μg/m3, annual
• average) is difficult to meet, at least at some sites
Description of the problem
• And yet, NO2 has faded a little, from current
thinking about the effects of air pollutants on
health.
• We have mainly focused on particles and on
ozone.
• Sulphur dioxide and carbon monoxide are now
less of an outdoor problem than they were.
Description of the problem
• In the EU: policies are cost-benefit tested
• This requires coefficients that are firmly based on
associations regarded as causal.
• And here is a problem: how many of the
coefficients linking NO2 and effects on health do
we regard as causal?
Description of the problem
• Nitrogen dioxide may have:
– Primary effects: the effects of exposure to NO2, per se.
– Secondary effects: the effects of ozone and nitrate particles:
formation dependant on NO2;
– And may be associated with “effects” by virtue of its acting as
a surrogate, an index or marker, for other pollutants.
• Here is the central problem:
• What evidence do we have for these primary, secondary
and surrogacy effects?
Description of the problem
• Primary effects: if true, we should control emissions of NO2 or,
perhaps, exposure to NO2
• Secondary: if true, we have options: there may be better ways of
controlling the production of ozone and fine particles than by
controlling emissions of NO2.
• This conceals a further problem: to what extent do nitrate particles
contribute to the toxicity of the aerosol we monitor as PM2.5
• Surrogacy: if NO2 is a non-toxic surrogate for some other
pollutant (or pollutants), then controlling NO2 will only lead to a
predictable reduction in effects on health if the ratio of NO2 to the
active component(s) remains constant.
The EC- WHO project
“Evidence on health aspects of
air pollution to review EU
policies – REVIHAAP”
Questions from EU to WHO
REVIHAAP timeline
• 25-26 June: SAC Meeting
• 21-23 Aug: REVIHAAP Expert Meeting
• 23 Aug - 21 Sept: Finalization of rationales by authors
• 1 Oct - 9 Nov: External review
• 19 Nov - 18 Dec: Preparation of final version by authors
• 18 Dec: Final version ready & sent to meeting
participants
• 15-17 Jan 2013: Adoption of REVIHAAP material
during REVIHAAP/HRAPIE Meeting
• April 2013: Final REVIHAAP report
Question C2
• Is there any new evidence on the health
effects of nitrogen dioxide (NO2) that
impact upon the current limit
values? Are long-term or short-term limit
values justified on the grounds that NO2
affects human health directly, or is it
linked to other co-emitted pollutants for
which NO2 is an indicator substance?
Question C4
• Based on currently available health
evidence, what NO2 metrics,
health outcomes and
concentration-response
functions can be used for health
impact assessment?
Per se….or…. not per se
Understanding the importance
• The question of the independence of effects
of NO2 and PM2.5 is important for policy, as
the effectiveness of NO2 standards for
health protection is being questioned, so this
should be considered carefully in the
development of the answers.
Approach
• Short Answers, longer Rationales
• Evidence summaries:
– Epi studies of short -term exposure
– Epi studies of long -term exposure
– Experimental studies – etc.
• Search criteria set out, for a set of answers; with detailed
references – clearly a huge amount of work
• Initially the questions were appreciated because they were specific
about pollutants – and they do capture important specific aspects.
BUT they don’t make it easy to present the necessary content in a
clear way.
• …Can
we change the Questions?
Style
• The questions are clear and the answers should directly
address the questions posed.
• The technical level of the answers should be the same as
the questions. The language used should be
understandable to the intended audience, in particular
policy makers who are not necessarily technical experts.
• The rationales should relate directly and to and clearly
support the answers provided.
• The rationales should be concise. More extensive
reference to existing reviews may help.
Methods
• The process of reviewing the new evidence (since 2005)
from epidemiology and experimental studies has been
straightforward.
• For epidemiologic studies (short and long term) evidence
of associations has been considered together with the
following aspects: the levels at which health effects have
been noted, the shape of the concentration response curve,
and the stability of the effects after adjustments for other
pollutants.
• For experimental studies (in animals and in humans), the
evidence of effects under controlled and consequently
limited sets of conditions has been evaluated.
• The overall main difficulty is in drawing all these aspects
together for an understanding and assessment of causality
and the key discussion is on the role of toxicological
evidence.
NO2 controlled human studies
-summary • In healthy subjects, changes in pulmonary
function, ↑ airway responsiveness, mild
inflammation& ↓host defences at concentrations
(>1800 μg/m3+/-) in excess to those outdoors
• Asthmatics more susceptible to acute effects
• In mild asthmatics, lowest concentration to change
pulmonary function: 500 μg/m3and to enhance
effect of allergens: 200 μg/m3
Uncertainty
• IPCC AR4 Summary for policy
makers:
- The changing climate is very likely (more
than 90%) due to the observed increase in
anthropogenic greenhouse gases
- IPCC have a heirarchy of probabilities
ranging with associated language
Impact assessment
Least uncertainty
• Respiratory hospital admissions (short term)
Increased degree of uncertainty
• All cause mortality (short-term). Increased degree of uncertainty for
cardiovascular mortality where there is an absence of a solid body of supporting
chamber study and toxicological evidence.
• Bronchitic symptoms in asthmatic children, long-term (McConnell et al., 2003).
Most uncertainty
• [For the pollutant-outcomes there was increased difficulty of controlling for
confounding by other pollutants, less data or less available supporting clinical or
toxicological evidence].
•
• Cardiovascular admissions (short-term).
• Asthma prevalence
• All cause mortality (long-term)
Broader issue

to consider what package of guideline
recommendations will maximise human
protection, rather than set of individual
guidelines
Key points
 Difficult to formulate policy relevant
questions
 Difficult to provide answers to those questions
 Difficult to fit a rationale for the answers
 When the answer is provided, how useful it
will be for the policy setting?