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Abstract
Background Policies and practice in many sectors affect
health. Health impact assessment (HIA) is a way to predict
these health impacts, in order to recommend improvements
in policies to improve health. There has been debate about
appropriate methods for this work. The Scottish Executive
funded the Scottish Needs Assessment Programme to con-
duct two pilot HIAs and from these to develop guidance on
HIA.
Methods Case study 1 compared three possible future
scenarios for developing transport in Edinburgh, based on
funding levels. It used a literature review, analysis of local
data and the knowledge and opinions of key informants.
Impacts borne by different population groups were com-
pared using grids. Case study 2 assessed the health impacts
of housing investment in a disadvantaged part of Edinburgh,
using published literature, focus groups with community
groups and interviews with professionals.
Results Disadvantaged communities bore more detrimental
effects from the low transport investment scenario, in the
areas of: accidents; pollution; access to amenities, jobs and
social contacts; physical activity; and impacts on community
networks. The housing investment had greatest impact on
residents’ mental health, by reducing overcrowding, noise
pollution, stigma and fear of crime.
Conclusion Although there is no single ‘blueprint’ for HIA
that will be appropriate for all circumstances, key principles
to inform future HIA were defined. HIA should be systematic;
involve decision-makers and affected communities; take into
account local factors; use evidence and methods appropriate
to the impacts identified and the importance and scope of the
policy; and make practical recommendations.
Keywords: health impact assessment, transport policy,
housing policy
Introduction
The health of individuals and populations is created or
destroyed by a complex set of factors that interact over the
whole life course.
1,2
Consequently, if the determinants of health
are multiple and interactive, actions to improve health rely on
interventions from many agencies other than the National
Health Service, including housing, education, transport, indus-
try and many others.
2
Therefore to improve health we need to
influence policies and practice in all these sectors. Equally, it is
important to detect policies or activities in these areas that
might have detrimental and perhaps unanticipated effects on
health.
3,4
An evidence-based approach to these tasks requires an
assessment of: the ways that each policy might have an impact
on health, how to improve this impact, and how to ensure that
the combined effects of diverse policies avoid contradictory
effects and create synergistic benefits.
5
Health impact assess-
ment (HIA) is a method of doing this and has been defined as
‘a combination of procedures, methods and tools by which a
policy, programme or project may be judged as to its potential
effects on the health of a population, and the distribution of
those effects within the population’.
6
In this context, health
impacts have been defined as the ‘overall effects, direct and indi-
rect, of a policy, strategy, programme or project on the health of
a population’ and include impacts on health determinants.
6
In the United Kingdom, the Government expressed commit-
ment to HIA in its recent public health White Papers
7,8
and the
Acheson report recommended that health inequalities impact
assessment (HIIA) should also be carried out.
9
In Europe, HIA
is seen as a way to meet the commitment made in Article 152 of
the European Union Amsterdam Treaty, that ‘a high level of
human health protection shall be ensured in the definition and
implementation of all Community policies and activities’.
10,11
The WHO strategy for Europe, Health 21, identifies HIA as a
way to achieve accountability for health and sets a target that all
member states should establish mechanisms for HIA by 2020.
12
Developing principles for health impact
assessment
Margaret J. Douglas, Lynn Conway, Dermot Gorman, Saskia Gavin and
Phil Hanlon
Journal of Public Health Medicine Vol. 23, No. 2, pp. 148–154
Printed in Great Britain
© Faculty of Public Health Medicine 2001
Common Services Agency, Trinity Park House, Edinburgh EH5 3SQ.
Margaret J. Douglas, Senior Registrar in Public Health Medicine
Scottish Needs Assessment Programme, University of Glasgow, Glasgow G12 8RZ
.
Lynn Conway, Research Assistant
Lothian Health, 148 Pleasance, Edinburgh EH8 9RS.
Dermot Gorman, Consultant in Public Health Medicine
Saskia Gavin, Public Health Epidemiologist
Public Health Institute of Scotland, Glasgow G3 7LS.
Phil Hanlon, Director
Address correspondence to Dr Margaret Douglas, Consultant in Public Health
Medicine, Lothian Health, 148 Pleasance, Edinburgh EH8 9RS.
E-mail: margaret.douglas@lhb.scot.nhs.uk
DEVELOPING PRINCIPLES FOR HEALTH IMPACT ASSESSMENT
149
Despite this commitment, sceptics doubt whether methods
exist that can fulfil these ambitious aims. Among practitioners
involved in HIA there remains uncertainty over appropriate
methods
13
and different approaches have been proposed.
14–20
In
particular, there is debate about the relative merits of quantita-
tive and qualitative methods in HIA, and about whether health
inequalities should be considered to be integral to HIA or must
be considered separately as HIIA.
The Scottish Needs Assessment Programme was funded by
the Scottish Executive to conduct two pilot HIAs, to inform
future HIA in Scotland. This paper reports some of the lessons
learnt from these and suggests principles for conducting HIA.
Case study 1: HIA of the City of Edinburgh
Council’s Urban Transport Strategy
21
The City of Edinburgh Council (CEC) has been concerned about
traffic congestion in Edinburgh for many years and has insti-
tuted policies designed to reduce private car use by encouraging
the alternatives such as cycling, walking and public transport,
and by restricting parking. However, car use continues to rise,
causing concern that increasing congestion will undermine
Edinburgh’s economy and reduce the quality of the urban
environment. This led to the development of a new local trans-
port strategy. One of the most contentious issues was a proposal
for road tolling to increase the funding available for transport
infrastructure. To aid decision-making, three possible transport
scenarios were developed, based on different levels of available
funding. This study compared the health impacts under each of
these scenarios so as to inform the strategy.
The study had three stages. First, the main areas of health
impact were identified from a literature review of the effects
of transport on health. Second, a profile of the population of
Edinburgh and recent trends in traffic and areas of impact was
compiled from routine data. From this profile, two main popu-
lation groups were described: (1) middle class, affluent, pre-
dominantly car owning; and (2) disadvantaged, predominantly
non-car owning. Within these groups the following subgroups
were identified: young children; adolescents; the elderly; work-
ing people; and the unemployed. Finally, two meetings were
held with a group of ‘key informants’, people living and working
in Edinburgh with interests in transport and/or health. At these
meetings the group discussed the findings and constructed six
grids to record the health impacts for each group within each of
the three scenarios. The group agreed ‘scores’ for each impact
and each population group using available evidence and their
own local knowledge. The grids used a simple ordinal scale to
aid comparison of impacts borne by different population groups
under the three funding assumptions. Where group members
disagreed on the appropriate score, this was resolved by dis-
cussion or an average score awarded. Table 1 summarizes the
grids presenting health impacts under scenario 1 (low spend)
and scenario 3 (high spend).
The main areas of health impact identified were: accidents;
pollution; access to amenities, jobs and social contacts; oppor-
tunities for physical activity in walking and cycling; and impacts
on community networks. Most detrimental impacts differen-
tially affected more disadvantaged communities. Pollution
affected all groups but people who spend a lot of time in cars
(young children and working people) are exposed to poorer air
quality than those using other modes of transport.
22,23
The
Table 1 Matrix showing health impacts to different population groups under transport policy scenario 1
(low spend) and scenario 3 (high spend)
Physical Access to goods Community
Accidents Pollution activity and services network
1313131313
Young children
Affluent — – – –
Deprived — – — — –
Adolescents
Affluent – — – — —
Deprived — – – — —
Elderly
Affluent – – — – –
Deprived — – — — –
Working people
Affluent 0 — – – –
Deprived – – – — –
Unemployed
Deprived – – – — —
Key: , very positive impact; , positive impact; 0, no impact; –, negative impact; —, very negative impact.
150
JOURNAL OF PUBLIC HEALTH MEDICINE
scenario with the greatest funding would produce the greatest
health gain, whereas scenarios with lower funding would have
detrimental effects on health and health inequalities. The high
spend option was also favourable to local business interests,
especially in financial and tourism sectors.
Case study 2: HIA of the North Edinburgh Area Renewal
housing strategy
24
This study assessed the health impacts of housing investment in
a disadvantaged part of Edinburgh, so as to inform a review of
the housing strategy.
Information for the study was gathered from a review of the
published evidence, focus group sessions involving community
groups and interviews with professionals working in the area.
Participants of the focus groups ranked the elements of the
housing strategy in order of importance in terms of impact on
health. The ranked list was used as the starting point for discus-
sion of the impacts on health. As the top rankings of all the
groups were broadly similar, they were combined to produce an
overall composite ranking. The literature review focused on the
seven highest ranked elements.
Table 2 summarizes the health impacts of the seven highest
ranked elements of the strategy, as perceived by participants of
focus groups. Both physical and mental health impacts were
identified. Overall, the housing strategy was perceived to have
greatest impact on mental health, especially stress and depres-
sion. Elements of the strategy reported to have a positive impact
on mental health included the following: central heating allows
all parts of the home to be warm, thus increasing living space
and reducing overcrowding; double glazing helps to reduce
noise pollution; security entry and window locks reduce the fear
of crime; a suitable size of home reduces overcrowding; having a
sense of control over your life by actively participating in the
renewal programme brings a sense of achievement. Also, the
redevelopment helped to reduce the stigma associated with
living there and created higher self-esteem among residents. The
physical impacts were due to central heating and double glazing,
with reported improvements in cold and damp-related illnesses.
The study provided qualitative data exploring the impacts
perceived by residents and the value they placed on these
impacts. The ranked lists showed the perceived importance to
health of different elements of the strategy to different groups in
the community.
Discussion
Qualitative and quantitative evidence
Both these examples assessed a broad policy rather than a more
specific project. The aim of this approach to HIA is to make
the health impacts of policies explicit and thereby to provide
evidence to inform better policy-making.
13
This will not satisfy
those who will only admit high-quality evidence that ‘proves’
cause and effect links, but in the practical world of policy-
making, the real challenge is to employ methods that are robust
(being explicit in their strengths and weaknesses) but also practi-
cal and timely. HIA is usually a way to apply existing evidence
to a local situation and policy, to inform policy-making, rather
than being research that generates new evidence.
In these case studies, we used a range of sources to identify
and describe health impacts. These included: published litera-
ture, routinely available data, interviews with key informants,
focus group discussions with community members, and group
meetings. These approaches created an understanding of the
possible or probable impacts of policy on many of the broad
determinants of health and, so by implication, on health status.
The views of local people and other stakeholders also provided
information on the relative importance of each of a variety of
possible consequences of the policies.
There is often a demand for quantitative data to support
decision-making.
15
But we found that qualitative and quantita-
tive data were both useful, giving different perspectives. Many
impacts are best explored using qualitative methods. In the
housing HIA the qualitative data gave insights into the strength
of feeling people had for each impact, and the priority placed on
them. For example, it was more important for people to feel safe
inside their homes than in the street. They also demonstrated
that some impacts were dependent on other factors. For exam-
ple, money saved from cost-efficient heating could only be spent
on ‘healthy’ foods if there were also better shopping facilities.
We found that a combination of methods gave a picture of
the health impacts and produced different kinds of evidence.
The appropriate kinds of evidence to inform policy develop-
ment will vary in different circumstances.
The scope of health impacts
Both case studies used a broad model of health to identify health
impacts. Some impacts were not immediately obvious and were
identified later in the process. Flexibility of process is needed to
ensure these are included in the assessment.
More positive than negative impacts were identified. If HIA
was concentrated on policies that might be health damaging,
it might help prevent health damage. But HIA can also find
opportunities to maximize health gain and be a positive way
to work across sectors to define and to promote healthy public
policy. This is an important difference from Environmental
Assessments, where the priority is to reduce damage.
14
Unresolved debates include the time-scale over which to pre-
dict impacts in prospective HIA and how direct an association
between the policy and the impacts should be recognized. Some
important impacts may arise indirectly or in the long term, but
we can predict with greater certainty direct impacts that occur in
the short term.
Defining the policy and local context
The case studies used detailed information on the relevant poli-
cies, and needed expertise from outside the health sector. It was
difficult to consider the policies in isolation of other relevant
DEVELOPING PRINCIPLES FOR HEALTH IMPACT ASSESSMENT
151
Table 2 Seven highest ranked elements of the housing strategy: health impacts identified by residents
Positive health impact Negative health impact
Central heating and double glazing
Mental health – reduces worries about bills; increases overall sense of Physical health – can aggravate asthma as air too dry,
well-being: reduces depression, degradation, stress, anger, anxiety, can cause more colds and snuffles
embarrassment; better sleepless irritable
Physical health – improves circulation, chest, recovery from operations,
reduces hypothermia, fevers, pneumonia, asthma, coughs, colds, stiffness,
aches and pains, passing out from epilepsy, angina, bronchitis, sore throats,
arthritis, cramp
Family functioning – children can go to own rooms, relieves strain on
parents; people less grumpy, more calm
Income – increases incomemore to spend on foodpotential for improved
diet, more to spend on socializing
Social networks and isolation – increases social life as feel better about
inviting friends roundreduces isolation
Physical environment – reduces dampless illness; reduces noiseless
stress
Education – increased ability to concentrate (because of less noise from
double glazing and heating in children’s bedrooms, etc.)better school
performance
Security entry system and improved window locks
Mental health – reduces distress and anxiety from fear of burglary or
unwelcome visitorsimproved mental health; improved asthma because of
less stress
Social environment – increased confidence to go out and socialize without
fear of burglary
Improvements to inside of house (including sound proofing)
Mental health – less stress/anxiety and better sleep because of decrease Mental health – jealousy and resentment between those
in noise (fear from noise disruptions leading to feelings of panic) who have had improvements and those who have not
Family functioning – more control over immediate environment if less
affected by noise
A choice of house size and type
Social environment – easier to get in and out with children if not in block of
flats – less exposure to racist attacks in own house compared with blocks
of flatsless fearbetter sleepless use of sleeping tablets
Family functioning – improved sleep and family relationships in larger
houseless stress and reduction in feelings of tiredness and sluggishness;
less affected by noise in own house compared with block of flatsbetter
sleep, fewer panic attacks
Physical health – less spread of illness in own house compared with block
of flats with shared stairs, etc.; fewer accidents
Resident input into choice of neighbour
Mental health – less stress if no noisy or annoying neighbours; less fear of Mental health – If this limited consultation does not lead
violence and racist attacks; less anger caused by nuisance children to a reduction in nuisance neighbours, there could be
coming into stair; less vandalism; less worry re drug users becoming role increased frustration that tenant voice is not being heard
models for children
Physical health – reduced threat of injury and spread of diseases via dirty
needles; less injury from racist attacks and other violent incidents
Social environment – better communication, improved social network
Tenant and resident participation
Mental health – sense of control Mental health – if consultation with tenants and
residents is not meaningful, and they feel their views
are not being taken into account, frustration and
increased stress levels could result
152
JOURNAL OF PUBLIC HEALTH MEDICINE
policies; for example, transport policy is interdependent with,
and arguably part of, land use policy. In a retrospective assess-
ment it may be difficult to distinguish the differential impacts of
these related policies. In a prospective assessment that seeks to
inform decision-making, it is necessary to define the policy pro-
posal being assessed, but the recommendations may be directed
to other related policies and other sectors.
There are few examples of HIA in the published literature,
but one similar assessment of a transport strategy has recently
been published.
25
This identified similar impacts to our HIA of
the transport strategy, but differences in the local context were
also important. For example, the existence of disadvantaged
estates on the outskirts of Edinburgh and the local tourism
industry affected the priority impacts. Evidence must be weighed
for its local relevance as well as its robustness.
Participation
Participation of affected people is crucial in HIA because of
their insight into how a proposal might affect their community,
their well-being and their behaviour.
19
It is also needed to study
the value that affected people place on different health impacts.
Affected communities may also suggest changes to maximize
the health benefit. Participation might be needed at different
stages of the HIA, to identify and describe impacts and to make
recommendations. It is difficult to engage meaningfully with
communities, but the mechanisms used will not be unique to
HIA. Often a range of different methods might be used to gather
community views. Mechanisms might include focus groups,
citizens panels, opinion polls and inviting views from existing
community groups.
Inequalities
Both case studies could be described as health inequalities
impact assessment as they explicitly addressed different impacts
affecting different population groups. For example, in the trans-
port HIA, deprived populations were most disadvantaged by
policies favouring car use. In the housing HIA, different groups
gave priority to different elements of the strategy. These differ-
ences have implications for the recommendations of the HIA.
We found it was an essential part of the HIA to identify the
population groups who would bear each impact. We believe
that HIA and HIIA should not be separate processes. Rather,
all HIA should consider impacts on inequalities.
This has implications for the presentation of findings,
especially if quantitative measures of health impact are used, for
example, the total number of people affected by each impact. If
quantitative measures are used to compare impacts, there might
be a temptation to sum them to reach a ‘bottom line’ value for
the health impacts of a proposal. This might allow easier com-
parison of policy options, but would hide the differences
between impacts borne by different groups. Instead, the health
benefits and costs for each group should be presented separ-
ately. For HIA to help tackle inequalities, it is essential that the
different impacts borne by different groups are made explicit.
Then the recommendations can seek to reduce any health
inequalities that might result from the proposed policy or pro-
ject.
Making recommendations
In making recommendations to prevent any adverse impacts
and enhance positive health impacts, we need to understand
what change to the proposal is possible. This implies working
closely with the policy developer. The recommendations should
be closely connected to the health impacts identified. The
recommended changes may be at the margin but still achieve
important improvements in health. Having made recommenda-
tions, their implementation and the future impacts on the health
of the population should be monitored. It is not clear who
should be responsible for this, and it is likely to vary with indi-
vidual circumstances.
Putting the evidence together
The two studies adopted different procedures to collate the
evidence. The housing HIA used the Merseyside guidelines.
14
The transport HIA adapted guidance circulated by the Scottish
Office.
26
Both groups progressed through the following stages:
(1) collate background information on policy and population;
(2) identify impacts; (3) describe and/or quantify and/or deter-
mine priorities of impacts; (4) make recommendations. How-
ever, these stages were not distinct or self contained, and earlier
stages were revisited in the light of later findings. The case
studies found that health impact assessment was an iterative
process.
We concluded that there is no single ‘blueprint’ for HIA that
will be appropriate for all circumstances. Different approaches
and methods will be required in different situations. However,
we have defined principles that highlight the key issues to con-
sider. These are presented below.
Key principles for health impact assessment
The HIA process should:
● Screen. Not all policies can be subjected to HIA; a screening
process
6
should be applied to select and determine priorities
of the topics with important health impacts.
● Negotiate. The scope of the HIA and implementation of
recommendations should be agreed with decision-makers.
● Share ownership. The HIA should be jointly owned by the
decision-makers, the investigators, the affected community
and other stakeholders.
● Be timely. The initial HIA should be carried out when the
policy is clearly defined but it is still possible to influence
decision-making.
● Define and analyse the policy. It is important to understand
the policy being assessed, including its rationale, its objec-
tives and evidence of the results of similar policies elsewhere.
This includes consideration of the policy context.
DEVELOPING PRINCIPLES FOR HEALTH IMPACT ASSESSMENT
153
● Define and profile the population. The population whose
health is being considered should be defined and its health
status, health problems and capacity should be profiled. This
should include separate identification and profiling of rele-
vant subgroups.
● Use an explicit model of health. The scope of the health
impacts to be identified, and the nature of causality assumed
should be clear. This requires a framework to define health
impacts, health determinants, and influences on health and
health determinants.
● Be aware of underlying values. HIA is as much art as science.
Judgements must be made in determining priorities of poten-
tial impacts, estimating risks and benefits and making rec-
ommendations. This is necessarily value laden. Investigators
should be explicit about the values or political position from
which HIA is undertaken.
● Be systematic. The HIA should be carried out in a systematic
way, using a comprehensive framework to identify all rele-
vant impacts and a transparent, credible approach.
● Think broadly. All relevant impacts should be identified and
considered, including indirect and long-term impacts.
● Use appropriate evidence. Both quantitative and qualitative
methods may be used in an HIA and the combination of
methods used will vary with circumstances. The evidence
and methods gathered should be appropriate to the impacts
identified and the importance and scope of the policy.
● Involve the community. They have unique insights into how
the proposal might affect their lives, their community, and
their health-related behaviour.
● Take into account local factors. HIA combines evidence from
elsewhere with consideration of local differences that might
influence how and by whom the impacts are borne locally.
● Recognize difference. Communities are not homogeneous.
Different impacts are borne by different sectors of the com-
munity and HIA should make these explicit.
● Monitor impacts prospectively. Having carried out an initial
prospective HIA, there should be a procedure for continuous
monitoring of resultant impacts, to identify any unexpected
impacts and inform future prospective HIA of similar poli-
cies.
● Make practical recommendations. Recommendations should
seek to mitigate adverse and enhance beneficial impacts, be
practical to implement and should aid the most effective use
of limited budgets.
(Note: ‘policies’ is used here to mean policies, programmes or
projects.)
Acknowledgements
The work was funded by the Scottish Executive Health Depart-
ment. We also thank the members of the Transport HIA
Working Group and the NEAR HIA Working Group, which
undertook the two case studies, and the urban regeneration
HIA group that discussed methods of HIA for urban regenera-
tion projects.
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Accepted on 1 February 2001
