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Future Challenges for Air-Quality and Health in Housing
New Horizons Project DO3
Final Report
Prepared for:
Office of the Deputy Prime Minister,
New Horizons Programme
Prepared by:
C H Sanders, M C Phillipson and C A Hunter
Centre for Research on Indoor Climate and Health
School of Engineering, Science and Design
Glasgow Caledonian University
Cowcaddens Road
Glasgow G4 0BA
Tel 0141 331 8821
Fax 0141 331 3690
Glasgow Caledonian University
April 2004
Future Challenges for Air-Quality and Health in Housing
Summary
Glasgow Caledonian University were commissioned in February 2004 by the Office of
the Deputy Prime Minister (ODPM) to undertake an assessment of “Future Challenges
for Air Quality and Health in Housing” under the Department's New Horizons
programme. This is the final report of this project. It seeks to summarise the study’s
findings, an accompanying technical report describes the background to the findings.
The four key drivers which will affect the air quality and the health of occupants within
housing over the next century have been identified as:
 climate change;
 demographic and social changes;
 changes in construction practice;
 legislation and regulations.
The effect of these drivers on ten important hazards to air quality in housing has
enabled a classification of the hazards in terms of their likely change over the next
century. Given current trends, most of these hazards will get worse, especially high
internal summertime temperatures, radon and other ground contaminants, and fungal
growth and mite and cockroach infestations. Only domestic accidents and problems
with tobacco smoke and other particulates, are expected to reduce in severity.
Quantitative modelling of the winter temperatures and mould risk suggests that the
variation in the changes between different regions will be small. The most important
impact of climate change is summertime overheating; it is not possible to model this
without simulated future hourly data, which preserve the interrelationships between the
variables; this is not currently available. Also, quantitative relationships are needed
linking release of Volatile Organic Compounds (VOCs) from furniture and fittings with
internal temperature and release of ground contaminants with ground temperature.
Air conditioning may become widely installed in housing as a response to rising
summer temperatures. These will add to the CO2 emissions from housing unless strict
measures are taken to control their use. Also, unless they are properly maintained
there is a serious risk of infections, such as Legionella developing in cooling systems.
The Department's current policies are responsive to likely future changes in the drivers
relevant to the internal environment of housing however there are risks from two
measures that may cause problems in the internal environment:

The drive to save energy by improving the sealing of housing, being discussed
in the current revision of Approved Document L1 of the Building Regulations,
may cause the indoor air quality to deteriorate unless compensating measures
are taken within Approved Document F.

The increased building on brownfield sites that was recommended in the
recently published Barker Report as a solution to the current problems in the
housing market, will increase the risk of contaminants entering houses unless
appropriate protection measures are taken.
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Future Challenges for Air-Quality and Health in Housing
Contents
1
Introduction
1
2
Air Quality
2
Drivers for Change
3
Climate Change
Demographic and social changes
Construction Practice
Regulations and Legislation
3
3
4
4
Hazards to indoor air quality
6
3
3.1
3.2
3.3
3.4
4
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
The hazards considered
Internal temperatures and humidities
Fungal growth, dust mites and cockroaches
Volatile Organic Compounds
Radon and other ground contaminants
Toilets, waste disposal and sewerage
Noise
Tobacco smoke and particulates
Lighting
Fire
Falls and other accidents
6
6
7
8
9
10
10
11
11
12
12
Risk Mapping
14
Introduction
Estimated future change of hazards
Mapping future risk priorities
Implications for society
14
15
15
16
6
Implications for Policy Development
18
7
Gaps in Knowledge and Implications for Further Research
20
8
Discussion
22
5
5.1
5.2
5.3
5.4
References
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1
Introduction
Glasgow Caledonian University were commissioned in February 2004 by the Office of
the Deputy Prime Minister (ODPM) to undertake an assessment of “Future Challenges
for Air Quality and Health in Housing” under the Department's New Horizons
programme. This is the final report of this project.
This report presents an overview of the current state of the art for indoor air quality and
health in housing. It seeks to highlight the issues that are driving research, and the
issues that are important to future performance.
Through a process of risk assessment informed by expert opinion, and consideration of
the interplay between future drivers, the change in risk for current hazards is mapped
onto an assessment of the health impacts of a series of risks. The study is therefore
able to prioritise these in terms of their potential consequences for UK health.
Section 2 describes the factors that make up the air quality within housing and affect
the health of the occupants.
Sections 3 details the four drivers that we consider will have the most effect on the air
quality and health in housing over this century.
Section 4 covers the ten 'hazards' that have been identified as having the most impacts
effect on air quality and health in housing.
Section 5 maps the changes in the severity of the hazards that have been identified
earlier onto an assessment of the health consequences of each. This enables the
impacts of each of these onto the health of the nation to be ranked in order of
importance.
Section 6 discusses the implication for the current and future policies of the ODPM,
which are relevant to the internal air quality in housing.
Section 7 discusses the areas that have been identified where further work is needed to
clarify issues or establish the likely risks to air quality in housing in the future.
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2
Air Quality
Indoor air quality is a fundamental determinant of the health, comfort and performance
of people in buildings. It is estimated that we spend approximately 90% of our lives
indoors, therefore exposure to airborne pollutants has direct implications for health.
The Department for International Development identifies indoor air pollution as one of
the four major risk factors for ill health globally [1]. According to a study by the
American College of Allergists 50% of illnesses are caused, or aggravated by, polluted
indoor air [2].
Indoor air quality depends on a combination of factors, any of which can lead to some
discomfort or cause health problems for occupants. As a result air quality cannot be
quantified in absolute terms, and requires careful evaluation. Knowledge and
understanding of the physiological implications of different airborne factors is
continually developing and so the list of potential issues is growing. There has been
considerable work by BRE looking at current performance of English housing with
respect to air quality issues [3, 4]. This has included a detailed survey used to identify
typical exposure levels of a range of pollutants.
The factors which influence the concentration of different pollutants vary depending on
the source of the pollutant [5]. Volatile Organic Compounds (VOCs) and formaldehyde
concentrations are associated with materials brought into the house, and, as such, will
be present in slowly declining concentrations as material sources outgas. Carbon
monoxide and nitrous oxides, however, are associated with combustion processes and
so their presence in indoor air will depend on the utilisation and ventilation quality of
combustion appliances in the dwelling.
VOC is a general characterisation applied to a wide range of different chemicals. The
total exposure contribution of these is used to determine the health implications through
assessment of the total VOC concentration of the air. However, it is recognised that the
sources of these different compounds may vary and, as a result, the affect of particular
drivers will vary depending on the situation. It can therefore be misleading to
generalise with overall VOC concentrations because the emission context determines
the nature and concentration of the compounds present. It is anticipated that changes
in key drivers will lead to a change in the balance and nature of future impacts from
poor air quality.
Other issues, which might not be considered directly relevant to air quality as such, also
have an important role in determining quality of the indoor environment and therefore
the health of the occupants. The most important of these are light levels within houses
and especially noise from adjoining houses and flats or from the outdoor environment.
These have therefore been included in the analysis in this report.
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3
Drivers for Change
This section discusses the four key drivers for change, which will have direct and
indirect influences on the future air quality and health in housing in England and Wales.
3.1
Climate Change
There is a growing recognition that climate change will have profound implications for
many human activities, and will have major impacts on the built environment [6]. Work
by the UK Climate Impacts Programme (UKCIP) has coordinated research activity in
the UK and has helped to focus climate science towards providing tools and information
to enable impact studies to be undertaken. In 2002 the UKCIP published four
scenarios, the UKCIP02 scenarios [7], which provide the current best estimates of the
future climate in the UK. The issues of most relevance to the buildings and their internal
environment are:

The UK climate will become warmer, with the average annual temperature
being between 2ºC and 3.5ºC warmer by the 2080s.

Hot summer temperatures and heat waves will occur more frequently, and
extreme cold winters will become less common.

Solar radiation levels will increase in the summer and fall in the winter.

Atmospheric vapour pressure will rise.

Heavy winter precipitation events will become more frequent, increasing the
frequency of flooding.

Wind speed, which is of particular importance to the performance and internal
environment of buildings, is not expected to change significantly, however there
may be a slight increase in the frequency of severe gales.
3.2
Demographic and social changes
Some of the changes predicted for the UK population over the next century will have
implications for the way in which housing is used and for the health of the occupants.
As with the other key factors identified in this report, there are numerous cross cutting
issues, which need to be considered in combination rather than in isolation. There are
a number of key authoritative sources of information, including the Office for National
Statistics [8] and the British Council [9].
The analysis in the Technical Report has shown that the following trends are relevant to
the indoor environment of buildings:

Regional population movements (net movements to the South of England).

Ageing population and increasing dependency (more people over 65).

Growing household requirement (more single person homes).
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
IT and Communications (more working from home).

Provision of good quality housing in regions with net population growth.
The housing requirement of the population is changing because of changes in
household size and the need for more accommodation suitable for the elderly.
Alongside the changing needs of housing are the associated changes in service
provision and infrastructure, which are required in response. The service levels needed
for an elderly population are quite different, leading to particular issues associated with
health in buildings.
3.3
Construction Practice
Recent trends in construction have moved away from traditional masonry house
building, towards novel, innovative techniques. This has largely been due to the
influence of the Egan Report “Rethinking Construction” published in July 1998 by the
Construction Task Force [10]. This found that UK construction needed to become more
efficient, improve the quality of its output and improve the satisfaction of construction
clients. This suggested that industry needed to:

Drive down construction costs.

Increase the quality of construction.

Move towards sustainable construction with an emphasis on prefabrication and
off-site assembly.

Become more innovative to streamline the construction process.

Develop partnering between contractors and suppliers to move towards a
dispute free industry.
The Egan Report led to a range of initiatives; in particular, prefabrication has been
identified as a major way forward in delivering these required improvements. Many of
the innovative techniques being developed use lightweight products, which tend to give
the finished dwelling a low thermal mass. This results in little thermal storage in the
building, which will respond quickly to heating and cooling. This leads to a greater
tendency for the indoor environment to overheat in the summer, which could cause
problems given the direction of climate change. These problems can be overcome with
an appropriate building service strategy, however, appropriate design and specification
is needed.
3.4
Regulations and Legislation
Building Regulations seek to ensure the health and safety of building users, promote
energy efficiency, and enable buildings to be accessible to those with disabilities. They
make functional performance requirements for building design and construction. Many
of the parts to the Building Regulations are relevant to the indoor environment and the
health of occupants. Development of the Regulations seeks to keep pace with
changing construction practice and tackle particular risks or hazards that are identified.
In recent years the issue of climate change has been included in the review process of
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the Building Regulations to determine how it may affect the performance requirements.
In particular, climate change has acted as the major driver for the revision of Approved
Document L of the Building Regulations, concerning the conservation of fuel and power
and limiting greenhouse gas emissions. Recent amendments to AD L have increased
insulation requirements and introduced new requirements for air tightness of buildings.
Whilst this should provide more energy efficient buildings, there is potential for conflict
with problems of air quality and health in buildings.
The World Health Organisation (WHO) produces guidelines for protecting human health
against a range of 35 air pollutants [11]. These include pollutants from both indoor and
outdoor sources. The guidance offered by the WHO is designed to protect public
health from the adverse effects of air pollutants by setting standards for pollutant
exposure levels below which there is no significant risk to public health. These
standards are intended to be used within the basis of a risk assessment or risk
management process to inform and guide decisions.
The European Commission have developed the General Product Safety Directive
(GPSD), 2001/95/EC, to provide a ‘broad-based, legislative framework of a horizontal
nature’ to ensure the sale of safe products [12]. The scope of the GPSD includes both
consumer products and ‘products which are designed exclusively for professional use
but have subsequently migrated to the consumer market.’ The provision of housing is
considered a product in the terms of this Directive.
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4
Hazards to indoor air quality
4.1
The hazards considered
The BRE publication ‘Building regulation, health and safety’ [13] identified twenty seven
‘hazards’ to health and safety in and around buildings that should be taken into
consideration in the formulation of Building Regulations. Those that are of most
relevance to the internal environment and the health of occupants have been grouped
into the ten categories shown below.

Internal temperature and humidity.

Fungi, dust mites and cockroaches.

Volatile Organic Compounds.

Radon and other ground contaminants.

Toilets, waste disposal and sewerage.

Noise.

Tobacco smoke and particulates.

Lighting.

Fire.

Falls and other accidents.
It is evident that, while some of these bear directly on indoor air quality, others, such as
lighting and noise, are less relevant. These factors are, however, important
determinants of the quality of the indoor environment and affect the health of the
occupants.
4.2
Internal temperatures and humidities
Human temperature regulation, thermal comfort and health are affected by a
combination of air temperature, radiant temperature, humidity and air movement.
Indoor air temperatures of 18–24 °C normally cause no discomfort or threat to health.
Outside this range, thermal stress increases progressively and defence mechanisms
(eg shivering, sweating) come into play. Humidity has little direct effect on comfort,
except in hot conditions, but damp clothing or bedding increases the cooling effect of
low temperatures. Low humidity can dry the eyes, and nasal passages and cause
problems with static electricity. The main effects of air movement are discomfort from
draughts and drying, both of which increase with air velocity and turbulence.
Age is the most important factor affecting human response to temperature, since the
elderly suffer impaired thermoregulation, mental or physical health and low socioeconomic status. While infants have a high ratio of surface area to volume, which
entails more rapid heat loss, and an immature thermoregulatory system. they are more
likely to be given special protection from serious risks from the thermal environment.
The following health consequences have been identified:
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Increased Risk of Summer Overheating There is expected to be an increase in
problems with summer overheating of housing, which, in extreme circumstances, can
lead to hyperthermia in vulnerable sections of the population. The anticipated reduction
in return periods of hot weather, and the associated increase in the levels of extremes
will have serious consequences for the population and will necessitate adaptation of
behaviour and the built environment to cope. Without adaptation this would translate
into an extra 2,000 deaths per year by the 2050s from hyperthermia and up to 200,000
extra days of NHS treatment [14]. Problems will be significantly worse in large urban
environments where the urban heat island effect will exacerbate the situation.
Legionella One response to hotter summers may be a wider uptake of air conditioning
systems in housing. Maintenance of domestic systems will be left to individual
householders; this could lead to an increased risk of Legionella problems unless
systems are appropriately designed.
Decreased Risk of Hypothermia Climate change predictions suggest that winters will
become warmer, effectively reducing hypothermia problems amongst vulnerable
sections of society. It has been estimated [14] that the increase in winter temperatures
will result in a reduction in winter mortality of some 20,000 deaths per year by the
2050s.
The elderly will be particularly at risk from overheating due to a combination of factors
including impaired thermoregulation, lack of mobility, and other mental and physical
health issues. Infants may also have a higher risk to health as a result of immature
thermoregulatory systems, however, they are also likely to be given special protection
from serious risks from the thermal environment.
Summer overheating effects are likely to be worse in large urban centres where the
urban heat island effect will exacerbate the situation. In addition there is likely to be a
divide between householders who can afford to install comfort cooling and those that
cannot. The lower economic status associated with the elderly may also inhibit their
ability to afford appropriate comfort cooling.
4.3
Fungal growth, dust mites and cockroaches
The growth of fungi and the occurrence of mites in buildings are dependent primarily
upon the relative humidity in the locations where moulds and mites are likely to grow.
Moulds can grow on a range of materials including wall coverings, bedding materials,
shoes, carpets, masonry and furnishings, in areas which are colder or less well
ventilated than normal. The most common health effects of moulds are allergic
reactions to the spores, especially asthma, however other health effects associated
with toxic and psychological reactions and fungal infections have been noted.
Dust mites are found in carpets and soft-furnishings in homes throughout the world and
are more common in humid conditions. Although the mites themselves die from
desiccation, the allergen contained in the faecal pellets they produce persists
throughout the year and is a major cause of asthma in the UK.
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Cockroaches which are much more frequent in cities and the built-up environment, are
all capable of picking up food poisoning bacteria from food and excreting them in the
faeces. They have been shown to be capable of transmitting the bacteria to other
cockroaches as well as to foodstuffs, clean water sources and their general
environment. Cockroach spread from building to building is partially limited by the
external temperature and therefore a progression to warmer summers may increase the
likelihood of infestations occurring in properties unconnected to the source. Risk of
spread of cockroach infestations will increase in urban centres if higher density urban
developments are required in response to housing need. Construction features that
provide potential harbourage for cockroaches (for example stud partition) encourage
cockroach infestation and with the move towards off-site construction there is the
increased potential for voids to result as part of this process.
Changes in demography may lead to a change of risk for some of the aspects of this
hazard. The trend towards single occupant households with lower internal humidity
loads, will reduce the risks of mould growth and mite infestation. However smaller
dwellings reduce the occupied space per person there will be an additional risk of
condensation on cool surfaces. The risks of condensation and mould growth will be
reduced by the increased levels of insulation required in houses.
The main impacts of Building Regulations will be the improved insulation standards
contained in Approved Document L and the more specific guidance for ventilation
provision based on the risks of condensation that will be contained in Approved
Document F. Thus while the building may become drier, any allergens released or
produced within the property have an increased chance of remaining in the internal
environment for longer and therefore having an effect on the health of the occupant.
4.4
Volatile Organic Compounds
The term 'Volatile Organic Compounds' (VOCs) covers a wide range of chemicals that
produce vapours at room temperature. There can be a wide range of potential sources
of VOCs in housing, including: natural metabolic processes, household consumables
(particularly cleaning products), the building fabric (particularly adhesives, solvents and
treatments), furniture and finishes (for example carpets, paints, etc) and external
pollution.
Exposure to individual VOCs can have adverse health effects, however, there are also
synergistic effects between different VOCs, so that a mixture, where all are individually
within a safe concentration threshold, can still have health consequences. The range of
different VOCs and these synergistic effects mean that generally the total VOC (TVOC)
level needs to be considered along with the particular effects of individual chemicals.
Internal VOC sources will be released into the air more quickly in warmer conditions,
however, they will also be used up more quickly and cease to be a problem sooner.
External sources of VOCs could become more of a problem in the future during the
summer as good ventilation of homes will become more important to control
overheating problems. Natural ventilation is important in controlling VOC
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concentrations within homes. Changes in wind speed are an essential component to
future natural ventilation levels, however, there is low confidence in the accuracy of
current predictions of future wind behaviour.
Potential changes towards innovative and lightweight construction techniques may well
be associated with increased solvent and adhesive use in construction, which would be
a greater source of VOCs for the internal environment. Careful specification and
technology can provide alternative construction options, although there may be
additional costs associated with this.
European Legislation will strongly influence the concentration of VOCs within dwellings.
Ongoing research work is informing the development of future performance guidelines,
such as the World Health Organisation guidelines which look at a range of airborne
pollutants, including VOCs. It is anticipated that regulations and legislation will continue
to strengthen requirements for protecting public health, and will in the future be a key
driver in controlling any hazards.
4.5
Radon and other ground contaminants
Land can be contaminated as a result of industrial processes (eg gasworks, metal
manufacturing, dockyards, etc), landfill activities and agricultural uses as well as
naturally occurring contaminants. The main contaminants are:

radon from the underlying igneous rocks in certain areas

heavy metals (eg lead, cadmium and mercury);

organic compounds (eg halogenated volatiles, pesticides and polychlorinated
biphenyls);

inorganic compounds (eg asbestos, chlorides, sulfates);

vapours (eg petrol/diesel fumes) and gases (eg landfill gas).
Building on contaminated sites raises a number of health issues because many of the
contaminants are toxic or carcinogenic. Occupiers of such sites can be exposed to
these contaminants through inhalation of airborne dust and vapours, absorption through
the skin, ingestion of produce grown on the site and, in the case of small children eating
soil, direct ingestion of the contaminated material.
Risk reduction can be achieved by: removal of the material generating the gases,
construction of barriers to prevent the entry of gases into building, containment to
reduce emissions of gases from the ground outside of the footprint of the building [15].
Climate change could increase the mobility of these types of gases and lead to greater
risk to householders. It is thought that warmer ground temperatures due to climate
change could increase the rate of generation of these gases in the ground, however,
more work is required to demonstrate and quantify this effect.
Population movements into some regions of England will increase pressure for housing
developments on brownfield sites, which may be contaminated, leading to a greater
need for ground remediation or effective protection measures.
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Robust technical guidance for protection of houses from the ingress of contaminants
exists. If this is taken into account in any novel designs, changes in construction will
not affect the risks of air quality in housing from ground contaminants.
The section of the Building Regulations dealing with this issue (Approved Document C)
has recently been revised taking climate change and the latest protection requirements
into account. This guidance will be valid for the foreseeable future, but should be
reviewed as better information about associated issues becomes available.
Risk from this hazard is constrained by geographical location and dwelling design.
There are no clearly susceptible subgroups of society.
4.6
Toilets, waste disposal and sewerage
Although infectious organisms and the mechanism by which they can infect people
present a health hazard associated with bathrooms and toilets, the presence of people
infected with a diarrhoea or other infective agent is a precondition of any risk. The most
likely associated disease is dysentery, other diseases include gastroenteritis caused by
viruses or protozoa. The greatest risks to health occur in sanitary accommodation in
multiple use, e.g. in houses in multiple occupation: old peoples homes, schools and
public places. Diarrhoea and faecal incontinence are very common in older people
especially in the frail and disabled and gastroenteritis is a serious illness in the aged,
since they are among those at greatest risk of dehydration from loss of fluids as a result
of vomiting or diarrhoea.
While, it is important to note that the conventional systems present negligible risk of
infection if they are in good repair and regularly cleaned, risks will increase with an
aging population This factor coupled with a warmer climate increasing the chance of
food-poisoning does imply a serious risk to the health of occupants.
Recent legislation, aimed at reducing water use, has encouraged a move away from
older-style toilets, which use between 7.5 and 13 litres per flush, to low flush toilets
using only 6 litres per flush. This, and the use of partially treated waste water
(greywater) from washbasins and showers for flushing toilets, has the potential to
permit the build-up of biological biofilms. The droplets formed by flushing toilets can
contain bacteria, viruses and oocysts which remain as aerosols for long enough to
settle on surfaces in the lavatory or bathroom. In addition, current flushing rates do not
completely remove the microorganisms, which may become absorbed into the
porcelain surfaces and reappear in further flushes.
The elderly are particularly vulnerable to the consequences of ill health associated with
poor sanitation. In addition, the increased difficulty of achieving adequate cleaning as
mobility decreases in an ageing population may increase the risks of such health
problems.
4.7
Noise
It is unlikely that noise within the home will ever be loud enough to cause damage to
the hearing of occupants. However noise from neighbours, traffic, children playing
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outside etc. is a major cause of annoyance to occupants and is associated with
psychological stress.
While changes in climate will not impact directly on noise levels within buildings, the
associated social changes such as increased use of gardens for barbecues in warm
summer weather and changes in window opening habits to provide better ventilation,
may lead to increased nuisance from noise outside the house.
The increased density of housing necessary to meet demand for accommodation in
certain areas of the country, especially the South of England, will lead to more
construction of terraced houses and flats. This will lead to more risk of sound
transmission between dwellings with consequent annoyance to occupants. Noise is
likely to be an increasing problem for people living in high density urban environments,
compared to those living in rural or suburban areas.
4.8
Tobacco smoke and particulates
Particles in buildings frequently come from external sources although tobacco smoke is
an important indoor source. A number of fibrous materials used in construction,
including asbestos, glasswool and rockwool can release dust when damaged.
However, as man-made mineral fibres do not split into extremely fine fibres, few of the
airborne fibres will be inhaled into the lung, but they can cause skin and upper
respiratory tract irritation.
In theory environmental tobacco smoke (ETS) can cause any of the health effects
normally associated with active smoking but at a lower level of risk. Between 5% and
10% of all lung cancers (several hundred extra deaths per year in Britain) occurring
among non-smokers and about 5% of coronary heart disease deaths (between 5000
and 10 000 extra deaths per year) are related to passive smoking. There are about 12
million adult cigarette smokers in Great Britain and in 2002 it was estimated that 24% of
women and 26% of men smoked, reflecting a steady decline since the mid 1970s. This
decline has been more pronounced in male than female smokers and exposure is likely
to decline, especially if a ban on smoking in public places is implemented. There is a
demonstrable correlation between social class, gender and the likelihood of being a
smoker. Generally there are higher numbers of manual/unskilled workers who currently
smoke than in other classes. There are also generally changes with age group with
statistics for young adults showing an increase in the rate of smoking offsetting some of
the decline in smoking in other age groups. Legislation and taxation may well have a
complex effect on the future social and gender balance of smokers.
The UK government forecast that congestion will grow faster than previously assumed,
by 2010 congestion levels on all roads could be up by at least 11%. The increased
congestion coupled with continued concentration of the UK population in the South East
of the country could lead to an increase in the incidence of summer smogs.
4.9
Lighting
Visual acuity increases with the level of illuminance, and hazardous situations can be
created by inadequate lighting. Studies indicate that this may be a significant
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contributory factor in domestic and industrial accidents. Inadequate lighting may also
affect the behaviour of people in buildings. If individuals cannot identify a hazard, they
may not be able to evaluate the potential harm.
It is expected that there will be increased sunshine in the summer, especially in the
south of England, leading to higher light levels, this may increase problems of glare in
houses. However winter sunshine will decrease, due to increased cloudiness; this will
lower light levels within housing. Also, one method of preventing excessive solar gain
and limiting the high summer temperatures that may result within housing, is to make
effective use of natural shading, or incorporate shading devices and smaller windows.
This may have the advantage of reducing glare in summer but may make houses
darker in the winter increasing the risks of accidents and depressive illness.
4.10
Fire
According to Home Office data, there are about 70,000 fires a year in dwellings; 80% of
these are accidental, the remainder being malicious in origin. Fire deaths are not
evenly spread among the whole population, rising steadily above average with
increasing age beyond 65. The physiological and psychological effects of exposure to
toxic smoke and heat from a fire result in varying degrees of harm, which include either
death or permanent injury.
The only possible effect of climate change on fires within homes is the increased risk of
scrub or woodland fires, occurring in summer drought conditions, spreading into the
house. This risk should be taken into account in the planning process for new housing.
Statistics show that there is an increased risk of fire affecting elderly people as a
consequence of an increased susceptibility to accidents in the home. In addition the
reduced mobility and increased confusion of this age group will act to impede safe
evacuation of the building in the event of a fire occurring. The ageing population will
therefore face an increased overall risk of fire and be less able to survive it. This is a
key demographic change for this hazard.
The move towards planning for higher density urban developments may result in fire
incidents affecting greater numbers of people. Regulations and legislation make
requirements for controlling this risk; these requirements need to be integral to an
innovation in urban space design.
4.11
Falls and other accidents
Slips, trips and falls are a major cause of accidents in and around buildings. A key
feature within buildings is the nature and condition of flooring and its affects upon the
safe circulation of users. Uneven and badly maintained floors are known to be
important causal factors in accidents in the workplace. Wetness is a particular problem;
for example, in the catering industry,
The only important relationship between climate change and accidents in buildings is
the lower possible light levels discussed in Section 4.9. This could lead to increased
risk of falls on stairs, especially by the elderly with poor eyesight.
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There are requirements within the Building Regulations, the Housing Fitness Standard,
and other legislation for measures to control the risk of these accidents occurring. It is
anticipated that these requirements will be maintained and where appropriate
strengthened in the future. Regulations should be a positive driver for this hazard in
future and act to further reduce its level of impact.
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5
Risk Mapping
5.1
Introduction
Risk mapping has been used to identify the issues which are anticipated to change
significantly and have affect the health of a significant number of people in the UK. This
can be expressed as:
Risk Mapping =
(potential change in the hazard) combined with (current level of Impact)
Most of the changes in the hazards are negative, i.e. they are acting to make the air
quality in housing worse and increase the risks to health. Because positive impacts
may also have implications for policy, no distinction between the two trends has been
made in the discussion below.
The results of the risk mapping can be used to identify those issues that have the
biggest current impact for health, and the most potential for future change; these will be
of most concern to future policy development.
This is summarised in Figure 1.
Current Level of
Health Impact
High
Low Concern
Most Concern
Low
Least Concern
Some Concern
Low
High
Potential Future
Change of Drivers
Figure 1 –Interpretation of Risk Mapping for Future Decision Prioritisation
Table 1 – Current Level of Hazard
Classification
1
2
3
4
5
Description
Associated with illness, rather than fatal consequences
Estimate to be responsible for between 1 and 9 deaths per year.
Estimate to be responsible for between 10 and 99 deaths per year.
Estimate to be responsible for between 100 and 999 deaths per year.
Estimate to be responsible for more than 1000 deaths per year.
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In order to undertake the risk mapping for this study, the current health impact of the
main hazards identified in Section 4 have been assessed from statistics [13] and
classified according to Table 1.
5.2
Estimated future change of hazards
Section 4 contains a detailed discussion of the key drivers for each hazard, and their
interplay; this is summarised in Table 2, in which the final column shows the net effect
of the different drivers.
Net Effect of
Drivers
4.2
Internal temperature and humidity
3+
0
2+
2+
4.3
Fungi, dust mites and cockroaches
3+
2+
2+
24.4
Volatile Organic Compounds
2+
0
3+
24.5
Radon and other ground contaminants
3+
2+
0
14.6
Toilets, waste disposal and sewerage
2+
1+
0
1+
4.7
Noise
1+
2+
2+
24.7
Tobacco smoke and particulates
0
0
0
14.9
Lighting
1+
0
1+
14.10 Fire
0
2+
1+
24.11 Burns, falls and other accidents
0
1+
0
2Key:
1 the driver has a minor influence on the hazard
2 the driver has a significant influence on the hazard
3 the driver is central to the hazard
0 change in the driver will not influence its current effect on the hazard
7+
5+
3+
4+
4+
3+
11+
1+
1-
Hazard
Climate
Section
Regulations
Construction
Demography
Table 2 - Potential influence of changes in key drivers on common hazards
+ The driver will exacerbate the future hazard
- The driver will reduce the future hazard
5.3
Mapping future risk priorities
The future change in hazard level shown in Table 2 can be combined through
multiplication with the risk classification given in Table 1 to provide a risk mapping of
the relative future health consequences associated with a hazard as shown in Table 3,
which is arranged in order of the potential significance of changing future risk. By
comparing the relative health change associated with different hazards, the most
significant future health hazards can be identified, with positive numbers indicating
levels of increased risk, and negative numbers indicating levels of reduced risk.
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Future Risk
Priority
Internal temperature and humidity
Radon and other ground contaminants
Fungi, dust mites and cockroaches
Toilets, waste disposal and sewerage
Volatile Organic Compounds
Noise
Fire
Lighting
Burns, falls and other accidents
Tobacco smoke and particulates
Current Risk
Classification
4.2
4.5
4.3
4.6
4.4
4.7
4.10
4.9
4.11
4.8
Hazard
Future Driver
Summary
Table 3 - Future Risk Priority
Section
16
7+
4+
5+
4+
3+
3+
1+
1+
11-
5
5
2
2
2
2
4
1
3
4
35
20
10
8
6
6
4
1
-3
-4
Table 3 shows that, on the present assessment, the two most important hazards are
internal temperatures and radon and other ground contaminants, both of which are
expected to become greater risks in the future, unless positive steps are taken to
counteract them.
5.4
Implications for society
Table 4 shows the sectors of society identified as being particularly vulnerable to these
hazards. For some hazards the principal driver may be geographical location, and
therefore there is no distinction in risk between social groups. In other cases there is
one or more particular elements of society for whom the risk or consequence may be
greater. Where possible, Table 4 has been developed on the basis of published
statistics and therefore reflects other research work.
It is noteworthy that Table 4 shows that for half of the risks the elderly section of
population may be particularly vulnerable. With demographics showing a continuing
trend for an ageing population, there may be an increased prominence of such
problems if these are not addressed.
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Internal temperature and humidity
4.3
4.4
4.5
4.6
4.7
Fungi, dust mites and cockroaches
Volatile Organic Compounds
Radon and other ground contaminants
Toilets, waste disposal and sewerage
Noise
4.8
Tobacco smoke and particulates
4.9
4.10
4.11
Lighting
Fire
Burns, falls and other accidents
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Elderly &
Children
Elderly
Elderly?
Elderly
Young
Adults
Elderly
Elderly
Wealth / Social
Background
4.2
Urban / Rural
Hazard
Age Groups
Table 4 - Vulnerable Sectors of Society
Section
17
Urban
Poor
Urban
Urban
Unskilled
Workers
-
Urban
-
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6
Implications for Policy Development
This section highlights the particular implications of this report for policy development
within the context of the key areas of interest within the ODPM, as detailed below. The
theme of providing decent homes is common to several of these areas of policy.
Building Regulations : A number of areas of the Building Regulations are likely to be
affected by future changes to the demands made on the indoor environment of housing.
The two key factors that must be taken into account are the ageing population and the
changing climate. The current revision of Approved Document L1 Conservation of Fuel
and Power, driven by the need to reduce greenhouse gas emissions, is proposing
higher insulation levels more stringent standards for air tightness. Warmer, more poorly
ventilated housing may lead to particular health problems, including hyperthermia,
hygiene and internal pollution problems. Care needs to be taken that appropriate
ventilation requirements are made through Approved Document F to compensate for
any loss of fabric infiltration.
Housing: The Barker Report published in 2004 recommended increased building in
higher densities on brownfield sites as a solution to the current problems in the housing
market. Higher density housing has particular health consequences for the indoor
environment, including: exacerbation of the urban heat island effect and increased
pressure on summer overheating risk, increased risk of biological pests spreading
between dwellings (eg cockroaches) and increase in annoyance cause by noise
transmission between dwellings. Use of brownfield sites will have an associated risk of
contaminants entering the home unless appropriate clean up and barrier technologies
have been applied.
The Housing Health and Safety Rating System (HHSRS) has been developed to
replace the housing fitness standard. It has been developed to form a basis for action
against unacceptable housing conditions and will be included in Regulations as a
means for determining the severity of housing. The hazards outlined in Section 4 to the
Indoor Environment and Health in Housing should therefore be implicit to the intent of
use of HHSRS. Future development of HHSRS, and any future successor, must take
note of these changing hazards to ensure that future assessments are based on a
complete understanding of the state of the art.
Neighbourhood Renewal Unit: In January 2001 the Prime Minister launched its
vision for neighbourhood renewal in the form of “New Commitment to Neighbourhood
Renewal: A National Strategy Action Plan”. Indoor air quality and health in housing is
particularly relevant to the these aims. And there is therefore a clear link between the
future of air quality and health in housing and the continuation of the current strategy
into the future.
Social Exclusion Unit The Social Exclusion Unit sets out in its report “Tackling Social
Exclusion: Taking stock `and looking to the future” the issues that is sees as relevant
for future development of its activities. There is some commonality between those
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issues affecting the future of indoor air quality and health in housing and those affecting
social exclusion. As a result, some of the health hazards associated with the future of
air quality in housing may become more strongly linked with social exclusion.
Sustainable Communities: The Communities Plan “Sustainable Communities:
Building for the Future” was launched in February 2003. This sets out a long term
strategy for delivering sustainable communities by tackling housing demand and
housing supply issues throughout the country. It identifies a series of key elements to
be addressed in achieving this, the most relevant to this report being associated with
delivering decent homes.
This report shows that in future there will be a series of issues that affect the quality of
the internal environment of housing, and which could lead to a deterioration in the
fitness of housing. Although winter thermal comfort may improve in housing, summer
overheating will introduce much greater thermal stress for housing occupants. The
dimension of thermal comfort therefore could be extended to consider summer and
winter comfort. All of the hazards outline in Section 4 could be relevant to housing
sustainability, and the priorities established in the Risk Mapping in Section 5 could be a
guide to where appropriate consideration may be given in future.
Urban Policy The urban policy unit was established in 2002 following the White Paper
“Our towns and cities: the future”. This paper identifies a number of key challenges for
urban life in the UK all of which are associated with the future hazards for air quality
and health identified in Section 4. Aside from reducing the sustainable value of housing
in urban centres, these hazards will have a direct impact on the quality of life of
individuals.
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7
Gaps in Knowledge and Implications for Further Research
The analysis and discussion in the preceding sections of this report has identified a
number of areas in which knowledge is currently lacking and in which further research
should be undertaken. These are discussed below in terms of the relevant drivers and
hazards.
Climate change data
The most important climate parameter which determines the ventilation of buildings,
and therefore the internal air quality, is the wind speed. Unfortunately this parameter is
the one which is most difficult to predict in the future. The present best estimate in the
UKCIP02 scenarios [7] is that mean wind speeds will not change over the present
century, however it is recognised that there is considerable uncertainty in this
prediction. Further research is needed to improve the predictions of future wind
speeds.
High internal temperatures and humidities during hot spells in the summer have been
clearly identified as the most significant risk to the health of buildings. Unlike, for
example, cold winter internal temperatures, which depend simply on the external air
temperature, high internal temperatures depend on the coincidence of high external
temperature, solar radiation and humidity and low wind speed. Currently available
future climate data cover only individual variables and do not take account of the
necessary interrelationships between variables. Work is needed to generate future
climate data which represents the all the interactions between variables in a realistic
way.
It is expected that release of potentially hazardous gasses from the ground and from
materials within buildings will increase as the ground and internal temperatures rise. It
is not, however, possible to quantify these effects at present. Work is needed to
establish the relationships between temperature and the release of gas from materials.
Demographic and social changes
In future increasing numbers of households will consist of single elderly people. This
will increase the chance of accidents in the home and similar problems, unless
buildings are designed accordingly. Consideration of appropriate strategies and
technical solutions to facilitate safe housing for the elderly is required.
Construction Practice
Excessively high indoor temperatures in summer have been identified as one of the
most significant impacts on the internal environment. At present the installation of
cooling by air conditioning in housing, is very unusual in the UK. There is, however,
evidence that these systems are becoming the latest 'fashion accessory' in housing,
comparable to double glazing in the eighties and conservatories in the nineties and are
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Future Challenges for Air-Quality and Health in Housing
being installed at the top end of the housing market. Manufacturers are anticipating
substantial sales in the future as the demand spreads to cheaper houses.
This situation will lead to a number of problems. Current air conditioning systems are
energy inefficient and their widespread use will add significantly to CO 2 production from
the housing stock. Cooling systems are not currently included in the SAP rating
procedure, which is the basis of the Carbon Index, which is referenced in Approved
Document L1. Inclusion of these systems in the SAP procedure, would make their
impact clear and drive research towards the development of more efficient systems or
methods of avoiding their use altogether by the more effective use of natural ventilation
or thermal mass.
Regulations and Standards
Building Regulations are reviewed regularly, and recent reviews (for example the
review of AD A (structures) completed in 2002 and the revision of AD C completed in
2004) have taken climate change into account. One issue where care needs to be
taken that improved regulations in one area do not cause problems in another is the
reduction in ventilation of housing that might be caused by the improved sealing
measures being specified in the current revision of AD L. It is important that
compensating changes are included in the ventilation provisions on AD F to ensure that
air quality within houses is not adversely affected.
A more complex area is the role of British and European Standards that are widely
referred to in Regulations. Because the standardisation process is based on
consolidation of past knowledge, it is very difficult for it to take account of future
changes.
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8
Discussion
The four key drivers which will affect the air quality and the health of occupants within
housing over the next century have been identified as:

climate change;

demographic and social changes;

changes in construction practice;

legislation and regulations.
The effect of these drivers on ten important hazards to air quality in housing has
enabled a classification of the hazards in terms of their likely change over the next
century. It is felt that, given the current direction of the drivers, most of these hazards
will get worse, especially high internal summertime temperatures, radon and other
ground contaminants, and fungal growth and mite and cockroach infestations. Only
accidents within the house and problems with tobacco smoke and other particulates,
are expected to reduce in severity.
Quantitative modelling of the winter temperatures and mould risk, using the monthly
values of the climate changes expected in the London, Plymouth and Newcastle areas,
suggests that the changes are similar in all parts of England with only small variations
between different regions. The most important impact of climate change is summertime
overheating; it is not possible to model this without simulated future hourly data, which
preserve the interrelationships between the variables; this is not currently available.
Also, quantitative relationships are needed linking release of Volatile Organic
Compounds (VOCs) from furniture and fittings with internal temperature and release of
ground contaminants with ground temperature.
There is a danger that air conditioning and mechanical cooling systems will become
widely installed in housing as a response to rising summer temperatures. These are
energy inefficient and will add to the greenhouse gas emissions from housing, unless
strict measures are taken to control their use. Also unless they are properly maintained
there is a serious risk of infections, such as Legionella developing in cooling systems.
The Department's current policies are responsive to likely future changes in the drivers
relevant to the internal environment of housing however there are risks from some
measures that may cause problems in the internal environment:
 The drive to save energy due to air leakage by improving sealing of housing,
being discussed in the current revision of Approved Document L1 of the
Building Regulations, may cause the indoor air quality to deteriorate unless
compensating measures are taken within Approved Document F.
 The increased building on brownfield sites that was recommended in the
recently published Barker Report as a solution to the current problems in the
housing market, will increase the risk of contaminants entering houses unless
appropriate protection measures are taken.
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References
1. Department for International Development. “Achieving Sustainability: poverty
elimination and the environment”.
www.dfid.gov.uk/polociesandpriorities/files/sustainability.htm
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3. Coward, S.K., et al. “Indoor air quality in homes in England”. BRE Report BR
433, Building Research Establishment, Watford. 2001.
4. Coward, S.K., Brown, V.M., Crump, D.R., Raw, G.J. and Llewellyn, J.W. “Indoor
air quality in homes in England: Volatile Organic Compounds”. BRE Report BR
446, Building Research Establishment, Watford. 2002.
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protocol for the assessment of indoor air quality in homes and office buildings”
BRE Report BR 450, Building Research Establishment, Watford. 2002.
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the Built Environment. Report 2, Foundation for the Built Environment, London.
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7. UK Climate Impacts Programme “Climate change scenarios for the United
Kingdom: The UKCIP02 Briefing Report”. Tyndall Centre for Climate Change
Research, Norwich. 2002.
8. The Office for National Statistics. http://www.statistics.gov.uk
9. The British Council. http://www.britishcouncil.org/
10. Construction Task Force. “Rethinking Construction”.
http://www.dti.gov.uk/construction/rethink/. July 1998.
11. World Health Organisation. “Air Quality Guidelines for Europe” 2 nd Edition,
Copenhagen, WHO Regional Office for Europe, 2000.
12. European Commission General Product Safety Directive (GPSD), 2001/95/EC
http://europa.eu.int/comm/consumers/cons_safe/prod_safe/gpsd/index_en.htm
13. Raw, G.J., Aizlewood, C.E. and Hamilton, R.M. “Building Regulation, health and
safety. BRE Report BR417, Building Research Establishment, Watford. 2001.
14. Department of Health. “Health Effects of Climate Change in the UK”. London.
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