Assessment of Cold and
Damp Hazards
Andrew T. Arthur MPH MCIEH FRSPH
Separate hazards for the purposes of
HHSRS
Interrelated in many circumstances
Factors related to cold may also be
factors relating to damp and vice versa
Excess Cold
Main hazard features
Covers threats to health from suboptimal indoor temperatures
Summary of hazard data
Table from Op. Guidance here
Summary of the evidence
Figures for C1 derived from data for
cold/winter related mortality. Estimates for C2
and C3 include cardiovascular and respiratory
illnesses serious enough to lead to hospital
admission. C4 estimates from GP Research
Database and 4th Morbidity Survey of
General Practice
Stat. evidence shows continuous relationship
between indoor temp. and vulnerability to cold
related death. Risk increases with lower
temperatures.
Summary of the evidence
Some indications that excess mortality occurs
up to 19oC, these stats. assume that no cold
related deaths occur in dwellings which
achieve 18oC hall temp. when ext. temp falls
to 5oC
A proportion of excess winter deaths,
particularly those due to respiratory disease is
attributable to cold indoor conditions
Mortality is linked to lack of home heating
independently of outdoor cold stress and vice
versa.
Summary of the evidence
Hypothermia may be implicated in <1% of the
winter excess and is not simply related to
temperature of dwellings.
Excess winter mortality has decreased as
home heating has improved
Health may be affected as a result of
inadequacies in heating, insulation, ventilation
and moisture generation in dwellings
Below 12oC indoors, increased risk of
cardiovascular strain
Summary of the evidence
Up to 15oC may be a risk to cardiovascular
and respiratory health in vulnerable people,
but less acute than below 12oC
Adverse health effects can be reduced by
improved heating and insulation designed to
achieve at least 18oC in living rooms and 16oC
elsewhere.
A significant number of homes in the UK have
temps. In winter consistently below these
thresholds
Problem is less in newer homes
Strength of the evidence
Main risk drivers
Low energy efficiency
Absence of central heating
Disrepair of heating system
Dampness
Excess ventilation
Property age - risk greatest in <1850 dwellings
and lowest in dwellings built >1980
Occupation factors e.g. under-occupation,
heating costs
Aims of hazard reduction
Efficient and controllable heating sufficient to
ensure dwelling can be adequately heated.
(What is adequate? Evidence suggests indoor temperatures
consistent with avoiding adverse health effects should be at least
18oC in living rooms and 16oC elsewhere in the home. In practice
most heating systems will exceed these minimums)
Structural thermal insulation sufficient to
minimise heat loss
Ventilation sufficient to ensure low level
background ventilation without excessive heat
loss or draughts
How are we assessing the
hazard?
Assessment of adequacy of heating,
insulation and ventilation systems
SAP calculation may be appropriate to
assess energy efficiency
Assessment of other factors which may
affect indoor temperature - dampness or
disrepair
What should we be doing to achieve
a reductions in significant hazards?
Worked examples useful with guidance
on remedial measures and re-scoring
Damp and Mould Growth
Main hazard features
Covers health threats associated with
increased prevalence of house dust mites and
mould or fungal growths
….resulting from dampness or high humidities
Includes threats to mental health and social
well-being caused by living with effects of
damp
Summary of hazard data
Table from Op. Guidance here
Summary of the evidence
Figures for C1 from Mortality stats. C2 and C3
from HES. C4 from GP consultations for
coughs and wheeze
High humidities without visible mould or damp
can result in high indoor humidities and greatly
increased house dust mite populations. Ave.
likelihoods may be an underestimate and
should be considered conservative
Consistent evidence for correlation between
level of exposure to mite allergen and degree
of sensitisation in children and adults
Summary of the evidence
Ctte. On Assessment of Asthma and Indoor Air
(Nat. Academy of Sciences, 2000) - sufficient evidence of a
causal relationship between mite allergen and
exacerbation of asthma symptons in sensitised
individuals and also evidence of a causal
relationship between mite allergen exposure
and development of asthma in susceptible
children
Mite allergy may contribute to perennial
allergic rhinitis and also the severtity of atopic
eczema
Summary of the evidence
Mould growth capable of causing may
symptoms, but only Type 1 allergy and
psychological symptoms could be considered
on current evidence to be a potential problem
in a significant number of properties
More serious health effects resulting from
mould exposure are less common, but in rarer
individual cases mould allergy may be a
significant contributory cause of severe
asthma
HDM growth relative to temperature and
relative humidity
Strength of the evidence
Strength of the evidence
Main risk drivers
High humidities (influenced by design,
construction and maintenance and
occupant density and activity)
Reduced levels of ventilation
Aims of hazard reduction
To ensure dwellings are warm, dry and well
ventilated. Indoor RH between 40% and 60%,
achieved by...
Minimising all sources of dampness
Ensuring sufficient ventilation
adequate structural thermal insulation and an
appropriate means of space heating
How are we assessing the
hazard?
Diagnose sources of dampness and humidity structural? Condensation? both?
Look at adequacy of heating provision and use
made of it
Look at adequacy of ventilation and use made
of it
Look at adequacy of structural thermal
insulation
Is there also an excess cold hazard?
What should we be doing to achieve
a reductions in significant hazards?
Worked examples useful and provide
guidance on remedial measures in
typically encountered situations
Questions?