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It is estimated that people in the developed world spend more than 85-90% of their time indoors. Of this, most is spent in homes. To minimize health risks from pollutants occurring in homes, exposures should be controlled. The most effective way to achieve this is to control sources of pollutants and to reduce emissions. Often, especially in existing buildings, this strategy is difficult to implement, in which case exposures are controlled by providing sufficient, presumably clean, outdoor ventilation air to dilute and remove the contaminants. The present paper attempts to find out how much ventilation is needed in existing homes to reduce health risks. This is achieved by reviewing the published scientific literature investigating the association between measured ventilation rates and the measured and observed health problems. The paper concludes that, generally, there are very few studies on this issue and many of them suffer from deficient experimental design, as well as a lack of proper characterization of actual exposures occurring indoors. Based on the available data, in the reviewed studies, it seems likely that health risks may occur when ventilation rates are below 0.4 air changes per hour in existing homes. No data were found indicating that buildings having dedicated natural ventilation systems perform less well than the dwellings in which mechanical ventilation systems are installed. Newly installed mechanical ventilation systems were observed to improve health conditions. In homes with existing ventilation systems this positive effect was less evident, probably due to poor performance of the system (too low ventilation rates and/or poor maintenance). Studies are recommended in which exposures are much better characterized (by for example measuring the pollutants indicated by the WHO Guidelines for Indoor Air Quality and improving ventilation measurements). Exposures should also be controlled using different ventilation methods for comparison. Future studies should also advance the understanding of how ventilation systems should be operated to achieve optimal performance. These data would create further input and support to the guidelines for ventilation based on health developed currently in the framework of the HealthVent project (
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International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
The Effects of Ventilation in Homes on Health
P. Wargocki
International Centre for Indoor Environment and Energy, DTU Civil Engineering,
Technical University of Denmark
It is estimated that people in the developed world spend more than 85-90% of their time indoors. Of this,
most is spent in homes. To minimize health risks from pollutants occurring in homes, exposures should be
controlled. The most effective way to achieve this is to control sources of pollutants and to reduce emissions.
Often, especially in existing buildings, this strategy is difficult to implement, in which case exposures are
controlled by providing sufficient, presumably clean, outdoor ventilation air to dilute and remove the
The present paper attempts to find out how much ventilation is needed in existing homes to reduce health
risks. This is achieved by reviewing the published scientific literature investigating the association between
measured ventilation rates and the measured and observed health problems.
The paper concludes that, generally, there are very few studies on this issue and many of them suffer from
deficient experimental design, as well as a lack of proper characterization of actual exposures occurring
indoors. Based on the available data, in the reviewed studies, it seems likely that health risks may occur
when ventilation rates are below 0.4 air changes per hour in existing homes. No data were found indicating
that buildings having dedicated natural ventilation systems perform less well than the dwellings in which
mechanical ventilation systems are installed. Newly installed mechanical ventilation systems were observed
to improve health conditions. In homes with existing ventilation systems this positive effect was less evident,
probably due to poor performance of the system (too low ventilation rates and/or poor maintenance).
Studies are recommended in which exposures are much better characterized (by for example measuring the
pollutants indicated by the WHO Guidelines for Indoor Air Quality and improving ventilation
measurements). Exposures should also be controlled using different ventilation methods for comparison.
Future studies should also advance the understanding of how ventilation systems should be operated to
achieve optimal performance. These data would create further input and support to the guidelines for
ventilation based on health developed currently in the framework of the HealthVent project
Key words: ventilation, ventilation rate, ventilation system, housing, homes, health, pollutants.
1. Introduction
1.1 Background
How much ventilation is needed indoors and which
requirements should be used to design ventilation?
These two questions have been high on the research
agenda for years. They can be readdressed again
especially when strict requirements for energy use in
buildings are implemented and when there is a need
to make buildings tight and energy efficient (EPBD,
2010) so that the quality of life is not compromised
(e.g., Fisk et al., 2011; Wargocki, 2011).
Undoubtedly human responses should be used to
define ventilation requirements. However, it is
relevant to ask whether comfort requirement should
be used, as has been the case for years in many
ventilation standards and guidelines (EN15251,
2007; ASHRAE, 2010; ECA, 1992), or if ventilation
requirements should be based on health outcomes. It
may be argued that both are the same thing if the
World Health Organization’s (WHO) definition of
health is considered (1948). Still the link between
comfort and health is not clearly established and it is
not certain whether ensuring comfort requirements
will abate health risks and vice versa.
P Wargocki
Ventilation modifies exposures occurring indoors.
It cannot reduce the emissions. It is used to dilute
and remove the pollutants occurring indoors. For
some pollutants the effectiveness of ventilation can
be quite high, and for some pollutants it can be
rather low. Ventilation can also bring the outdoor
pollutants that are otherwise not present indoors.
Consequently, ventilation requirements should be
defined based on the exposures occurring indoors.
The ventilation requirement can be estimated based
on the emission rates of pollutants, so that the
pollutants occurring indoors are at levels without
concern for human health and comfort. The
problem is that there are very limited data on the
relationship between pollutants occurring indoors,
their concentrations and health (WHO, 2010). Even
if the data for all pollutants were available, it
would be difficult to take into account all possible
interactions between pollutants, reactions occurring
between pollutants and all potential
A pragmatic approach for setting ventilation
requirements can be proposed by observing, in real
buildings, whether there is an elevated risk for
health and comfort complaints in the case when the
ventilation rate is at or below a certain level; this
approach is now being exercised by the HealthVent
project (Wargocki et al., 2012). The disadvantage of
this approach is that buildings can differ between
each other in terms of exposures and pollutants
occurring indoors, as well as by other factors which
are difficult to control, such as temperatures,
moisture level and relative humidity (RH), noise,
light, surroundings, etc. They all potentially can
have an impact on human response and can obscure
the relationship with ventilation. Furthermore,
different buildings can be populated by different
people and thus the experimental observations from
these buildings may not be representative for the
general population.
Several studies have been carried out to investigate
the relationship between ventilation and human
responses both in the laboratory and as field studies.
Summaries and critical assessments can be found in
many reviews published previously (e.g., Mendell,
1993; Godish and Spengler, 1996; Seppänen et al.,
1999; Seppänen et al., 2002; Wargocki et al., 2002;
Davies et al., 2004; Angell et al., 2005; Richardson
et al., 2005; Grimsrud, 2006; Bonnefoy, 2007; Li et
al., 2007; Bone et al., 2010; Sundell et al., 2011).
An important limitation of the previous studies on
ventilation and health is that they have each used
different methods to characterize ventilation and
human response outcome. This makes it very
difficult to compare the results obtained in these
different studies. In some studies proxies for
ventilation were used, such as the concentration of
carbon dioxide (CO2), as well as proxies for human
response outcomes, such as the concentration and
prevalence of house dust mite (HDM) allergens
because there is consistent evidence that the
prevalence of HDM allergens increases the risk of
asthma. Another predicament is that when the
performance of different ventilation systems were
compared in different buildings there was
insufficient control for potentially disturbing factors
such as differences in exposures to air pollutants. In
spite of these limitations the previous studies
provide direct data on the importance of ventilation
for human health and comfort.
The present work tries to recapitalize on the results
of these past studies and reviews, particularly with
regard to the importance of ventilation for health in
residential buildings.
1.2 Objective
The main objective of the present work was to
prepare a state-of-the-art report on ventilation and
health in homes. In particular, the following
research questions were addressed: (i) Does a
relationship exist between health and ventilation in
residential buildings?; (ii) What is the potential
reason for the observed relationship?; (iii) Which
health problems are related to ventilation?; (iv) Are
there any differences in prevalence of health
symptoms in residential buildings having different
ventilation systems?; (v) Are there any differences
in the prevalence of health problems among
different population groups?; and (vi) Does
ventilation itself contribute to the pollution of
indoor air in residential buildings?
2. Method
2.1 Approach
To address these research questions the following
approach was implemented: (i) hypotheses and
search terms were defined; (ii) a literature search
was performed; (iii) abstracts of all identified papers
and reports were screened; (iv) literature was
grouped as follows: literature providing information
on ventilation and its proxies, and health and its
proxies; literature providing information on
exposure ventilation and its proxies, but not on
International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
health and its proxies; surveys and reviews; and
literature not relevant for the objective of the present
work; (v) reference lists in surveys and reviews
were screened to identify whether there were any
other papers that were missed in the literature
search, and if so they were included; and (vi) papers
providing information on ventilation and health,
addressing the objective, were reviewed and used to
form conclusions.
2.2 Literature Survey
Scientific literature on the association between
ventilation and health in nonindustrial residential
indoor environments was gathered by searching
through the following databases: MEDLINE by
National Library of Medicine; Cambridge Scientific
Abstracts (including Mechanical Engineering
Abstracts, Environmental Sciences and Pollution
Management Search sub-files, Biological Sciences
Search sub-files, TOXLINE, ERIC, Computer and
Information System Abstracts) and AIRBASE by
the Air Infiltration and Ventilation Centre (AIVC).
In addition, the Proceedings of Indoor Air, Healthy
Buildings, RoomVent, AIVC and CLIMA
congresses taking place in the last 10 years, i.e.
since 1999 were also surveyed.
The term “ventilation” was considered as both the
ventilation rate, i.e. amount of outdoor air supplied
to indoor spaces, and as the ventilation system, i.e.,
the way the air is supplied to indoor spaces – using
natural or mechanical forces, or combined, with or
without air-conditioning (AC). Proxies for
ventilation were also accepted including
concentration of CO2. Information on condensation
on windows was collected as a proxy for elevated
RH and low ventilation rate, but no specific term
was created for relative humidity in order not to
obscure the search. Health was considered to
follow the basic definition of the World Health
Organization (WHO, 1948): health is a state of
complete physical, mental and social well-being
and not merely the absence of disease or infirmity.
Proxies for health were also accepted, i.e.
pollutants for which there are documented effects
on health such as concentration of HDM allergens,
radon, etc. Nonindustrial residential indoor
environments were considered to represent all
kinds of housing: dwellings, row houses and
detached houses.
Only papers including records in each of the three
search categories were selected (as a source of
search records, keyword indexes of the international
conferences Indoor Air ’90, ’93 and ’99, and
Healthy Buildings ’97 and ’00 were used): (1) the
category “ventilation” including different records
pertaining to ventilation rates, e.g., air change rate,
air supply rate, etc., as well as ventilation systems,
e.g., infiltration, dedicated natural ventilation,
mechanical ventilation, etc.; (2) the category
“environment” including different records
pertaining to nonindustrial residential indoor
environments, e.g., dwellings, houses, etc.; and (3)
the category “health” including different records
pertaining to health, e.g. symptoms, diseases,
allergy, asthma, etc.; comfort and productivity were
not included.
3. Results
More than 140 papers and reports were identified
through the literature search. Among these, 34
documents were considered to provide information
relevant for the objective of the present work; their
details are given in Table 1. As many as 20 reviews
and surveys were identified on the topic of
ventilation and health. More than 60 papers were
irrelevant for the present work.
3.1 Asthma and Allergy Symptoms
Several studies, in some cases with large cohorts,
have been carried out to observe whether there is an
association between ventilation and asthma and
allergy symptoms. The results are inconsistent.
In studies with children, low ventilation rates were
strongly associated with increased risk of having
self-reported asthma and allergy symptoms (at least
2 out of 3 symptoms such as wheezing, eczema and
rhinitis) when conditions in homes of children with
symptoms (cases) and children without symptoms
(controls) were compared (Bornehag et al., 2005;
Hägerhed-Engman et al., 2009). The odds ratios
(indicating the risk) for wheezing and rhinitis were
significantly lower among infants in homes where
heat recovery ventilators were installed; similarly
there were reduced CO2 levels compared with
homes with placebo units without such a system
(Kovesi et al., 2009). Nocturnal chest tightness in
adults, a symptom of problems with the respiratory
system as a consequence of asthma, was associated
with higher CO2 levels indicating lower ventilation
rates in homes (Norbäck et al., 1995). Improper
ventilation defined as a ventilation problem was
associated with elevated risk of asthma (Ezratty et
al., 2003).
P Wargocki
Table 1. Short summary of studies considered relevant for the purpose of the present work;
AC=air conditioning; PM=particulate matter; GLM=general linear model; RR=response rate;
SBS=Sick Building Syndrome; HDM=house dust mites; RH=relative humidity; PFT=perfluorocarbon tracer;
SARS=severe acute respiratory syndrome; CFD=computational fluid dynamics.
Reference Results Design Buildings Population Ventilation
rate Ventilation
type Health
Bell et al.
Presence of AC
reduced PM
exposure and
health effects
through GLM
Houses (ca.
Elderly (>65
years old);
N/A N/A, only
whether AC
present or
absent (from
Mortality and
and respiratory
and PM2.5
Bornehag et
al. 2005
Engman et
al. 2009
rates associated
with the risk of
being the case
(having asthma
and allergy
Case-control 390 houses 198 cases
and 202
(from cohort
of 14,077)
with PFT
0.34 h-1
0.38 h-1
present and
eczema and
Clausen et
al. 2011
Toftum et al.
Bekö et al.
Ventilation rate
not associated
with being case
Case-base Houses Children,
200 cases
asthma and
and 293
bases among
which 15
were cases
(from cohort
of 11,082)
0.46 h-1 for
cases and
with CO2
present and
asthma and
eczema and
Coelho et al.
systems (dirty
filters, blocked
associated with
Elderly (60-
95 years
old), 96
N/A Mechanical Health
Deger et al.
Increased risk
of asthma for
leaving along
streets with
highly dense
traffic and on
ground floor
Homes Children
(n=980 out
of 7980)
N/A Only
Drinka et al.
Presence of
increased risk
of attack rates
of Influenza A
4 nursing
N/A Mechanical
with 0%,
30% and
Influenza A
Table continues on next page.
International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
Table 1. (continued).
Reference Results Design Buildings Population Ventilation
rate Ventilation
type Health
Emenius et
al. 2004
No association
ventilation and
being a case
(but with RH
on windows
markers of
Case-control Homes Children
181 cases
and 359
from 4089
0.68±0.32 h-1,
69% >0.5 h-1
with PFT
present and
Engvall et
al. 2003
Presence of
system reduced
ocular and
231 multi-
3241 of
N/A With
present and
ocular, nasal,
dermal and
Engvall et
al. 2005
caused the air
to be perceived
as poor and
stuffy but had
no effects on
SBS symptoms
1-year cross-
44 people 0.5-0.8 h-1 vs.
reduced to
0.4-0.5 h-1
Mechanical SBS symptoms
Ezratty et al.
headache and
associated with
ventilation but
can also be
caused by other
in 8
N/A With forced
present and
et al. 1996
symptoms not
associated with
type of system;
complaints of
poor air quality
and mucous
related with
on windows
Homes 638 children N/A With
present and
absent l
Harving et
al., 1993
ventilation rate
of HDM
because of
higher RH
Homes 96 families
with at least
1 asthmatic
<0.25h-1 vs.
vs. >0.5 h-1
with PFT
present and
diagnosis of
asthma; skin
prick test
Harving et
al. 1994
rates reduced
HDM and RH
Case-control Houses 53 asthmatic
patients (of
which 23
0.4 to 1.5 h-1
with PFT
Mechanical N/A (measured
HDM as a
Table continues on next page.
P Wargocki
Table 1. (continued).
Reference Results Design Buildings Population Ventilation
rate Ventilation
type Health
Howieson et
al. 2003
Installation of
system with
heat recovery
(reduced HDM
and RH)
Case- control Houses 68
<15 years
old, 32 +17
in active
(cases) and
19 as
N/A Mechanical Health
symptoms and
peak flow
Jacobs et al.
Increased in
lead poisoning,
asthma and
associated with
increased use
of AC
Houses 2 national
register of
changes in
use of AC
from 1970s
to 2000s)
register of
Jones et al.
factors were
not associated
with case status
Case-control Houses Children,
from 11,000
matched by
age and
(incl. ducted
heating) and
other factors
related to
wheeze and
hay fever
Kishi et al.
ventilation not
associated with
risks of sick
houses of
Residents N/A With
present and
sick housing
Kovesi et al.
Installation of
reduced rhinitis
and wheeze
(and RH) and
had no effect
on health
encounters and
51 houses of
68 selected
Inuit infants
in 37 homes
with placebo
and 14 in
homes with
measured and
averaged 900
ppm with
system and
1,400 ppm
Mechanical Self-assessed
symptoms and
health centre
Leech et al.
cough, fatigue
and irritability
reduced for
Case-control Cases = 52
houses with
and best
houses in
the same
price range
128 cases
and 149
N/A Mechanical
Li et al.
CFD modelling
of wind
ventilation rate
and virus
spread between
Simulation by
CFD; no
N/A N/A With
infection rate
Table continues on next page.
International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
Table 1. (continued).
Reference Results Design Buildings Population Ventilation
rate Ventilation
type Health
Risk of
doubled during
heat waves in
homes w/o AC
N/A N/A ( with
or w/o AC)
Mortality rate
Norbäck et
al. 1995
At high CO2
the prevalence
of nocturnal
(a symptom of
asthma) was
88 homes
(51% flats
and 40%
1,020 ppm
(natural) and
850 ppm
present and
and clinical
examination of
Øie et al.
Low air change
rates increased
risk of
Case-control Homes 172 cases
from Oslo
Birth cohort
and 172
Above and
below 0.5h-1,
with PFT
(also quartiles
6.9, 11.5 and
17.6 L/s per
present and
Palonen et
al. 2008
Air was
stuffy with
ventilation and
it was noisy
natural and
and cold floors
102 single
210 adults
and 152
(natural); 0.34
h-1 (exhaust)
and 0.4 h-1
PFT method
and in
present and
Rogot et al.
Risk of death
42% lower in
homes with
Homes n=72,740 N/A N/A (with or
w/o AC)
Mortality rate
et al. 1991
symptoms in
dwellings than
in houses;
symptoms in
houses with
ventilation and
in dwellings
and houses
present and
and SBS
Low air
changes rates
infestation of
29 homes N/A 0.1h-1 to
0.8 h-1
with PFT
N/A N/A (HDM, a
proxy for
Table continues on next page.
P Wargocki
Table 1. (continued).
Reference Results Design Buildings Population Ventilation
rate Ventilation
type Health
Warner et al.
Installation of
reduced HDM
and RH but no
effects on
12 months
40 houses 27 children
and 13
Aimed at
0.4-0.5 h-1
present and
with vacuum
asthma and
Measured lung
functions and
bronchial hypo
Willers et al.
between health
outcomes and
Homes 647 children
at age of 4
from 3,000
birth cohort
on asthma
and allergy
N/A Assessment
of whether
ventilation in
kitchen (with
gas cooking)
sufficient or
Blood samples,
respiratory and
Wong et al.
Prevalence of
symptoms was
higher in
dwellings with
3 residential
adults, 105
in naturally
and 58 in
with AC
CO2 up to
1,600 ppm in
with AC vs.
550-600 ppm
without AC
system (with
and w/o AC)
SBS symptoms
Wright et al.
Installation of
evening peak
expiratory flow
(not morning),
reduced RH
but not HDM
Homes 120 adults
with asthma
N/A, aimed to
0.5 h-1
present and
expiratory flow
Xu et al.
Exhaled breath
reduced ph
improved and
peak expiratory
flow improved
units with air
Homes 30 children
with asthma
CO2 averaged
1500 ppm
w/o system
800-900 ppm
with system
With and
w/o unit
system with
air cleaner
Exhaled breath
condensate and
peak expiratory
Yu et al.
infection rates
matched virus
predicted by
using plumes
and wind flows
no field
infection rates
International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
Contrary to the above no association was observed
between ventilation rates in homes of children with
asthma and allergy symptoms (cases) and children
with and without symptoms (bases) in a study which
used a similar approach to that of Bornehag et al.
(2005) described above (Clausen et al., 2011).
Clausen et al. used a case-base design rather than
case-control design and they also used CO2
measurements to estimate ventilation rates rather
than a PFT method used by Bornehag et al. (2005).
This could, among other factors, contribute to the
different results obtained in both studies which
otherwise had the same protocols for registering
symptoms. Also, no association between ventilation
rate and self-estimated asthma and allergy
symptoms was observed when the odds ratios for
cases and controls were compared in a study of
Emenius et al. (2004) in which the PFT method was
used for ventilation rate measurements. In this study
RH and window-pane condensation (a marker of
elevated humidity) were however associated with
the elevated risk of symptoms.
Data on the presence and type of ventilation system
and increased risk of self-estimated asthma and
allergy symptoms have also shown to be
inconsistent. After installation of mechanical
ventilation with heat-recovery in homes where no
such system was previously present, the risk for
symptoms was reduced both for infants (Kovesi et
al., 2009) and adolescents (Howieson et al., 2003),
but not for the adults and children with asthma
(Warner et al., 2000). In the latter study the levels of
RH and HDM allergens were, however, reduced.
Homes judged to have sufficient or not sufficient
kitchen ventilation were not a risk factor for
respiratory and allergic symptoms among children
(Willers et al., 2006). Neither were the houses with
characteristics likely to affect indoor air quality,
other than ventilation (Jones et al., 1999), a study
that actually did not look specifically at the effect of
ventilation. Gustafsson et al. (1996) showed that
heating and ventilation systems were not associated
with allergy symptoms in children.
Ventilation rate and ventilation system type were in
some studies associated with exposures and markers
of exposures likely to cause allergic symptoms. One
of these markers is the concentration of HDM
allergens. Any methods and remedial actions
reducing this allergen can be considered as effective
methods for improving health conditions. Several
studies showed that increased ventilation rate
reduced the concentration of HDM allergens
(Harving et al., 1993; 1994; Sundell, 1994). Also
installation of a new mechanical ventilation system
in homes which did not previously have this system,
reduced the concentration of HDM allergens
(Warner et al., 2000). This was most likely because
the ventilation rates were increased. In these studies
no direct measurements of symptoms or complaints
among building occupants were made. In some
studies increased ventilation rate reduced RH, which
was often observed and documented by lack of
condensation on window panes. Also proliferation
of HDM allergens depends on moisture level and is
inhibited when the relative humidity is low. Because
both elevated RH and window-pane condensation
are indicators of potential dampness problems in
homes, which are considered to be strong risk
factors for health problems (Bornehag et al., 2001;
2004), these data suggest indirectly that increased
ventilation rate can reduce health problems by
reducing the moisture level in homes.
3.2 Building-Related Symptoms and Complaints
The presence of mechanical ventilation systems in
homes was associated with reduced self-estimated
health symptoms, typical of sick building syndrome
symptoms among adults, compared with homes
without mechanical ventilation (Engvall et al., 2003;
Leech et al., 2004; Palonen et al., 2004), probably
because of higher ventilation rates. This is implied
by Ruotsalainen et al. (1991) who showed that the
presence of mechanical ventilation was associated
with a lower prevalence of symptoms when the air
change rates were higher. Kishi et al. (2009) found
no relationship between the existence and operation
of mechanical ventilation systems and the risk of
building-related symptoms. Maintenance of the
mechanical ventilation system could cause the
inconsistency between the results from different
studies. For example, Coehlo et al. (2005) showed
that mechanical ventilation systems in homes having
dirty filters, blocked vents, etc. were associated with
increased rates of health complaints of elderly
people. Also noise generated by the mechanical
ventilation system could contribute to complaints
and cause the association between mechanical
ventilation systems and health complaints to be
inconsistent (Palonen et al., 2008).
Generally, no studies were found directly
associating ventilation rates in homes with self-
estimated building related symptoms. Indirectly
Wong et al. (2004) showed that houses where AC is
used increase the risk of health symptoms; these
houses were usually sealed and had much lower
ventilation rates. Indirect evidence on the
P Wargocki
association between ventilation and health was also
suggested in studies showing that increased
ventilation rate lowered the perceptions of poor air
quality and stuffy air (Engvall et al., 2005; Palonen
et al., 2008), under the assumption that these
perceptions are markers of a health risk.
3.3 Respiratory Tract/Lung Functions and
Bronchial Obstruction
Reduced ventilation rates were associated with the
risk of bronchial obstruction but only when homes
had verified dampness problems and plasticizer
containing surfaces (Øie et al., 1999). Increased
ventilation rates following installation of new
mechanical ventilation systems with heat recovery
in homes without such a system was associated with
improved lung functions (Wright et al., 2009; Xu et
al., 2010). In the study of Xu et al. the effect could
not be separated from the effect of an air cleaner
installed together with the system. No effect on lung
functions was observed by Warner et al. (2000) after
new mechanical ventilation systems were installed
in homes without such a system, although
ventilation rates were increased. In their study the
installation of mechanical ventilation systems
reduced levels of RH and HDM allergens.
Installation of heat recovery ventilators in homes of
infants, previously without such systems, brought
levels of CO2 down to 900 ppm compared with
placebo units installed in other homes where CO2
levels were 1400 ppm. Levels of RH were also
reduced but did not affect health centre encounters
and hospitalizations due to respiratory problems
(Kovesi et al., 2009). Actually, no hospitalizations
occurred during the study. Since the population of
homes where interventions were made was small it
was unlikely to expect that a rather small change in
ventilation would have a strong effect on respiratory
problems that can be demonstrated by the effect on
3.4 Infectious Diseases
No studies have been found that directly associate
infectious diseases with the ventilation rate or type
of ventilation system in homes. However, the design
of ventilation systems should avoid mixing of return
air with supply air and assure proper air distribution,
considering that increased recirculation of air in
nursing homes was associated with an increased risk
of attack rates of Influenza A among the elderly
(Drinka et al., 1996). Also air distribution played an
important role in the spread of SARS (Yu et al.,
2004; Li et al., 2005).
3.5 Other Outcomes
Studies with other health outcomes than those listed
above have also been found including mortality,
cardiovascular hospitalizations, obesity and lead
poisoning. None of them was directly associated
with either ventilation rate, ventilation system type,
or the maintenance of ventilation systems in homes.
These are mentioned here only because the data
provide some indirect evidence.
Use of central AC in homes has been shown to
reduce exposure to particulate matter (PM) mainly
from outdoor traffic, and was associated with
reduced cardiovascular and respiratory
hospitalizations, as well as mortality among the
elderly (Bell et al., 2009). The data on both AC and
health outcomes were obtained from the local
community registers and it is difficult to judge
whether proximity to PM sources outdoors was
included in the models. Nevertheless, it can be
hypothesized that reducing exposures to outdoor
sources, by e.g. sealing houses, which is usually the
case when central AC are used, may have a positive
effect on health. This is somewhat confirmed by
studies of Deger et al. (2010), who showed that
children living along streets with highly dense
traffic have an increased risk of asthma, particularly
for children living on the ground floor and having
no adequate control of pollution causing asthma.
Proper filtration of outdoor air would thus be
important. Sealing houses can, at the same time,
reduce the outdoor air supply rate which may be
detrimental for health as well.
The data from two national longitudinal studies in
the US on house characteristics show that increased
use of AC, resulting in most cases in lowered
ventilation rates as a response to energy saving, was
associated with obesity and lead poisoning (Jacobs
et al., 2009). It must be emphasized though that
many other factors could also contribute to the
observed association including changes in lifestyle,
nutrition, etc. AC has also been shown, in many
studies, to reduce mortality for elderly during hot
weather (Marmor, 1978; Rogot et al., 1992). This is
most likely due to control of indoor temperature by
cooling, but may also be caused by reduced
exposure to outdoor air pollutants occurring during
hot weather because AC is often associated with
sealing houses.
International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
4. Discussion
The present data provide important reference
material to the project HealthVent defining health-
based ventilation guidelines for Europe
( (Wargocki et al., 2012). The
guidelines will have two parts, one prescribing rates
at which ventilation is supplied to reduce health
risks among the population exposed in buildings,
and on prescribing how to achieve compliance,
proper design, operation and maintenance of
ventilation systems. Both aspects are addressed in
the reviewed studies.
4.1 Ventilation Rate in Homes and Health
The results of studies on ventilation and health risks
in homes suggest that increased ventilation rates,
also demonstrated by reduced concentration of CO2,
generally reduce health problems; only in a few
cases were no effect or reverse effect observed.
To observe which level of ventilation rate can be
considered to protect people in homes against
negative health effects Figures 1 and 2 were created.
Figure 1 shows that increasing ventilation rate
consistently reduced the concentration of HDM
allergens in houses. The effect was significant over
a large range of ventilation rates, from about 0.1 to
1.4 h-1, suggesting that there can be a dose–response
relationship, i.e. a lower concentration of HDM
allergens when ventilation rate is increased. Lung
functions were seen to be improved by ventilation
rates above 0.5 h-1, but the data are only from one
study so it would be imprudent to form
recommendations based only on these results. For
self-reported asthma and allergy symptoms the
results seem to be equivocal and only one study
shows that increased ventilation rate reduced the
risk of asthma/allergy; in two studies no statistically
significant effect was observed. Figure 2 shows that
lowering CO2 levels, i.e. increasing ventilation rate,
reduced significantly symptoms of asthma and
allergy. No effects of increased ventilation rate on
SBS symptoms were shown, and sometimes
symptoms increased with increased ventilation rate
(Figure 1). Only one study showed that reduced
CO2, i.e. increased ventilation rate, reduced
symptoms (Figure 2). These results suggest that this
health outcome may not be very sensitive to changes
in ventilation in homes, although SBS symptoms are
clearly associated with changes in ventilation rates
Figure 1. Ventilation rate in homes and health; black bars show the studies in which increase in ventilation rate
caused statistically significant reduction in health outcomes; empty bars show that health outcome has not been
statistically significantly changed in the indicated range of air change rates, while grey bars show that increasing
ventilation rates increased significantly health problems.
0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6
Borne hagetal(2005)
(lung functions)
(asthma &aller gy)
(house dustmites)
(SBS symptoms)
(SBS symptoms)
(housedust mites)
P Wargocki
in offices (Seppänen et al., 1999; Wargocki et al.,
2002; Sundell et al., 2011).
Taking only the studies in which significant effects
of ventilation rate on health were observed, the
minimum ventilation rate in homes at which no
health risk exist seems to be about 0.4 h-1 (Figure 1).
This is the lowest ventilation rate at which no
increased health risk was observed in the reviewed
literature. This level is close to the requirements of,
e.g. Danish Building Regulations (BR10, 2010) set
at 0.5 h-1, as well as the measured ventilation rates
in US residencies, which is from 0.5 to 0.7 h-1
(Pandian et al., 1998). Taking the studies in which
significant effects of CO2 on health were observed,
the maximum level of CO2 in homes at which no
health risk was observed seem to be about 900 ppm
(Figure 2).
4.2 Ventilation System in Homes and Health
Present results show consistently that newly
installed mechanical ventilation systems reduced
health risks in homes. The reason for this is most
likely that outdoor air supply rates were also
increased when the system was installed, and the
system when new was not a source of pollution.
Furthermore, the installation of a mechanical
ventilation system could also contribute to fixing
other problems in homes which could, if existing,
contribute to health problems, such as e.g. leaky
roof, unsealed ceilings, etc.
Present results show also that there was less evident
effect on health in buildings with already existing
mechanical ventilation systems. Mechanical
ventilation systems can become strong pollution
sources as a result of their poor maintenance, as e.g.
shown in a recently published study in 299 Dutch
homes (Dijken et al., 2011). Although there is a
wealth of data showing that dirty filters and dirty
ventilation systems contribute to elevated health
risks (e.g., Sieber et al., 1996; Seppänen et al., 2002;
Mendell et al., 2003; 2008), these data are mainly
from offices. On the other hand the present survey
found no studies which associated the maintenance
of ventilation systems in homes with health. Only
the study of Coehlo et al. (2005) showed association
between improper operation of the system (blocked
vents, switched-off fans, etc.) and elevated health
complaints. Poor performance of ventilation systems
could also contribute to less evident effects on
health in buildings with existing mechanical
ventilation systems. Mechanical ventilation systems
should be properly designed, balanced and operated
because, as shown by Palonen et al. (2005), they can
become a source of nuisance, e.g. due to increased
noise levels indoors. This result was confirmed
recently by Bogers et al. (2011).
No studies were found which associated dedicated
natural ventilation systems and hybrid systems with
4.3 Source Control and Filtration
Increasing ventilation rates reduces the
concentration of HDM allergens. These results may
also suggest that ventilation modifies moisture
levels, thus it is modifying conditions which are
Figure 2. Concentration of CO2 in homes and health; black bars show the studies in which reduction of CO2
(i.e. increase in ventilation rate) caused statistically significant reduction in health outcomes.
0 200 400 600 800 1000 1200 1400 1600 1800
Norbac ketal.(1995)
Carbondioxideconce ntr at ion(ppm)
(asthma &allergy )
(asthmaandalle rgy)
International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
promoting the proliferation of HDM. Most of the
studies on the association between HDM allergens
and ventilation were performed in Nordic countries
and in the UK, where increased ventilation rates
during cold periods reduce RH in homes, thereby
inhibiting the growth of mites. Reduction of
moisture has also many other benefits for health, as
moisture is generally known to be a marker of
elevated health risk in homes (Bornehag et al.,
Too low RH can also cause problems and could be
one of the reasons why Ruotsalainen et al. (1991)
observed in Finland that increased ventilation rate
caused an increase of SBS symptoms, such as
dryness, nasal problems and itching. Their study
was actually performed from November to April so
it is likely that RH was quite low, although
measured to be on average approximately 36%.
Moisture can also be controlled by creating barriers
in the building structure and/or local exhaust in
laundries, bathrooms and kitchens, as well as by the
banning of drying of laundry in spaces where people
Ventilation air can also transport outdoor pollutants
(particles, pollens, etc.) into indoor spaces. This is
suggested by studies of Bell et al. (2009) who
showed that the use of AC reduced health effects
related with PM from outdoors because houses were
sealed. These results show the connection between
indoor and outdoor environment and the need for
reducing exposures to particles entraining indoors.
This should rather be achieved by, e.g. efficient
filtration, than by sealing homes, i.e. reducing
ventilation rates, which can also be detrimental for
health. The risk of elevated health effects due to
exposure to particles will depend on the location of
houses (urban, rural), proximity to outdoor sources,
etc. Again, reviewed studies have not sufficiently
documented these factors so it is difficult to assess
their impact on the presented results.
4.4 Populations Studied
Among all studies reviewed in the present report,
thirteen studies concerned health risks for children,
twelve for adults and five for the elderly. They have
thus reasonably well addressed different population
All studies that did not show association between
ventilation system type and ventilation rate and self-
reported asthma and allergy symptoms were carried
out with children. In most cases the prevalence of
asthma and allergy is based on parental reports (self-
assessments). Perhaps this caused inconsistent
results. Verification of parental reports with
objective methods would be useful.
All studies in which there was no association
between ventilation type and/or ventilation rate, and
self-reported SBS symptoms concerned adults.
In the case of exposure of the elderly none of the
studies showed direct association between
ventilation type and or ventilation rate and health
4.5 Limitations
There are numerous confounding factors that could
influence and disturb the observed associations.
They include among others: study design,
controlling and measuring of ventilation rates,
differences in source strength; interactions between
sources and ventilation rates; dose-response effects
that are likely to be log-linear; ventilation systems
as sources of pollution, multifactorial genesis of
health problems, climatic differences, different
thresholds of effects for people and location of the
study, as well as different methods by which health
outcomes were measured.
Quality of data plays an important role when
forming conclusions on ventilation and health. No
attempt however was made in the present report to
grade the studies according to their quality as
regards experimental design, measurements and
analysis of results.
If such a grading had been based on the study
design, case-base, case-control and placebo-
controlled interventions with double blinding would
be ranked high while cross-sectional studies and
longitudinal observations would be ranked quite
low. In the former, many of the confounding factors
are controlled experimentally while in the latter the
control can only be made by adjusting the statistical
models for the factors likely to obscure the
If such a grading had been based on the method of
ventilation measurements, the method using
perfluorocarbon as tracer (PFT method) would be
ranked high (although largely debated as regards its
accuracy in the scientific community) because it
accounts only for outdoor air supply rate, while
using CO2 would be ranked low because the
calculated ventilation rates provide information on
P Wargocki
total dilution including outdoor air and make-up air
(the air from other rooms in a house) rather than
only outdoor air supply rate (Bekö et al., 2009) as is
the case for PFT method.
If such a grading had been based on categorization
of the ventilation systems, the studies which
installed mechanical ventilation systems would be
ranked high compared with the buildings with
existing mechanical ventilation systems because of
their good maintenance and close to design
performance. Also studies in which categorization
of the system had been made through inspections
rather by examining registers or blue-prints would
be ranked high because they would use the actual
data rather than unverified information.
The grading could have also been made based on the
measurements of health outcomes. Many studies
used self-administered questionnaires and may be
ranked low compared to objective medical
measurements and/or diagnosis made by the doctors
which would be ranked high. However using
questionnaires is the most efficient, low-cost
method of collecting data, widely used in large
epidemiological studies of the type discussed in the
present report. Besides, there is some evidence on
the consistency between self-reports of health
problems and doctor-diagnosed health problems.
Even if objective medical measurements had been
used, the information on the thresholds at which
health effects are observed would be needed. These
can vary between people and in many cases are not
available. Also lack of the effect on objectively
measured health symptoms does not preclude the
effect on health, especially if the objective method is
not properly selected and not properly applied.
Consequently the studies in which self-reported and
doctor-diagnosed symptoms were used can be
ranked evenly.
It is worth noting that consistent observations
regarding associations between ventilation rate and
ventilation system and health stem generally from
the studies which would have been ranked high.
4.6 Implications for Future Work
Present results show that more evidence of the role
of ventilation for health is needed. Despite the
paramount importance of ventilation, especially
considering the impact on energy, it has not
received proper attention. The need for reducing
energy and future buildings being much tighter than
today will require that the proper ventilation of
homes, obtained by, e.g. mechanical systems with
heat recovery in cold periods and dedicated natural
ventilation systems in warm periods, will be the
essential part of the future building structure.
The performance of different ventilation solutions
and their impact on health should be better
understood. There is an obvious need for producing
guidelines as regards commissioning and
installation as well as maintenance of systems
supplying air to indoor spaces, not only for
mechanical systems but also for other systems.
Regular inspections of ventilation systems can be
forced, as it is done for example in Sweden
(Boverket, 2009); these inspections can actually
become a part of energy certification of buildings.
Future studies should try to answer the fundamental
question on how much ventilation is actually
needed. This question is only partially answered by
the present report due to limited data and the
limitations of different studies. A series of studies
on ventilation and health would be needed to answer
this question. They should take into account all
possible limitations and, what is probably most
important, should link ventilation to actual
exposures, admitting thus that ventilation is not a
mitigation measure and should not be used as such.
5. Conclusions
Ventilation rate in homes is associated with
health in particular with asthma, allergy, airway
obstruction and SBS symptoms. This
association is based on the limited evidence.
Ventilation rates above 0.4 h-1 or CO2 below
900 ppm in homes seem to protect against
health risks.
No specific ventilation system can be
recommended to provide minimum ventilation
Increasing ventilation rates in homes reduces
house dust mites known to cause allergic
symptoms, most likely because of reduced
moisture levels which inhibits their
Newly installed mechanical ventilation systems
nearly always reduced the risk of health
problems. This was not the case for buildings
with existing mechanical ventilation systems,
International Journal of Ventilation ISSN 1473-3315 Volume 12 No 2 September 2013
most likely due to their poor maintenance, lack
of commissioning, regular checks and
inspections, etc.
Buildings in which air conditioning is installed
increase the risk of health problems probably
due to lowered ventilation rates (tightening and
sealing of buildings to reduce energy).
No differences were observed in the prevalence
of health problems between different age
groups, children, adults and elderly.
A series of studies on ventilation and health in
buildings with different ventilation systems
would be desirable.
6. Practical Implications
Required ventilation rates depend strongly on
exposures, i.e. with a high load of pollution more
ventilation is needed than if the loads are low. The
ventilation rates can be reduced by controlling
sources of pollution both being of outdoor origin
(e.g., particulate matter) and indoor origin (e.g.,
relative humidity (RH), particulate matter (PM),
house dust mite (HDM) allergens, emissions from
building products and appliances, anthropogenic
emissions). Future homes should secure proper
control of exposures to pollutants in order to reduce
health risks for occupants on one hand, and at the
same time they should secure that the energy needed
to support sufficient ventilation is as low as
possible. This control can be implemented by
different solutions including provision of sufficient
ventilation, which should be closely connected to
estimated exposures.
Different ventilation systems can be applied from
dedicated natural ventilation systems, hybrid
systems to mechanical ventilation systems with heat
recovery, all depending on the conditions which
promote application of one system over another.
Ventilation should not be considered to be the only
mitigation measure to control exposures but
complementary and supplementary to other
measures, such as, e.g. source control, air cleaning
and/or local exhausts. These measures are easy to
implement in newly constructed homes, and more
difficult but still possible to apply in existing homes
unless they are renovated or refurbished.
It is of utmost importance that systems securing
ventilation rates in homes are inspected for their
performance. Regular annual or bi-annual
inspections should be implemented and regulated so
that the proper operation and maintenance of
systems is ensured. They can become, e.g., a part of
energy audits, chimney sweep control, etc., or can
be performed completely separately.
Thanks are due to Velux A/S for supporting present
work. Thanks are due to Nuno da Silva, M.Sc. for
finding the literature and for creating the data base
with articles used to prepare the present paper.
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... According to several research, using ventilation systems properly might greatly enhance indoor air quality (Ghanizadeh and Godini, 2018). Based on the data available, it is likely that health hazards might arise in existing dwellings with ventilation rates below 0.4 air changes per hour (Wargocki, 2013). There is no evidence to support the claim that homes with mechanical ventilation systems function better than those with specialised natural ventilation systems in structures (Wargocki, 2013;SeppȨnen, 2008). ...
... Based on the data available, it is likely that health hazards might arise in existing dwellings with ventilation rates below 0.4 air changes per hour (Wargocki, 2013). There is no evidence to support the claim that homes with mechanical ventilation systems function better than those with specialised natural ventilation systems in structures (Wargocki, 2013;SeppȨnen, 2008). Mechanical ventilation systems that have recently been implemented have been found to enhance health conditions. ...
... Mechanical ventilation systems that have recently been implemented have been found to enhance health conditions. This beneficial impact was less noticeable in homes with existing ventilation systems, most likely as a result of the system's subpar performance (too little ventilation and/or inadequate maintenance) (Wargocki, 2013;SeppȨnen, 2008). ...
Indoor air quality (IAQ) is one of the fundamental elements affecting people's health and well-being. Currently, there is a lack of awareness among people about the quantification, identification, and possible health effects of IAQ. Airborne pollutants such as volatile organic compounds (VOCs), particulate matter (PM), sulfur dioxide (SO2), carbon monoxide (CO), nitrous oxide (NO), polycyclic aromatic hydrocarbons (PAHs) microbial spores, pollen, allergens, etc. primarily contribute to IAQ deterioration. This review discusses the sources of major indoor air pollutants, molecular toxicity mechanisms, and their effects on cardiovascular, ocular, neurological, women, and foetal health. Additionally, contemporary strategies and sustainable methods for regulating and reducing pollutant concentrations are emphasized, and current initiatives to address and enhance IAQ are explored, along with their unique advantages and potentials. Due to their longer exposure times and particular physical characteristics, women and children are more at risk for poor indoor air quality. By triggering many toxicity mechanisms, including oxidative stress, DNA methylation, epigenetic modifications, and gene activation, indoor air pollution can cause a range of health issues. Low birth weight, acute lower respiratory tract infections, Sick building syndromes (SBS), and early death are more prevalent in exposed residents. On the other hand, the main causes of incapacity and early mortality are lung cancer, chronic obstructive pulmonary disease, and cardiovascular disorders. It's crucial to acknowledge anticipated research needs and implemented efficient interventions and policies to lower health hazards.
... The term "ventilation" refers to the process of bringing pleasant external air into a room to provide comfort for occupants and control the indoor air quality by diluting and displacing indoor air pollutant in that space [24]. Human reactions, according to [25], should be utilized to determine ventilation needs since, according to estimates, individuals in the industrialized world spend more than 85% to 90% of their time inside, whether at home or at work. ...
... Thus, many studies comparing the same building are often based on virtual models. Having the opportunity to conduct this study in real life would progress the understanding of the impact of ventilation [30,31], airtightness, mechanical ventilation [32] and outdoor air pollution [33]. ...
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The ongoing climate change and policies around it are changing how we design and build homes to meet national carbon emission targets. Some countries such as Scotland are adopting higher-energy-efficient buildings as minimum requirements in the building regulations. While net zero homes might be more energy-efficient and emit fewer operational carbon emissions, we have yet to fully understand the influence on the indoor environment, particularly on indoor air quality (IAQ) and thermal comfort. This study compares the IAQ of three homes in Scotland with equal internal layouts and designs but different building fabrics. The homes represent the minimum Scottish building regulations (2015), the Passivhaus standard and the Scottish 'Gold Standard'. Temperature, relative humidity, PM 2.5 and total volatile organic compounds (tVOC) were measured at five-minute intervals for seven months and compared to occupants' subjective responses to the IAQ. All three homes had temperatures above the recommended thresholds for overheating. Measured hygrothermal conditions were within the ideal range 66.4% of the time in the Passivhaus, 56.4% in the Gold Standard home and 62.7% in the control home. Measured IAQ was better in homes with higher energy efficiency, particularly tVOC. For instance, indoor PM 2.5 in the Passivhaus were 78.0% of the time below the threshold, while in the standard home the figure was 51.5%, with a weak correlation with outdoor PM 2.5 (Passivhaus: B r s = 0.167, K r s = 0.306 and L r s = 0.163 (p < 0.001); Gold: B r s = −0.157, K r s = 0.322 and L r s = 0.340 (p < 0.001); Control: B r s = −0.111, K r s = 0.235 and L r s = 0.235 (p < 0.001)). TVOCs in the Passivhaus were 81.3%, while in the control home they were 55.0%. While the results cannot be generalised, due to the small sample, this study has significant policy implications, particularly in Scotland, exhibiting the importance of IAQ in current building legislation and sustainable assessment methods.
... Em outro caso, verificou-se redução na prevalência de sintomas SBS em ocupantes de um edifício após uma intervenção para limpeza geral e renovação do sistema de AC (GRAUDENZ et al., 2004). Existe, portanto, uma relação entre ventilação e exposição a poluentes; se houver maior controle das fontes de poluição, as taxas requeridas de ventilação poderão ser menores (WARGOCKI, 2013). Limpeza e manutenção são recursos essenciais para atingir este objetivo. ...
... Good ventilation is vital in maintaining good health, but current air quality regulations are not as developed as, for example, for food safety A c c e p t e d M a n u s c r i p t (Morawska, et al., 2021). Wargocki indicated that health risks increase when the ventilation rate in homes is below 0.4 air changes per hour (ACH) (Wargocki, 2013). Many high-rise and office buildings are now equipped with Heating, Ventilation and Air-Conditioning (HVAC) systems, which control the movement of air within a building. ...
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For many respiratory diseases, a primary mode of transmission is inhalation via aerosols and droplets. The COVID-19 pandemic has accelerated studies of aerosol dispersion in indoor environments. Most studies of aerosol dispersion present computational fluid dynamics results, which rarely include detailed experimental verification, and many of the computations are complex, making them hard to scale to larger spaces. This study presents a comparison of computational simulations and measurements of aerosol dispersion within a typical ventilated classroom. Measurements were accomplished using a custom-built low-cost sensor network composed of 15 commercially available optical particle sizers, which provided size-resolved information about the number concentrations and temporal dynamics of 0.3-40 µm diameter particles. Measurement results are compared to the computed dispersal and loss rates from a steady-state Reynolds-Averaged Navier-Stokes k-epsilon model. The results show that a newly developed aerosol-transport-model can accurately simulate the dispersion of aerosols and faithfully predict measured aerosol concentrations at different locations and times. The computational model was developed with scalability in mind such that it may be adapted for larger spaces. The experiments highlight that the fraction of aerosol recycled in the ventilation system depends on the aerosol droplet size and cannot be predicted by the recycled-to-outside air ratio. Moreover, aerosol recirculation is not negligible, as some computational approaches assume. Both modelling and measurements show that, depending on the location within the room, the maximum aerosol concentration can be many times higher than the average concentration, increasing the risk of infection.
... According to the research results, the most significant feature to be considered is the availability of natural light and ventilation. In general, studies have proved that natural light and ventilation in households are the key elements for maintaining residents' health and wellbeing [34]. Their impact on promoting health and resisting infections has been well recognized. ...
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The long stay at home during the COVID-19 pandemic implied that most people had to perform all their daily activities at home. That raised the need for special home features related to the health, safety, and well-being of residents. This study aimed to explore the most essential features of home design during the pandemic and to meas- ure the perception of their importance by Cairenes (Egypt) and construction industry experts for their further implementation in the future home design as part of the buy- ers’ preferences and house quality features. The study employed an exploratory survey, identifying eight design features, followed by a quantitative questionnaire to measure the importance of each feature among the stakeholders. The results showed that all eight indicators were of a certain degree of importance. It was found that the avail- ability of natural ventilation and natural light were the most essential features, followed by the availability of a private outdoor space, such as a terrace with a good-looking view or a private garden, and the availability of at least one bedroom with an enclosed bathroom for the isolation needs. In contrast, the availability of an extra storage space for food and supplies, as well as the availability of an indoor family entertainment space was reported as the least important.
... People spend 90% of their lives inside the traditional closed buildings, whether they are homes, workplaces, or schools. The traditional multi-storey buildings (sick building syndrome) cause many diseases to their users, such as asthma, heart diseases, and other diseases; this is due to insufficient natural ventilation inside the building [43][44][45][46][47][48][49]. Many environmental pollutants are generated inside homes, which cause many diseases, including asthma, lung cancer, and other diseases. ...
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Many issues have emerged more clearly than before in multi-storey residential buildings during quarantine and lockdown caused by the global pandemic COVID-19. Among these problems is the deterioration in people’s mental and physical health inside the home caused by quarantine and closure. This deterioration is due to inadequate passive ventilation, natural lighting, and the lack of green open spaces in and around traditional multi-storey residential buildings. Also, one of the most severe problems is the airborne infection transmission from a positive covid-19 person to others due to the lack of control in the entrance of buildings against an infected person. In this paper, we modified the shape of a traditional multi-storey residential building. Using Design-Builder and Autodesk CFD software, we create a simulation to compare the amount of natural ventilation and lighting before and after modifying the building’s shape. This work aims to increase the passive ventilation and daylight inside the building. Also, to achieve the biophilic concept to provide open spaces for each apartment to improve the mental and physical health of the residents. In addition, it protects the building users from infection with the virus. Through this study, we found that passive ventilation and daylight achieved more efficiency in the building that we have modified in its shape, which led to a 38% reduction in energy consumption. In summary, these findings suggest that by modifying the mass of the traditional multi-storey residential building with open green spaces provided for each apartment, the natural connection with the inhabitants of the building was sufficiently provided. Moreover, all this will significantly help improve residents’ mental and physical state, and it will also help prevent the spread of various diseases inside the homes.
Purpose Poor indoor air quality (IAQ) contributing to occupants’ health symptoms is a universal, typically ventilation-related, problem in schools. In cold climates, low-cost strategies to improve IAQ in a naturally ventilated school are rare since conventional methods, such as window opening, are often inappropriate. This paper aims to present an investigation of strategies to relieve health symptoms among school occupants in naturally ventilated school in Finland. Design/methodology/approach A case study approach is adopted to thoroughly investigate the process of generating the alternatives of ventilation redesign in a naturally ventilated school where there have been complaints of health symptoms. First, the potential sources of the occupants’ symptoms are identified. Then, the strategies aiming to reduce the symptoms are compared and evaluated. Findings In a naturally ventilated school, health symptoms that are significantly caused by insufficient ventilation can be potentially reduced by implementing a supply and exhaust ventilation system. Alternatively, it is possible to retain the natural ventilation with reduced number of occupants. The selected strategy would depend considerably on the desired number of users, the budget and the possibilities to combine the redesign of ventilation with other refurbishment actions. Furthermore, the risk of poorer indoor air caused by the refurbishment actions must also be addressed and considered. Practical implications This study may assist municipal authorities and school directors in decisions concerning improvement of classroom IAQ and elimination of building-related symptoms. This research provides economic aspects of alternative strategies and points out the risks related to major refurbishment actions. Originality/value Since this study presents a set of features related to indoor air that contribute to occupants’ health as well as matters to be considered when aiming to decrease occupants’ symptoms, it may be of assistance to municipal authorities and practitioners in providing a healthier indoor environment for pupils and teachers.
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This systematic review investigates the emissions from ultrasonic humidifiers (e.g., cool mist humidifiers) within indoor air environments, namely soluble and insoluble metals and minerals as well as microorganisms and one organic chemical biocide. Relationships between ultrasonic humidifier fill water quality and the emissions in indoor air are studied, and associated potential adverse health outcomes are discussed. Literature from January 1, 1980, to February 1, 2022, was searched from online databases of PubMed, Web of Science, and Scopus to produce 27 articles. The results revealed clear positive proportional relationships of the concentration of microorganisms and soluble metals/minerals between fill water qualities and emitted airborne particles, for both microbial (n = 9) and inorganic (n = 15) constituents. When evaluating emissions and the consequent health outcomes, ventilation rates of specific exposure scenarios affect the concentrations of emitted particles. Thus, well‐ventilated rooms may alleviate inhalation risks when the fill water in ultrasonic humidifiers contains microorganisms and soluble metals/minerals. Case reports (n = 3) possibly due to the inhalation of particles from ultrasonic humidifier include hypersensitivity pneumonitis in adults and a 6‐month infant; the young infant exhibited nonreversible mild obstructive ventilator defect. In summary, related literature indicated correlation between fill water quality of ultrasonic humidifier and emitted particles in air quality, and inhalation of the emitted particles may cause undesirable health outcomes of impaired respiratory functions in adults and children.
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This paper is concerned with historical changes in domestic ventilation rates, relative humidity and the associated risk of house dust mite colonization. A controlled trial evaluated allergen and water vapour control measures on the level of house dust mite (HDM) Der p1 allergen and indoor humidity, concurrently with changes in lung function in 54 subjects who completed the protocol. Mechanical heat recovery ventilation units significantly reduced moisture content in the active group, while HDM allergen reservoirs in carpets and beds were reduced by circa 96%. Self reported health status confirmed a significant clinical improvement in the active group. The study can form the basis for assessing minimum winter ventilation rates that can suppress RH below the critical ambient equilibrium humidity of 60% and thus inhibit dust mite colonization and activity in temperate and maritime in‘ uenced climatic regions.
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The LARES Housing and Health survey conducted in representative samples of eight European towns provides substantial data from 3,373 households about housing conditions and the health of 8,519 residents. We assessed the relation between residential thermal comfort, weather-tightness, ventilation, mould or dampness and some common diseases and symptoms. We observed that reporting bad health was significantly associated with temperature, weather-tightness and mould or dampness problems. Asthma was significantly linked with mould or dampness, temperature, and ventilation problems. Hypertension and cold/throat illness were associated with temperature, mould or dampness, and weather tightness problems in the dwellings. These results make it possible to recommend improvements in existing dwellings, in particular of the weather tightness accompanied by better information and verification of the ventilation systems. These simple and not too costly actions might have a beneficial impact not only on comfort but on health too, as well as for energy savings.
People spend a significant part of their life indoors mainly in the built environment (in public and residential buildings). In developed parts of the world, the proportion of time spent indoors can be as high as 80% to 90%. Many non-industrial buildings do not provide adequate conditions as regards indoor environmental quality especially indoor air quality. This is due to elevated exposures to air pollutants. These conditions reduce quality of life by increasing the risks for health problems that can, among others, result in disability to perform work. Significant societal costs are then generated including costs to individuals, building owners and employers. There are potentially considerable health and productivity benefits of improving indoor air quality in non-industrial buildings. Crude estimates suggest that 2 million healthy life years can be saved in Europe by avoiding exposures to air pollutants indoors in non-industrial buildings. Similar estimates have been made for the U.S. as regards exposures to air pollutants in residential buildings. The potential annual savings and productivity gains have been estimated to be as high as $168 billion in the U.S. (1997 estimate as no newer data are available). A saving of $400 per employee per year (2000 estimate) was estimated due to reduced absenteeism being the result of improving indoor air quality. In Europe, the annual productivity benefits were estimated to be at the level of ca. €330 per worker (2000 estimate as no newer data are available). Despite the obvious significance, the potential health and productivity benefits have not yet been integrated in the conventional economic calculations pertaining to building design and operation. Such integration would provide economic arguments for applying measures to reduce air pollution and thereby would support the arguments that arise from the public health perspective. The present article attempts to provide such arguments by summarizing the potential costs and economic benefits of improved indoor air quality.
For many years, the housing environment has been acknowledged as one of the main settings that affect human health. Living and housing conditions are the basis of many factors influencing residential health. Still, to date there is no commonly agreed upon definition of 'healthy housing', and there are still major gaps in the knowledge on how housing conditions may affect health. Epidemiological findings suggest strong associations between housing conditions and health effects. This paper explores the relevance of housing conditions as a key factor influencing mental health, sleep quality, indoor air, home safety, accessibility, obesity, mould growth, hygrothermal conditions and energy consumption, perception of crime, and residential quality.
Associations between environmental factors and work-related health conditions were assessed using regression techniques with environmental and health data for 2435 respondents in 80 office buildings included in the National Institute for Occupational Safety and Health Health Hazard Evaluation program. The health conditions analyzed included two symptom groupings—multiple lower respiratory symptoms and multiple atopic symptoms—and the presence of asthma diagnosed after beginning work in the building. Four categories of environmental variables were included: heating, ventilation, and air conditioning (HVAC) system design; HVAC maintenance; building design; and building maintenance. Female gender and age over 40 years showed increased relative risks (RRs) for each health condition. In regression models adjusted for age and gender, RRs of multiple lower respiratory symptoms were increased for variables in the HVAC design and maintenance categories, with the highest RR for presence of debris inside the air intake [RR = 3.1, confidence interval (CI) = 1.8, 5.2] and for poor or no drainage from drain pans (RR = 3.0, CI = 1.7, 5.2). Elevated RRs of multiple atopic symptoms were found for variables in three of the four environmental categories, with the highest for presence of suspended ceiling panels (RR = 2.3, CI = 1.0, 5.5). The RR of asthma was highest if recent renovation with new drywall had been performed (RR = 2.5, CI = 1.4, 4.5). These data are from office spaces about which there was some level of occupant concern, and thus it may not be appropriate to use them to estimate the magnitude and distribution of symptoms found in all office spaces within U.S. buildings. Furthermore, the high degree of correlation among environmental variables makes it difficult to disentangle which are the most important predictors of work-related health conditions. The analysis is useful, however, for determining factors that may be associated with development of health conditions in the office environment and which might be considered in any building plan to reduce indoor air-related symptoms.
The paper highlights some of the key features of the design procedures in ASHRAE Standard 62 (Ventilation for Acceptable Indoor Air Quality) and summarizes the status of the related review process. The Standard contains design procedures and guidelines for ventilation rates in 'all indoor or enclosed spaces that people may occupy, except where other applicable standards and requirements dictate larger amounts of ventilation than this standard.' It is the basis for ventilation requirements in many codes for commercial, institutional, and residential buildings in North America. The Standard is reviewed every 5 years or less, and updated as needed to incorporate new information or improve its usefulness to building designers and code officials.
In 1993, Pandian, Ott, and Behar published statistical summaries of residential air exchange rates in the perfluorocarbon tracer (PFT) data base as a function of geographic region, season, and number of home levels. Unfortunately, after the paper was published, some readers noticed discrepancies in the air exchange rates representing one region, the southwestern United States. The present paper answers the following questions: (1) What is the nature of errors in the PFT data base? (2) What was the likely cause of errors in the PFT data base? and (3) What are the statistics of the correct data from the PFT data base? Our objective, in this paper is to correct the errors in the earlier paper by presenting the revised summary statistics and to make others aware of the data coding problems in the original diskettes containing the Versar PFT data base. These overall statistics are useful for exposure assessors and for characterizing residential air exchange rates across the nation.
Epidemiologic research into the causes of non-specific symptoms among office workers has produced a variety of conflicting findings which are difficult to synthesize. This paper first discusses methodologic issues important in the interpretation of epidemiologic studies, and then reviews the findings of 32 studies of 37 factors potentially related to office worker symptoms. Among environmental factors assessed, there were generally consistent findings associating increased symptoms with air-conditioning, carpets, more workers in a space, VDT use, and ventilation rates at or below 10 liters/second/person. Studies with particularly strong designs found decreased symptoms associated with low ventilation rate, short-term humidification, negative ionization, and improved office cleaning, although studies reviewed showed little consistency of findings for humidification and ionization. Relatively strong studies associated high temperature and low relative humidity with increased symptoms, whereas less strong studies were not consistent. Among personal factors assessed, there were generally consistent findings associating increased symptoms with female gender, job stress/dissatisfaction, and allergies/asthma. For other environmental or personal factors assessed, findings were too inconsistent or sparse for current interpretation, and there were no findings from strong studies. Overall evidence suggested that work related symptoms among office workers were relatively common, and that some of these symptoms represented preventable physiologic effects of environmental exposures or conditions. Future research on this problem should include blind experimental and case-control studies, using improved measurements of both environmental exposures and health outcomes
Abstract Adjustment of ventilation rates in buildings is widely practised, both to provide good air quality on a proactive basis and to mitigate air quality problems associated with occupant complaints. However, both cross-sectional and experimental epidemiological studies have reported mixed results and have for the most part failed to establish definitive relationships between ventilation rates and symptom prevalence or dissatisfaction with air quality. The difficulties involved in establishing such relationships may be due to a variety of confounding factors which include limitations in study design and interaction effects; difficulties in controlling ventilation rates in experimental studies; inadequate mixing of supply air in occupied spaces; high source strengths for some contaminants; dynamic interactions between sources and ventilation rates that result in increased contaminant emissions; contaminant dose-response sensory effects which are log-linear; potential contaminant generation within ventilation systems themselves; and multifactorial genesis of sick building symptoms. There is limited evidence to suggest that ventilation rate increases up to 10 L/s person may be effective in reducing symptom prevalence and occupant dissatisfaction with air quality and that higher ventilation rates are not effective. Because of complex relationships between ventilation rates, contaminant levels, and building-related health complaints/dissatisfaction with air quality, the use of ventilation as a mitigation measure for air quality problems should be tempered with an understanding of factors which may limit its effectiveness.
The purpose of the study was to evaluate the occurrence of symptoms and the perception of poor indoor air quality among the occupants of houses and apartments with different ventilation systems. The study population consisted of the 473 occupants of 242 dwellings in the Helsinki metropolitan area who responded to a self-administered questionnaire (response rate 93.1%) after a two-week period of indoor air quality measurements. The symptoms of interest were those often related to poor indoor air quality including dryness or itching of the skin; dryness, irritation or itching of the eyes; nasal congestion (“blocked nose”) nasal dry-ness; nasal discharge (“runny nose”); sneezing; cough; breathlessness; headache or migraine; and lethargy, weakness or nausea. Perception of coldness; warm-ness; draught; dryness; stuffiness; and sufficiency of air exchange was also requested. The age-standardized period prevalences of the symptoms and complaints were systematically more common among the occupants of the apartments than those of the houses. The occupants of the houses with natural ventilation seemed to have more symptoms and complaints than those with balanced ventilation. However, in the apartments with balanced ventilation the occupants reported, in general, more symptoms and complaints than those with natural ventilation.