FINNISH RESEARCH PROGRAMME
ON ENVIRONMENTAL HEALTH
SCHOOLS, MOLD AND HEALTH - AN INTERVENTION STUDY
Project leader: Aino
Nevalainen, National Public Health Institute (KTL), Laboratory of
Environmental Microbiology, P.O.Box 95, FIN-70701 Kuopio, Finland, tel.
+358-17-210 342, e-mail: Aino.Nevalainen@ktl.fi
Researchers:
Teija Meklin, KTL, tel. +358-17-201 364, first name.surname@ktl.fi
Tuula Husman, KTL, tel. +358-17-201 325
Jari Koivisto KTL, tel. +358-17-201 381
Juho Halla-aho KTL, tel. +358-17-201 381
Anne Hyvärinen KTL, tel. +358-17-201 364
Ulla Haverinen KTL, tel. +358-17-201 154
Maija-Riitta Hirvonen, KTL, tel. +358-17-201 303
Johanna Immonen KTL, tel. +358-17-201 180
Taina Taskinen, Kiuruvesi Health Care Center, tel.+358-17-76851,
Taina.Taskinen@kiuruvesi.fi
Consortium: Moisture, Mold
and health
Financing SYTTY organization:The Academy of Finland, The Finnish Work
Environment Fund Funding from SYTTY / Total funding of project (€):
183627 / 379667
Person-months of work funded by SYTTY / Total person-months of work: 62,5
/ 155,5
KEY WORDS: moisture, mold,
health, repair, intervention
EXTENDED ABSTRACT
1 Introduction
In moisture damaged
schools, higher prevalence of respiratory symptoms and infections as well
as general symptoms like headache, tiredness and nausea have been reported
[1,2,3,4]. The problem has also an economical consequences due to costs of
sick leaves and health care, and because considerable resources are put on
the renovations. It is essential to know how the repairs of moisture
damage in school environment affect the exposure and health of
schoolchildren and personnel, and thus assess the achieved benefits of the
renovation.
The aim of the intervention
study was to find out whether the moisture and mold repairs of the school
buildings have an effect on the exposure to indoor air pollutants, on the
respiratory health of the school children, studied with both questionnaire
and clinical methods. This intervention study had a core design around
which several connected studies were carried out, and a basic characterization of moisture damage and associated microbial growth in
school buildings were performed. As a part of the clinical study the
association between serum mold-specific IgG levels of schoolchildren and
the microbial exposure in their school environment was measured.
2 Material and methods
A total of 30 schools,
consisting of 41 school buildings, were technically investigated according
to a standardized protocol by trained surveyors, and moisture damage
status of each building was assessed. A total of 32 school buildings were
studied to determine whether the microbial indoor air quality and
associated health status of children in schools with visible moisture and
mold problems differed from those in non-damaged schools. The following
questions were set: What are the distributions of fungal concentrations in
school buildings, and how does a moisture damage alter the concentrations?
Is the moisture damage of school building associated with symptoms i.e.,
are the exposure times sufficient to cause symptoms to schoolchildren?
Also the effect of the building frame (concrete/brick or wood) and the
moisture damage on the microbial quality of school buildings was analyzed
in a more accurate characterization of indoor air microbes of school
buildings. The size distributions of airborne microorganisms in school
buildings were considered. Special focus was paid on effects of moisture
and mold damage repairs in the schools. Four school buildings were
selected to study the effect of repair measures on microbial exposure and
health effects of schoolchildren.
The microbial levels and
flora in buildings were characterized by sampling indoor air with a
six-stage impactor (Andersen 10-800) and materials from damaged
structures. An epidemiological symptom survey of students was done with a
previously developed questionnaire that consists of 32 questions on
personal characteristics, home environment, perceived indoor air quality
characteristics and occurrence of respiratory and other symptoms and
infections.
As a background
characterization of building mycoflora, the diversity of the mycobiota and
concentration distributions of fungi and bacteria were analyzed in a
database of building material samples (n=1140) taken from various
buildings. The occurrence of microbes was analyzed in seven different
moisture damaged building materials, grouped according to the major
constituent or use.
In the intervention study,
the sampling of indoor air microbes and health questionnaire of children
were performed before any dismantling and repair work in the two schools.
After the repairs were completed, the measurements on the exposure and
health status of the school students were repeated. Part of the follow-up
was done during the renovation. Changes in the prevalence of the symptoms
and diseases in different buildings were analyzed. Two non-damaged schools
served as control schools.
Follow-up of children
included clinical measurements: heart and lung auscultation, checking of
infection focuses, skin prick tests (SPT) to 11 common allergens and to
mold antigens and also lung function measurements including exercise
challenge test. In addition, serum samples were drawn for analysis of
mold specific immunoglobulin G (IgG) determination to 24 antigens and
mold-spesific immunoglobulin E (IgE) determination to 10 antigens.
One aim was to develop a
method to monitor the toxicity and biological activity of the indoor
particulate material. As a part of this work filter samples from indoor
air of a school building before and after renovation were taken. The mouse
macrophage cell line RAW264.7 (American Type Culture Collection,
Rockville, MD, USA) was used in the cell exposure study. The effects of
indoor air particles on cell viability and production of inflammatory
mediators (nitrite, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFalpha))
were analyzed.
3 Results and discussion
Moisture damage in school
buildings
Moisture and mold damage was common in school buildings. Only 10% of the
buildings were assessed to be non-damaged. Out of the damaged buildings,
19 % had minor damage and 71% had evident damage. Evident odor of mold in
24% of the schools, weak mold odor was recorded in 2% of the studied
schools. About 23% of the damage were located in classrooms, and most of
the damage was less than 4 m2 of size. A total of 930 individual damage
observations in the 18 buildings with concrete/brick frame and 157
observations in the 23 buildings with wooden frame were recorded, but the
number of damage / building size [m2] was slightly greater in the
buildings with wooden frame.
Indoor air microbes in
school buildings
The frame material was a determinant of airborne microflora in school
buildings. In wooden school buildings the concentrations and composition
of the microbes differed clearly from concrete schools. Mean
concentrations of viable airborne fungi were significantly and
systematically higher in wooden schools than in concrete schools.
Evidently, a wooden frame acts as a microbial source and creates its
specific microbial conditions that differ from indoor environment of a
concrete building. The material of the building frame should also be taken
into account when matching buildings for exposure assessment in
epidemiological studies.
Associations between mean
fungal concentrations and moisture damage was seen only in concrete
schools. The geometric mean concentration in the index schools (GM=19 cfu/m3)
was significantly higher (p=0.001) than in the reference schools (GM=9 cfu/m3).
Distributions of fungal spore concentrations can be regarded as
characteristic to the two types of studied schools. Typical to the school
buildings with concrete frame and moisture damage were frequent occurrence
(>10%) of samples with concentration between 50 and 200 cfu/m3, and low
frequency (<6%) of samples with value under detection limit. This
applies to wintertime sampling in a cold climate. Temporal variation of
fungal concentrations in indoor air even within short period is evident
[9]. Therefore, several air samples, from 5 to 20 depending on the size of
the building are needed to ensure accurate assessment of microbial
concentrations. The most common fungal genera or groups were similar in
both frame types of buildings, i.e., Penicillium, yeasts, Cladosporium and
Aspergillus. Occurrence of Aspergillus versicolor and Stachybotrys
indicated moisture damage in both school types. Elevated concentrations of
Cladosporium and actinobacteria associated with moisture damage in
concrete/brick schools.
Symptoms and infections of
schoolchildren
Moisture damage in a school building was a risk factor for respiratory
symptoms i.e. nocturnal cough, dry cough and cough with phlegm among
schoolchildren. There were significant differences in the prevalence of
respiratory symptoms between the schoolchildren occupying damaged and
non-damaged schools. Differences in symptom prevalence during the spring
season were more often significant than during fall season, which may
suggest the effect of longer exposure period. The association between
moisture damage and respiratory symptoms was also significant in
concrete/brick school buildings alone, while the trend in wooden schools
was similar with no statistical significance.
An association between
occurrence of common colds and moisture damage in all school buildings was
found. In addition, sinusitis, tonsillitis and bronchitis were more common
in concrete/brick buildings than in buildings with wooden frame
irrespective with moisture observations. Occurrence of respiratory
infection was also strongly correlated with background factors such as
age, female gender, smoking, atopy and moisture damage in home
environment.
Microbial diversity in
damaged building materials
Microbial analysis of 1140 visibly damaged samples of building material,
viz. wood, paper, non-wooden building boards, ceramic products, mineral
insulation materials, paints and glues, and plastics confirmed that
microbial growth occurs in many different building materials and showed
associations between fungal genera and type of material. The range of
fungi and bacteria numbers was between 100-108 cfu g-1 in all materials,
but significant differences in counts were observed between materials.
Highest median concentrations of fungi were observed in wooden and paper
materials, and lowest in mineral insulation, ceramic products, and paints
and glues. A rich variety of fungi was found in wooden materials, with
Penicillium and yeasts occurring most frequently. In paper materials, a
clear difference from wood was the more frequent occurrence of
Cladosporium and Stachybotrys. In gypsum boards, Stachybotrys was common,
occurring in 30% of the samples. Ceramic products and paints and glues
seemed to favour Acremonium and Aspergillus versicolor. Yeasts and members
of the Sphaeropsidales occurred often in parallel in most materials.
Cell viability and
production of inflammatory mediators
The particle material collected from the indoor air of the renovated
school was less cytotoxic in raw264.7 macrophages than that collected
before the renovation. Moreover, a similar change in the biological
activity of the airborne particle sample before and after renovation was
observed as production of nitrite and proinflammatory cytokines il-6 and
tnf-alpha in the macrophages.
Repairs of moisture and
mold damage
After a thorough renovation in the intervention school, a significant
decrease in mean concentrations of viable airborne fungi (p=0.002) was
seen. GMs of total concentration of airborne fungi decreased after
renovation from 22.6 cfu/m3 to 6.3 cfu/m3, and there was no difference
compared to the reference school. Successful effects of the renovation
were also seen as lower number of different microbial genera or species or
groups and higher frequency of samples with low levels (<20 cfu/m3) of
viable fungi. In the other intervention school with only partial repair of
moisture damage, no decrease in microbial levels was observed.
In the intervention study,
differences in symptom prevalence between the damaged school and its
reference school were significant for 10 symptoms out of 12 before the
renovation of the damaged school. After the thorough renovation, a
significant decrease in all other symptoms but general symptoms was seen
(Figure 1). The differences in prevalence between the intervention and
reference school disappeared.
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Figure 1. The proportions of schoolchildren with respiratory and
other symptoms in the intervention school before and after
thorough repairs.
In the intervention
school with minor, uncompleted repairs, the prevalence of
hoarseness and general symptoms i.e. fatigue, headache and
difficulties in concentration was significantly higher than in its
reference school at the beginning of the study, and no changes in
these prevalences were seen after the repair measures in the index
school. Only the prevalence of rhinitis (spring term), sore throat
(spring term) and cough with phlegm (spring term) were lower than
before preliminary repairs.
Clinical
measurements in schoolchildren
Mold allergy diagnosed by skin prick tests to molds was
relatively rare, in 4% of the school children. No tendency from
mild to positive reactions was seen during the three-year
follow-up period. Most reactions to molds were in children with
multiple skin test reactions to common allergens. No association
with exposure to molds was seen any more although that was the
case at the time preceding the repair. A fairly good agreement was
seen between SPT and IgE responses to molds. Mold-specific IgE was
mostly present in atopic children, showing no association with
dampness or mold exposure in the school. Only a few associations
were found between IgG antibodies to molds and exposure to
moisture or molds in schools.
4 Conclusions
Decrease in symptom
prevalence after renovation of moisture and mold damage confirms
the association between the symptoms and damage of school
building. The majority of adverse health consequences is obviously
due to irritation or non-specific inflammation and not type I
allergy, and is therefore reversible. Moisture and mold damage was
common in studied school buildings. The monitoring of viable
microbes in the indoor air as markers of the microbial status of
large buildings like schools needs effort to be put on sampling,
sample size and analyzing and thus is not recommended as a first
routine method in daily work of health inspectors and authorities.
The clear difference in microbial levels between the wooden and
concrete buildings and the association between damage observations
and microbial findings only in buildings of concrete construction
shows that building frame has impact for indoor air quality.
Knowledge about association between certain microbes and building
materials gives fundamental information on behavior of microbes in
built environments.
5 References
[1] Haverinen U.,
Husman T., Toivola M., Suonketo J., Pentti M., Lindberg R.,
Leinonen J., Hyvärinen A., Meklin T. and Nevalainen A. 1999. An
approach to management of critical indoor air problems in school
buildings. Environmental Health Perspectives, 107, 509-514.
[2] Taskinen, T., Hyvärinen, A., Meklin, T., Husman, T.,
Nevalainen, A., and Korppi, M. (1999). “Asthma and respiratory
infections in school children with special reference to moisture
and mold problems in the school”, Acta Pediatr, 88, 1373-1379.
[3] Sigsgaard, T., Jensen, H.L.C., Nichum, E., Gravesen, S.,
Larsen, L. and Hansen, M.Ø. (1999) “Symptoms associated to work
in a water damaged school building”. In: Bioaerosols, Fungi and
Mycotoxins: Health effects, Assessment, Prevention and Control.
Ed. Johanning, Albany: Eastern New York Occupational and
Environmental Health Center. pp. 99 – 105.
[4] Meklin, T., Husman, T., Vepsäläinen, A., Vahteristo, M.,
Koivisto, J., Halla-aho, J., Hyvärinen, A., Moschandreas, D., and
Nevalainen, A. (2002). Indoor Air Microbes and Respiratory
Symptoms of Children in Moisture Damaged and Reference Schools.
Accepted in Indoor Air.
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