Effect of moisture-damage intervention on the immunotoxic potential and microbial content of airborne particles and on occupants' upper airway inflammatory responses.

This intervention study evaluated the effect of moisture-damage repairs on the exposure and on the upper airway inflammatory responses of the occupants. The airborne microbial exposure was followed by quantitative PCR analyses of 13 microbial species in repeated long-term indoor air samples before (N = 26) and after (N = 28) repairs of the school building. Airborne particulate matter was collected similarly from the same premises (before N = 25, after N = 34) for determination of nitric oxide (NO), tumor necrosis factor α (TNFα), and interleukin-6 (IL-6), measured in the cell culture medium of mouse macrophages. NO, TNFα, IL-6, and IL-4 were also analyzed in the nasal lavage (NAL) samples of the occupants (N = 13) to characterize their upper airway inflammatory responses during the exposure and after its cessation. After the repairs, concentrations of the measured airborne microbes decreased, the difference being significant for six of 13 species. After renovation, airborne particulate matter also caused significantly lower production of IL-6 and TNF-α in mouse macrophages than the material collected before the renovation. The concentration of IL-4 in the NAL samples was significantly lower after the renovation. These results show that the inflammatory potential of the airborne material decreases after intensive repair of the moisture damage.

Evaluation of quantitative PCR and culture methods for detection of house dust fungi and streptomycetes in relation to moisture damage of the house.

AIMS: Microbial concentrations in vacuumed house dust samples (n = 71) were analysed by culture and quantitative polymerase chain reaction (qPCR) methods and their association with extent of moisture damage in the house was studied. METHODS AND RESULTS: Microbial concentrations measured by qPCR correlated with concentrations obtained by culture method, but were orders of magnitude higher. qPCR also had better sensitivity. Concentrations of several microbes in house dust, determined with qPCR, were associated with the extent of moisture damage in the house. This association was strongest for Penicillium brevicompactum, one of the fungi detected in highest concentrations by qPCR. Furthermore, house dust concentrations of Wallemia sebi, Trichoderma viride, Cladosporium sphaerospermum, Eurotium amstelodami and the combined assay group for Penicillium spp., Aspergillus spp. and Paecilomyces variotii were significantly associated with the extent of the moisture damage. CONCLUSION: These species or assay groups could probably be used as indicators of moisture damage in the house. SIGNIFICANCE AND IMPACT OF THE STUDY: This finding indicates the benefits of the qPCR method, which is sensitive enough to reveal the differences in microbial concentrations of house dust between moisture-damaged and undamaged houses.

Analysis of fungal flora in indoor dust by ribosomal DNA sequence analysis, quantitative PCR, and culture.

In recent years increasing attention has been given to the potential health effects of fungal exposure in indoor environments. We used large-scale sequencing of the fungal internal transcribed spacer region (ITS) of nuclear ribosomal DNA to describe the mycoflora of two office buildings over the four seasons. DNA sequencing was complemented by cultivation, ergosterol determination, and quantitative PCR analyses. Sequences of 1,339 clones were clustered into 394 nonredundant fungal operational taxonomical units containing sequences from 18 fungal subclasses. The observed flora differed markedly from that recovered by cultivation, the major differences being the near absence of several typical indoor mold genera such as Penicillium and Aspergillus spp. and a high prevalence of basidiomycetes in clone libraries. A total of 55% of the total diversity constituted of unidentifiable ITS sequences, some of which may represent novel fungal species. Dominant species were Cladosporium cladosporioides and C. herbarum, Cryptococcus victoriae, Leptosphaerulina americana and L. chartarum, Aureobasidium pullulans, Thekopsora areolata, Phaeococcomyces nigricans, Macrophoma sp., and several Malassezia species. Seasonal differences were observed for community composition, with ascomycetous molds and basidiomycetous yeasts predominating in the winter and spring and Agaricomycetidae basidiomycetes predominating in the fall. The comparison of methods suggested that the cloning, cultivation, and quantitative PCR methods complemented each other, generating a more comprehensive picture of fungal flora than any of the methods would give alone. The current restrictions of the methods are discussed.

Comparison of populations of mould species in homes in the UK and USA using mould-specific quantitative PCR.

AIMS: To compare the populations of 81 mould species in homes in the USA and UK using mould-specific quantitative polymerase chain reaction (MSQPCR) technology. METHODS AND RESULTS: Dust samples were obtained from randomly selected homes in the UK (n=11). The mould populations in British homes were compared with those found in typical homes (no visible mould) in the USA (in the state of Ohio, n=45). Only 13 of 81 species screened showed significantly different concentrations in these two sets of home. CONCLUSIONS: Although only a small survey, the results suggest that typical mould profiles in the USA (Ohio) and British homes are very similar. Analysis of 26 mould indicator species revealed that the British homes fell into two clusters, tentatively identified as 'atypical' and 'typical' mould conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: MSQPCR analysis of dust samples can provide an objective measure of indoor moulds which could lead to better management of their health effects.

Effects of moisture-damage repairs on microbial exposure and symptoms in schoolchildren.

UNLABELLED: Effects of renovation on symptom prevalence and microbial status were studied in two moisture-damaged schools and in two non-damaged schools with longitudinal cross-sectional surveys before and after repairs. Over 1300 schoolchildren aged 6-17 returned questionnaires before and after repairs. After full renovation in one of the damaged schools, elevated concentrations and increased frequencies of indoor air fungi normalized and a significant decrease in the prevalence of 10 symptoms of 12 studied was observed among schoolchildren. No change in microbial conditions was seen after partial repairs in the other damaged school, and only slight improvement was observed in symptom prevalence. The change in the prevalence of symptoms in the reference schools was minor. The results suggest that increased symptom prevalence among schoolchildren in moisture-damaged schools can be managed with proper repair of the moisture damage. PRACTICAL IMPLICATIONS: This longitudinal intervention study showed the positive effects of the moisture and mold damage repairs of a school building on children's health. The success necessitates however, a thorough renovation including appropriate ventilation. Monitoring of airborne viable microbes revealed the damage status of the building and thus could be used as a tool in evaluating the quality of repairs.

The bedding of laboratory animals as a source of airborne contaminants.

In work environments with laboratory animals, the bedding of animals binds the excreta as well as other compounds originating from the animals and their environment. These may be generated into the ambient air when the personnel handle bedding in different procedures. This study compares the dustiness of different types of six clean and four soiled beddings from rat or mouse cages. The dust generation of clean bedding varied from <1 to 25 mg/m(3). When used in the cages of rats or mice for 4 days, the dust concentration of the beddings decreased, increased or stayed the same, depending on the type of bedding and animal species. A decrease in dustiness was, however, more common. The levels in the soiled beddings varied from <1 to 8.6 mg/m(3). In the case of the aspen chip bedding, the contents of bedding used in mouse, rat or rabbit cages were analysed for mesophilic bacteria and fungi, mycobacteria and endotoxins. All of these contaminants were variably found in the bedding samples, the maximal concentrations for bacteria were >6 500 000 colony-forming units (cfu)/g, for fungi 212 000 cfu/g, and for endotoxins 6500 ng/g (81 000 EU/g). The results showed that the bedding of laboratory animals may contain biologically effective compounds, and that these may be distributed into the ambient air depending on the characteristics of the bedding material. The dustiness of different bedding types is an important factor affecting the amount and quality of the occupational exposure of the personnel to airborne contaminants.

Indoor air microbes and respiratory symptoms of children in moisture damaged and reference schools.

Microbial indoor air quality and respiratory symptoms of children were studied in 24 schools with visible moisture and mold problems, and in eight non-damaged schools. School buildings of concrete/brick and wooden construction were included. The indoor environment investigations included technical building inspections for visible moisture signs and microbial sampling using six-stage impactor for viable airborne microbes. Children's health information was collected by questionnaires. The effect of moisture damage on concentrations of fungi was clearly seen in buildings of concrete/brick construction, but not in wooden school buildings. Occurrence of Cladosporium, Aspergillus versicolor, Stachybotrys, and actinobacteria showed some indicator value for moisture damage. Presence of moisture damage in school buildings was a significant risk factor for respiratory symptoms in schoolchildren. Association between moisture damage and respiratory symptoms of children was significant for buildings of concrete/brick construction but not for wooden school buildings. The highest symptom prevalence was found during spring seasons, after a long exposure period in damaged schools. The results emphasize the importance of the building frame as a determinant of exposure and symptoms.

Immunoglobulin G antibodies to moulds in school-children from moisture problem schools.

BACKGROUND: The purpose of the present study was to evaluate mould-specific immunoglobulin G (IgG) antibodies in children exposed to moisture and mould problems in their school, and the association between IgG antibodies and mould allergy, active or passive smoking and respiratory symptoms. METHODS: IgG antibodies were studied to 24 moulds in 93 children from three moisture problem schools and in 33 children from a reference school. The antibodies were measured by enzyme-linked immunosorbent assay and compared to positive adult sera. RESULTS: There were no significant differences in mould-specific IgG concentrations between exposed and non-exposed school-children. Antibodies to moulds common in moisture damaged buildings were associated with allergic diseases, as well as with mould-specific immunoglobulin E (IgE) or skin prick test (SPT) findings. Aspergillus fumigatus and A. versicolor were the moulds with the most consistent findings. Active and passive smoking were associated with low levels of antibodies to many moulds. Though the association between asthma, wheezing or cough symptoms, and IgG to moulds was not significant, 7 (39%) of the 18 children with multiple (> 7) elevated IgG findings suffered from asthma or wheezing. CONCLUSIONS: Allergy was, but asthma was not, associated with IgG antibodies to the moulds that can be found in moisture damaged buildings. However, no association was found between IgG antibodies to moulds and exposure to moisture and moulds in school.

Airborne contaminants in conventional laboratory rabbit rooms.

Besides the well known allergens, several other risk factors may exist for health in a laboratory animal unit. The exposure to these factors may be significant in animal units with poor general or local ventilation systems. Moreover, means to prevent the distribution of airborne contaminants may be limited in animal units housing rabbits or other bigger laboratory animals. Airborne contaminants in conventional laboratory rabbit rooms were sought to evaluate the occupational exposure of animal care personnel. Concentrations of airborne dust, bacteria, fungi, ammonia and endotoxins were measured during 2 days in three phases: before working activities began, during them and afterwards. Both stationary and some personal samples were taken. All of the contaminants sought were found in the rabbit room air. When compared to reported levels in farm animal production areas, the concentrations measured were generally low. However, moderate or high levels of airborne bacteria and fungi were found occasionally during work routines. Airborne contaminants should be considered as a potential occupational health risk for persons working with laboratory animals.

Differences in inflammatory responses and cytotoxicity in RAW264.7 macrophages induced by Streptomyces Anulatus grown on different building materials.

Streptomyces anulatus, an indicator microbe of mold in buildings, was grown on different building materials in order to study the impact of growth conditions on the ability of the spores of this microbe to induce toxicity and inflammatory responses. The microbes were grown for 2 months on sterilized and unsterilized wood, chipboard, concrete, plaster board and mineral wool in tight glass vessels under humid conditions. The highest microbial spore concentration was detected on the sterilized mineral wool followed by the sterilized plaster board and the unsterilized mineral wool. Mouse RAW264.7 macrophages were exposed in vitro for 24 h to the spores of S. anulatus and the production of the inflammatory mediators, nitric oxide (NO), tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), interleukin-10 (IL-10) and cytotoxicity, were measured. The dose equivalent to 5 x 10(5) spores/ml of medium was used to compare the different materials. The most intense production of NO (11.6 microM), TNF alpha (560 pg/ml) and IL-6 (2800 pg/ml) in macrophages was induced by the spores grown on sterilized plaster board. They also caused the greatest loss of cell viability (39%). The spores grown on sterilized concrete induced significant production of NO (1.5 microM) and decreased cell viability (22%), and the spores grown on unsterilized and sterilized mineral wool increased production of NO (4.1 microM and 0.8 microM, respectively). The spores did not stimulate production of the anti-inflammatory cytokine IL-10. These results indicate that the ability of S. anulatus to induce inflammatory responses and cytotoxicity in macrophages is dependent on the growth conditions provided by different building materials.

Skin-prick test findings in students from moisture- and mould-damaged schools: a 3-year follow-up study.

Dampness and moisture problems in a building may cause growth of moulds, leading to sensitization and symptoms in the inhabitants. The mechanism by which sensitization to moulds takes place has remained obscure; in particular, the role of atopy is not clear. In 1996, 622 pupils (7-13 years of age) attending a school with a moisture problem (index school; 414 pupils) and a control school (208 pupils) were screened using a questionnaire. Two-hundred and twelve children had doctor-diagnosed asthma, parental-reported wheezing or prolonged cough, and they participated in a clinical study, which included skin prick tests (SPT) to 12 moulds. An identical, follow-up study was performed 3 years later in 1999. In the follow-up study, 144 of the original 212 students participated. They were now attending four different schools: the index primary school had been renovated and the control school remained unchanged, but the two secondary schools had moisture and mould problems. The purpose of the study was to evaluate the occurrence of mould allergy in children of school age and to compare sensitization to moulds in relation to age, exposure, asthma, and atopy. In 1999, SPT responses to moulds were demonstrated in 17 (12%) of the 144 children. Six children had SPT reactions > or = 3 mm and all but one were older than 14 years. During the 3-year follow-up period, mould allergy developed in five children and disappeared in two children. Five of the six children with reactions > or = 3 mm to moulds had positive responses to other allergens, five had clinical atopy but only two had asthma. Likewise, all six children had been exposed to moisture and dampness in the school buildings. In conclusion, mould allergy diagnosed by SPTs was rare in students. Most reactions to moulds were in students older than 14 years with multiple SPT reactions to common allergens, and there was no significant association with asthma.

Changes in pro-inflammatory cytokines in association with exposure to moisture-damaged building microbes.

Several epidemiological studies have described an association between adverse health effects and exposure to mould and microbes present in the indoor air of moisture-damaged buildings. However, the biochemical linkage between microbial exposure and the large variety of reported respiratory symptoms is poorly understood. In the present study, the authors compared the respiratory symptoms, the production of inflammatory mediators interleukin (IL)-1, IL-4, IL-6, tumour necrosis factor-alpha (TNF-alpha) and cell count in nasal lavage fluid and induced sputum samples of subjects working in moisture-damaged and control school buildings. The sampling was performed and the questionnaires were completed at the end of the spring term, at the end of the summer vacation (2.5 months), during the winter term and after a 1-week winter holiday. The authors found a significant elevation of IL-1, TNF-alpha and IL-6 in nasal lavage fluid and IL-6 in induced sputum during the spring term in the subjects from the moisture-damaged school building compared to the subjects from the control building. The exposed workers reported sore throat, phlegm, eye irritation, rhinitis, nasal obstruction and cough in parallel with these findings. The present data suggests an association between microbial exposure, and symptoms as well as changes in pro-inflammatory mediators detected from both the upper and lower airways.

An approach to management of critical indoor air problems in school buildings.

This study was conducted in a school center that had been the focus of intense public concern over 2 years because of suspected mold and health problems. Because several attempts to find solutions to the problem within the community were not satisfactory, outside specialists were needed for support in solving the problem. The study group consisted of experts in civil engineering, indoor mycology, and epidemiology. The studies were conducted in close cooperation with the city administration. Structures at risk were opened, moisture and temperature were measured, and the causes of damage were analyzed. Microbial samples were taken from the air, surfaces, and materials. Health questionnaires were sent to the schoolchildren and personnel. Information on the measurements and their results was released regularly to school employees, students and their parents, and to the media. Repairs were designed on the basis of this information. Moisture damage was caused mainly by difficult moisture conditions at the building site, poor ventilation, and water leaks. Fungal genera (concentrations <200 colony-forming units (cfu)/m(3), <3000 cfu/cm(2)) typical to buildings with mold problems (e.g., Aspergillus versicolor, Eurotium) were collected from the indoor air and surfaces of the school buildings. Where moisture-prone structures were identified and visible signs of damage or elevated moisture content were recorded, the numbers of microbes also were high; thus microbial results from material samples supported the conclusions made in the structural studies. Several irritative and recurrent symptoms were common among the upper secondary and high school students. The prevalence of asthma was high (13%) among the upper secondary school students. During the last 4 years, the incidence of asthma was 3-fold that of the previous 4-year period.

The relationship between moisture or mould observations in houses and the state of health of their occupants.

This work was conducted in order to study how the health of adults is affected by the presence of moisture or mould in the home. A random sample of 310 houses in Finland was studied during the years 1993-1994. The houses were investigated for visual signs of moisture by a surveyor, and observations of mould were reported by the occupants. A moisture problem was observed in 52% and a mould problem in 27% of the houses. Health data was collected by means of a postal questionnaire from 699 adults. Exposure to moisture was significantly associated with sinusitis, acute bronchitis, nocturnal cough, nocturnal dyspnoea and sore throat, and the exposed inhabitants had significantly more episodes of common cold and tonsillitis. Exposure to mould was significantly associated with common cold, cough without phlegm, nocturnal cough, sore throat, rhinitis, fatigue and difficulties in concentration. Building-related moisture or mould increased the risk of upper and lower respiratory infections and symptoms as well as of nonrespiratory symptoms.

Asthma and respiratory infections in school children with special reference to moisture and mold problems in the school.

AIM OF THE STUDY: Initially, we performed a questionnaire study on 622 school children aged 7 to 13 y. The study was supplemented with a clinical study including skin prick tests to 13 molds in 212 (34%) children with doctor-diagnosed asthma or parental-reported wheezing or prolonged cough. These children were attending one of two elementary schools, one with moisture problems (index) school, the other being the control school. The objective of the study was to evaluate whether exposure to moisture and sensitization to molds are associated with respiratory manifestations in school children. RESULTS: The prevalence of asthma was 4.8%, which was similar in the children from both schools. The children from the index school more often had wheezing (16% vs 6%; p <0.001) and cough (21% vs 9%: p < 0.001) symptoms than control children. Positive skin reactions to molds were rare (2.4%), being present in 7% of asthmatic and in 1-2% of non-asthmatic children (NS). Lower respiratory tract infections were more common in the spring than in the fall in children from the index school, but not in control children, and the difference between the schools was significant in emergency visits (OR =2.0, p <0.01) and antibiotic courses (OR = 2.1, p < 0.01). CONCLUSIONS: We found evidence of an association between moisture or mold problems in the school building and the occurrence of respiratory infections, repeated wheezing and prolonged cough in school children.

Moisture and mould problems in schools and respiratory manifestations in schoolchildren: clinical and skin test findings.

OBJECTIVE: We performed a clinical study in 99 children attending schools with moisture problems and compared the findings with those of 34 children from a reference school. The aim of the study was to evaluate the possible association between respiratory or allergic diseases in the pupils and moisture or mould problems in the school buildings. RESULTS: Asthma was diagnosed in nine (6.7%) children: eight of them came from the moisture-problem schools and all were over 10 y old. In addition, 17 non-asthmatic children had suffered from wheezing and 21 from long-term cough, both symptoms being suggestive of occult asthma. If moisture problems were observed both at home and in the school, the frequency of asthma was 21% and the combined frequency of asthma and wheezing was 43%. The presence of allergic rhinoconjuntivitis or atopic dermatitis had no association with moisture or mould problems. We performed skin-prick tests to 13 moulds in all the 133 children. A positive reaction (> 3 mm) was observed in only six (5%) of them. All six positive children reacted to at least one moisture-indicative mould, Fusarium roseum, Aspergillus fumigatus, Phoma herbarum or Rhodotorula rubra. None of these cases came from the reference school. There was a significant association between positive reactions to moisture-indicative moulds and asthma; four (44%) of the nine children with asthma had such reactions. In addition, all the 6 reactive children had either asthma or wheezing. CONCLUSIONS: We report preliminary evidence for an association between moisture or mould problems in the school building and the presence of manifest and occult asthma in the pupils. Our results show that skin-test positivity to moulds is rare in children. However, reactivity to moisture-indicative moulds seems to be associated with the occurrence of asthma or wheezing.