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The relationship between indicators of building dampness and respiratory health in young Swedish adults
Vol. 97 (2003) 302^307
The relationship between indicators of building dampness and respiratory health in young Swedish adults M. I.GUNNBJOºRNSDOTTIR*, D. NORBAºCKw, P. PLASCHKEz, E. NORRMAN}, E. BJOºRNSSONz AND C. JANSON* Department of Medical Sciences, Respiratory Medicine and Allergology, wDepartment of Occupational and Environmental Medicine, Akademiska University Hospital, Uppsala, Sweden, zDepartment of Medicine, Hilleroed Hospital, Denmark, }Department of Pulmonary Medicine and Allergology, University Hospital of Northern Sweden, Ume-, Sweden and zDepartment of Lung Medicine,Vi¢lstadir Hospital, Gardabaer Island, Sweden
*
Abstract Several epidemiological studies have indicated that building dampness affects the respiratory health of the inhabitants.Inthis study, we investigated the relationship between building dampness and respiratory symptomsinyoung Swedish adults.In1993, as a partofthe European Community Respiratory Health Survey stage II, subjects wereinvited to participate in a detailed interview-led questionnaire, spirometry, methacholine challenge and measurement of total and specific IgE. A total of 1853 of the 2084 selected subjects participated in this study (88.9%).One hundred and thirty-six (7.4%) subjects reported water damage in their homes in the last year and 318 (17.3%) subjects reported visible molds during the same period. Seventy-four (4%) subjects reported both water damage and visible molds in the last year.This subgroup, with 74 subjects had significantly more attacks of breathlessness both when resting (OR 3.2 (95% CI1.4^7.2)) and after e¡ort (OR 2.7 (95% CI1.3^5.6)) compared to subjects reporting no water damage or molds. Long-term cough was also more common in this group (OR 2.2 (95% CI1.2^4.0)).This study adds evidence to a relationship between damp buildings and respiratory symptoms.r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1053/rmed.2002.1389, available online at http://www.sciencedirect.com
Keywords epidemiology; respiratory symptoms; building dampness.
INTRODUCTION Respiratory symptoms are common in our society and the prevalence of asthma has increased in the industrialized world during the last decade (1). Modern man spends a large amount of his time indoors (2) and it has been proposed that the increase in asthma may be partially due to allergic and non-allergic reactions to indoor environment (3).The interest in indoor environment has consequently increased. The indoor environment is in£uenced by many biological, chemical and physical agents (4). High air humidity, condensation on cold surfaces, permanent dampness in the building construction and episodes of water leakage facilities microbial growth (3,5). Exposure to fungal toxins and spores (6), bacteria (7) and house dust mites (8) Received 29 April 2002 Correspondence should be addressed to: Maria I.Gunnbj˛rnsdottir, Department of Medical Science, Respiratory Medicine and Allergology, Akademiska University Hospital, S-75185 Uppsala, Sweden.Fax: +4618 611 0228; E-mail: [email protected]
are among the various dampness-related environmental indoor factors that may in£uence the respiratory health of the inhabitants. The present study is a part of the European Community Respiratory Health Survey, ECRHS (9).The aim is to investigate the relationship between indicators of building dampness and respiratory symptoms in young Swedish adults.
METHOD Population The methodology for the ECRHS has been described elsewhere (9). Participating centers selected an area de¢ned by pre-existing administrative boundaries with a population of at least 150 000. In each center in Sweden the population registry was used to randomly select 1800 men and 1800 women in the age group 20 ^ 44. In stage I, subjects were sent the ECRHS screening questionnaire. The subjects were queried on symptoms
THE RELATIONSHIP BETWEEN INDICATORS OF BUILDING DAMPNESS AND RESPIRATORY HEALTH
suggestive of asthma, the use of medication for asthma, and the presence of hay fever and nasal allergies. In stage II, a smaller random sample of subjects who had completed the screening questionnaire was invited to attend for a more detailed interview-led questionnaire, blood tests for the measurement of total and speci¢c IgE, a skin-prick test, spirometry and methacholine challenge. Our study is based on the subjects participating in stage II of the ECRHS. All the three centers in Sweden that participate in the ECRHS were included in this study. These centers are based in VIsterbotten, a large county in northern Sweden with a sub-arctic climatic; Uppsala, a university city located 60 km inland and north-west of Stockholm, located on the east coast and G˛teborg, Sweden’s second largest city, located on the south-western seaboard.
Questionnaire The interview-led questions covered a broad range of topics, including questions on respiratory symptoms, asthma and allergic disorders, on date of birth, gender, smoking habits and environmental exposure.
Building-related questions The participants were asked to respond to the following question: Has there ever been any water damage to the building or its contents, for example, from broken pipes, leaks or £oods?
Participants that responded positively were subsequently asked: Has there been any water damage in the last 12 months?
The participants were also asked: Has there ever been any mold or mildew on any surface, other than food inside the home?
Those who responded positively to this question were then asked: Has there been mold or mildew on any surfaces inside the home in the last12 months?
The participants were queried as to the age of their present home, type of building, on ¢tted carpets in the room most used at home during the day and in the bedroom and on the type of glazing installed.
Asthma-related questions The participants were asked whether they had experienced the following symptoms at any time in the preceding12 months: (a) ‘wheezing or whistling in the chest’, (b) ‘being woken by a feeling of tightness in the chest’, (c) ‘an
303
attack of shortness of breath during the day when resting’, (d) ‘an attack of shortness of breath following strenuous activity’, and (e) ‘being woken by an attack of shortness of breath’. Current asthma was in this analysis de¢ned as the subject answering ‘yes’ to the question ‘Have you ever had asthma?’ as well as answering ‘yes’ to the question if the subject had experienced an attack of asthma during the preceding 12 months.
Bronchitis-related questions Nocturnal cough was de¢ned as the subject answering ‘yes’ to the question: ‘Have you been woken by an attack of coughing at any time in the last 12 months?’. Long-term cough was de¢ned as the subject answering ‘yes’ to at least one of the following questions: ‘Do you usually cough ¢rst thing in the morning in the winter?’ and ‘Do you usually cough during the day or at night in the winter?’. Long-term phlegm production was de¢ned as the subject answering ‘yes’ to at least one of the following questions: ‘Do you usually bring up any phlegm from your chest ¢rst thing in the morning in the winter’ and ‘Do you usually bring up any phlegm from your chest during the day or at night in the winter?’.
Smoking history The participants were asked whether they had smoked at least one cigarette/day or one cigar a week for 1 year or 360 g tobacco in a lifetime.The subjects were categorized into three groups: never-smokers, ex-smokers and current smokers. Subjects that had stopped smoking less than12 months before the examination were for the purpose of this study de¢ned as current smokers (10). Environmental tobacco smoke exposure (ETS) was de¢ned as the estimated average numbers of hours exposed to other people’s tobacco smoking.
Lung function and allergy testing Forced expiratory volume in 1s (FEV1) and forced vital capacity (FVC) was recorded by spirometry using a standardized method (9). Methacholine challenge was carried out using a dosimeter (Mefar, Brescia, Italy). The level of bronchial responsiveness was expressed using the ECRHS slope (11). Total and speci¢c IgE was measured using the Pharmacia CAP System (Pharmacia Diagnostics, Uppsala, Sweden). In all centers, speci¢c IgE was measured against Dermatophagoides pteronyssinus, cat, timothy grass, birch and Cladosporium herbarum. Detection of speci¢c IgE (40.35 kU/l) was used as the de¢nition of sensitization.
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RESPIRATORY MEDICINE
Atopy was de¢ned as being sensitized to any of the allergens above.
Statistical analysis The statistical analysis was performed using Stata 6.0 (Stata Corporation, College Station, Texas). Logistic regression was used when calculating odds ratios (OR) for the in£uence of household water damage, molds or both on respiratory symptoms. Multiple linear regression was used when analyzing the e¡ect of water damage on lung function and bronchial responsiveness.The adjusted odds ratios and regression coe⁄cients were ¢rst analyzed on pooled data from all three centers adjusting for center. In order to detect heterogeneity between centers, the adjusted odds ratios and regression coe⁄cients were thereafter calculated separately in each center. Average e¡ect estimates were derived and potential heterogeneity between centers was examined using standard methods for random-e¡ects meta-analysis (12).
RESULTS Information on reported water damage was available from 1853 subjects (mean age 33.3 (range (20 ^ 45 years)) of the 2084 subjects invited to participate (response rate 88.9%). Household characteristics of the participants from the three centers are presented in Table 1. Of the 1853 subject included, spirometry was performed on 1607, IgE measurements on 1521 and methacholine challenge on 1455. TABLE 1. Household characteristics (%) VCsterbotten Uppsala (n¼551) (n¼622) Detached/ semidetached houses House built Before1960 1960^1970 1971^1980 After1980 Double or triple glazing Fitted carpet in day room Fitted carpet in bedroom Water damage inthe last12 months Visible moulds in the last12 months
G˛teborg (n¼680)
61.0
41.0
39.7
21.3 18.3 27.7 32.7
30.0 20.0 23.7 26.3
29.8 25.2 21.1 23.8
99.6
99.8
99.6
3.1
6.1
6.5
12.1
14.1
17.7
6.5
8.8
6.6
14.7
20.6
16.3
FIG. 1. Of 1845 persons, 380 (20.6%) report molds or water damage. Of those, 244 (13.2%) report molds only, 62 (3.6%) report water damage only and 74 (4.0%) report both in the last 12 months.
In the total sample,136 subjects (7.4%) reported having had water damage in the household during the preceding 12 months and 318 subjects (17.3%) reported having observed visible molds in the household within the last 12 months.The prevalence and overlap of these two indicators of building dampness is presented in Fig. 1. A signi¢cantly higher prevalence of attacks of breathlessness when resting or following strenuous activity and a higher prevalence of long-term cough was found in the group of subjects that reported both water damage and visible molds when compared with subjects that reported neither of these indicators (Table 2). The prevalence of respiratory symptoms was not signi¢cantly increased in the group of subjects that reported only water damage or visible molds when compared to the control group. Multivariate analysis was performed where adjustments were made for age, sex, smoking history, ETS, total serum IgE and allergic sensitivity to mite, cat timothy grass, birch and Cladosporium.The combination of water damage and visible molds was independently associated with attacks of breathlessness when resting and after activity and long-term cough (Table 3). All these associations remained statistically signi¢cant when other household factors (age of house, type of house and ¢tted carpeting in day room or bedroom) were added as additional independent variables. The association between the combination of water damage and visible molds and attacks of breathlessness when resting, breathlessness after activity and longterm cough remained signi¢cant when using meta-analysis. No heterogeneity between centers was found for the association between the humidity indicators and any of the respiratory symptoms.The possibility of a gender difference between the association of household water damage with symptoms, asthma and bronchitis was investigated by test of interaction. No signi¢cant gender di¡erences in the association between water damage and any of the variables above were found. No signi¢cant interaction was found in the association between water damage and symptoms, asthma or bronchitis in non-atopic or atopic subjects.
THE RELATIONSHIP BETWEEN INDICATORS OF BUILDING DAMPNESS AND RESPIRATORY HEALTH
305
TABLE 2. Prevalence of respiratory symptoms and diagnosis in subjects without any molds or water damage, reporting molds only or water damage only or reporting both in the last12 months (%) No molds or water damage (n=1465)
Only molds (n=244)
Only water damage (n=62)
Molds and water damage (n=74)
26.1 11.3 4.7 6.9 4.5 4.5 35.6 16.9 16.5 8.3
26.6 8.6 4.5 8.6 4.5 3.7 40.6 19.7 17.4 7.6
29.0 13.1 6.5 11.3 4.8 9.7 48.4 24.2 27.9 15.5
33.8 11.1 10.8* 16.2** 4.1 5.4 37.8 29.7** 21.9 14.3
Wheeze Nocturnal chesttightness Breathless when resting Breathless after e¡ort Nocturnal breathlessness Current asthma Nocturnal cough Long-term cough Long-term phlegm production Chronic bronchitis [*Po0.05, **Po0.01.]
TABLE 3. Adjusted odds ratio (OR) and 95% con¢dence interval (95% CI)a for respiratory symptoms and current asthma in subjects with reported water damage and/or visible molds in the household in the last12 months compared to subjects without reported water damage and visible molds. Only molds OR
95% CI
Only water damage OR
95% CI
Molds and water damage OR
95% CI
Wheeze 1.00 0.71^1.42 1.41 0.73^2.72 1.40 0.78^2.52 Nocturnal chesttightness 0.76 0.46^1.26 1.21 0.52^2.77 1.18 0.54^2.57 Breathless when resting 0.90 0.45^1.81 1.15 0.34^3.85 3.24 1.44^7.29 Breathless after e¡ort 1.10 0.64^1.88 1.70 0.70^4.16 2.76 1.36^5.60 Nocturnal breathlessness 0.94 0.47^1.87 0.75 0.18^3.21 1.00 0.30^3.21 Current asthma 0.84 0.38^1.86 2.46 0.89^6.79 1.58 0.52^4.84 Nocturnal cough 1.21 0.90^1.64 1.67 0.93^2.98 1.18 0.68^2.04 Long-term cough 1.10 0.74^1.61 1.46 0.72^2.94 2.23 1.24^4.00 Long-term phlegm production 1.00 0.66^1.49 1.57 0.78^3.19 1.38 0.73^2.61 a Adjusted for age, sex, smoking history, environmental tobacco smoke, total serum IgE and sensitization to mite, cat, Cladosporium, timothy grass and birch. a
Adjusted for age, sex, smoking history, environmental tobacco smoke, total serum IgE and sensitization to mite, cat, Cladosporium, timothy grass and birch.
In addition to this, no signi¢cant independent association was found between any of the humidity indicators and bronchial responsiveness or lung function (Table 4).
DISCUSSION The main results of this study are that some respiratory symptoms are more common in subjects reporting dampness in their homes. However, the increased prevalence of respiratory symptoms was predominately present in subjects reporting both visible molds and water damage. Building dampness was reported by 20% of the population in or study. This is in accordance with three other Swedish studies, where the reported prevalence of building dampness was17%,19% and 24% in randomly selected
buildings (13,14,3). From Finland, Pirhonen et al. report dampness in 23% of buildings (4). Brunekreef found dampness in 25% of homes in the Netherlands (15) and in Canada, Dates et al. reported 38% of the homes as being damp (16). All these prevalence ¢gures are based on a self-reported questionnaire with no objective measurements. We found a positive association between the combination of visible molds and water damage and most kinds of respiratory symptoms.The association was strongest for symptoms related to daytime attacks of breathlessness and long-term cough. The positive association between building dampness and wheeze was not statistical signi¢cant, but of the same magnitude as has previously been reported in two review papers where the association was analyzed by meta-analysis (5,17).
306
RESPIRATORY MEDICINE
TABLE 4. Estimated e¡ect and 95% con¢dence interval (95% CI) for lung function (FEV1 and FVC) and bronchial responsiveness (ECRHS slope) in subjects with reported water damage and/or visible molds in the household in the last 12 months compared to subjects without reported water damage and visible molds Only molds
ECRHS slope (units) FEV1 (ml) FVC (ml)
Only water damage
Molds and water damage
OR
95% CI
OR
95% CI
OR
95% CI
0.17 36 16
0.44, 0.10 103, 32 98, 65
0.40 77 29
0.94, 0.14 207, 54 129, 186
0.20 20 85
0.31, 0.71 141, 102 231, 61
We were unable to ¢nd an association between indicators of building dampness and objective measurements such as bronchial responsiveness or lung function. This could indicate that building dampness does not a¡ect more underlying mechanisms related to asthma such as bronchial in£ammation and remodeling. In a previous analysis of the subjects from one of the centers, NorbIck et al. did however note an increased level of eosinophils in the blood of subjects that reported water damage in the household (3). The association between building dampness and some respiratory symptoms remained una¡ected by adjustments for variables related to the socio-economic status of the subjects such as smoking history and type of building. It was also una¡ected by adjustments for other indoor factors such as ¢tted carpeting and the age of the building.The underlying mechanisms explaining the association between dampness and respiratory symptoms is, however, still unknown. Molds thrive in damp environment and it has been demonstrated that water damage which persists for more than 3 days causes an increase in the levels of spores inside a building (18). The major structural components of fungal cell wall are glucans, compounds that can cause respiratory symptoms (19,20). Organic volatile compounds can be the cause of odor in damp homes (21) and it is known that molds that produce mycotoxins thrive in such environments (21,22). Some studies have indicated that women may be more a¡ected by environmental indoor factors. Jarvis et al. noted an association between gas cooking and respiratory symptoms that was present among women but not among men (23,24). In our analysis, however, we found no evidence of a gender di¡erence in the association between building dampness and symptoms. In accordance with Dales et al. (16) we found no di¡erence in the relationship between markers of building humidity and respiratory symptoms when comparing subjects with and without atopy. Many methodological problems are inherent in epidemiological studies with regards to validity. In this study, selection bias due to low response rates is unlikely, as the average response rate was high (86%) in the initial postal questionnaire and repeatedly high (89%) in the subsequent interview-led questionnaire. There was no
di¡erence in responders and non-responders regarding age, sex or smoking habits. Previous studies have showed a fairly good reproducibility of self-administered questions on building humidity, visible molds and £ooding (3,25,26). Subjects with and without respiratory symptoms had a similar reporting rate, but the discrepancies between self-reported house dampness and what research investigators discover can vary as much as up to 30% (27,28). Subjects with respiratory symptoms could be more aware of environmental risk factors such as dampness and visible molds than subjects with no symptoms. A study by Williamson et al. did however ¢nd that both occupants with and without respiratory symptoms were prone to report less dampness in their homes (29) when compared to dampness observed by outside inspectors. It should also be noted that our study is crosssectional with no control over possible selection bias caused by selective migration of people with respiratory symptoms from homes with molds or water damage. The authors conclude that building dampness is a common problem in Sweden and is related to an increased prevalence of some respiratory symptoms. A considerable body of evidence now exists that supports that dampness and molds do a¡ect people’s health.This health risk can be reduced and partly prevented by increasing general public awareness of the problem, by avoiding water leaks in the building construction, with su⁄cient ventilation in the homes and avoiding building sites where risk for building dampness is increased.
Acknowledgements The Swedish Heart and Lung Foundation and the Bror Hjerpstedt Foundation supported this study.
REFERENCES 1. Brunetreet B. Respiratory epidemiology in Europe. Eur Resp Mon 2000; 15: 384–399. 2. Moschandreas DJ. Exposure to pollutants and daily time budgets of people. Bull NYAcad Med 1981; 57: 845–859. 3. Norba¨ck, D, Bjo¨rnsson E, Janson C, Palmgren U, Boman G. Current asthma and biochemical signs of inflammation in relation to building dampness in dwellings. Int J Tuberc Lung Dis 1999; 3: 368–376.
THE RELATIONSHIP BETWEEN INDICATORS OF BUILDING DAMPNESS AND RESPIRATORY HEALTH
4. Pirrhonen I, Nevalainen A, Husman T, Pekkanen J. Home dampness, moulds and their influence on respiratory infections and symptoms in adults in Finland. Eur Resp J 1996; 9: 2618–2622. 5. Peat JK, Dickerson J, Li J. Effects of damp and mould in the home on respiratory health: a review of the literature. Allergy 1998; 53: 120–128. 6. Miller JD. Fungi as contaminants in indoor air. Atmos Environ 1992; 26A: 2163–2172. 7. Bjo¨rnsson, E, Norba¨ck, D, Janson C, Widstro¨m J, Palmgren U, Stro¨m G, Boman G. Asthmatic symptoms and indoor levels of micro-organisms and house dust mites. Clin Exp Allergy 1995; 25: 423–431. 8. Sporik R, Holgate ST, Platts-Mills TEA, Cogdwell JJ. Exposure to house-dust mite allergen (der p I) and the development of asthma in childhood. N Engl J Med 1990; 323: 502–507. 9. Burney PGJ, Luczynska C, Chinn S, Jarvis D. The European Community Respiratory Health Survey. Eur Respir J 1994; 7: 954–960. 10. Leynaert B, Bousquet J, Henry C, Liard R, Neukirch F. Is bronchial hyperresponsiveness more frequent in women than in men? A population-based study. Am J Respir Crit Care Med 1997; 156: 1413– 1420. 11. Chinn S, Burney P, Jarvis D, Luczynska C. Variation in bronchial responsiveness in the European Community Respiratory Health Survey. Eur Res J 1977; 10: 2495–2501. 12. Der Somonian R, Liard N. 1986. Meta-analysis in clinical trials. Control ClinTrials 1986; 7: 117–188. 13. Nordba¨ck D, Edling C, Wieslander G. Asthma symptoms and the sick building syndrome (SBS)Fthe significance of microorganisms in the indoor environment. In: Samson RA, Flanningan B, Flanningan ME, Verhoeff AP, Adan OCH, Hoekstra ES (eds). Health Implications of Fungi in Indoor Environment. Air Quality Monographs, Vol. 2. Amsterdam: Elsevier, 1994: 229–239. 14. Nordba¨ck D, Bjo¨rnsson E, Janson C, Widstro¨m J, Boman G. Asthmatic symptoms and the volatile organic compounds, formaldehyde and carbon dioxide in dwellings. Occup Environ Med 1995; 52: 388–395. 15. Brunekreef B. Damp housing and adult respiratory symptoms. Allergy 1992; 47: 498–502. 16. Dales RE, Burnett R, Zwanenburg H. Adverse health effects among adults exposed to home dampness and molds. Am Rev Respir Dis 1991; 143: 505–509.
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17. Bornehag CG, Blomquist G, Gyntelberg F, Ja¨rvholm B, Malmberg L. Nielsen A, Pershagen G, Sundell J. Dampness in buildings and health. Nordic interdisciplinary review of the scientific evidence on associations between exposure to ‘‘dampness’’ in buildings and health effects. Indoor Air 2001; 11: 72–86. 18. Gallup J, Korzac P, Cummins L, Gillman S. Indoor mold spore exposure: characteristics of 127 homes in Southern California with endogenous mold problems. Adv Aerobiol 1987; EXS 51: 139–142. 19. Rylander R. Airborne (1-3)-beta-D-glucan and airway disease in a day-care center before and after renovation. Arch Environ Health 1997; 52: 281–285. 20. Thor J, Rylander R. Airways inflammation and glucan in a rowhouse area. Am J Resp Crit Care Med 1998; 157: 1798–1805. 21. Pieckova E, Jesinska Z. Microscopic fungi in dwellings and their health implication in humans. Ann Agric Environ Med 1999; 6: 1–11. 22. Federal-Provincial Committee on Environmental and Occupational Health, Fungal Contamination in Public Buildings: A Guide to Recognition and Management. Ottawa, Ontario, Canada, 1995. 23. Jarvis D, Chinn S, Luczynska C, Burney P. Association of respiratory symptoms and lung function in young adults with use of domestic gas appliances. Lancet1996; 347: 426–431. 24. Jarvis D, Chinn S, Sterne J, Luczynska C, Burney P. The association of respiratory symptoms and lung function with the use of gas for cooking. European Community Respiratory Health Survey. Eur Respir J 1998; 11: 651–658. 25. Dales RE, Schweitzer I, Bartlett S, Raizenne M, Burnett R. Indoor air quality and health: reproducibility of respiratory symptoms and reported home dampness and molds using a self-administered questionnaire Indoor Air 1994; 4: 2–7. 26. Brunekreef B, Verhoeff AP, van Strien RT, van Wijnen JH. Homes dampness and childhood respiratory symptoms: the role of sensitization to dust mites and molds. In: Samson RA, Flannigan B, Verhoeff AP, Adan OCH, Hoekstra ES (eds). Health Implications of Fungi in Indoor Environments. Air Quality Monographs, Vol. 2. Amsterdam: Elsevier, 1995: 189–199. 27. Platt SD, Martin CJ, Hunt SM, Lewis CW. Damp housing, mold growth, and symptomatic health state. Br Med J 1989; 298: 1673–1678. 28. Verhoeff AP, Burge HA. Health risk assessment of fungi in home environments. Ann Allergy Asthma Immunol 1997; 78: 544–556. 29. Williamsson IJ, Martin CJ, McGill G, Monie RDH, Fennerty AG. Damp housing and asthma: a case–control study. Thorax 1997; 52: 229–234.
The relationship between indicators of building dampness and respiratory health in young Swedish adults M. I.GUNNBJOºRNSDOTTIR*, D. NORBAºCKw, P. PLASCHKEz, E. NORRMAN}, E. BJOºRNSSONz AND C. JANSON* Department of Medical Sciences, Respiratory Medicine and Allergology, wDepartment of Occupational and Environmental Medicine, Akademiska University Hospital, Uppsala, Sweden, zDepartment of Medicine, Hilleroed Hospital, Denmark, }Department of Pulmonary Medicine and Allergology, University Hospital of Northern Sweden, Ume-, Sweden and zDepartment of Lung Medicine,Vi¢lstadir Hospital, Gardabaer Island, Sweden
*
Abstract Several epidemiological studies have indicated that building dampness affects the respiratory health of the inhabitants.Inthis study, we investigated the relationship between building dampness and respiratory symptomsinyoung Swedish adults.In1993, as a partofthe European Community Respiratory Health Survey stage II, subjects wereinvited to participate in a detailed interview-led questionnaire, spirometry, methacholine challenge and measurement of total and specific IgE. A total of 1853 of the 2084 selected subjects participated in this study (88.9%).One hundred and thirty-six (7.4%) subjects reported water damage in their homes in the last year and 318 (17.3%) subjects reported visible molds during the same period. Seventy-four (4%) subjects reported both water damage and visible molds in the last year.This subgroup, with 74 subjects had significantly more attacks of breathlessness both when resting (OR 3.2 (95% CI1.4^7.2)) and after e¡ort (OR 2.7 (95% CI1.3^5.6)) compared to subjects reporting no water damage or molds. Long-term cough was also more common in this group (OR 2.2 (95% CI1.2^4.0)).This study adds evidence to a relationship between damp buildings and respiratory symptoms.r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1053/rmed.2002.1389, available online at http://www.sciencedirect.com
Keywords epidemiology; respiratory symptoms; building dampness.
INTRODUCTION Respiratory symptoms are common in our society and the prevalence of asthma has increased in the industrialized world during the last decade (1). Modern man spends a large amount of his time indoors (2) and it has been proposed that the increase in asthma may be partially due to allergic and non-allergic reactions to indoor environment (3).The interest in indoor environment has consequently increased. The indoor environment is in£uenced by many biological, chemical and physical agents (4). High air humidity, condensation on cold surfaces, permanent dampness in the building construction and episodes of water leakage facilities microbial growth (3,5). Exposure to fungal toxins and spores (6), bacteria (7) and house dust mites (8) Received 29 April 2002 Correspondence should be addressed to: Maria I.Gunnbj˛rnsdottir, Department of Medical Science, Respiratory Medicine and Allergology, Akademiska University Hospital, S-75185 Uppsala, Sweden.Fax: +4618 611 0228; E-mail: [email protected]
are among the various dampness-related environmental indoor factors that may in£uence the respiratory health of the inhabitants. The present study is a part of the European Community Respiratory Health Survey, ECRHS (9).The aim is to investigate the relationship between indicators of building dampness and respiratory symptoms in young Swedish adults.
METHOD Population The methodology for the ECRHS has been described elsewhere (9). Participating centers selected an area de¢ned by pre-existing administrative boundaries with a population of at least 150 000. In each center in Sweden the population registry was used to randomly select 1800 men and 1800 women in the age group 20 ^ 44. In stage I, subjects were sent the ECRHS screening questionnaire. The subjects were queried on symptoms
THE RELATIONSHIP BETWEEN INDICATORS OF BUILDING DAMPNESS AND RESPIRATORY HEALTH
suggestive of asthma, the use of medication for asthma, and the presence of hay fever and nasal allergies. In stage II, a smaller random sample of subjects who had completed the screening questionnaire was invited to attend for a more detailed interview-led questionnaire, blood tests for the measurement of total and speci¢c IgE, a skin-prick test, spirometry and methacholine challenge. Our study is based on the subjects participating in stage II of the ECRHS. All the three centers in Sweden that participate in the ECRHS were included in this study. These centers are based in VIsterbotten, a large county in northern Sweden with a sub-arctic climatic; Uppsala, a university city located 60 km inland and north-west of Stockholm, located on the east coast and G˛teborg, Sweden’s second largest city, located on the south-western seaboard.
Questionnaire The interview-led questions covered a broad range of topics, including questions on respiratory symptoms, asthma and allergic disorders, on date of birth, gender, smoking habits and environmental exposure.
Building-related questions The participants were asked to respond to the following question: Has there ever been any water damage to the building or its contents, for example, from broken pipes, leaks or £oods?
Participants that responded positively were subsequently asked: Has there been any water damage in the last 12 months?
The participants were also asked: Has there ever been any mold or mildew on any surface, other than food inside the home?
Those who responded positively to this question were then asked: Has there been mold or mildew on any surfaces inside the home in the last12 months?
The participants were queried as to the age of their present home, type of building, on ¢tted carpets in the room most used at home during the day and in the bedroom and on the type of glazing installed.
Asthma-related questions The participants were asked whether they had experienced the following symptoms at any time in the preceding12 months: (a) ‘wheezing or whistling in the chest’, (b) ‘being woken by a feeling of tightness in the chest’, (c) ‘an
303
attack of shortness of breath during the day when resting’, (d) ‘an attack of shortness of breath following strenuous activity’, and (e) ‘being woken by an attack of shortness of breath’. Current asthma was in this analysis de¢ned as the subject answering ‘yes’ to the question ‘Have you ever had asthma?’ as well as answering ‘yes’ to the question if the subject had experienced an attack of asthma during the preceding 12 months.
Bronchitis-related questions Nocturnal cough was de¢ned as the subject answering ‘yes’ to the question: ‘Have you been woken by an attack of coughing at any time in the last 12 months?’. Long-term cough was de¢ned as the subject answering ‘yes’ to at least one of the following questions: ‘Do you usually cough ¢rst thing in the morning in the winter?’ and ‘Do you usually cough during the day or at night in the winter?’. Long-term phlegm production was de¢ned as the subject answering ‘yes’ to at least one of the following questions: ‘Do you usually bring up any phlegm from your chest ¢rst thing in the morning in the winter’ and ‘Do you usually bring up any phlegm from your chest during the day or at night in the winter?’.
Smoking history The participants were asked whether they had smoked at least one cigarette/day or one cigar a week for 1 year or 360 g tobacco in a lifetime.The subjects were categorized into three groups: never-smokers, ex-smokers and current smokers. Subjects that had stopped smoking less than12 months before the examination were for the purpose of this study de¢ned as current smokers (10). Environmental tobacco smoke exposure (ETS) was de¢ned as the estimated average numbers of hours exposed to other people’s tobacco smoking.
Lung function and allergy testing Forced expiratory volume in 1s (FEV1) and forced vital capacity (FVC) was recorded by spirometry using a standardized method (9). Methacholine challenge was carried out using a dosimeter (Mefar, Brescia, Italy). The level of bronchial responsiveness was expressed using the ECRHS slope (11). Total and speci¢c IgE was measured using the Pharmacia CAP System (Pharmacia Diagnostics, Uppsala, Sweden). In all centers, speci¢c IgE was measured against Dermatophagoides pteronyssinus, cat, timothy grass, birch and Cladosporium herbarum. Detection of speci¢c IgE (40.35 kU/l) was used as the de¢nition of sensitization.
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RESPIRATORY MEDICINE
Atopy was de¢ned as being sensitized to any of the allergens above.
Statistical analysis The statistical analysis was performed using Stata 6.0 (Stata Corporation, College Station, Texas). Logistic regression was used when calculating odds ratios (OR) for the in£uence of household water damage, molds or both on respiratory symptoms. Multiple linear regression was used when analyzing the e¡ect of water damage on lung function and bronchial responsiveness.The adjusted odds ratios and regression coe⁄cients were ¢rst analyzed on pooled data from all three centers adjusting for center. In order to detect heterogeneity between centers, the adjusted odds ratios and regression coe⁄cients were thereafter calculated separately in each center. Average e¡ect estimates were derived and potential heterogeneity between centers was examined using standard methods for random-e¡ects meta-analysis (12).
RESULTS Information on reported water damage was available from 1853 subjects (mean age 33.3 (range (20 ^ 45 years)) of the 2084 subjects invited to participate (response rate 88.9%). Household characteristics of the participants from the three centers are presented in Table 1. Of the 1853 subject included, spirometry was performed on 1607, IgE measurements on 1521 and methacholine challenge on 1455. TABLE 1. Household characteristics (%) VCsterbotten Uppsala (n¼551) (n¼622) Detached/ semidetached houses House built Before1960 1960^1970 1971^1980 After1980 Double or triple glazing Fitted carpet in day room Fitted carpet in bedroom Water damage inthe last12 months Visible moulds in the last12 months
G˛teborg (n¼680)
61.0
41.0
39.7
21.3 18.3 27.7 32.7
30.0 20.0 23.7 26.3
29.8 25.2 21.1 23.8
99.6
99.8
99.6
3.1
6.1
6.5
12.1
14.1
17.7
6.5
8.8
6.6
14.7
20.6
16.3
FIG. 1. Of 1845 persons, 380 (20.6%) report molds or water damage. Of those, 244 (13.2%) report molds only, 62 (3.6%) report water damage only and 74 (4.0%) report both in the last 12 months.
In the total sample,136 subjects (7.4%) reported having had water damage in the household during the preceding 12 months and 318 subjects (17.3%) reported having observed visible molds in the household within the last 12 months.The prevalence and overlap of these two indicators of building dampness is presented in Fig. 1. A signi¢cantly higher prevalence of attacks of breathlessness when resting or following strenuous activity and a higher prevalence of long-term cough was found in the group of subjects that reported both water damage and visible molds when compared with subjects that reported neither of these indicators (Table 2). The prevalence of respiratory symptoms was not signi¢cantly increased in the group of subjects that reported only water damage or visible molds when compared to the control group. Multivariate analysis was performed where adjustments were made for age, sex, smoking history, ETS, total serum IgE and allergic sensitivity to mite, cat timothy grass, birch and Cladosporium.The combination of water damage and visible molds was independently associated with attacks of breathlessness when resting and after activity and long-term cough (Table 3). All these associations remained statistically signi¢cant when other household factors (age of house, type of house and ¢tted carpeting in day room or bedroom) were added as additional independent variables. The association between the combination of water damage and visible molds and attacks of breathlessness when resting, breathlessness after activity and longterm cough remained signi¢cant when using meta-analysis. No heterogeneity between centers was found for the association between the humidity indicators and any of the respiratory symptoms.The possibility of a gender difference between the association of household water damage with symptoms, asthma and bronchitis was investigated by test of interaction. No signi¢cant gender di¡erences in the association between water damage and any of the variables above were found. No signi¢cant interaction was found in the association between water damage and symptoms, asthma or bronchitis in non-atopic or atopic subjects.
THE RELATIONSHIP BETWEEN INDICATORS OF BUILDING DAMPNESS AND RESPIRATORY HEALTH
305
TABLE 2. Prevalence of respiratory symptoms and diagnosis in subjects without any molds or water damage, reporting molds only or water damage only or reporting both in the last12 months (%) No molds or water damage (n=1465)
Only molds (n=244)
Only water damage (n=62)
Molds and water damage (n=74)
26.1 11.3 4.7 6.9 4.5 4.5 35.6 16.9 16.5 8.3
26.6 8.6 4.5 8.6 4.5 3.7 40.6 19.7 17.4 7.6
29.0 13.1 6.5 11.3 4.8 9.7 48.4 24.2 27.9 15.5
33.8 11.1 10.8* 16.2** 4.1 5.4 37.8 29.7** 21.9 14.3
Wheeze Nocturnal chesttightness Breathless when resting Breathless after e¡ort Nocturnal breathlessness Current asthma Nocturnal cough Long-term cough Long-term phlegm production Chronic bronchitis [*Po0.05, **Po0.01.]
TABLE 3. Adjusted odds ratio (OR) and 95% con¢dence interval (95% CI)a for respiratory symptoms and current asthma in subjects with reported water damage and/or visible molds in the household in the last12 months compared to subjects without reported water damage and visible molds. Only molds OR
95% CI
Only water damage OR
95% CI
Molds and water damage OR
95% CI
Wheeze 1.00 0.71^1.42 1.41 0.73^2.72 1.40 0.78^2.52 Nocturnal chesttightness 0.76 0.46^1.26 1.21 0.52^2.77 1.18 0.54^2.57 Breathless when resting 0.90 0.45^1.81 1.15 0.34^3.85 3.24 1.44^7.29 Breathless after e¡ort 1.10 0.64^1.88 1.70 0.70^4.16 2.76 1.36^5.60 Nocturnal breathlessness 0.94 0.47^1.87 0.75 0.18^3.21 1.00 0.30^3.21 Current asthma 0.84 0.38^1.86 2.46 0.89^6.79 1.58 0.52^4.84 Nocturnal cough 1.21 0.90^1.64 1.67 0.93^2.98 1.18 0.68^2.04 Long-term cough 1.10 0.74^1.61 1.46 0.72^2.94 2.23 1.24^4.00 Long-term phlegm production 1.00 0.66^1.49 1.57 0.78^3.19 1.38 0.73^2.61 a Adjusted for age, sex, smoking history, environmental tobacco smoke, total serum IgE and sensitization to mite, cat, Cladosporium, timothy grass and birch. a
Adjusted for age, sex, smoking history, environmental tobacco smoke, total serum IgE and sensitization to mite, cat, Cladosporium, timothy grass and birch.
In addition to this, no signi¢cant independent association was found between any of the humidity indicators and bronchial responsiveness or lung function (Table 4).
DISCUSSION The main results of this study are that some respiratory symptoms are more common in subjects reporting dampness in their homes. However, the increased prevalence of respiratory symptoms was predominately present in subjects reporting both visible molds and water damage. Building dampness was reported by 20% of the population in or study. This is in accordance with three other Swedish studies, where the reported prevalence of building dampness was17%,19% and 24% in randomly selected
buildings (13,14,3). From Finland, Pirhonen et al. report dampness in 23% of buildings (4). Brunekreef found dampness in 25% of homes in the Netherlands (15) and in Canada, Dates et al. reported 38% of the homes as being damp (16). All these prevalence ¢gures are based on a self-reported questionnaire with no objective measurements. We found a positive association between the combination of visible molds and water damage and most kinds of respiratory symptoms.The association was strongest for symptoms related to daytime attacks of breathlessness and long-term cough. The positive association between building dampness and wheeze was not statistical signi¢cant, but of the same magnitude as has previously been reported in two review papers where the association was analyzed by meta-analysis (5,17).
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TABLE 4. Estimated e¡ect and 95% con¢dence interval (95% CI) for lung function (FEV1 and FVC) and bronchial responsiveness (ECRHS slope) in subjects with reported water damage and/or visible molds in the household in the last 12 months compared to subjects without reported water damage and visible molds Only molds
ECRHS slope (units) FEV1 (ml) FVC (ml)
Only water damage
Molds and water damage
OR
95% CI
OR
95% CI
OR
95% CI
0.17 36 16
0.44, 0.10 103, 32 98, 65
0.40 77 29
0.94, 0.14 207, 54 129, 186
0.20 20 85
0.31, 0.71 141, 102 231, 61
We were unable to ¢nd an association between indicators of building dampness and objective measurements such as bronchial responsiveness or lung function. This could indicate that building dampness does not a¡ect more underlying mechanisms related to asthma such as bronchial in£ammation and remodeling. In a previous analysis of the subjects from one of the centers, NorbIck et al. did however note an increased level of eosinophils in the blood of subjects that reported water damage in the household (3). The association between building dampness and some respiratory symptoms remained una¡ected by adjustments for variables related to the socio-economic status of the subjects such as smoking history and type of building. It was also una¡ected by adjustments for other indoor factors such as ¢tted carpeting and the age of the building.The underlying mechanisms explaining the association between dampness and respiratory symptoms is, however, still unknown. Molds thrive in damp environment and it has been demonstrated that water damage which persists for more than 3 days causes an increase in the levels of spores inside a building (18). The major structural components of fungal cell wall are glucans, compounds that can cause respiratory symptoms (19,20). Organic volatile compounds can be the cause of odor in damp homes (21) and it is known that molds that produce mycotoxins thrive in such environments (21,22). Some studies have indicated that women may be more a¡ected by environmental indoor factors. Jarvis et al. noted an association between gas cooking and respiratory symptoms that was present among women but not among men (23,24). In our analysis, however, we found no evidence of a gender di¡erence in the association between building dampness and symptoms. In accordance with Dales et al. (16) we found no di¡erence in the relationship between markers of building humidity and respiratory symptoms when comparing subjects with and without atopy. Many methodological problems are inherent in epidemiological studies with regards to validity. In this study, selection bias due to low response rates is unlikely, as the average response rate was high (86%) in the initial postal questionnaire and repeatedly high (89%) in the subsequent interview-led questionnaire. There was no
di¡erence in responders and non-responders regarding age, sex or smoking habits. Previous studies have showed a fairly good reproducibility of self-administered questions on building humidity, visible molds and £ooding (3,25,26). Subjects with and without respiratory symptoms had a similar reporting rate, but the discrepancies between self-reported house dampness and what research investigators discover can vary as much as up to 30% (27,28). Subjects with respiratory symptoms could be more aware of environmental risk factors such as dampness and visible molds than subjects with no symptoms. A study by Williamson et al. did however ¢nd that both occupants with and without respiratory symptoms were prone to report less dampness in their homes (29) when compared to dampness observed by outside inspectors. It should also be noted that our study is crosssectional with no control over possible selection bias caused by selective migration of people with respiratory symptoms from homes with molds or water damage. The authors conclude that building dampness is a common problem in Sweden and is related to an increased prevalence of some respiratory symptoms. A considerable body of evidence now exists that supports that dampness and molds do a¡ect people’s health.This health risk can be reduced and partly prevented by increasing general public awareness of the problem, by avoiding water leaks in the building construction, with su⁄cient ventilation in the homes and avoiding building sites where risk for building dampness is increased.
Acknowledgements The Swedish Heart and Lung Foundation and the Bror Hjerpstedt Foundation supported this study.
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