RESUMEN
Particle mass and number concentrations were measured in a mechanically ventilated classroom as part of a study of ventilation strategies for energy conservation. The ventilation system was operated either continuously, intermittently, or shut down during nights while it was on during workdays. It appears that the nighttime ventilation scheme is not important for indoor particle concentrations the following day if fans are operated to give five air exchanges in advance of the workday. The highest concentrations of PM10 were found during and after workdays and were due to human activity in the classroom. The average workday PM10 concentration was 14 µg/m(3) , well below the WHO guideline values. The number concentration of particles with diameter <0.750 µm was typically between 0.5 × 10(3) and 3.5 × 10(3) particle/cm(3) . These concentrations were largely independent of the occupants. Transient formation of small particles was observed when ventilation was shut down. Then remaining ozone reacted with terpenes emitted by indoor sources and gave up to 8 × 10(3) particle/cm(3) before formation stopped due to lack of ozone. The intermittent ventilation regime was found least favorable for the indoor air quality in the classroom.
Asunto(s)
Contaminación del Aire Interior/análisis , Material Particulado/análisis , Instituciones Académicas , Ventilación/métodos , Conservación de los Recursos Energéticos , Humanos , Tamaño de la Partícula , Material Particulado/normasRESUMEN
UNLABELLED: The Dampness in Buildings and Health study (DBH) started in the year 2000 in Värmland, Sweden, with a baseline questionnaire sent to all children (n = 14,077) aged 1-6. Five years later, a follow-up questionnaire was sent to the children who were 1-3 years at baseline. A total of 4779 children participated in both the baseline and the follow-up studies and constitute the study population in this cohort study. The aim of this study was to examine the association between exposure to PVC-flooring in the child's and parent's bedroom in homes of children aged 1-3 and the incidence of asthma, rhinitis, and eczema during the following 5-year period. Adjusted analyses showed that the incidence of asthma among children was associated with PVC-flooring in the child's bedroom (AOR 1.52; 95% CI 0.99-2.35) and in the parent's bedroom (1.46; 0.96-2.23). The found risks were on borderline of significance and should therefore be interpreted with caution. There was further a positive relationship between the number of rooms with PVC-flooring and the cumulative incidence of asthma. PVC-flooring was found to be a stronger risk factor for incident asthma in multifamily homes when compared with single-family houses and in smoking families compared with non-smoking families and in women. PRACTICAL IMPLICATIONS: These longitudinal data from the DBH study found an association between the presence of PVC-flooring in the home and incident asthma in children. However, earlier results from the DBH study have shown that PVC-flooring is one important source for phthalates in indoor dust, and exposure to such phthalates was found to be associated with asthma and allergy among children. This emphasizes the need for prospective studies that focus on the importance of prenatal and neonatal exposure to phthalates in the development of asthma and allergy in children.
Asunto(s)
Asma/epidemiología , Eccema/epidemiología , Pisos y Cubiertas de Piso , Ácidos Ftálicos/toxicidad , Rinitis Alérgica Perenne/epidemiología , Asma/etiología , Preescolar , Estudios de Cohortes , Eccema/etiología , Femenino , Humanos , Incidencia , Lactante , Masculino , Cloruro de Polivinilo , Rinitis Alérgica Perenne/etiología , Suecia/epidemiologíaRESUMEN
UNLABELLED: In a nested case-control study with 198 children with asthmatic and allergic symptoms (cases) and 202 healthy controls in Värmland, Sweden, we have investigated the relationship between mold spore exposure (mean colony-forming unit) indoor and (i) different indexes of moldy odor indoor (observed by professional inspectors and reported by parents), (ii) visible signs of dampness in the homes of the children (observed and reported), and (iii) doctor-diagnosed asthma/allergy in children. No association was found between the spore concentration indoor and moldy odor and signs of visible dampness in the homes. When a semi-quantitative method in distinguishing between moldy houses or non-moldy houses was used, there were no significant differences between the observed indexes of moldy odor or visible signs of dampness (both observed and reported). No association could be found between the spore concentration in indoor air and asthma/allergy in the children. PRACTICAL IMPLICATIONS: Mold spore exposure indoor have been suggested as a possible explanation for airway problems such as asthma and allergy among people living in buildings with moisture-related problems. However, this investigation could not find any associations between the spore concentrations in indoor air and signs of dampness and moldy odor reported by parents or observed by professional inspectors. Neither was there any association between the indoor spore concentration and asthma/allergy among children. With these results, there is no reason for one-time air sampling of mold colony-forming unit (CFU) in indoor air of homes to identify risk factors for asthma/allergy in children living in Scandinavian countries.
Asunto(s)
Contaminación del Aire Interior/análisis , Hongos/aislamiento & purificación , Vivienda , Hipersensibilidad/epidemiología , Asma/epidemiología , Niño , Preescolar , Estudios Transversales , Humanos , Lactante , Factores de Riesgo , Esporas Fúngicas/aislamiento & purificación , Células Madre , Suecia/epidemiología , VentilaciónRESUMEN
UNLABELLED: There are consistent findings on associations between asthma and allergy symptoms and residential mold and moisture. However, definitions of 'dampness' in studies are diverse because of differences in climate and building construction. Few studies have estimated mold problems inside the building structure by odor assessments. In a nested case-control study of 400 Swedish children, observations and measurements were performed in their homes by inspectors, and the children were examined by physicians for diagnoses of asthma, eczema, and rhinitis. In conclusion, we found an association between moldy odor along the skirting board and allergic symptoms among children, mainly rhinitis. No associations with any of the allergic symptoms were found for discoloured stains, 'floor dampness' or a general mold odor in the room. A moldy odor along the skirting board can be a proxy for hidden moisture problem inside the outer wall construction or in the foundation construction. There are indications that such dampness problems increase the risk for sensitization but the interpretation of data in respect of sensitization is difficult as about 80% of the children with rhinitis were sensitized. Furthermore, low ventilation rate in combination with moldy odor along the skirting board further increased the risk for three out of four studied outcomes, indicating that the ventilation rate is an effect modifier for indoor pollutants. PRACTICAL IMPLICATIONS: This study showed that mold odor at the skirting board level is strongly associated with allergic symptoms among children. Such odor at that specific place can be seen as a proxy for some kind of hidden moisture or mold problem in the building structure, such as the foundation or wooden ground beam. In houses with odor along the skirting board, dismantling of the structure is required for an investigation of possible moisture damage, measurements, and choice of actions. In homes with low ventilation in combination with mold odor along the skirting board, there was even a higher risk of health effects. This emphasizes the need for the appropriate remediation as this is an ever increasing problem in poorly ventilated houses that are damp.
Asunto(s)
Contaminación del Aire Interior/efectos adversos , Hipersensibilidad/etiología , Asma/etiología , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Hongos , Vivienda , Humanos , Humedad , Masculino , Odorantes , Factores de Riesgo , Suecia , VentilaciónRESUMEN
AIM: To estimate the incidence rates for asthma, rhinitis and eczema symptoms and to investigate the importance of different influential factors for the incidence of these symptoms. METHODS: The Dampness in Building and Health study commenced in the year 2000 in Värmland, Sweden with a parental questionnaire based on an ISAAC protocol to all children in the age of 1-6 years. Five years later a follow-up questionnaire was sent to the children that were 1-3 years at baseline. In total, 4779 children (response rate = 73%) participated in both surveys and constitute the study population in this cohort study. RESULTS: The 5-year incidence of doctor-diagnosed asthma was 4.9% (95% CI 4.3-5.3), rhinitis was 5.7% (5.0-6.4) and eczema was 13.4% (12.3-14.5). However, incidence rates strongly depend on the health status of the baseline population. Risk factors for incident asthma were male gender and short period of breast-feeding. Allergic symptoms in parents were also a strong risk factor for incident asthma, as well as for rhinitis and eczema. CONCLUSION: When comparing incident rates of asthma between different studies it is important to realize that different definitions of the healthy baseline population will give rise to different incident rates.
Asunto(s)
Asma/epidemiología , Dermatitis Atópica/epidemiología , Rinitis Alérgica Perenne/epidemiología , Asma/etiología , Niño , Dermatitis Atópica/etiología , Composición Familiar , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Modelos Logísticos , Masculino , Rinitis Alérgica Perenne/etiología , Factores de Riesgo , Suecia/epidemiologíaRESUMEN
BACKGROUND: The reported impact of day-care attendance on respiratory and atopic symptoms has varied between studies from different countries. Regarding to the 'hygiene-hypothesis', day-care attendance may lead to less sensitization later in life, but the question still is whether day-care attendance and subsequent exposure to more frequent early infections is a risk or a protection against future allergic disease or asthma (atopic and nonatopic). METHODS: A cross-sectional postal questionnaire was replied by parents of 10,851 children, aged 1-6 years, in the year 2000 in a Swedish region (DBH-phase 1). The questionnaire focused on respiratory and atopic symptoms, the home environment and information on day care of the children. RESULTS: Children in day care were reported to have more symptoms than children in home care: adjusted odds ratio (AOR) for wheezing last 12 months, AOR 1.33 (CI 95%: 1.12-1.58), cough at night apart from colds last 12 months AOR 1.56 (CI: 1.17-2.07), doctor diagnosed asthma AOR 1.23 (CI: 0.88-1.71), rhinitis last 12 months AOR 1.15 (CI: 0.92-1.44), doctor diagnosed hay fever AOR 1.75 (CI: 0.94-3.23), eczema last 12 months, AOR 1.49 (CI: 1.24-1.79), allergic reactions to foods, AOR 1.27 (CI: 1.07-1.52), >6 colds last 12 months of 2.57 (CI: 2.12-3.12) and ear infection ever AOR 2.14 (CI: 1.87-2.45). The increased risks were mainly seen and reached significance in the youngest group of children, aged 1-4 years. Adjusting and stratification for the number of airway infections last year did not change the risk associated with day-care attendance for allergic diseases. CONCLUSIONS: Attending day care was associated with an increased risk of symptoms related to airways infections as well with eczema and allergic reactions to food. No sign of protection from day-care attendance for allergic diseases was found up to 6 years of age. Multiple airway infections and day-care attendance were found to be independently associated with asthma and allergic symptoms.
Asunto(s)
Asma/etiología , Guarderías Infantiles , Hipersensibilidad/etiología , Factores de Edad , Asma/epidemiología , Niño , Preescolar , Humanos , Hipersensibilidad/epidemiología , Hipersensibilidad/prevención & control , Lactante , Padres , Prevalencia , Ruidos Respiratorios , Infecciones del Sistema Respiratorio/inmunología , Factores de RiesgoRESUMEN
UNLABELLED: The aim of the study was to test the hypothesis that a low-ventilation rate in homes is associated with an increased prevalence of asthma and allergic symptoms among children. A total of 198 cases (with at least two of three symptoms: wheezing, rhinitis, eczema) and 202 healthy controls, living in 390 homes, were examined by physicians. Ventilation rates were measured by a passive tracer gas method, and inspections were carried out in the homes. About 60% of the multi-family houses and about 80% of the single-family houses did not fulfill the minimum requirement regarding ventilation rate in the Swedish building code (0.5 air changes per hour, ach). Cases had significantly lower ventilation rates than controls and a dose-response relationship was indicated. PRACTICAL IMPLICATIONS: A low-ventilation rate of homes may be a risk factor for allergies among children. Families with allergic children should be given the advice to have good ventilation in the home. In investigations, of associations between environmental factors and allergies, the air change rate in homes has to be considered.
Asunto(s)
Asma/epidemiología , Asma/etiología , Hipersensibilidad/epidemiología , Hipersensibilidad/etiología , Ventilación , Estudios de Casos y Controles , Niño , Protección a la Infancia , Preescolar , Femenino , Vivienda , Humanos , Lactante , Masculino , Prevalencia , SueciaRESUMEN
UNLABELLED: There is convincing epidemiological evidence that 'dampness' in buildings is associated with respiratory effects. In order to identify health-relevant exposures in buildings with 'dampness', the study 'Dampness in Buildings and Health' (DBH) was initiated. In the first step of the study, cross-sectional data on home characteristics including 'dampness' problems, and symptoms in airway, nose, and skin among 10,851 children (1-6 years), were collected by means of a questionnaire to the parents. The prevalence of wheezing during the last 12 months was 18.9% and doctor-diagnosed asthma 5.4%. Rhinitis during the last 12 months was reported for 11.1% of the children and eczema during the last 12 months 18.7%. Gender, allergic symptoms among parents, and age of the child were associated with symptoms. Water leakage was reported in 17.8% of the buildings, condensation on windows in 14.3%, and detached flooring materials in 8.3%. Visible mould or damp spots were reported in only 1.5% of the buildings. The four 'dampness' indices were associated to higher prevalence of symptoms in both crude and adjusted analysis. Furthermore, it was found that the combination of water leakage in the home and PVC as flooring material in the child's or parent's bedroom was associated to higher prevalence of symptoms among children. However, the interpretation of this finding is unclear. The combination of water leakage and PVC may be a proxy, for example, reconstruction because of water damages. PRACTICAL IMPLICATIONS: The study have showed that moisture-related problems in buildings are a risk factor for asthma and allergic symptoms among preschool children. The recommendation to the general public is to remediate damp buildings.