Exacerbation of asthma among adults in relation to the home environment in multi-family buildings in Sweden.

OBJECTIVE: To study the association between the home environment and asthma medication and exacerbation of asthma among adults with physician-diagnosed asthma. METHODS: Adults aged 18 years in a stratified sample of multi-family buildings throughout Sweden were invited to respond to a postal questionnaire (the BETSI Study). A total of 639 adults (11.5%) with physician-diagnosed asthma were included. RESULTS: Of the 639 adults, 62.0% were females, 10.8% were current smokers, 62.6% had pollen or furry pet allergy, 61.7% were on current asthma medication and 48.6% had experienced an asthma exacerbation in the past year. Logistic regression models were applied to study the association between the home environment and asthma medication and asthma exacerbation, adjusting for sex, age and smoking status. Asthma medication was more commonly prescribed for those who kept dogs as pets (OR 2.66, 95%CI 1.05-6.75) and in homes with mouldy odour (OR 5.72, 95%CI 1.29-25.4). Asthma exacerbation was more frequent among those living in buildings constructed in 1961-1975 (OR 2.56, 95%CI 1.22-5.34), in areas with a high population density (OR 4.69, 95%CI 1.42-15.5), in rented apartments (OR 1.77, 95%CI 1.12-2.78) and in homes with a greater degree of window opening (OR 1.47, 95%CI 1.12-1.94). CONCLUSIONS: Factors in the home environment were associated with exacerbation of asthma in adults. Certain construction periods (1961-1975), rented apartments, mould, having dogs as pets and living in urban areas were associated with asthma exacerbations.

Current wheeze, asthma, respiratory infections, and rhinitis among adults in relation to inspection data and indoor measurements in single-family houses in Sweden-The BETSI study.

In the Swedish Building Energy, Technical Status and Indoor environment study, a total of 1160 adults from 605 single-family houses answered a questionnaire on respiratory health. Building inspectors investigated the homes and measured temperature, air humidity, air exchange rate, and wood moisture content (in attic and crawl space). Moisture load was calculated as the difference between indoor and outdoor absolute humidity. Totally, 7.3% were smokers, 8.7% had doctor' diagnosed asthma, 11.2% current wheeze, and 9.5% current asthma symptoms. Totally, 50.3% had respiratory infections and 26.0% rhinitis. The mean air exchange rate was 0.36/h, and the mean moisture load 1.70 g/m3 . Damp foundation (OR=1.79, 95% CI 1.16-2.78) was positively associated while floor constructions with crawl space (OR=0.49, 95% CI 0.29-0.84) was negatively associated with wheeze. Concrete slabs with overlying insulation (OR=2.21, 95% CI 1.24-3.92) and brick façade (OR=1.71, 95% CI 1.07-2.73) were associated with rhinitis. Moisture load was associated with respiratory infections (OR=1.21 per 1 g/m3 , 95% CI 1.04-1.40) and rhinitis (OR=1.36 per 1 g/m3 , 95% CI 1.02-1.83). Air exchange rate was associated with current asthma symptoms (OR=0.85 per 0.1/h, 95% CI 0.73-0.99). Living in homes with damp foundation, concrete slabs with overlying insulation, brick façade, low ventilation flow, and high moisture load are risk factors for asthma, rhinitis, and respiratory infections.

Comparing mixing and displacement ventilation in classrooms: pupils' perception and health.

UNLABELLED: Several studies have found that indoor air quality (IAQ) in schools is often poor and may affect the health of the pupils. Building ventilation is a means to reduce pollutants indoors, but different designs should be evaluated for their effectiveness in different environments. In a field experiment performed at four classrooms in one school building, air was supplied either in the mixing or in the displacement mode, and we collected information on exposures, pupils' perception of IAQ and climate, and health symptoms and performed clinical examinations. The room temperature, relative humidity, concentration of CO2, and cat allergen were measured at the breathing height and were similar during each ventilation mode. The children perceived IAQ were similar in the two ventilation regimes, and there were few differences in symptom reports or clinical parameters. However, the pupils reported more eye symptoms during displacement ventilation. PRACTICAL IMPLICATIONS: Both mixing and displacement ventilation may be appropriate in school classrooms as long as the overall design, ventilation rates, and maintenance of systems are satisfactory.

Indoor molds, bacteria, microbial volatile organic compounds and plasticizers in schools--associations with asthma and respiratory symptoms in pupils.

UNLABELLED: We investigated asthma and atopy in relation to microbial and plasticizer exposure. Pupils in eight primary schools in Uppsala (Sweden) answered a questionnaire, 1014 (68%) participated. Totally, 7.7% reported doctor-diagnosed asthma, 5.9% current asthma, and 12.2% allergy to pollen/pets. Wheeze was reported by 7.8%, 4.5% reported daytime breathlessness, and 2.0% nocturnal breathlessness. Measurements were performed in 23 classrooms (May-June), 74% had <1000 ppm CO(2) indoors. None had visible mold growth or dampness. Mean total microbial volatile organic compound (MVOC) concentration was 423 ng/m(3) indoors and 123 ng/m(3) outdoors. Indoor concentration of TMPD-MIB (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, Texanol) and TMPD-DIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate, TXIB), two common plasticizers, were 0.89 and 1.64 microg/m(3), respectively. MVOC and plasticizer concentration were correlated (r = 0.5; P < 0.01). Mold concentration was 360 cfu/m(3) indoors and 980 cfu/m(3) outdoors. At higher indoor concentrations of total MVOC, nocturnal breathlessness (P < 0.01) and doctor-diagnosed asthma (P < 0.05) were more common. Moreover, there were positive associations between nocturnal breathlessness and 3-methylfuran (P < 0.01), 3-methyl-1-butanol (P < 0.05), dimethyldisulfide (P < 0.01), 2-heptanone (P < 0.01), 1-octen-3-ol (P < 0.05), 3-octanone (P < 0.05), TMPD-MIB (P < 0.05), and TMPD-DIB (P < 0.01). TMPD-DIB was positively associated with wheeze (P < 0.05), daytime breathlessness (P < 0.05), doctor-diagnosed asthma (P < 0.05), and current asthma (P < 0.05). In conclusion, exposure to MVOC and plasticizers at school may be a risk factor for asthmatic symptoms in children. PRACTICAL IMPLICATIONS: Despite generally good ventilation and lack of visible signs of mold growth, we found an association between respiratory symptoms and indoor MVOC concentration. In addition, we found associations between asthmatic symptoms and two common plasticizers. The highest levels of MVOC, TMPD-MIB, and TMPD-DIB were found in two new buildings, suggesting that material emissions should be better controlled. As MVOC and plasticizers concentrations were positively correlated, while indoor viable molds and bacteria were negatively correlated, it is unclear if indoor MVOC is an indicator of microbial exposure. Further studies focusing on health effects of chemical emissions from indoor plastic materials, including PVC-floor coatings, are needed.

Current asthma and respiratory symptoms among pupils in relation to dietary factors and allergens in the school environment.

UNLABELLED: The aim was to study asthma and allergy in relation to diet and the school environment. Pupils (5-14 years) in eight schools received a questionnaire, 1014 participated (68%). Settled dust was collected on ALK-filters and analyzed for allergens from cat (Fel d 1), dog (Can f 1), horse (Equ cx), house dust mites (Der p 1, Der f 1), and cockroach (Bla g 1) by ELISA. In total, 6.8% reported cat allergy, 4.8% dog allergy, 7.7% doctor's diagnosed asthma and 5.9% current asthma, and 7.8% reported wheeze. Current asthma was less common among those consuming more fresh milk (P < 0.05) and fish (P < 0.01). Poly-unsaturated fatty acids was associated with more wheeze (P < 0.05), olive oil was associated with less doctors' diagnosed asthma (P < 0.05). Totally, 74% of the classrooms had mean CO(2) <1000 ppm. The median concentration per gram dust was 860 ng/g Fel d 1, 750 ng/g Can f 1 and 954 U/g Equ cx. Horse allergen was associated with more wheeze (P < 0.05), daytime breathlessness (P < 0.05), current asthma (P < 0.05) and atopic sensitization (P < 0.05). Dog allergen was associated with wheeze (P < 0.05) and daytime breathlessness (P < 0.05). The associations between allergens and respiratory symptoms were more pronounced among those consuming margarine, not consuming butter, and with a low intake of milk. In conclusion, cat, dog and horse allergens in schools could be a risk factor for asthma and atopic sensitization, and dietary factors may interact with the allergen exposure. PRACTICAL IMPLICATIONS: Previous school studies performed by us in mid-Sweden, showed that most classrooms did not fulfill the ventilation standards. In this study, most of the classrooms fulfilled the ventilation standard, but despite that had widespread allergen contamination. Most previous studies have focused on cat allergen, but our study has shown that also dog and horse allergens can be risk factors for asthma and allergy in schools. As allergens are transported from other environments, mainly the home environment, the main prevention should be to minimize transfer of allergens. This could be achieved by reducing contacts with furry pets and horses, or using different clothes at home and at school (e.g. school uniforms). Increased cleaning in the schools may reduce allergen levels, but the efficiency of this measure must be evaluated in further intervention studies. Finally, our study supports the view that dietary habits among pupils should not be neglected and interaction between dietary factors and indoor allergen exposure needs to be further investigated.

Incidence of asthma diagnosis and self-reported allergy in relation to the school environment--a four-year follow-up study in schoolchildren.

SETTING: In schools, the indoor air quality is often poor and there is growing concern about its impact on the pupils' health. OBJECTIVE: To study the incidence of asthma diagnosis and self-reported allergy in schoolchildren in relation to the school environment. DESIGN: Data on asthma and allergies were collected through a postal questionnaire answered in 1993 and 1997 by 1347 (78%) pupils (initially aged 7-13 years) in 39 randomly chosen schools. Indoor pollutants were measured in about 100 classrooms in 1993 and 1995. Relationships between indoor pollutants and incidence of asthma diagnosis and self-reported allergy were studied by multiple logistic regression, adjusting for age, sex, atopy and smoking. RESULTS: The incidence of asthma diagnosis was higher in pupils attending schools with more settled dust and more cat allergen (Fel d 1) in this dust. Incidence of self-reported furry pet allergy was higher in schools with more respirable particles. Among children without a history of atopy, a new asthma diagnosis was more common at higher concentrations of formaldehyde and total moulds in the classroom air. CONCLUSION: A school environment with more dust, cat allergen, formaldehyde and moulds may affect the incidence of asthma and sensitivity to furry pets in schoolchildren.

Irritants and allergens at school in relation to furnishings and cleaning.

In order to study the influence of furnishings and cleaning on the indoor air quality at school, 181 randomly chosen classrooms were investigated. The amounts of open shelves, textiles and other fittings were noted, data were gathered on cleaning routines, and a number of pollutants were measured in the classrooms. In classrooms with more fabrics there was more settled dust and the concentration of formaldehyde was higher. Classrooms with more open shelves had more formaldehyde, and more pet allergens in settled dust, and classrooms with a white board, instead of a chalk board, were less dusty. Classrooms mainly cleaned through wet mopping had more airborne viable bacteria but less settled dust than classrooms mainly cleaned by dry methods. In rooms where the desks and curtains were more often cleaned, the concentrations of cat and dog allergen in settled dust were lower. It is concluded that furnishings and textiles in the classroom act as significant reservoirs of irritants and allergens and have an impact on the indoor air quality at school.

Acoustic rhinometry and lavage biomarkers in relation to some building characteristics in Swedish schools.

It has been suggested that certain building factors can be associated with specific exposures, such as dampness, chemical emissions and dust. The aim of the study was to examine the relationships between some selected building factors, on the one hand, and signs of inflammation or obstruction in the upper airways on the other. Acoustic rhinometry and nasal lavage were used in a field study among 234 school personnel in 12 randomly selected schools (participation rate 84%). Eosinophil cationic protein (ECP), lysozyme, albumin and myeloperoxidase (MPO) were analyzed in the lavage fluid. Building related factors selected for the study were: roof inclination, fundament, building construction, signs of water damage, floor material, building age, ceiling height, bookcases and plants in the classroom. Control was made for potential confounders. The results indicate a pattern of nasal responses: less patent noses and an inflammatory biomarker response could be related to flat roof and a concrete slab fundament, factors that are known risk factors for water leakage, building dampness and possibly microbial growth. A reduced nasal patency without an inflammatory biomarker response was related to factors associated with plasticizers and dust. Positive effects were observed for plants in the classroom and in older buildings.

New ventilation systems at select schools in Sweden--effects on asthma and exposure.

The air-exchange rate is often low in schools. The authors studied the possible impact of improving school ventilation on health and exposure of pupils. Questionnaire data on allergies, asthma, and asthmatic symptoms were obtained in 1993 and 1995 for 1,476 primary- and secondary-school pupils in 39 randomly selected schools. Various exposure factors were measured in 1993 and 1995 in approximately 100 classrooms. In 12% of the classrooms, new ventilation systems were installed between 1993 and 1995; the subsequent air-exchange rate increased and the relative humidity and concentration of several airborne pollutants were reduced compared with classrooms in nonimproved buildings. The reporting of at least one asthmatic symptom and the reporting of more asthmatic symptoms in 1995 than in 1993 were less common among the 143 pupils who attended schools with new ventilation systems.

Indoor air pollutants in schools: nasal patency and biomarkers in nasal lavage.

BACKGROUND: There is growing concern about the respiratory health aspects of the indoor air quality in schools. METHODS: A standardized investigation, including nasal lavage (NAL), measurement of the nasal cavity by acoustic rhinometry, and hygienic measurements of airborne pollutants, was performed in classrooms, outside the pollen season. All 279 school personnel working in the main buildings of 12 randomly selected primary schools in an urban community in central Sweden (Uppsala) were invited to enroll in the study; 234 (84%) participated. Eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme, and albumin were analyzed in NAL fluid. Crude statistical analysis, as well as multiple regression analysis, was performed, controlling for room temperature, age, sex, current smoking, and a history of atopy. RESULTS: Most classrooms (83%) did not meet the Swedish ventilation standards. A lower degree of nasal patency was found at higher concentrations of respirable dust, nitrogen dioxide (NO2), formaldehyde, and total molds, and in the presence of Aspergillus spp. in the classroom air. The most consistent findings were observed for formaldehyde, NO2, and Aspergillus spp., related to both decreased nasal patency and increase of ECP and lysozyme in NAL. The presence of yeast was associated with an increase of ECP and lysozyme in NAL, but was not related to nasal patency. CONCLUSIONS: Ventilation flow was below current hygienic standards in the classrooms. Air pollutants in the classroom air may influence nasal patency and inflammatory response in the nasal mucosa.

Acoustic rhinometry in epidemiological studies--nasal reactions in Swedish schools.

A cross-sectional study was performed on the relationships between hygienic measurements and nasal investigations in 234 personnel in 12 primary schools in mid-Sweden. Hygienic data included building characteristics, measurements of indoor air pollutants, air change rate, temperature and humidity. Clinical examinations included symptom reports, acoustic rhinometry and nasal lavage, with the determination of biomarker levels for eosinophil cationic protein (ECP), lysozyme, myeloperoxidase (MPO) and albumin. Subjective nasal obstruction was increased in schools with mechanical ventilation (adjusted prevalence OR = 2.0; 95 CI 1.1-3.7) and subjects reporting nasal obstruction had higher levels of dust in the classroom, compared to those not reporting this symptom (p = 0.008 by Mann-Whitney U-test). Congruently, a decreased nasal patency measured by acoustic rhinometric minimum cross-sectional areas (MCA1 and MCA2) was related to the use of mechanical ventilation (p = 0.008 and p = 0.02 respectively, by Mann-Whitney U-test), dust levels (p = 0.03 and p < 0.001 respectively, by Kendall's tau correlation analysis), a lower cleaning frequency of desks (p < 0.001 and p = 0.02 respectively, by Kendall's tau correlation analysis), the use of wet mopping (p < 0.001 and p = 0.04 respectively, by Mann-Whitney U-test) and PVC floor material (p < 0.001 and p = 0.034 respectively, by Mann-Whitney U-test). The cleaning frequency of floors was positively correlated with MCA1 (p = 0.049 by Kendall's tau correlation analysis). In buildings with signs of water damage, flat roof or a concrete slab fundament the personnel had increased ECP, lysozyme or albumin levels in nasal lavage. A reduced nasal patency and an increased inflammatory biomarker response were seen for higher levels of formaldehyde (MCA1, MCA2, VOL1, VOL2, ECP and lysozyme) and nitrogen dioxide (MCA1, VOL2, ECP and lysozyme) in the classrooms. In conclusion, the results indicate that acoustic rhinometry in combination with the determination of nasal lavage biomarkers can be used to study effects on the upper airways of the indoor environment. Actual exposures to indoor air pollutants in Swedish schools can affect the occurrence of subjective nasal obstruction and give clinical signs of reduced nasal patency together with an inflammatory biomarker response in the nasal mucosa.

Nasal patency and lavage biomarkers in relation to settled dust and cleaning routines in schools.

OBJECTIVES: This study determined the relations between settled dust and cleaning routines in classrooms on one hand, and nasal symptoms, nasal cavity dimensions, and the concentration of selected biomarkers of inflammation in nasal lavage on the other. METHODS: Measurements of settled dust via standardized vacuum cleaning and an investigation of the cleaning routines were performed in 12 randomly selected primary schools in the municipality of Uppsala. Clinical examinations including acoustic rhinometry and nasal lavage were performed in the school environment among 279 school personnel working in the main buildings of the schools. Eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme, and albumin were analyzed in the lavage fluid. The relationships between the medical and hygienic data were analyzed both bivariately and with a multiple regression model controlling for age, gender, smoking, atopy, room temperature, and urban vicinity of the school. RESULTS: The amount of settled dust was positively related to subjective nasal obstruction and smaller nasal cavity dimensions measured with acoustic rhinometry. The noses were less patent, and the levels of ECP or lysozyme in the lavage were increased for the subjects in schools with a lower frequency of floor mopping, a lower frequency of desk cleaning, and where wet mopping was used. CONCLUSIONS: Our results indicate that the actual dust levels in Swedish classrooms can affect the occurrence of nasal obstruction among school personnel. A beneficial effect on the clinical signs of the nasal mucosa was observed for a higher frequency of both floor mopping and desk cleaning, whereas the use of wet mopping seemed disadvantageous in comparison with dry mopping. These findings illustrate the need for adequate cleaning procedures to minimize the environmental effects on the airway mucosa.

Nasal patency and biomarkers in nasal lavage--the significance of air exchange rate and type of ventilation in schools.

OBJECTIVES: The aim of the present study was to examine the relationships between the ventilation rate and the type of ventilation system, on the one hand, and objective nasal measures, on the other. METHODS: A standardized investigation, including acoustic rhinometry and nasal lavage, was performed in the school environment. All 279 school personnel working in the main buildings of 12 randomly selected primary schools in the municipality of Uppsala were invited, and 234 (84%) participated. The dimensions of the nasal cavity were measured with acoustic rhinometry. Eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme, and albumin were analyzed in the lavage fluid. The air exchange rate and the room temperature were measured in the classrooms. Relationships between nasal symptoms, nasal patency, and the concentration of biomarkers, on the one hand, and the type of ventilation system, the air exchange rate, and the temperature, on the other, were analyzed by both crude bivariate analysis and multiple regression models, controlling for the type of ventilation, the air exchange rate, room temperature, age, gender, smoking, atopy, and the urban vicinity of the school. RESULTS: A lower degree of nasal patency as measured by acoustic rhinometry and increased levels of ECP and lysozyme in nasal lavage were associated with a lower air exchange rate in the schools. Although mechanically ventilated schools had higher air exchange rates, they were associated with more nasal symptoms, and nasal mucosal swelling and with increased lavage levels of ECP and lysozyme as compared with schools with natural ventilation only. In contrast, 12 subjects working in a school with mechanical displacement ventilation had more patent noses and lower levels of inflammatory markers as compared with the personnel in schools with natural ventilation only. CONCLUSION: Our results indicate that both a low air exchange rate and mechanical ventilation systems based on dilution can be associated with reduced nasal patency and an inflammatory biomarker response of the nasal mucosa among school personnel. The only school with sufficient ventilation according to the current Swedish recommendations had a displacement system and the fewest signs of nasal reactions among the personnel.

Nasal congestion in relation to low air exchange rate in schools. Evaluation by acoustic rhinometry.

Upper airway symptoms are common, but there is little information available on clinical findings in relation to indoor air pollution. This pilot study was conducted to test whether increased levels of indoor air pollutants in schools may correlate to a swelling of the nasal mucosa. The assumption was made that the degree of swelling could be related to the degree of decongestive effect of xylometazoline, and measured by acoustic rhinometry. The study was performed among 15 subjects in a school with low air exchange rate (0.6 air changes/h) and 12 subjects in a school with high air exchange rate (5.2 air changes/h). Hygienic measurements were performed in both schools. Acoustic rhinometry was performed for each individual under standardized forms. Cross-sectional areas and volumes of the nasal cavity were measured before and after decongestion with xylometazoline hydrochloride. Absolute values of the minimal cross-sectional area were lower in the school with poor ventilation. The decongestive effect of xylometazoline was significantly higher in the school with low air exchange, when correction for the influence of age was made. A diminished decongestive effect was seen with increasing age. The exposure measurements showed that indoor concentrations of volatile organic compounds, bacteria and moulds were higher in the school with low ventilation. In conclusion, raised levels of indoor air pollutants due to inadequate ventilation in schools may affect the upper airways and cause a swelling of the nasal mucosa, and acoustic rhinometry could be a useful objective method to measure human nasal reactions to the indoor environment.

Asthma among secondary schoolchildren in relation to the school environment.

BACKGROUND: Poor indoor air quality has been suggested to be related to the increase in the prevalence of asthma that has occurred in the western world, especially among children and young persons. Apart from the home, school is the most important indoor environment for children. OBJECTIVES: The aims were to study the prevalence of current asthma among secondary pupils and its relationship to the school environment, but also to personal factors and domestic exposures. METHODS: Data on asthmatic symptoms, other health aspects, and domestic exposures were gathered using a questionnaire which was sent to 762 pupils in the seventh form (13-14 years old) in 11 randomly chosen schools in the county of Uppsala in Sweden. Pupils answering 'yes' to having had asthma diagnosed by a physician, and having had recent asthma attacks, or who used asthma medication were defined as having current asthma. Data on exposures at school were gathered by measurements in 28 classrooms. The relationship between asthma and exposures was analysed by multiple logistic regression. RESULTS: The questionnaire was completed by 627 (82%). Current asthma was found among 40 pupils (6.4%). Current asthma was more common in those who had an atopic disposition, or food allergy, or who had attended a day care centre for several years. Controlling for these factors, current asthma was related to several factors in the school environment. There were more pupils with current asthma in schools that were larger, had more open shelves, lower room temperature, higher relative air humidity, higher concentrations of formaldehyde or other volatile organic compounds, viable moulds or bacteria or more cat allergen in the settled dust. CONCLUSIONS: Although the pupils attended school for a minor part of their time, our study indicates that the quality of the school environment is of importance and may affect asthmatic symptoms.