Allergen Levels In Dust Research Articles

Association of tobacco smoke exposure and atopic sensitization

BackgroundForty million children are regularly exposed to environmental tobacco smoke (ETS) each year, increasing their risk for premature death and middle ear and acute respiratory infections. Early life exposure to ETS also is clearly associated with wheezing. However, there is no clear understanding of the influence of ETS on the development of allergic sensitization. ObjectiveTo determine the association of combined exposure to ETS and indoor allergens on IgE sensitization to aeroallergens in children. MethodsThis case–control study enrolled 116 cases and 121 controls from low-income families from Kansas City, Missouri. The adjusted odds ratio was calculated using a logistic model to assess the association between ETS and allergic sensitization using dust allergen levels as a covariate. ResultsThirty-six percent of atopic children and 39% of controls were exposed to ETS (P < .05). Unadjusted analyses showed no significant influence of ETS on IgE sensitization to indoor allergens. Logistic regression analyses also showed no significant influence of ETS on sensitization when adjusted for levels of allergens in the home dust and family history of allergic rhinitis. ConclusionThese data suggest that ETS exposure was not associated with IgE sensitization to indoor allergens, even when home allergen levels were taken into consideration. Further understanding of how components of tobacco smoke influence the immune response is necessary to interpret the disparate findings across studies.

Allergens in Household Dust and Serological Indicators of Atopy and Sensitization in Detroit Children with History-Based Evidence of Asthma

Background. Home exposure to allergens is an important factor in the development of sensitization and subsequent exacerbations of allergic asthma. We investigated linkages among allergen exposure, immunological measurements, and asthma by examining (1) reservoir dust allergen levels in homes, (2) associations between presence of allergens in homes and sensitization status of resident children, and (3) associations between asthma status and total IgE, atopy (by Phadiatop), and positive allergen-specific tests. Methods. The study protocol was approved by Institutional Review Boards (IRBs) of the University of North Carolina Chapel Hill; Westat, Inc.; and the US Environmental Protection Agency Human Research Protocol Office. Data were collected from questionnaires, serum analyses, and household vacuum dust. Children (n = 205) were predominately African American (AA) (85.4%) and 51.6% were asthmatic. Sera from 185 children and home dust samples (n = 141) were analyzed for total and specific IgE antibodies to allergens from cat and dog dander, cockroach, dust mites, mice, rats, and molds. Results. Sixty percent of the homes had detectable levels of three or more dust allergens. The proportions of children with positive allergen-specific IgE tests were dust mite (32%), dog (28%), cat (23%), cockroach (18%), mouse (5%), rat (4%), and molds (24–36%). Children testing positive to a single allergen also had positive responses to other allergens. Those children with positive serum tests for cat, dog, and dust mite lived in homes with detectable levels of cat (51%), dog (90%), and dust mite (Der f 1) (92%) allergens. Correlations between children’s specific IgE levels and dust levels were linearly related for dog (p < .04), but not for cat (p = .12) or dust mite (Der f 1) (p = .21). Odds ratios (95% CI) for the associations between asthma and serum-specific IgE were over 1.0 for cat, dog, dust mite (Der f 1), cockroach, and four types of molds. House dust allergen exposure levels, however, exhibited no differences between asthmatic and non-asthmatic homes. Conclusions. Both the co-occurrence of multiple allergens in dust and the high frequency of multiple allergen sensitizations indicate that a broad-based intervention aimed at reducing multiple allergens (pets, pests, and molds) would be more successful than any approach that aimed at reducing one type of allergen.

Allergen‐specific IgE as a biomarker of exposure plus sensitization in inner‐city adolescents with asthma

Relationships among allergen-specific IgE levels, allergen exposure and asthma severity are poorly understood since sensitization has previously been evaluated as a dichotomous, rather than continuous characteristic. Five hundred and forty-six inner-city adolescents enrolled in the Asthma Control Evaluation study underwent exhaled nitric oxide (FE(NO)) measurement, lung function testing, and completion of a questionnaire. Allergen-specific IgE levels and blood eosinophils were quantified. Dust samples were collected from the participants' bedrooms for quantification of allergen concentrations. Participants were followed for 12 months and clinical outcomes were tracked. Among sensitized participants, allergen-specific IgE levels were correlated with the corresponding settled dust allergen levels for cockroach, dust mite, and mouse (r = 0.38, 0.34, 0.19, respectively; P < 0.0001 for cockroach and dust mite and P = 0.03 for mouse), but not cat (r = -0.02, P = 0.71). Higher cockroach-, mite-, mouse-, and cat-specific IgE levels were associated with higher FE(NO) concentrations, poorer lung function, and higher blood eosinophils. Higher cat, dust mite, and mouse allergen-specific IgE levels were also associated with an increasing risk of exacerbations or hospitalization. Allergen-specific IgE levels were correlated with allergen exposure among sensitized participants, except for cat. Allergen-specific IgE levels were also associated with more severe asthma across a range of clinical and biologic markers. Adjusting for exposure did not provide additional predictive value, suggesting that higher allergen-specific IgE levels may be indicative of both higher exposure and a greater degree of sensitization, which in turn may result in greater asthma severity.

Environmental Predictor of Allergen in Dust Samples and Its Relation to Total IgE Levels in Cord Blood in Cuernavaca, Morelos Mexico

ISEE-0859 Background and Objective: House dust mite exposure is an important risk factor for sensitization and subsequent development of allergic disease in genetically susceptible patients. Early infancy seem to be a critical period for primary sensitization. Our objectives were to identify predictors of indoor allergen exposure and to evaluate if indoor allergen exposure has a relationship with cord blood IgE levels. Methods: In a cohort of 264 pregnant mothers, we evaluated prenatal environmental exposures by questionnaire. Allergen concentrations in dust samples (n = 264) and total IgE levels in cord blood (n = 184) were assessed. We used the lower limit of detection as a cutoff point to define increased allergen levels in dust samples and total IgE levels in cord blood as binary response (detectable vs. non detectable level (0.1 UI/ml)). We identified the main predictors of allergen levels in dust and used logistic regression models to predict total IgE levels in cord blood. Results: 51.5% of homes had at least 4 detectable allergens. The main predictors of allergen levels in dust were size of housing, maid in the home, number of cars that pass by the house, pets at home, years of use of mattress, and insecticide use (P < 0.1). Cord blood total IgE levels were significantly associated with Fel d 1 in dust (OR = 2.03, 95% CI 1.03 to 3.88) after adjustment for season. Conclusions: Many environmental factors related to household hygiene can influence allergen levels in homes. An increase in cat allergen in the home is associated with high levels of total IgE in umbilical cord.

Influence of cat characteristics on Fel d 1 levels in the home

Previous studies investigating cat characteristics and cat allergen production focused on clinical experiments that quantified allergen from either the shaved skin or the fur of the animal; however, these studies did not address these experimental relationships in the home. To determine the relationships between cat characteristics and cat allergen isolated from household dust. Fel d 1 allergen levels in dust from homes participating in a population-based study of environmental effect on allergy development were analyzed using a standard monoclonal antibody-based assay. Cat characteristics were based on interviews conducted during home visits by study personnel. Households with any cats had higher geometric mean Fel d 1 levels than households without cats (32.88 vs 0.43; P < .01), and cat allergen levels increased with increasing numbers of cats in the home (P < .01). Length of cat hair, cat sex, reproductive status, and time spent indoors were analyzed; the only characteristic associated with higher levels of Fel d 1 was whether the cat had been neutered or spayed. Having cats in the home is significantly associated with increased Fel d 1 levels, and having more cats in the home is correlated with more cat allergen. Cat reproductive characteristics may be associated with measurable differences in cat allergen levels.

Prevalence of Indoor Allergen Exposures among New Orleans Children with Asthma

Studies of inner-city asthmatic children have shown significant regional variation in dust allergen exposures. The home environment of asthmatic children in the Gulf South region of the USA has not been characterized. This study describes indoor dust allergen levels in the homes of 86 asthmatic children in New Orleans and explores regional variability in dust allergen exposure. Data were used from baseline home visits of children in the New Orleans Healthy Homes Initiative. Interview, visual observation, and environmental dust sampling data of 86 children between 4 and 17 years of age were analyzed. Seventy-seven percent of households had moderate (>2.0-9.9 microg/g) or high (> or =10.0 microg/g) levels of either Der p 1 or Der f 1 dust mite allergen and 56.6% had moderate (>2.0-8.0 U/g) or high (>8.0 U/g) levels of cockroach allergen (Bla g 1). The prevalence of high (>10 microg/g) levels of dog (Can f 1) allergen was 26.5%, and few households (6.0%) had high cat allergen (Fel d 1) levels (>8.0 microg/g). Households with average humidity levels >50% were three times more likely to have elevated dust mite levels (odds ratio = 3.2; 95% confidence interval = 1.1, 9.3; p = 0.03). Home ownership and education level were inversely associated with cockroach and dust mite allergen levels, respectively. Our findings reinforce the evidence of regional variability in dust allergen exposure levels. Asthmatic children living in the Gulf South are exposed to multiple indoor allergen exposures and live in a highly allergenic environment.

Regional Variation in Dust Allergen Levels in the Homes of Urban Children with Asthma

Studies of inner-city asthmatic children have shown significant regional variation in dust allergen exposures. The home environment of asthmatic children in the Gulf South region of the U.S. has not been characterized. This study describes indoor dust allergen levels and characteristics of asthmatic children in New Orleans and explores regional variability in dust allergen exposure. Data were used from baseline home visits of children in the New Orleans Healthy Homes Initiative. Interview, visual observation and environmental dust sampling data of 86 children between 4–17 years of age were analyzed. Seventy-seven percent of households had moderate (> 2.0–9.9 μg/g) or high (≥10.0 μg/g) levels of either Der p 1 or Der f 1 dust mite allergen and 56.6% had high (> 2.0–8.0 U/g) or very high (> 8.0 U/g) levels of cockroach allergen (Bla g 1). The prevalence of high (>10 μg/g) levels of dog (Can f 1) allergen was 25.3% and few households (4.8%) had high cat allergen (Fel d 1) levels (>8.0 μg/g). Households with average humidity levels > 50% were three times more likely to have elevated dust mite levels (odds ratio = 3.2; 95% CI =1.1, 9.3; p=0.03). Home ownership and education level was associated with roach and dust mite allergen levels. Our findings reinforce evidence of regional variability in dust allergen exposure levels. Children living in the Gulf South may be exposed to a greater number of allergens at levels known to cause sensitization than in other regions of the country.

Home Indoor Pollutant Exposures among Inner-City Children With and Without Asthma

BackgroundEvidence for environmental causes of asthma is limited, especially among African Americans. To look for systematic differences in early life domestic exposures between inner-city preschool children with and without asthma, we performed a study of home indoor air pollutants and allergens.MethodsChildren 2–6 years of age were enrolled in a cohort study in East Baltimore, Maryland. From the child’s bedroom, air was monitored for 3 days for particulate matter ≤ 2.5 and ≤ 10 μm in aerodynamic diameter (PM2.5, PM10), nitrogen dioxide, and ozone. Median baseline values were compared for children with (n = 150) and without (n = 150) asthma. Housing characteristics related to indoor air pollution were assessed by caregiver report and home inspection. In addition, indoor allergen levels were measured in settled dust.ResultsChildren were 58% male, 91% African American, and 88% with public health insurance. Housing characteristics related to pollutant exposure and bedroom air pollutant concentrations did not differ significantly between asthmatic and control subjects [median: PM2.5, 28.7 vs. 28.5 μg/m3; PM10, 43.6 vs. 41.4 μg/m3; NO2, 21.6 vs. 20.9 ppb; O3, 1.4 vs. 1.8 ppb; all p > 0.05]. Settled dust allergen levels (cat, dust mite, cockroach, dog, and mouse) were also similar in bedrooms of asthmatic and control children.ConclusionsExposures to common home indoor pollutants and allergens are similar for inner-city preschool children with and without asthma. Although these exposures may exacerbate existing asthma, this study does not support a causative role of these factors for risk of developing childhood asthma.

Indoor Environmental Differences between Inner City and Suburban Homes of Children with Asthma

We conducted this study to compare environmental exposures in suburban homes of children with asthma to exposures in inner city homes of children with asthma, to better understand important differences of indoor pollutant exposure that might contribute to increased asthma morbidity in the inner city. Indoor PM(10), PM(2.5), NO(2), O(3), and airborne and dust allergen levels were measured in the homes of 120 children with asthma, 100 living in inner city Baltimore and 20 living in the surrounding counties. Home conditions and health outcome measures were also compared. The inner city and suburban homes differed in ways that might affect airborne environmental exposures. The inner city homes had more cigarette smoking (67% vs. 5%, p < .001), signs of disrepair (77% vs. 5%, p < .001), and cockroach (64% vs. 0%, p < .001) and mouse (80% vs. 5%, p < .001) infestation. The inner city homes had higher geometric mean (GM) levels (p < .001) of PM(10) (47 vs. 18 microg/m(3)), PM(2.5) (34 vs. 8.7 microg/m(3)), NO(2) [19 ppb vs. below detection (BD)], and O(3) (1.9 vs. .015 ppb) than suburban homes. The inner city homes had lower GM bedroom dust allergen levels of dust mite (.29 vs. 1.2 microg/g, p = .022), dog (.38 vs. 5.5 microg/g, p < .001) and cat (.75 vs. 2.4 microg/g, p = .039), but higher levels of mouse (3.2 vs. .013 microg/g, p < .001) and cockroach (4.5 vs. .42 U/g, p < .001). The inner city homes also had higher GM airborne mouse allergen levels (.055 vs. .016 ng/m(3), p = .002). Compared with the homes of suburban children with asthma, the homes of inner city Baltimore children with asthma had higher levels of airborne pollutants and home characteristics that predispose to greater asthma morbidity.

Gene-environment interactions with CD14 C-260T and their relationship to total serum IgE levels in adults

Both endotoxin exposure and a single nucleotide polymorphism in one of its receptors, CD14 C-260T, have been separately associated with total serum IgE levels. Furred pets might also influence IgE levels through their effects on endotoxin levels. However, how these factors interact to influence total IgE levels is not well known, especially in adults. We sought to investigate the interactive relationship between endotoxin levels, pet exposure, and CD14 C-260T genotype on total serum IgE levels in adults. Mothers enrolled in an ongoing cohort study were genotyped for the CD14 C-260T polymorphism. Exposure to pets was assessed by using questionnaires and dust allergen levels collected in the home. Endotoxin exposure was estimated by using dust collected from mothers' bedroom floors. The primary outcome measure was total serum IgE level. CD14 C-260T genotype was assessed in 517 (85.2%) of the 607 women enrolled in the study. The CD14 C-260T genotype was significantly associated with total IgE levels; however, this relationship appeared to be modified by the level of endotoxin exposure. Similar interactions between CD14 C-260T and pet exposure were not seen, regardless of the measure of pet exposure used. The CD14 C-260T genotype and endotoxin exposure together appear to influence total serum IgE levels in adults. The absence of a similar gene-environment interaction for pet exposure suggests separate mechanisms of action. A common polymorphism in the endotoxin receptor, CD14 C-260T, and dust endotoxin levels in the home might interact to influence total serum IgE levels into adulthood.

Respiratory symptoms, asthma and allergen levels in schools ? comparison between Korea and Sweden

We studied reports on respiratory symptoms, asthma and atopic sensitisation in relation to allergen contamination in Korean schools and compared with data from a previous Swedish study performed in eight primary schools. Korean pupils (n = 2365) in 12 primary schools first completed a questionnaire. Then airborne and settled dust were collected from 34 classrooms and analyzed for allergens by ELISA. In both countries, boys reported more symptoms. The prevalence of wheeze was similar, while daytime [odds ratio (OR) = 14.0, 95% confidence interval (CI) = 9.0-21.9] and nocturnal breathlessness (OR = 3.1, 95% CI = 1.5-6.4) were much higher among Korean students. In Korean schools, dog allergen (Can f 1) was the most common followed by mite allergen (Der f 1), while cat (Fel d 1), dog, and horse allergen (Equ cx) were abundant in Sweden. Moreover, CO(2) levels were high in most Korean schools (range 907-4113 ppm). There was an association between allergen levels in dust and air samples, and number of pet-keepers in the classrooms. In conclusion, allergen contamination in Korean schools may be an important public issue. This study showed that furry pet allergen contamination was common in both Korean and Swedish schools. In addition, house dust-mite (Der f 1) allergen contamination was common in Korean schools, probably because of transport of allergen from other environments. Transfer should therefore be minimized. Korean schools had high CO(2) levels and the concept of mechanical ventilation should be introduced. Measurement of airborne allergen levels is quite new and seems to be a more convenient and correct way to monitor allergen exposure in classrooms.

Do airborne particle and allergen exposures in inner city homes of asthmatic children differ from exposures in suburban homes of asthmatic children?

Background Exposure to excessive home cockroach allergens and to pollutants has been implicated in asthma morbidity in inner city children. We asked whether home exposures differ in inner city and suburban asthmatic children. Methods Indoor PM 10, PM 2.5, and airborne and dust allergen levels were measured in the homes of 106 asthmatic children, 100 living in inner city Baltimore and 6 living in the surrounding counties. Home conditions and health outcome measures were also compared. Results Inner city and suburban children had similar asthma symptoms, medications and healthcare provider visits, but differed with respect to inhaled steroid use (17%, 50%, p=0.08) and asthma-induced activity limitations (66%, 17%, p=0.026). The inner city homes had more cigarette smoking (65%, 0%, p=0.009), more mouse (68%, 0%) and cockroach (70%, 0%) infestation (p=0.002), were in poorer repair (77%, 0%, p<0.001), and had fewer central air conditioners (17%, 100%, p<0.001) and dryers vented to the outside (33%, 100%, p=0.003). PM 10 and PM 2.5 levels were higher ( p<0.001, p=0.006) in the inner city homes (medians 48.3 μg/m 3, 37.3 μg/m 3) than in suburban homes (medians 20.1 μg/m 3, 10.8 μg/m 3). The inner city homes had higher dust-borne mouse (medians 3550 ng/g, 21.0 ng/g) and cockroach (medians 4.3 u/g, 0.39 u/g) allergen levels ( p<0.001). Surprisingly, dust mite and airborne mouse allergen levels were similar. Conclusions Our data suggest that homes of inner city Baltimore asthmatic children are in worse repair and have higher levels of many airborne pollutants, but similar airborne mouse allergen levels, compared with homes of suburban asthmatic children.

Variability of airborne cat allergen, Fel d1, in a public place.

Allergen exposure is a risk to develop an IgE-mediated sensitization. The amount of allergen inhaled per unit time should be related to the amount present in the air, i.e. airborne allergen. Thus, measuring allergen levels in the air would be more relevant than measuring allergen levels in dust. Allergens are present in the air in very minute quantities and usually become airborne after disturbance. Large variation of allergen levels have been found in dust. In this study, we measured variability of airborne cat allergen, Fel d1, in a public place using a high-volume air-sampler. We also studied the distribution and relationship between dust and airborne cat allergens in homes and schools. Air samples were collected at three different airflow rates, i.e. 55, 40, and 30 m3 of air per hour. The concentration of airborne Fel d1 in the community gymnastic hall varied from 1 to 10 pg/m3 within a period of 3 weeks, at airflow rates 55-30 m3/h. The coefficient of variation for repeated samplings was 14-43% (day-to-day variation) and 27-38% (within-day variation). As expected, higher levels of airborne cat allergens were found in homes with cats than in cat-free environments. There was a significant relationship between cat allergen levels in dust and air (r=0.7, P<0.01). Our study demonstrates that when measuring airborne cat allergen a large variation is observed within a day and between days. The large variability of measurement may be explained by the disturbance in the environments. We suggest, that when exposure assessment is made the environment in question should be analyzed, if possible in several occasions.

Asthma severity, atopic status, allergen exposure and quality of life in elderly persons.

Although asthma can be associated with significant airflow obstruction in those over the age of 65, it is often underdiagnosed and undertreated. To describe severity of asthma, allergy skin test sensitivities, indoor allergen exposures, and the impact on quality of life (QOL) and health status in elderly persons with asthma. A cross-sectional data analysis with 80 elderly persons with asthma recruited from medical, geriatric, and allergy/immunology tertiary care centers. Asthma severity was determined by symptoms and measurements of lung function. House dust specimens were collected from mattresses and bedroom carpets and analyzed separately for the major allergens of house dust, using monoclonal antibody-based immunoenzymetric assays. QOL was measured using Juniper's Asthma Quality of Life Questionnaire. Health status was measured using the Short Form Health Survey Medical Outcome Questionnaire which included Ferrans and Powers' Quality of Life Index subscales. Two-thirds of participants had either moderate or severe persistent asthma. Skin tests to a battery of common airborne allergens were positive to at least one allergen in 56 of the 75 participants tested (74.7%). Reservoir dust allergen levels were often high enough to place participants at risk of symptoms or at risk of developing sensitization. Increased asthma severity was associated with significantly lower QOL and a trend toward decreased health status. Asthma is a significant chronic problem in the elderly. Atopy was common. Asthma severity impacts on these participants' QOL and health status. Results support interventions aimed at identifying allergens precipitating attacks and reducing them in the home.

Influence of interaction of environmental risk factors and sensitization in young asthmatic children

Background: The increasing prevalence of asthma and allergy in many countries demands evaluation of potential risk factors to improve the possibility of prevention. Objective: We studied the association between exposure to cat and dog allergen and allergic sensitization in young children with asthma and interactions with potential environmental risk factors. Methods: One hundred eighty-nine young children with asthma were evaluated. IgE antibodies to cat and dog were analyzed. Questionnaires were filled in focusing on exposure to cats and dogs, environmental tobacco smoke (ETS), and signs of home dampness as indicated by window pane condensation (WPC) during the first years of life. House dust was analyzed for content of cat (Fel d 1) and dog (Can f 1) allergen. Results: There was a strong association between the degree of reported exposure to cat and dog and the concentration of the respective allergens in floor dust. A dose-response relationship was found between cat exposure, measured as either reported degree of cat exposure or cat allergen levels in dust, and sensitization both to cat and dog. No such relationship was found between exposure and sensitization to dog. WPC increased the risk for sensitization to cat (odds ratio = 2.6, 95% confidence interval 1.2-5.8), whereas ETS strongly tended to do so both to cat and dog. Interaction was found between exposure to ETS, WPC, and high levels of cat allergen (>8 μg/g dust). The presence of all 3 risk factors revealed a multiplicative interaction with a high risk of sensitization to cat (odds ratio = 42.0, 95% confidence interval 3.7-472.8). Conclusions: Keeping cats indoors may be a health hazard for infants and young children at risk for development of asthma, particularly when they live in a damp house and their parents smoke. (J Allergy Clin Immunol 1999;104:755-62.)

Cat and dog allergen in mattresses and textile covered floors of homes which do or do not have pets, either in the past or currently.

The aim of this study was to measure the levels of cat and dog allergen in homes of families that had either never kept pets or kept or had kept cats or dogs. From a small residential area outside Stockholm consisting of 250 houses with similar exteriors 70 homes were included. Dust samples were collected from mattresses and textile-covered floors. The levels of cat and dog allergen were analysed by ELISA. Fel d1 was found in mattress dust in all 70 homes, median 0.5 micrograms/g [0.24-8.89 micrograms/g (quartiles)] and textile-covered floors 0.7 micrograms/g (0.20-2.52 micrograms/g). Can f1, was found in 98% of the collected samples, mattress dust 1.89 micrograms/g (0.70-9.20 micrograms/g) and textile-covered floor dust 2.5 micrograms/g (1.04-2.72 micrograms/g). There was a positive correlation (p < 0.001) between allergen levels in dust from mattresses and textile-covered floors for both Fel d1 (r = 0.68) and Can f1 (r = 0.78). The highest levels of cat and dog allergen were found in homes with furred pets (p < 0.001). A significant (p < 0.001) difference was seen in the levels of Fel d1 and Can f1 between the homes of former pet-owners and homes without pets. In summary; cat and dog allergens are present in homes regardless of whether such animals live in the house or not. Mattresses seem to be an underestimated reservoir for pet allergens even in homes without pets. It is important to note that the homes of former pet owners have much lower levels of allergen than current pet owners.

Niveles de alergenos de ácaros en el polvo de habitación en Cartagena, Colombia

Domestic mites Dermatophagoides pteronyssinus, Dermatophagoides faringe and Blomia tropicalis house dust allergen levels in Cartagena were investigated. Dust samples were collected monthly from the homes of twenty asthmatic patients in Cartagena having allergy to these mites, using a portable vacuum cleaner throughout a 12-month period. The major allergens from D. pteronyssinus and D. faringe, Derp 1 and Der f 1 respectively, were determined by immunoassay using monoclonal antibodies. D. pteronyssinus and B. tropicalis total allergen levels were determined by RAST inhibition assay. The highest Derp 1 mean level in mattress samples was 109.49 nglg dust detected in August and represented more than twice the lowest levels (50.3 ng/g) detected in November. Derf 1 was detected in only three floor-dust samples. The highest levels of D. pteronyssinus allergens in mattress samples were detected during the months of May, June, July and August and the lowest levels from December to April. The highest levels of B. tropicalis allergens in mattress samples were detected in June, July and August and the lowest levels during September. The allergen levels in mattress-dust which were correlated with floor-dust levels were significantly higher than the latter (pc 0.0001). There was a good correlation between B. tropicalis and D. pteronyssinus allergen levels and absolute humidity. This study describes the presentation of minimal variation, throughout the year, in allergen levels from domestic mites in a tropical environment, and that B. tropicalis allergen levels are high and constant. Patients allergic to domestic mites in Cartagena are exposed throughout the year to an important allergenic load.

Childhood asthma and exposure to indoor allergens: low mite levels are associated with sensitivity.

The prevalence and level of sensitivity to indoor allergens were studied in relation to current exposure at home in 124 children with perennial asthma living in three climatic zones of Sweden. The house dust mite (HDM) allergen levels were higher in the South than in the North (p < 0.001), while cat and dog allergen levels tended to be higher in the North than the South (n.s.). Thirty-four percent of the children were sensitive to the HDM Dermatophagoides pteronyssinus, as determined by IgE antibodies in vitro, 27% were sensitive to D. farinae, 57% to cat and 55% to dog. Sensitivity to HDM was significantly more prevalent in Southern, than in Central and Northern Sweden (p = 0.001) where the children were more often sensitive to pets (cat p = 0.005, dog p = 0.002). A significant association between the concentration of Der p I and Der fI in the house dust and both the prevalence of sensitivity to HDM and the IgE antibody levels against mites was found even at concentrations well below the commonly suggested risk level for sensitisation of 2 micrograms/g dust. No relationship was found between pet allergen concentration in the home dust and sensitivity to pets, possibly because of exposure outside home, e.g. in schools and meeting places for leisure activities. Similarly, there was no consistent association between the level of mite or pet allergen exposure at home and asthma severity as judged by symptom and medication score. The study indicates that there is no threshold value for sensitisation to mite allergens in asthmatic children, and therefore, dust allergen levels at home should be kept as low as possible in homes of children at risk for asthma.

House dust mite allergen levels in dust from schools with smooth and carpeted classroom floors.

A study was conducted to investigate the levels of house dust mite allergen Der p I in classroom floor dust from 49 schools with smooth (n = 18) or carpeted (n = 31) floors. Schools were located in the city of Rotterdam (n = 29) and in a number of small communities in the Province of Gelderland (n = 20). Data on building characteristics of the schools were obtained. Dust samples were analysed for Der p I content, the major allergen of the house dust mite Dermatophagoides pteronyssinus. The results showed that in schools with carpeted classroom floors, larger amounts of settled dust and higher Der p I levels either expressed as concentrations (in ng/g) or loadings (in ng/m2) were found than in schools with smooth classroom floors. However, the levels of Der p I were considerably lower than in dust collected from floors in homes. Although the Der p I levels were low, effects of several building characteristics on the levels were found. Age of the floor cover, the number of classrooms in the school and the presence of damp spots in the building were related to Der p I concentrations and loadings mainly on carpeted floors. Remarkably, schools in the rural area contained significantly more dust and Der p I than schools in the urban area. We conclude that dust from carpeted classroom floors contains more house dust mite allergen than dust from smooth classroom floors, but much less than dust from floors in homes.

Mite (Der p I, Der f I), cat (Fel d I) and dog (Can f I) allergens in dust from Swedish day‐care centres

Early exposure to allergens is important for sensitization to inhalant allergens and it has been reported that there is a causal relationship between allergen exposure and bronchial asthma. We investigated the levels of major mite (Der p I/Der f I), cat (Fel d I) and dog (Can f I) allergen levels in dust collected from various locations in seven day-care centres (22 sections). The allergen levels were related to the characteristics of the day-care centres. Children and staff were questioned about contacts with animals, and cleaning personnel were asked about methods and frequency of cleaning. Mite allergen was found in nine of the 22 sections. The concentrations varied between < 16 ng/g and 106 ng/g dust (median < 16 ng/g). Mite allergen was not detected in any floor dust sample. Cat and dog allergen was detected in all centres and sections. The concentrations of dog allergen (median 4.3 micrograms/g; range < 60 ng-21 micrograms/g) were significantly higher (P < 0.05) than that of cat allergen (median 1.6 micrograms/g; range < 16 ng-22.8 micrograms/g). Higher amounts of both Fel d I and Can f I were observed on mattresses/sofas/cushion like toys and curtains than on tables/chairs and floors. The levels of cat or dog allergen on floors significantly correlated with the total number of children and staff with either a cat or a dog at home and or frequent contacts with them. Neither cleaning methods nor the frequency of cleaning influenced the allergen concentrations. The concentration of Fel d I was significantly lower (P < 0.05) in washed than in never washed curtains.(ABSTRACT TRUNCATED AT 250 WORDS)