Dust mite, cockroach, cat, and dog allergen concentrations in homes of asthmatic children in the northeastern United States: impact of socioeconomic factors and population density

Home exposures to aeroallergens are an important environmental factor in allergic sensitization and in the development and exacerbation of asthma. We assessed variations in home concentrations of dust mite, cockroach, cat, and dog allergens in dust collected in the main living areas of asthmatics' homes by family income, mother's education, dwelling type, population density, household population density, and ethnicity in Connecticut and south-central Massachusetts. Dust samples were collected at the time of home interview in 999 homes as part of an ongoing longitudinal birth cohort study of 1,002 infants and their asthmatic siblings. The analysis employed lower and upper cut points for group 1 dust mite (> or = 2.0 microg/g and > or = 10 microg/g), cockroach (> or = 1.0 U/g and > or = 4.0 U/g), cat (> or = 1.0 microg/g and > or = 8.0 ug/g), and dog (> or = 2.0 microg/g and > or = 10.0 microg/g) allergens. Subject residences were geocoded to assess population density from the U.S. Census, and multiple logistic regression was used to control for confounding. The portion of homes at the lower cut point for dust mite, cockroach, cat, and dog allergens were 46.9%, 24.9%, 42.2%, and 35.6%, respectively; the upper cut point for each of the allergens was reached in 22.4%, 13.4%, 21.0%, and 22.9% of the homes, respectively. In all, 86.0% of the homes had at least one allergen at the lower cut point, and 58.0% had at least one allergen at the upper cut point. Forty-nine percent of the homes had two or more allergens at the lower cut point, and 19.7% had two or more allergens at the upper cut point. Higher education of the mother, higher household income, living in a single-family home in a less densely populated area with fewer people per room, and being a white household were associated with elevated dust mite, cat, and dog allergens and low cockroach allergen. In contrast, low income, living in a multifamily home in a high population density area with a higher occupancy rate per room, and being a Hispanic or black household were associated with elevated cockroach allergens and low concentrations of dust mite, cat, and dog allergens. Although the presence of an individual allergen is more likely associated with one or more socioeconomic or ethnic factors, most homes typically have multiple allergen burdens in excess of concentrations thought to be associated with sensitization and exacerbation of asthma. Mite and cockroach allergens have distinct and opposite associations with socioeconomic factors and population density.     

Arthropod allergens in urban homes

Dust mites, cockroaches, and pets (cats, dogs) are common in homes worldwide, and many species are the source of potent allergens which cause allergic diseases. These diseases are influenced by genetic predisposition and environmental exposure. Generally, the levels of house dust mite (Der p 1 and Der f 1) and cockroach (Bla g 1, Bla g 2) allergens are used as markers of indoor exposure to arthropods.This article reviews the findings of allergens Der p 1, Der f 1, and Bla g 1 in randomly selected urban households in Zagreb (Croatia) measured from 2006 to 2010 and compares them with exposure to arthropod allergens in other countries. In short, house dust mite allergen levels in Croatian homes are low, but exposure is common; Der p 1 was found in 73 % and Der f 1 in 83 % of the households. By contrast, exposure to cockroach allergen Bla g 1 was both low and uncommon (13 %). Exposure to multiple allergens associated with sensitisation and asthma was not frequent in urban homes in Croatia. However, further studies should include monitoring of both arthropod and pet allergens in high-risk populations in inland and coastal Croatia. They should also investigate a complex dose-response relationship between exposure and sensitisation/asthma development, especially in early childhood.     

Housing and allergens: A pooled analysis of nine US studies

Background

Housing conditions can contribute to allergen exposures that are linked to asthma, but little is known about which of those conditions are most likely to predict high levels of allergens in settled house dust.

Methods

We pooled allergen, housing condition, occupant behavior, demographic, and other data from nine asthma studies (n=950 homes in 6 US cities). Dust mite (Der f 1 or Der p 1), cockroach (Bla g 1 or Bla g 2), mouse (Mus m 1), cat (Fel d 1) and dog (Can f 1) allergens were measured in settled dust from kitchens or bedrooms, and concentrations were categorized according to previously published asthma symptom thresholds. We calculated odds ratios (OR) using logistic regression to identify those housing conditions and occupant behaviors that were associated with clinically significant allergen levels, after adjusting for numerous confounding variables.

Results

The adjusted results show that high cockroach allergen was associated with cracks or holes in walls (OR=2.1), high dust mite allergen was associated with mold odor (OR=2.5), housing built before 1951 (OR=2.1), and single-family home with slab on grade (OR=1.9); and mouse allergen was associated with rodent control or signs of rodents (OR=3.62) and inversely associated with presence of a cat (OR=0.20). Water leaks and below average housekeeping had unadjusted high odds ratios for high cockroach allergen.

Conclusion

We have identified a number of housing conditions that are consistently associated with increased allergen dust concentrations. This study indicates that screening for housing-based asthma triggers should include presence of cats, dogs, cockroaches, or rodents; water leaks; mold or mold odor; holes or cracks in walls; and below average housekeeping. Single family houses that have basements or crawl spaces or are built before 1951are also important predictors for increased allergens in housing.     

Home indoor pollutant exposures among inner-city children with and without asthma

BACKGROUND: Evidence 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. METHODS: Children 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 0.05]. Settled dust allergen levels (cat, dust mite, cockroach, dog, and mouse) were also similar in bedrooms of asthmatic and control children. CONCLUSIONS: Exposures 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.     

Survey of Pest Infestation, Asthma, and Allergy in Low-income Housing

Low-income housing often has multiple indoor health risks. Among them, pest infestation, pesticide use, and pest allergens are recognized as common risks which affect residents’ health. Cockroach and rodent allergens are associated with morbidity and mortality of asthmatics. To characterize the levels of pest infestation, residents’ attitudes toward pest control, and the relationships among cockroaches, mice, cockroach allergen level, asthma and allergy rate in public housing, we interviewed residents from 358 randomly selected apartments in Gary, Indiana and assessed the environmental conditions. Dust samples were collected from 101 apartment kitchen floors to analyze for cockroach allergen (Bla g 1 and Bla g 2) levels. Eighty one percent of the apartments were found infested by cockroaches, mice, ants, spiders, or flies. In the 101 apartments evaluated, 98% of the kitchen dust samples had detectable levels of Bla g 1 allergen (≥0.4 U/g), 52% had ≥2 U/g, and 33% had ≥8 U/g of Bla g 1. Among the 1,173 residents, 13% and 9% had physician-diagnosed asthma and allergy, respectively. Existence of diagnosed asthmatic was positively correlated with mouse infestations.     

Efficacy of occupant-collected dust samples in the evaluation of residential allergen and fungal levels

This study evaluated the ability of a resident to evaluate their home for allergens and mold using a settled dust test kit compared with evaluation and collection of settled dust by an industrial hygienist. Forty-three home residents were provided with a kit containing written instructions and a vacuum cleaner attachment for collecting a settled dust sample. Within 2 weeks of receiving the occupant-collected sample, an industrial hygienist evaluated these homes, including a visual inspection, collection of settled dust, and collection of spore trap samples. Settled dust samples were analyzed for major dog, cat, dust mite, and cockroach allergens using immunoassay methods, and for mold spore equivalents using quantitative polymerase chain reaction methods for the 13 mold species or species groups comprising the American Relative Moldiness Index (ARMI). Allergen concentrations and ARMIs were compared between the resident- and industrial hygienist-collected samples. Linear regression between the two sets of samples showed strong correlations for dog allergen (r(2) = 0.92) and cat allergen (r(2) = 0.90). Correlations for dust mite (r(2) = 0.57) and cockroach allergens (r(2) = 0.22) were lower, likely due to most samples being near the limit of detection. ARMIs were highly correlated (r(2) = 0.68) and were in categorical (high, medium, or low) agreement for 76% of residences. These results show that residents can reliably follow directions and collect settled dust samples, providing an efficient method to remotely screen homes for elevated allergen levels and to identify homes with a potential mold or moisture problem that may need further evaluation.     

Allergen levels in inner city homes: baseline concentrations and evaluation of intervention effectiveness

Allergens in house dust are risk factors for asthma causation and exacerbation, and asthma interventions often focus on exposure reduction using methods that may not be sustainable over time in low-income communities. A randomized controlled trial with up to six home visits was used to evaluate the effectiveness of two interventions focused on reducing dust loading and allergen concentrations in 47 low-income inner-city households in Minneapolis, MN. The interventions, which included education and relatively inexpensive cleaning procedures, were developed using a community-based participatory consultation process with focus groups held in English, Somali, and Spanish to incorporate community feedback from participants into protocols and study design decisions. Change in levels of cat, cockroach, dust mite, and culturable fungi as well as overall dust loading were evaluated by measuring the difference in concentrations before and after the cleaning intervention, and mixed models were used to assess the effect of education and cleaning on baseline allergen levels during the final three home visits. The cleaning intervention significantly lowered dust loading in all households and culturable fungi levels in single family homes, reduced cat allergen concentrations in homes with cats, but had no significant effect on cockroach allergen levels. The cleaning intervention also modestly decreased the frequency of observed allergen concentrations above suggested health benchmarks for cat, cockroach, and fungi. The cleaning and education interventions had similar effects on baseline allergen levels measured during subsequent home visits; both interventions significantly reduced baseline levels of cat and fungal allergens observed in pre-cleaning samples, but had no significant effect on cockroach allergen levels. Overall, the cleaning intervention modestly reduced potential exposure to risk factors associated with asthma mortality and morbidity in a way that can be implemented by most homeowners or renters, independent of education, income, or the ability to speak English.     

Indoor allergens in settled dust from kindergartens in city of Łódź, Poland

Objectives

The main objective of the study was to determine the levels of house dust mite (Der p1), dog (Can f1), cat (Fel d1) and cockroach (Bla g2) allergens in kindergartens localized in an urban agglomeration.

Material and Methods

A quantitative analysis of allergens was carried out in settled dust samples collected by vacuuming the floor surface in three kindergartens (N = 84) and children’s clothing (N = 36). The samples were collected in spring-summer and autumn-winter periods as well as at the beginning and end of the week. The allergen dust concentration was determined by enzyme-linked immunoenzymatic assay (ELISA).

Results

The mean geometric concentrations (±geometric standard deviations) of allergens Der p1, Can f1, Fel d1 and Bla g2 determined in kindergartens were: 0.02±3.21 μg/g of dust; 0.97±4.49 μg/g of dust; 0.30±4.43 μg/g of dust and 0.01±3.08 μg/g of dust, respectively. Younger classrooms (children aged from 3 to 4 years) were characterized by almost twice higher mean concentration of allergen Fel d1, as compared to older classrooms (children aged from 5 to 6 years) (p < 0.05). A significant impact of seasonality on the level of dog allergen Can f1 was found (p < 0.05). No significant weekly variation was found in average concentrations of the allergens. Children who had a dog and/or cat at home were characterized by high concentrations of allergens Can f1 and Fel d1 on their clothes (59.2±5.39 μg Can f1/g of dust; 3.63±1.47 μg Fel d1/g of dust), significantly higher than concentrations of allergens in children who did not have any pets (p < 0.001).

Conclusions

Special attention should be paid to keeping the kindergarten rooms tidy and clean and to an appropriate choice of furnishings and fittings which would prevent the proliferation of the house dust mite and accumulation of allergens.     

Deteriorated housing contributes to high cockroach allergen levels in inner-city households

The high prevalence of childhood asthma in low-income, inner-city populations is not fully understood but has been at least partly attributed to the disproportionate exposures associated with socioeconomic disadvantage. The contribution of indoor allergens to asthma is well documented, but links between socioeconomic disadvantage and indoor allergen levels are not clear. We investigated levels of cockroach allergens (Bla g 2) in a sample of 132 Dominican or African American low-income households with young children in northern Manhattan in New York City (40% were receiving public assistance) to determine whether the distribution of allergens is a function of housing deterioration. Deterioration was measured by the presence and number of physical housing problems (holes in the ceilings and walls, water damage, etc.). More than 50% of the sample had two or more types of housing dilapidation, and 67% of the sample reported cockroach sightings in their homes. Samples of dust were collected from kitchen and bedroom surfaces. We hypothesized that the greater the dilapidation, the higher the allergen levels, independent of income, sociocultural factors, and pest-control methods. In addition, we hypothesized that the homes of families characterized by frequent moves (23.5%) would have higher allergen levels than more stable families. Results showed significant positive associations between housing deterioration and allergen levels in kitchens, after adjusting for income and ethnicity, with independent effects of residential stability (p< 0.05). Bedroom allergen levels were associated with housing instability (p < 0.01) and ethnicity (p< 0.01). Findings demonstrated that indoor household allergen levels are related to degree of household disrepair, after adjusting for individual family attributes, suggesting that social-structural aspects of housing may be appropriate targets for public health interventions designed to reduce allergen exposure.     

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 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 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 μg/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 μg/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. Rabito, Iqbal, Holt, and Islam are with the Department of Epidemiology, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, USA; Grimsley is with the Department of Environmental Health Sciences, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, USA; Scott is with the Division of Epidemiology, College of Public Health, Ohio State University, Columbus, OH, USA.     

Cockroach allergy and asthma in a 30-year-old man

A growing body of evidence has implicated allergens derived from cockroaches as an important environmental factor that may aggravate asthma in sensitized persons. We present the case of a 30-year-old man with asthma and a cockroach allergy. Allergy skin testing confirmed hypersensitivity to cockroach extract, and a home visit revealed visual evidence of infestation and the presence of Bla g 1 German cockroach allergen in vacuumed dust. As is typical of patients with a cockroach allergy and asthma, multiple factors in addition to cockroach allergen appeared to aggravate the patient's asthma. A multimodality therapeutic regimen, which included medications as well as cleaning of the home, integrated pest management, and professional application of chemical controls, resulted in substantial clinical improvement. The pathophysiology, epidemiology, and clinical features of cockroach-allergic asthma are reviewed, and an approach to diagnosis and management is suggested.     

Effects of physical interventions on house dust mite allergen levels in carpet, bed, and upholstery dust in low-income, urban homes

House dust mite allergen exposure is a postulated risk factor for allergic sensitization, asthma development, and asthma morbidity; however, practical and effective methods to mitigate these allergens from low-income, urban home environments remain elusive. The purpose of this study was to assess the feasibility and effectiveness of physical interventions to mitigate house dust mite allergens in this setting. Homes with high levels of house dust mite allergen (Der f 1 + Der p 1 > or = 10 microg/g dust by enzyme-linked immunosorbent assay) in the bed, bedroom carpet, and/or upholstered furniture were enrolled in the study. Carpets and upholstered furniture were subjected to a single treatment of either dry steam cleaning plus vacuuming (carpet only) or intensive vacuuming alone. Bed interventions consisted of complete encasement of the mattress, box spring, and pillows plus either weekly professional or in-home laundering of nonencased bedding. Dust samples were collected at baseline and again at 3 days (carpet and upholstery only) and 2, 4, and 8 weeks posttreatment. We compared pretreatment mean allergen concentrations and loads to posttreatment values and performed between-group analyses after adjusting for differences in the pretreatment means. Both dry steam cleaning plus vacuuming and vacuuming alone resulted in a significant reduction in carpet house dust mite allergen concentration and load (p < 0.05). Levels approached pretreatment values by 4 weeks posttreatment in the intensive vacuuming group, whereas steam cleaning plus vacuuming effected a decrease that persisted for up to 8 weeks. Significant decreases in bed house dust mite allergen concentration and load were obtained in response to encasement and either professional or in-home laundering (p < 0.001). Between-group analysis revealed significantly less postintervention house dust mite allergen load in professionally laundered compared to home-laundered beds (p < 0.05). Intensive vacuuming and dry steam cleaning both caused a significant reduction in allergen concentration and load in upholstered furniture samples (p < 0.005). Based on these data, we conclude that physical interventions offer practical, effective means of reducing house dust mite allergen levels in low-income, urban home environments.     

A side-by-side comparison of sampling methods for settled, indoor allergens

Exposure to indoor allergens is associated with asthma, but there is no standardized sampling method for measuring allergens. We compared the association of measured allergen exposure and serum-specific IgE levels and the precision of three sampling methods (Cyclone, Mighty Mite, and Readivac II) to identify a standardized sampling method for indoor allergens. A random sample of 72 children, 5 to 17 years old, with doctor-diagnosed asthma who lived in the same residence >or=2 years were enrolled. Composite, side by side floor samples were obtained with all three methods. Dust allergen concentrations and serum-specific IgE levels were measured for Der f I, Fel d I, and Bla g I. Mean allergen concentration did not differ significantly by sampling method. Cat allergen was significantly correlated with serum-specific IgE for Cyclone (P=0.003) and Mighty Mite (P=0.008), but only marginally for Readivac II (P=0.07). Dust mite allergen was significantly correlated with serum-specific IgE for Readivac II (P=0.02) and Cyclone (P=0.038), but not for Mighty Mite (P=0.12). Cockroach allergen was not correlated with serum-specific IgE for any sampling method. In multiple linear regression, cat allergen was associated with serum-specific IgE for Cyclone (P=0.007) and Mighty Mite (P=0.02), but not for Readivac II (P=0.06). In contrast, dust mite allergen was marginally associated with serum-specific IgE for Readivac II (P=0.07), but not for Mighty Mite (P=0.64) or Cyclone (P=0.27). The Cyclone and Mighty Mite were more precise than Readivac II for cat allergen, but there was no difference for dust mite allergen (P>0.05). No single method is superior for measurement of indoor allergens. In general, cat allergen collected with the Cyclone was a better predictor of serum-specific IgE levels to Fel d I, whereas dust mite allergen collected with the Readivac II was a better predictor of serum-specific IgE levels to Der f I.     

Bla g 1 allergen levels in Zagreb area household dust

Cockroach allergy is a health problem in many parts of the world. In urban environments, indoor exposure to cockroach allergens involves a risk of asthma. The aim of this study was to measure the mass fraction of Bla g 1, a major allergen of the German cockroach (Blatella germanica) in 30 house samples, collected at random from Zagreb area households, Croatia. Dust samples were collected on cellulose filters by vacuuming living rooms floors. After extraction, Bla g 1 was detected using the commercial enzyme-linked immunosorbent assay (ELISA). Only four of the thirty households had detectable Bla g 1 levels, and only in one was its concentration higher than 2.0 U g(-1), the threshold associated with sensitisation. The Bla g 1 ELISA proved highly sensitive, with the detection limit of 0.12 U g(-1). The within- and between-assay imprecision was 8.9 % and 14.4 %, respectively, and accuracy 85 % to 120 %. Low Bla g 1 levels in the household dust support previously reported low prevalence of skin sensitisation to B. germanica among Zagreb residents. Further monitoring should reveal if there are differences in cockroach allergen exposure and sensitisation between households from other geographic areas in Croatia.     

Determinants of Allergen Concentrations in Apartments of Asthmatic Children Living in Public Housing

There is growing evidence linking poor housing conditions and respiratory diseases, including asthma. The association between housing conditions and asthma in the inner city has been attributed in part to cockroach and mouse infestation and the resulting allergen exposures. Multiple social and behavioral factors can influence environmental exposures and health conditions, necessitating a thorough examination of such factors. As part of the Healthy Public Housing Initiative, we evaluated the association between physical and household characteristics and pest-related allergen levels in three public housing developments in Boston, MA. We detected cockroach allergens (Bla g 1 and Bla g 2) in bedroom air, bed, and especially high concentrations in kitchen samples. In multivariate Tobit regressions controlling for development and season, clutter and lack of cleanliness in the apartment were associated with a tenfold increase in Bla g 1 concentration in the air, a sevenfold increase in Bla g 1 and an eightfold increase in Bla g 2 concentrations in the bed, and an 11-fold increase in Bla g 2 in the kitchen (p<0.05 for all). Holes in the wall/ceiling were associated with a six- to 11-fold increase in kitchen cockroach allergen concentrations (p<0.05). Occupancy in an apartment unit of 2 years or more was also associated with increased cockroach allergen concentrations. In contrast, there were low concentrations of mouse urinary protein in this population. In conclusion, these results suggest that interventions in these homes should focus on reducing cockroach allergen concentrations and that building-wide interventions should be supplemented with targeted efforts focused on high-risk units. Peters, Levy, Rogers, Burge, and Spengler are with the Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA; Burge is also with the Environmental Microbiology Laboratory, San Bruno, CA, USA; Rogers is also with the University of Massachusetts Amherst, Morrill 1 N 239A Amherst, MA 01003, USA.     

Association of pediatric asthma severity with exposure to common household dust allergens

Background

Reducing exposure to household dust inhalant allergens has been proposed as one strategy to reduce asthma.

Objective

To examine the dose-response relationships and health impact of five common household dust allergens on disease severity, quantified using both symptom frequency and medication use, in atopic and non-atopic asthmatic children.

Methods

Asthmatic children (N=300) aged 4-12 years were followed for 1 year. Household dust samples from two indoor locations were analyzed for allergens including dust mite (Der p 1, Der f 1), cat (Fel d 1), dog (Can f 1), cockroach (Bla g 1). Daily symptoms and medication use were collected in monthly telephone interviews. Annual disease severity was examined in models including allergens, specific IgE sensitivity and adjusted for age, gender, atopy, ethnicity, and mother's education.

Results

Der p 1 house dust mite allergen concentration of 2.0 μg/g or more from the main room and the child's bed was related to increased asthma severity independent of allergic status (respectively, OR 2.93, 95% CI 1.37, 6.30 for 2.0-10.0 μg/g and OR 2.55 95% CI 1.13, 5.73 for ?10.0 μg/g). Higher pet allergen levels were associated with greater asthma severity, but only for those sensitized (cat OR 2.41 95% CI 1.19, 4.89; dog OR 2.06 95% CI 1.01, 4.22).

Conclusion

Higher levels of Der p 1 and pet allergens were associated with asthma severity, but Der p 1 remained an independent risk factor after accounting for pet allergens and regardless of Der p 1 specific IgE status.     

Children’s residential exposure to selected allergens and microbial indicators: endotoxins and (1→3)-β-D-glucans

Objectives

The study was aimed at assessment of exposure to endotoxins, (1→3)-β-D-glucans and mite, cockroach, cat, dog allergens present in settled dust in premises of children as agents which may be significantly correlated with the occurrence of allergic symptoms and diseases in children.

Materials and Methods

The study covered 50 homes of one-or two-year-old children in Poland. Samples of settled dust were taken from the floor and the child’s bed. The levels of (1→3)-β-D-glucans (floor), endotoxins (floor) and allergens of mite, cat, dog and cockroach (floor and bed) were analyzed.

Results

Average geometric concentrations (geometric standard deviation) of endotoxins, (1→3)-β-D-glucans, Der p1, Fel d1, Can f1 and Bla g1 in children homes were on the floor 42 166.0 EU/g (3.2), 20 478.4 ng/g (2.38), 93.9 ng/g (6.58), 119.8 ng/g (13.0), 288.9 ng/g (3.4), 0.72 U/g (4.4) and in their beds (only allergens) 597.8 ng/g (14.2), 54.1 ng/g (4.4), 158.6 ng/g (3.1) 0.6 U/g (2.9), respectively. When the floor was covered with the carpet, higher concentrations of endotoxins, (1→3)-β-D-glucans and allergens (each type) were found in the settled dust (p < 0.05). The trend was opposite in case of allergens (except dog) analyzed from bed dust and significantly higher concentrations were found in the rooms with smooth floor (p < 0.05).

Conclusions

Among the analyzed factors only the type of floor significantly modified both the level of biological indicators and allergens. The results of this study could be the base for verifying a hypothesis that carpeting may have a protective role against high levels of cockroach, dog and cat allergens.     

Environmental allergens and irritants in schools: a focus on asthma

As part of the Partners in School Asthma Management Program, environmental data were collected from 385 rooms in 60 elementary schools in southeast Texas, using an Environmental Observation Checklist and a Q-TRAK Indoor Air Quality Monitor. Dust samples for allergen analysis were collected from floors, carpets, and area rugs in 80 classrooms in a subset of 20 schools. CO2 levels > 1,000 ppm were found in 86% of rooms; 69% had indoor humidity above recommended levels. Der p I dust mite allergen levels > 2,000 ng/g were present in 20% of rooms, but only 2.5% of rooms had Der f I mite allergen levels exceeding recommended tolerances. Detectable levels of cockroach allergen (Bla g II) were found in all schools (median 5.5 ng/g), with 10% of rooms over the recommended threshold. Almost two-thirds of classrooms had mold spore counts > 10,000 col/g (median, 14,400 col/g; range, 2,000-52,000 col/g).     

Allergens in school settings: results of environmental assessments in 3 city school systems

Environmental allergens are major triggers for pediatric asthma. While children's greatest exposure to indoor allergens is in the home, other public places where children spend a large amount of time, such as school and day care centers, may also be sources of significant allergen encounters. The purpose of this article is to describe schoolroom allergen levels from 3 different geographic sites obtained from dust samples collected in the fall and in spring. Environmental dust samples were collected from elementary schools in Birmingham (AL), Detroit (MI), and Houston (TX), from 4 room locations, including the cafeteria, library, upper grades, and lower grades. Samples were assayed for dust mite (Dermatophagoides pteronyssinus and Dermatophagoides farinae), cat (Felis domesticus), and cockroach (Blatella germanica 2) allergen levels. Allergen levels varied by geographic location and type of schoolroom. Schoolroom settings differed by the type of flooring (hard and carpet), room characteristics and use (food service, library shelves with books, and general classroom with multiple types of materials [individual desks and different types of furniture]), and the average age of the schoolroom dwellers (younger vs. older children). Dust mite, cat, and cockroach allergens were present in all schoolrooms and all sites at varying levels by season and by type of room. Schools may be important sources of direct allergen exposure and reservoirs that could potentially contribute to allergic sensitization and disease exacerbation in children. Further studies are needed to carefully examine the environmental allergen load in schools and its effect on children.