Respiratory and allergic health effects of dampness, mold, and dampness-related agents: a review of the epidemiologic evidence

OBJECTIVES

Many studies have shown consistent associations between evident indoor dampness or mold and respiratory or allergic health effects, but causal links remain unclear. Findings on measured microbiologic factors have received little review. We conducted an updated, comprehensive review on these topics.

DATA SOURCES

We reviewed eligible peer-reviewed epidemiologic studies or quantitative meta-analyses, up to late 2009, on dampness, mold, or other microbiologic agents and respiratory or allergic effects.

DATA EXTRACTION

We evaluated evidence for causation or association between qualitative/subjective assessments of dampness or mold (considered together) and specific health outcomes. We separately considered evidence for associations between specific quantitative measurements of microbiologic factors and each health outcome.

DATA SYNTHESIS

Evidence from epidemiologic studies and meta-analyses showed indoor dampness or mold to be associated consistently with increased asthma development and exacerbation, current and ever diagnosis of asthma, dyspnea, wheeze, cough, respiratory infections, bronchitis, allergic rhinitis, eczema, and upper respiratory tract symptoms. Associations were found in allergic and nonallergic individuals. Evidence strongly suggested causation of asthma exacerbation in children. Suggestive evidence was available for only a few specific measured microbiologic factors and was in part equivocal, suggesting both adverse and protective associations with health.

CONCLUSIONS

Evident dampness or mold had consistent positive associations with multiple allergic and respiratory effects. Measured microbiologic agents in dust had limited suggestive associations, including both positive and negative associations for some agents. Thus, prevention and remediation of indoor dampness and mold are likely to reduce health risks, but current evidence does not support measuring specific indoor microbiologic factors to guide health-protective actions.

Exposure to foodborne and orofecal microbes versus airborne viruses in relation to atopy and allergic asthma: epidemiological study

OBJECTIVE

To investigate if markers of exposure to foodborne and orofecal microbes versus airborne viruses are associated with atopy and respiratory allergies.

DESIGN

Retrospective case-control study.

PARTICIPANTS

240 atopic cases and 240 non-atopic controls from a population sample of 1659 participants, all Italian male cadets aged 17-24.

SETTING

Air force school in Caserta, Italy.

MAIN OUTCOME MEASURES

Serology for Toxoplasma gondii, Helicobacter pylori, hepatitis A virus, measles, mumps, rubella, chickenpox, cytomegalovirus, and herpes simplex virus type 1; skin sensitisation and IgE antibodies to relevant airborne allergens; total IgE concentration; and diagnosis of allergic asthma or rhinitis.

RESULTS

Compared with controls there was a lower prevalence of T gondii (26% v 18%, P=0.027), hepatitis A virus (30% v 16%, P=0.004), and H pylori (18% v 15%, P=0.325) in atopic participants. Adjusted odds ratios of atopy decreased with a gradient of exposure to H pylori, T gondii, and hepatitis A virus (none, odds ratio 1; one, 0. 70; two or three, 0.37; P for trend=0.000045) but not with cumulative exposure to the other viruses. Conversely, total IgE concentration was not independently associated with any infection. Allergic asthma was rare (1/245, 0.4%) and allergic rhinitis infrequent (16/245, 7%) among the participants (245/1659) exposed to at least two orofecal and foodborne infections (H pylori, T gondii, hepatitis A virus).

CONCLUSION

Respiratory allergy is less frequent in people heavily exposed to orofecal and foodborne microbes. Hygiene and a westernised, semisterile diet may facilitate atopy by influencing the overall pattern of commensals and pathogens that stimulate the gut associated lymphoid tissue thus contributing to the epidemic of allergic asthma and rhinitis in developed countries.

Respiratory symptoms and atopy in Aberdeen schoolchildren: evidence from two surveys 25 years apart

OBJECTIVE

To estimate changes in the prevalence of respiratory symptoms and the reported diagnoses of asthma, eczema, and hay fever in primary school children in Aberdeen between 1964 and 1989.

DESIGN

Determination of incidence prevalence and prevalence from survey data.

SETTING

Aberdeen, Scotland.

PARTICIPANTS

2743 primary school children (aged 8-13) from 1964 and 4003 [corrected] from 1989.

MAIN OUTCOME MEASURES

Survey data on whether, according to the parent or guardian, the child wheezed or was troubled with shortness of breath; the number of episodes of breathlessness in the past year; and whether asthma, eczema, or hay fever had ever been diagnosed.

RESULTS

Questionnaires were completed by the parents of 2510 children in 1964 and 3403 children in 1989. The prevalence of wheeze rose from 10.4% in 1964 to 19.8% in 1989, and the prevalence of episodes of shortness of breath increased from 5.4% to 10.0%. In both surveys wheeze and shortness of breath were more prevalent in boys than in girls. The reported diagnosis of asthma rose from 4.1% to 10.2%, hay fever from 3.2% to 11.9%, and eczema from 5.3% to 12%. The proportion of boys suffering from eczema rose from 47.7% to 60.0%. Hay fever showed a similar increase, from 49.4% to 60.1%, in boys over the 25 year period. Though the parents of a higher proportion of children with wheeze were aware of the diagnosis of asthma in 1989, because of the increased prevalence of wheeze the absolute number of parents of wheezy children who were not aware of a diagnosis of asthma increased from 7.4% to 9.6% of the population studied.

CONCLUSION

The higher diagnosis rate for asthma is due not simply to changes in diagnostic fashion but reflects an increase over the past 25 years in the prevalence of respiratory symptoms, which in turn may reflect a more general change in the prevalence of atopy, the increase in which was particularly noticeable in boys. This increase explains some of the increase in hospital admission rates for children with asthma.

Breastfeeding as prophylaxis against atopic disease: prospective follow-up study until 17 years old

Atopic diseases constitute a common health problem. For infants at hereditary risk, prophylaxis of atopy has been sought in elimination diets and other preventive measures. We followed up healthy infants during their first year, and then at ages 1, 3, 5, 10, and 17 years to determine the effect on atopic disease of breastfeeding. Of the initial 236 infants, 150 completed the follow-up, which included history taking, physical examination, and laboratory tests for allergy. The subjects were divided into three groups: prolonged (> 6 months), intermediate (1-6 months), and short or no (< 1 month) breastfeeding. The prevalence of manifest atopy throughout follow-up was highest in the group who had little or no breastfeeding (p < 0.05, analysis of variance and covariance with repeated measures [ANOVA]). Prevalence of eczema at ages 1 and 3 years was lowest (p = 0.03, ANOVA) in the prolonged breastfeeding group, prevalence of food allergy was highest in the little or no groups (p = 0.02, ANOVA) at 1-3 years, and respiratory allergy was also most prevalent in the latter group (p = 0.01, ANOVA) having risen to 65% at 17 years of age. Prevalences in the prolonged, intermediate, and little or no groups at age 17 were 42 (95% CI 31-52)%, 36 (28-44)%, and 65 (56-74)% (p = 0.02, trend test) for atopy, respectively, and 8 (6-10)%, 23 (21-25)%, and 54 (52-56)% (p = 0.0001, trend test) for substantial atopy. We conclude that breastfeeding is prophylactic against atopic disease--including atopic eczema, food allergy, and respiratory allergy--throughout childhood and adolescence.

Asthma and allergic inflammation

Studies of the initiation and maintenance of asthma and allergic inflammation implicate dysregulated interactions between mucosal epithelia and innate immune cells as the underlying cause of these disorders. The similarities of these responses with mucosal responses to parasitic intestinal worms may reveal pathways relevant to the perplexing rise of these chronic inflammatory disorders.

Longitudinal changes in atopy during a 4-year period: relation to bronchial hyperresponsiveness and respiratory symptoms in a population sample of Australian schoolchildren

A total of 380 schoolchildren living in Belmont, New South Wales, a coastal town where the predominant aeroallergens are house dust mites, were studied on three occasions at 2-year intervals. At each study, atopy was measured by skin prick tests to 13 allergens, bronchial responsiveness was measured by histamine inhalation test, and respiratory illness history was assessed by a self-administered questionnaire to parents. The age of the group was 8 to 10 years at enrollment. We found that skin wheals less than 4 mm were not associated with respiratory or allergic illness, and therefore, we defined atopy as the presence of a skin wheal of greater than or equal to 4 mm. In the sample, 24% of the children were atopic at 8 to 10 years (early-onset atopy), and an additional 15% became atopic during the study (late-onset atopy). Both early- and late-onset atopy had a close association with hay fever. Late-onset atopy was strongly associated with inconsistent reporting of symptoms. Early-onset atopy was an important risk factor for bronchial hyperresponsiveness (BHR), diagnosed asthma, and continuing symptoms of wheeze, and was a particularly important risk factor for BHR with current wheeze in late childhood years. We conclude that atopy acquired at an early age is an important predictive factor for respiratory symptoms occurring with BHR and continuing into late childhood.

Symptoms of bronchial hyperreactivity and asthma in relation to environmental factors

A questionnaire study regarding airway morbidity in children and environmental factors was performed in April 1985. The parents of 5301 children, aged 6 months to 16 years, from different rural areas in mid Sweden were sent a validated questionnaire and 4990 (94%) responded. The cumulative prevalence of bronchial hyperreactivity was 9.7% and of allergic asthma 5.2%. Children living near a paper pulp plant more often had symptoms suggesting bronchial hyperreactivity (124 (13.0%), relative risk 1.3) and allergic asthma (68 (7.1%), relative risk 1.3). In children living in a damp house problem bronchial hyperreactivity was found in 76 (19.0%) (relative risk 1.9) and allergic asthma in 35 (8.7%) of the children (relative risk 1.9). Children living in a damp house with parents who smoked had the highest figures: bronchial hyperreactivity was found in 44 (23.5%) (relative risk 2.8) and allergic asthma in 22 (11.6%) (relative risk 2.5). The results indicate that various moderate environmental pollutants may act synergistically to increase bronchial hyperreactivity and allergy especially in children with a family history of allergy.

Bronchial hyperresponsiveness in two populations of Australian schoolchildren. I. Relation to respiratory symptoms and diagnosed asthma

In order to explore the relationship between bronchial hyperresponsiveness (BHR) to inhaled histamine, respiratory symptoms and diagnosed asthma in children, we undertook a cross-sectional study of 2363 Australian schoolchildren aged 8-11 years. The methods used included a self-administered questionnaire to parents, which was shown to have a high degree of repeatability, and a histamine inhalation test to measure bronchial responsiveness (BR). The study showed that 17.9% of children had BHR, defined as a 20% fall in FEV1 at a provoking dose of histamine (PD20 FEV1) of less than 7.8 mumol. The distribution of PD20 FEV1 appeared to be continuous. Most children with PD20 FEV1 values less than 1.0 mumol had symptoms of asthma. However, 6.7% of children had BHR without symptoms or a previous diagnosis of asthma and 5.6% had had a diagnosis of asthma but had no BHR. Although there was a good association between BHR and respiratory symptoms, questionnaire data of wheeze and diagnosed asthma do not reflect accurately the level of BHR in the community. We conclude that cross-sectional studies of BR to identify children with BHR probably do not reflect the prevalence of asthma in populations of children. However, the strong association between BHR and symptoms, particularly in children with severe and moderate BHR, suggests that measurements of BR in populations are useful for defining a group of children whose airways behave differently from those of the majority. Prospective studies are needed to define the level of BHR that is associated with important sequelae.

The link between allergic rhinitis and allergic asthma: a prospective population-based study. The Copenhagen Allergy Study

BACKGROUND

It has been hypothesized that allergic rhinitis and allergic asthma are manifestations of the same disease entity. We aimed to investigate the relationship between allergic rhinitis and allergic asthma.

METHODS

Participants in a population-based study of 15-69-year-olds in 1990 were invited to a follow-up in 1998. A total of 734 subjects were examined on two occasions eight years apart. Allergic rhinitis to pollen was defined as a history of nasal symptoms on exposure to pollens and IgE specific to pollen. Allergic asthma to pollen was defined as a history of lower airway symptoms on exposure to pollens and IgE specific to pollen. Similarly, diagnoses of allergic rhinitis and allergic asthma to animals or mite were defined.

RESULTS

At follow-up, all subjects with allergic asthma to pollen (n = 52) had in addition allergic rhinitis to pollen. In the longitudinal analysis, there were a total of 28 new (incident) cases of allergic asthma to pollen. They all had allergic rhinitis to pollen at baseline, or had developed allergic rhinitis to pollen at follow-up. Accordingly, allergic rhinitis to animals and mite were ubiquitous in subjects with allergic asthma to animals and mite, respectively.

CONCLUSIONS

The results support the hypothesis that allergic rhinitis and allergic asthma are manifestations of the same disease entity.

Economic impact of workplace productivity losses due to allergic rhinitis compared with select medical conditions in the United States from an employer perspective

OBJECTIVE

To evaluate the cost of lost productivity in the workplace due to allergic rhinitis compared to other selected medical conditions from an employer perspective.

SETTING AND PARTICIPANTS

A total of 8267 US employees at 47 employer locations who volunteered to participate in health/wellness screenings.

MEASUREMENTS

The Work Productivity Short Inventory was used to assess the impact of a predefined group of health conditions on workplace productivity for the previous 12 months. Both absenteeism and presenteeism (lost productivity while at work) were recorded. Costs were calculated using a standard hourly wage.

RESULTS

Allergic rhinitis was the most prevalent of the selected conditions; 55% of employees reported experiencing allergic rhinitis symptoms for an average of 52.5 days, were absent 3.6 days per year due to the condition, and were unproductive 2.3 h per workday when experiencing symptoms. The mean total productivity (absenteeism + presenteeism) losses per employee per year were 593 US dollars for allergic rhinitis, 518 US dollars for high stress, 277 US dollars for migraine, 273 US dollars for depression, 269 US dollars for arthritis/rheumatism, 248 US dollars for anxiety disorder, 181 US dollars for respiratory infections, 105 US dollars for hypertension or high blood pressure, 95 US dollars for diabetes, 85 US dollars for asthma, and 40 US dollars for coronary heart disease. The mean total productivity loss per employee per year due to caregiving was 102 US dollars for pediatric respiratory infections, 85 US dollars for pediatric allergies, 49 US dollars for Alzheimer's disease, and 42 US dollars for otitis media/earache.

CONCLUSIONS

Allergies are major contributors to the total cost of health-related absenteeism and presenteeism. Payers and employers need to consider this when determining health benefits for employees.

Prevalence and nature of allergy and chemical sensitivity in a general population

The objectives of this study were (a) to determine the self-reported prevalence of allergy and chemical sensitivity in a rural population of eastern North Carolina, (b) to determine the type and frequency of symptoms for each condition, and (c) to determine the demographic groups affected. A random general telephone survey was conducted during the period May 14, 1993, to September 10, 1993, and questions about allergy and chemical sensitivity were asked. Of the 1 446 households contacted, 1 027 (71%) individuals agreed to participate. Allergies were reported by 365 (35%) individuals. Thirty percent of allergic individuals reported that symptoms occurred once or more each week, whereas 61% reported that symptoms occurred, at most, once each month. Allergic symptoms that occurred daily were reported by 5.3% of the total population. Chemical sensitivity was reported by 336 (33%) individuals. Thirty-five per cent of chemically sensitive individuals reported symptoms at least once each week, whereas 53% reported that symptoms occurred once (or less) each month. Symptoms of chemical sensitivity that occurred daily were reported by 3.9% of the total population. Both allergy and chemical sensitivity were distributed widely across age, income, race, and educational groups. Simultaneous allergy and chemical sensitivity were reported by 16.9% of the population, allergy without chemical sensitivity by 16.0%, chemical sensitivity without allergy by 18.2%, and neither condition by 48.9%. If the prevalence of sensitivity to chemical irritants is, in fact, equivalent to that of allergy, as was found in this study, then support for the scientific investigation of chemical sensitivity is justified.

Effect of allergen avoidance in infancy on allergic manifestations at age two years

BACKGROUND

One hundred twenty children, identified before birth as being at high risk for atopy, were prenatally assigned to prophylactic or control groups.

METHODS

The infants in the prophylactic group either received breast milk from mothers on an exclusion diet or an extensively hydrolyzed formula. Their bedrooms and living rooms were treated repeatedly with an acaricide, and they used polyvinyl-covered mattresses with vented head areas. The infants in the control group were fed conventionally, and no environmental control was recommended.

RESULTS

A significant advantage, first demonstrated at 1 year of age, persists for children in the prophylactic group. They have less of any allergy or eczema, but the reduced prevalence of asthma is no longer significant. Only three children in the prophylactic group had positive skin prick test results compared with 16 in the control group, suggesting a significant reduction in sensitization.

CONCLUSION

A dual approach to allergen avoidance, focusing on foods and aeroallergens, appears to be beneficial in selected high-risk infants. Avoidance of potent allergens in early life increases the threshold for sensitization in these high-risk infants. Whether sensitization has been avoided or merely deferred has yet to be proved.

Role of current and childhood exposure to cat and atopic sensitization. European Community Respiratory Health Survey

BACKGROUND

Clinical and population studies have shown that exposure and sensitization to allergens derived from furred pets, particularly cats, represent an important risk factor of allergic respiratory disease and also a significant risk factor for asthma.

OBJECTIVE

In the framework of the multicenter European Community Respiratory Health Survey an analysis of the association of current and childhood exposure to cat with atopic sensitization to cat was conducted.

METHODS

This study included cross-sectional data from 35 centers representing 16 countries. Altogether, 18,097 subjects were included, of whom 13,509 (75%) provided a blood sample for the measurement of specific IgE. Exposure data and data for potential confounders were extracted from an interviewer-led questionnaire.

RESULTS

The prevalence of sensitization to cat (serum specific IgE >0.35 kU/L) was 9%. Among those who did not report allergic symptoms in the presence of pets or house dust, those who owned cats were significantly more likely to be sensitized to cats than were those who did not (odds ratio [95% confidence interval] 1.57 [1.20-2.06]. Childhood exposure to pets including cats was associated with lower sensitization to cats in adulthood, particularly among those with a positive family history of atopy (odds ratio [95% confidence interval] 0.68 [0.51-0.93]. Positive correlations were found between the community prevalence of cat and the prevalences of sensitization to cat, respiratory symptoms, physician-diagnosed asthma, and current asthma medication.

CONCLUSIONS

Current cat ownership represents a significant risk for sensitization to cat if cats are allowed indoors. Our results support the hypothesis that childhood exposure to pets, including cats, might modulate immunologic mechanisms and reduce sensitization to cat in adulthood. The significant correlation found between the community prevalence of cat ownership and community prevalence of specific sensitization to cat represents the first documentation of such a relationship.

The association of individual allergen reactivity with respiratory disease in a national sample: data from the second National Health and Nutrition Examination Survey, 1976-80 (NHANES II)

The independent association of individual allergen reactivity with respiratory disease was evaluated with use of the second National Health and Nutrition Examination Survey, a sample of the U.S. white civilian population, ages 6 to 24 years (n = 4295). Eight, 1:20 wt/vol, 50% glycerol, unstandardized extracts were administered by prick puncture. Allergen reactivity was reported as the percent with a mean erythema diameter 10.5 mm or greater at 20 minutes. Only the prevalence of asthma and allergic rhinitis increased with the increasing number of positive allergen skin tests. The independent association of individual allergen reactivity with respiratory disease was quantified with logistic models that included other allergen reactivity, age, sex, smoking, and region. Asthma was associated with reactivity to house dust (odds ratio, 2.9; 95% confidence interval [CI] 1.7 to 5) and Alternaria (odds ratio, 5.1; 95% CI: 2.9 to 8.9). Allergic rhinitis was associated with reactivity to ragweed (odds ratio, 2.3; 95% CI: 1.5 to 3.3); ryegrass (odds ratio, 2.8; 95% CI: 1.8 to 4.3); house dust (odds ratio, 2.5; 95% CI: 1.6 to 3.9); Alternaria (odds ratio, 2.3; 95% CI: 1.5 to 3.4). Asthma only (without allergic rhinitis) was associated with dust and Alternaria. Allergic rhinitis only (without asthma) was associated with ryegrass, ragweed, and house dust. When both asthma and allergic rhinitis were present, only house dust and Alternaria remained associated. These findings highlight the association of specific allergens with upper and lower respiratory diseases and the interactions among coexisting respiratory diseases.

Childhood environment and adult atopy: results from the European Community Respiratory Health Survey

BACKGROUND

Previous literature has indicated that environmental exposures in childhood influence development of atopic sensitization.

OBJECTIVE

We sought to study the association between childhood environment and adult atopy.

METHODS

Thirteen thousand nine hundred thirty-two subjects aged 20 to 44 years from 36 areas in Europe, New Zealand, the United States, and Australia took part in the European Community Respiratory Health Survey, answering interviewer-led questionnaires and providing blood tests for measurement of specific IgE to grass, house dust mite, cat, and Cladosporium allergens.

RESULTS

Atopy was negatively associated with family size (OR = 0. 93; 95% CI = 0.90-0.96 per 1 sib), partly attributable to an independent protective effect of a greater number of brothers (OR = 0.92; 95% CI = 0.89-0.95 per 1 brother). Accounting for total number of siblings, no further influence was detected for number of older or younger siblings. Bedroom sharing was associated with a lower prevalence of atopy, particularly to cat allergen. A protective effect of family size and bedroom sharing could only be detected in subjects reporting no parental allergy (family size, test for interaction P =.012). The presence of a dog in the home in childhood was negatively associated with adult atopy (OR = 0.85, 95% CI = 0. 78-0.92), an effect that remained after adjustment for parental allergy, sibling allergy, and adult pet ownership.

CONCLUSION

Subjects from large families with brothers, shared bedrooms, and dogs in childhood were less often atopic as adults. Our findings are consistent with the hypothesis that infectious agents could inhibit development of atopy during childhood. However, in subjects with a strong genetic predisposition, environmental factors in childhood are possibly of less importance.

Atopic sensitization and respiratory symptoms among Polish and Swedish school children

Allergic sensitization and symptoms from the airways in relation to air pollution were compared in 10-12-year-old school children (n = 1113) from urban Konin in central Poland and both urban and rural parts of Sundsvall in northern Sweden. The measurements included parental questionnaires, skin-prick tests and serial peak flow measurements during 2 weeks with simultaneous monitoring of outdoor air pollutants. The skin-prick test technique was validated by IgE antibody determinations. The levels of common industrial pollutants, SO2 and smoke particles were much higher in Konin than in urban Sundsvall and the levels of NO2 were similar. Various respiratory symptoms were more often reported among school children in Konin (except for wheezing and diagnosed asthma). Multiple logistic regression analyses yielded the following increased odds ratios for children in Konin as compared with the reference group (rural Sundsvall): chest tightness and breathlessness 3.48 (95% confidence interval 2.08-5.82), exercise-induced coughing attacks 3.69 (95% confidence interval 1.68-8.10), recurrent episodes of common cold 2.79 (95% confidence interval 1.53-5.09) and prolonged cough 4.89 (95% confidence interval 2.59-9.23). In contrast, as compared with rural Sundsvall, the adjusted odds ratio for a positive skin-prick test was decreased in Konin, but increased in urban Sundsvall, 0.58 (95% confidence interval 0.37-0.91) and 1.67 (95% confidence interval 1.15-2.42) respectively. The study confirms that living in urban, as compared with rural areas, is associated with an increased prevalence of respiratory symptoms and sensitization to allergens. These differences could be explained by air pollution. Respiratory symptoms were more common in a similar urban group of Polish children who were exposed to even higher levels of air pollution. These children, however, had a much lower prevalence of sensitization to allergens, as compared with the Swedish children. This indicates that differences in lifestyle and standard of living between western Europe and a former socialist country influences the prevalence of atopy.

Prevalence of symptoms of asthma, rhinitis and eczema in 13- to 14-year-old children in Africa: the International Study of Asthma and Allergies in Childhood Phase III

Phase I of the International Study of Asthma and Allergies in Childhood has provided valuable information regarding international prevalence patterns and potential risk factors in the development of asthma, allergic rhinoconjunctivitis and eczema. However, in Phase I, only six African countries were involved (Algeria, Tunisia, Morocco, Kenya, South Africa and Ethiopia). Phase III, conducted 5-6 years later, enrolled 22 centres in 16 countries including the majority of the centres involved in Phase I and new centres in Morocco, Tunisia, Democratic Republic of Congo, Togo, Sudan, Cameroon, Gabon, Reunion Island and South Africa. There were considerable variations between the various centres of Africa in the prevalence of the main symptoms of the three conditions: wheeze (4.0-21.5%), allergic rhinoconjunctivitis (7.2-27.3%) and eczema (4.7-23.0%). There was a large variation both between countries and between centres in the same country. Several centres, including Cape Town (20.3%), Polokwane (18.0%), Reunion Island (21.5%), Brazzaville (19.9%), Nairobi (18.0%), Urban Ivory Coast (19.3%) and Conakry (18.6%) showed relatively high asthma symptom prevalences, similar to those in western Europe. There were also a number of centres showing high symptom prevalences for allergic rhinoconjunctivitis (Cape Town, Reunion Island, Brazzaville, Eldoret, Urban Ivory Coast, Conakry, Casablanca, Wilays of Algiers, Sousse and Eldoret) and eczema (Brazzaville, Eldoret, Addis Ababa, Urban Ivory Coast, Conakry, Marrakech and Casablanca).

The prevalence of house dust mites, Dermatophagoides spp, and associated environmental conditions in homes in Ohio

Abundance of the house dust mites, Dermatophagoides farinae and D. pteronyssinus, in various sites in the homes of dust-sensitive patients was sequentially monitored at approximately 3 wk intervals for 2 yr, and mite density was correlated with indoor physical and climatic factors. Significantly higher mite levels occurred on the most heavily used fabric-upholstered furniture and carpeted floor areas of the living/family room and bedrooms. Mattresses were not found to be the major foci for mites. No significant positive correlation was noted between mite abundance and frequency or thoroughness of cleaning, amount of dust, and age of furnishings or dwelling. Significantly higher mite levels occurred on carpeted floors than on noncarpeted floors. Successive vacuuming did not significantly reduce mite abundance. Mite density exhibited a seasonal fluctuation, with highest density occurring in the humid summer months and the lowest density during the dryer, late heating season. Live mites were more abundant than dead mites during the period when total abundance was high. In homes inhabited by both species, D. farinae was the dominant species, except in one home that had a significantly higher relative humidity.

The burden of atopy and asthma in children

BACKGROUND

There has been a world-wide increase in the prevalence of atopic diseases. These atopic diseases, including asthma, allergic rhinoconjunctivitis and atopic eczema/dermatitis, are common in childhood and create a challenge of management for physicians and parents.

METHODS

MEDLINE was searched for articles related to atopy, allergy asthma, allergic rhinoconjunctivitis and atopic eczema/dermatitis.

RESULTS AND CONCLUSIONS

The conditions of asthma, allergic rhinoconjunctivitis and atopic eczema/dermatitis cause very significant burdens regarding the discomfort to the affected individual, management problems for the parent and physician and the economic cost to the family and the nation.

Prevalence of respiratory symptoms, bronchial hyperresponsiveness and atopy among adults: west and east Germany

The prevalence of respiratory symptoms, atopic sensitization and bronchial hyperresponsiveness was compared in a random sample of adults, 20-44 yrs of age, in two cities in West and East Germany, Hamburg and Erfurt, respectively. There were much higher levels of outdoor air pollution due to sulphur dioxide and suspended particulates in Erfurt, and major differences in living conditions during the last 40 yrs. Within the European Respiratory Health Survey, a short questionnaire was answered by 3,156 (80% response rate) subjects in Hamburg and 3,272 (74%) in Erfurt. A subset of responders to the short questionnaire completed a long questionnaire, spirometry, methacholine or bronchodilator test, skin test, and total and specific immunoglobulin E (IgE) measurements, with a total number of 1,159 participants in Hamburg and 731 in Erfurt. Six out of 8 questions on respiratory symptoms and diagnoses were answered in the affirmative more frequently in Hamburg than in Erfurt. In Hamburg, mean forced expiratory volume in one second (FEV1)% of predicted was 105 vs 107% in Erfurt (p < 0.0001), and bronchial hyperresponsiveness was more frequently observed in Hamburg than in Erfurt (25 vs 19%; p < 0.05). Atopic sensitization was more prevalent in Hamburg than in Erfurt regarding the results of skin tests against grass pollen (24 vs 19%; p < 0.05), birch pollen (19 vs 8%; p < 0.0005), cat (10 vs 2%; p < 0.0005), and Dermatophagoides pteronyssinus (14 vs 10%; p < 0.05). This was reflected by the prevalences of positive specific IgE values, which were higher in Hamburg than in Erfurt for grass (26 vs 20%; p < 0.05), birch (20 vs 10%; p < 0.0005) and cat (12 vs 8%; p < 0.05). In Hamburg, compared to Erfurt, there was: a lower mean number of siblings (p < 0.005); a higher degree of childhood and current exposure to environmental tobacco smoke (p < 0.005); and a higher frequency of fitted carpets and reported mould or mildew inside the house (p < 0.005). Therefore, these data may support the hypothesis that childhood factors and exposure to indoor allergens and irritants may have been more relevant for the development of asthma and atopy than the potential long-term exposure to high concentrations of sulphur dioxide and particulate matter.

Indoor air quality and personal factors related to the sick building syndrome

The "sick building syndrome" involves symptoms such as eye, skin and upper airway irritation, headache, and fatigue. A multifactorial study was performed among personnel in consecutive cases of sick buildings to investigate relationships between such symptoms, exposure to environmental factors, and personal factors. The total indoor hydrocarbon concentration was significantly related to symptoms. Other indoor exposures such as room temperature, air humidity, and formaldehyde or carbon dioxide concentration did not correlate with the symptoms. Personal factors such as reported hyperreactivity and sick leave due to airway diseases were strongly related to the sick building syndrome. Other factors associated with the sick building syndrome were smoking, psychosocial factors, and experience of static electricity at work. Neither atopy, age, sex, nor outdoor exposures correlated significantly with the number of symptoms. It was concluded that the sick building syndrome is of multifactorial origin and related to both indoor hydrocarbon exposure and individual factors.

Altitude and allergy to house-dust mites. A paradigm of the influence of environmental exposure on allergic sensitization

To further investigate the possibility of a cause and effect relationship between exposure to house-dust mite (HDM) allergens and respiratory disease associated with dust mite sensitivity, we compared schoolchildren living in the Alps, where exposure to HDM is low, with those living at sea level, where it is high. The study included 933 schoolchildren from the fourth and fifth grades. The protocol included the standardized 1978 American Thoracic Society (ATS) questionnaire for children, skin testing using common aero-allergens and controls, and antigenic measurements of dust samples from mattresses (Group I antigen). The prevalence of asthma with positive skin test to HDM and the overall prevalence of positive skin test to HDM were significantly lower in mountain schoolchildren. The mean geometric HDM antigenic level in mattresses was much lower in the Alps (0.36 micrograms/g dust) than at sea level (15.8 micrograms/g dust). In contrast, the prevalence of hay fever and positive skin test to grass pollens as well as the overall prevalence of positive skin tests to grass pollens were significantly higher in the Alps. These data illustrate a striking relationship between exposure to environmental allergens and atopic sensitization.

Association of asthma with serum IgE and skin test reactivity to allergens among children living at high altitude. Tickling the dragon's breath

Asthma in children and young adults is strongly associated with immediate hypersensitivity to indoor allergens, notably those derived from the house dust mite. In addition, outdoor air pollution is considered to aggravate existing asthma. We investigated the prevalence of asthma and the pattern of allergen sensitization in a mite-free environment with low levels of outdoor air pollution. A total of 567 children aged between 12 and 14 attending Los Alamos Middle School, NM (altitude 7,200 feet) were screened using a respiratory questionnaire; 120 children (53 control children) underwent allergen skin testing and serum IgE measurement, and their bronchial reactivity to histamine was measured. Dust was collected from 111 homes and the level of indoor mite and cat allergen measured. The prevalence of respiratory symptoms was high (13%), and from the detailed testing it was estimated that 6.3% of the children had asthma (defined as symptomatic bronchial reactivity). Children with asthma had elevated IgE, 367 (179 to 755) versus 38 (23 to 61), and predominant sensitization to cat, 68 versus 20% (p < 0.001). A high number of households (77%) had a pet cat or dog. The concentration of mite allergen was very low (mean 0.18 micrograms Der p milligrams sieved house dust), whereas that of cat allergen was high in homes with a cat (80.8 micrograms Fel d milligrams) but also in homes with no cat (3.2 micrograms Fel d milligrams). The results show that in a mite-free environment with low levels of outdoor air pollution, asthma was still a major cause of morbidity among schoolchildren.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory health and long-term exposure to air pollutants in Swiss schoolchildren. SCARPOL Team. Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution, Climate and Pollen

The impact of long-term exposure to air pollution on respiratory and allergic symptoms and illnesses was assessed in a cross-sectional study of schoolchildren (ages 6 to 15 yr, n = 4,470) living in 10 different communities in Switzerland. Air pollution measurements (particulate matter less than 10 microns in diameter [PM10], nitrogen dioxide [NO2], sulfur dioxide [SO2], and ozone) and meteorologic data were collected in each community. Reported symptom rates of chronic cough, nocturnal dry cough, and bronchitis, adjusted for individual risk factors, were positively associated with PM10, NO2, and SO2. The strongest relationship was observed for PM10 (adjusted odds ratios for chronic cough, nocturnal dry cough, and bronchitis between the most and the least polluted community for PM10 were 3.07 [95% CI: 1.62 to 5.81], 2.88 [95% CI: 1.69 to 4.89], and 2.17 [95% CI: 1.21 to 4.89], respectively). The high correlation between the average concentrations of the pollutants makes the assessment of the relative importance of each pollutant difficult. No association between long-term exposure to air pollution and classic asthmatic and allergic symptoms and illnesses was found. There was some indication that frequency of fog is a risk factor of chronic cough and bronchitis, independent of air pollution. In conclusion, this study provides further evidence that rates of respiratory illnesses and symptoms among children augment with increasing levels of air pollution even in countries like Switzerland with moderate average air pollution concentrations.