Indoor Environmental Interventions and their Effect on Asthma Outcomes

Avoidance of Inhaled Pollutants and Irritants in Asthma from a Salutogenic Perspective

Much is known about the role of aeroallergens in asthma, but little is described about the damage caused by inhaled pollutants and irritants to the respiratory epithelium. In this context, the most frequent pollutants and irritants inhaled in the home environment were identified, describing the possible repercussions that may occur in the respiratory tract of the pediatric population with asthma and highlighting the role of the caregiver in environmental control through a salutogenic perspective. Searches were carried out in the MEDLINE/PubMed, Web of Science, Lilacs and Scopus databases for articles considered relevant for the theoretical foundation of this integrative review, in which interactions between exposure to pollutants and inhaled irritants and lung involvement. Articles published in the last 10 years that used the following descriptors were considered: air pollution; tobacco; particulate matter; disinfectants; hydrocarbons, fluorinated; odorants; chloramines; pesticide; asthma; and beyond Antonovsky's sense of coherence. Exposure to smoke and some substances found in cleaning products, such as benzalkonium chloride, ethylenediaminetetraacetic acid and monoethanolamine, offer potential risks for sensitization and exacerbation of asthma. The vast majority of the seven main inhaled products investigated provoke irritative inflammatory reactions and oxidative imbalance in the respiratory epithelium. In turn, the caregiver's role is essential in health promotion and the clinical control of paediatric asthma. From a salutogenic point of view, pollutants and irritants inhaled at home should be carefully investigated in the clinical history so that strategies to remove or reduce exposures can be used by caregivers of children and adolescents with asthma.

Environmental management of asthma in clinical practice: Results from the 2012 National Ambulatory Medical Care Survey

Background

The National Asthma Education and Prevention Program guidelines emphasize environmental control as an integral part of asthma management; however, limited national-level data exist on how clinicians implement environmental control recommendations.

Objective

We analyzed data on clinicians' self-reported use of recommended environmental control practices in a nationally representative sample (n = 1645) of primary care physicians, asthma specialists, and advanced practice providers from the National Asthma Survey of Physicians, a supplemental questionnaire to the 2012 National Ambulatory Medical Care Survey.

Methods

We examined clinician and practice characteristics as well as clinicians' decisions and strategies regarding environmental trigger assessment and environmental control across provider groups. Regression modeling was used to identify clinician and practice characteristics associated with implementation of guideline recommendations.

Results

A higher percentage of specialists assessed asthma triggers at home, school, and/or work than primary care or advanced practice providers (almost always: 53.6% vs 29.4% and 23.7%, respectively, P < .001). Almost all clinicians (>93%) recommended avoidance of secondhand tobacco smoke, whereas recommendations regarding cooking appliances (eg, proper ventilation) were infrequent. Although assessment and recommendation practices differed between clinician groups, modeling results showed that clinicians who reported almost always assessing asthma control were 5- to 6-fold more likely to assess environmental asthma triggers. Use of asthma action plans was also strongly associated with implementation of environmental control recommendations.

Conclusions

Environmental assessment and recommendations to patients varied among asthma care providers. High adherence to other key guideline components, such as assessing asthma control, was associated with environmental assessment and recommendation practices on environmental control.

Association of School Infrastructure on Health and Achievement Among Children With Asthma

OBJECTIVE

To determine whether school infrastructure is associated with health and academic outcomes among elementary school children with asthma.

METHODS

We conducted a retrospective cohort study of linked medical, academic, and facilities data from a large mid-Atlantic school district of the United States. All K-5 students with asthma who were enrolled under the state's Children's Health Insurance Program were included. We estimated associations of the infrastructure quality of the student's school, as assessed by an engineering firm in Summer 2011 and represented by the Facility Condition Index (FCI), with asthma health outcomes, absenteeism, and standardized test scores in math and reading in the 2 academic years thereafter.

RESULTS

A total of 6558 students were identified, the majority non-Hispanic Black, across 130 schools. Most schools (97/130, 75%) were in very poor or worse condition. In cluster-adjusted models accounting for demographics, grade, school-specific area deprivation, and inhaled corticosteroid use, a one standard deviation increase in FCI, corresponding to greater infrastructure deficiency, was associated with higher rates of asthma-related hospitalizations (incidence rate ratio [IRR] 1.16; 95% confidence interval [CI] 1.03, 1.32), more absenteeism (IRR 1.05; 95% CI 1.01, 1.08), and lower scores in math (mean difference [MD] -3.3; 95% CI -5.5, -1.2) and reading (MD -3.0; 95% CI -5.1, -0.9). There were no differences in rates of asthma-related emergency visits or steroid prescriptions.

CONCLUSIONS

Children with asthma attending schools with poorer infrastructure had worse health and academic outcomes. Public policy emphasizing reinvestment in school infrastructure may be a potential means of addressing asthma disparities.

Environmental Interventions for Asthma

Exposure and sensitization to environmental factors play a fundamental role in asthma development and is strongly associated with asthma morbidity. While hereditary factors are critical determinants of asthma, exposures to environmental factors are implicated in the phenotypic expression of asthma and have been strongly associated in the risk of its development. Significant interest has thus been geared toward potentially modifiable environmental exposures which may lead to the development of asthma. Allergen exposure, in particular indoor allergens, plays a significant role in the pathogenesis of asthma, and remediation is a primary component of asthma management. In the home, multifaceted and multitargeted environmental control strategies have been shown to reduce home exposures and improve asthma outcomes. In addition to the home environment, assessment of the school, daycare, and workplace environments of patients with asthma is necessary to ensure appropriate environmental control measures in conjunction with medical care. This article will discuss the role of the environment on asthma, review targeted environmental therapy, and examine environmental control measures to suppress environmental exposures in the home and school setting.

Household determinants of biocontaminant exposures in Canadian homes

Exposure to biocontaminants, such as dust mites, animal dander, bacteria, and mold, is associated with a range of health effects. This study identified household characteristics associated with indoor biocontaminant loadings in four Canadian cities. Floor dust was collected in 290 Canadian homes in Edmonton, Halifax, Montreal, and Windsor. The dust samples were analyzed for house dust mite allergens (Der f 1 and Der p 1), cat allergen (Fel d 1), cockroach allergen (Bla g 1), beta-(1,3)-D-glucan, and endotoxin. Household information was obtained through questionnaires and home inspections. We performed univariate and multivariate analyses to identify household determinants of biocontaminant loadings and mold odor presence. We observed large regional variations for all biocontaminants, except for cockroach allergen. The ranges of the contaminants measured in loadings and concentrations were similar to that of previous Canadian studies. Household characteristics including presence of carpeting, low floor cleaning frequency, older home age, presence of pets, and indoor relative humidity above 45% were positively associated with the presence of multiple indoor biocontaminants. High floor cleaning frequency and use of dehumidifiers were negatively associated with the presence of multiple indoor biocontaminants. Mold odor was positively associated with older home age, past water damage, and visible mold growth.

Fungal populations in the bedroom dust of children in Havana, Cuba, and its relationship with environmental conditions

The study of the fungal community composition in house dust is useful to assess the accumulative exposure to fungi in indoor environments. The objective of this research was to characterize the fungal diversity of house dust and its association with the environmental conditions of bedrooms. For this, the dust was collected from 41 bedrooms of children between the ages of 8 and 9 with a family history of asthma, residents of Havana, Cuba. The fungal content of each sample was determined by two methods: plate culture with malt extract agar and by direct microscopy. An ecological analysis was carried out from the fungal diversity detected. To describe the factors associated with the fungi detected, bivariate logistic regression was used. Through direct microscopy, between 10 and 2311 fragments of hyphae and spores corresponding mainly to Cladosporium, Coprinus, Curvularia, Aspergillus/Penicillium, Xylariaceae, and Periconia were identified. Through the culture, 0-208 CFU were quantified, where Aspergillus, Cladosporium, and Penicillium predominated. The culturability evidenced the differences between the quantification determined by both methods. A positive relationship was found between the type of cleaning of the furniture, the presence of trees in front of the bedroom, indoor relative humidity, indoor temperature, the presence of air conditioning, and natural ventilation with specific spore types and genera. The use of two different identification methods allowed to detect a greater fungal diversity in the residences evaluated. Monitoring the exposure to these fungal allergens in childhood can help to prevent sensitization in the allergic child, the development of asthma, and other respiratory diseases.

Knowledge, attitudes, and practices concerning cockroach exposure among caregivers of children with asthma

Background

Cockroach allergen is one of the most important asthma triggers for children. There is an extensive body of research on interventions to reduce exposure. However, adherence to these interventions is low. Insight into the knowledge, attitudes, and practices (KAP) associated with cockroach remediation is needed. We assessed KAP using the Health Beliefs Model (HBM) as a framework for predicting behavior. This study aimed to assess the socio-demographic and psycho-social characteristics associated with cockroach KAP and to quantify the relationship between KAP and number of cockroaches in the home.

Methods

To identify factors associated with cockroach KAP a cross-sectional study was conducted using a structured questionnaire administered to caregivers of children with asthma in New Orleans, Louisiana. Positive scores in each metric of the KAP signified better cockroach knowledge, increased concern about cockroaches’ impact on health (attitudes), and participation in recommended cockroach remediation practices (practices). To evaluate cockroach KAP scores as a predictor of cockroach exposure in the home, a cohort study was conducted among a sub-sample of participants.

Results

Fifty-six caregivers participated in the study. Participants had positive scores on all subscales of KAP with knowledge having a lower score compared to attitudes and practices. Cockroach knowledge was inversely correlated with age at asthma diagnosis (ρ = − 0.36, p = 0.01). Caregivers identifying as black/African American had higher cockroach knowledge scores compared to other races (Median: 6.0 v 3.0; p = 0.05). Caregivers other than mothers had higher cockroach attitude scores (Median 6.5 v 4.0; p = 0.003) and total KAP scores (Median 18.0 v 14.0; p = 0.05). Twenty-six participants completed the cohort study. Cockroach exposure was not significantly associated with higher cockroach knowledge, cockroach practice, or total KAP score. For attitude scores, participants in the highest quartile had significantly lower exposure (β: -1.96, 95% CI: − 3.50 - 0.42) compared to those in the lowest quartile (p = 0.01).

Conclusions

Different socio-demographic and psycho-social factors were associated with the components of cockroach KAP. Greater concern about cockroaches (attitude) was significantly associated with reduced cockroach exposure. This highlights the importance of identifying the key elements of caregiver KAP to improve cockroach remediation among caregivers of children with asthma.

The Indoor Environment and Childhood Asthma

PURPOSE OF REVIEW

Sensitization and exposure to triggers in the indoor environment, including aeroallergens, indoor air pollution, and environmental tobacco smoke, have a significant role in asthma development and morbidity. This review discusses indoor environmental exposures and their effect on children with asthma as well as environmental interventions and their role in improving asthma morbidity.

RECENT FINDINGS

Recent research has emphasized the role of aeroallergen sensitization and exposure in asthma morbidity and the importance of the school indoor environment. There is an established association between indoor exposures and asthma development and morbidity. Recent evidence has highlighted the importance of the indoor environment in childhood asthma, particularly the role of the school indoor environment. While home environmental interventions have had mixed results, interventions in the school environment have the potential to significantly impact the health of children, and ongoing research is needed to determine their effectiveness.

Structural and Social Determinants of Health in Asthma in Developed Economies: a Scoping Review of Literature Published Between 2014 and 2019

PURPOSE OF REVIEW

Using the WHO Conceptual Framework for Action on the Social Determinants of Health, this review provides a discussion of recent epidemiologic, mechanistic, and intervention studies of structural and social determinants of health and asthma outcomes covering the period from 2014 to 2019.

RECENT FINDINGS

A majority of studies and interventions to date focus on the intermediary determinants of health (e.g., housing), which as the name suggests, exist between the patient and the upstream structural determinants of health (e.g., housing policy). Race/ethnicity remains a profound social driver of asthma disparities with cumulative risk from many overlapping determinants. A growing number of studies on asthma are beginning to elucidate the underlying mechanisms that connect social determinants to human disease. Several effective interventions have been developed, though a need for large-scale policy research and innovation remains. Strong evidence supports the key role of the structural determinants, which generate social stratification and inequity, in the development and progression of asthma; yet, interventions in this realm are challenging to develop and therefore infrequent. Proximal, intermediary determinants have provided a natural starting point for interventions, though structural interventions have the most potential for major impact on asthma outcomes. Further research to investigate the interactive effect of multiple determinants, as well as intervention studies, specifically those that are cross-sector and propose innovative strategies to target structural determinants, are needed to address asthma morbidities, and more importantly, close the asthma disparity gap.

A meta-analysis of baseline characteristics in trials on mite allergen avoidance in asthmatics: room for improvement

BACKGROUND

Evidence regarding the clinical effectiveness of mite allergen avoidance for the treatment of asthma is lacking. In previous meta-analyses on mite allergen control, the baseline data were not discussed in detail. This study updates and extends the existing Cochrane review by Gøtzsche and Johansen (Cochrane Database of Systematic Reviews, 2008, Art. No: CD001187), with a focus on baseline asthma outcomes and allergen exposures.

METHODS

We used the existing trials in the original Cochrane review and included newly published studies. The baseline data for the mite allergen load from the mattress, the standardized asthma symptom score (ASS), the forced expiratory volume in 1 s percentage of predicted (FEV1 %pred.), and the histamine provocative concentration causing a 20% drop in FEV1 (PC20) were extracted. First, the mean values of the outcomes were calculated. The influence of the mite allergen load was examined with a random-effect meta-regression using the Metafor package in R.

RESULTS

Forty-five trials were included; 39 trials reported strategies for concurrent bedroom interventions, and 6 trails reported strategies for air purification. The mite allergen load ranged from 0.44 to 24.83 μg/g dust, with a mean of 9.86 μg/g dust (95% CI 5.66 to 14.05 μg/g dust, I2 = 99.8%). All health outcomes showed considerable heterogeneity (standardized ASS mean: 0.13, 95% CI 0.08 to 0.18, I2 = 99.9%; FEV1 %pred. mean: 85.3%, 95% CI 80.5 to 90.1%, I2 = 95.8%; PC20 mean: 1.69 mg/mL, 95% CI 0.86 to 2.52 mg/mL, I2 = 95.6%). The covariate mite allergen load did not significantly influence health outcomes.

DISCUSSION

This meta-analysis shows that mite avoidance studies are characterized by the inclusion of patients with rather mild to moderate asthma and with varying and sometimes negligible levels of allergen exposure. Future studies should focus on patients with severe asthma and increased levels of allergen exposure.

Ecological interactions in asthma: from environment to microbiota and immune responses

PURPOSE OF REVIEW

Asthma is a heterogeneous condition shaped not only by genetics but also host conditioning by environmental factors. Recognizing the ecological context of microbe-immune interactions across environments and body sites is a necessary step toward better understanding how human microbiota influence or drive the pathogenesis and pathophysiology of asthma in its various presentations.

RECENT FINDINGS

There is increasing evidence of a critical role for microbiota in asthma pathogenesis and outcomes across various body compartments, including the upper and lower airways, and gut. We discuss recent studies from this area including: development of a method to quantify microbial farm-effect in nonfarm environments, relationships between environmental microbial exposures and asthma prevalence across different geographies, microbiome-mediated responses to ozone, and microbiome-immune interactions within and across body compartments. Beyond bacteria, recent reports of asthma-associated differences in archaea and fungal organisms also are highlighted.

SUMMARY

Collective evidence warrants application of an ecological framework to advance mechanistic insights into microbiota-immune interactions in asthma. This is necessary to achieve goals of developing successful therapeutic interventions targeting modification of microbiomes.

Asthma

This review provides an evidence-based guide for the diagnosis, evaluation, and treatment of patients with asthma. It addresses typical questions that arise in the clinic-based care of patients with asthma and provides a basic and comprehensive resource for asthma care.

Update in Pediatric Asthma: Selected Issues

Asthma is a complex condition that affects 14% of the world's children and the approach to management includes both pharmacologic as well as non-pharmacologic strategies including attention to complex socioeconomic status phenomena. After an historical consideration of asthma, allergic and immunologic aspects of asthma in children and adolescents are presented. Concepts of socioeconomic aspects of asthma are considered along with environmental features and complications of asthma disparities. Also reviewed are links of asthma with mental health disorders, sleep disturbances and other comorbidities. A stepwise approach to asthma management is discussed that includes pharmacologic and non-pharmacologic strategies in the pediatric population. The role of immunotherapy and use of various immunomodulators are considered as well.

A reintroduction of environmental mite allergen control strategies for asthma treatment and the debate on their effectiveness

Asthma affects three hundred million people worldwide. The effectiveness of house dust mite allergen control for asthma treatment is debatable. One aspect that has been little discussed in existing meta-analyses is the possible role of environmental strategies. Here, we reintroduce the previously defined strategies for mite allergen control and discuss their importance to the debate on clinical effectiveness. The strategy of concurrent bedroom interventions is related to the combined use of a priori defined interventions, while the strategy of exposure-based control relates to the treatment of relevant textiles after assessing exposure. The air purification strategy aims to purify the human breathing zone of airborne allergens. In Western European patient practice, the use of these strategies differs. A post hoc study of the dominant Cochrane review by Gøtzsche and Johansen (Cochrane Database of Systematic Reviews, 2008, Art. No: CD001187) appears to indicate that a majority of the underlying trials reported on the strategy of concurrent bedroom interventions, which were mainly executed in a minimal manner. Some trials have reported on the air purification strategy and may potentially alter the debate on effectiveness. No trial has reported on the strategy of exposure-based control. We therefore hypothesize that the absence of evidence for the effectiveness of mite allergen control for asthma treatment applies to the strategy of concurrent bedroom interventions. The evidence-based effectiveness of the exposure-based control strategy appears to be undetermined. The results of our post hoc reanalysis urge that future meta-analyses of mite allergen control should a priori define the environmental strategy under study. Future trials of mite allergen control are warranted to test the exposure-based strategy as well as the sparsely tested strategy of air purification.

Bedroom Allergen Exposure Beyond House Dust Mites

PURPOSE OF REVIEW

The review provides insight into recent findings on bedroom allergen exposures, primarily focusing on pet, pest, and fungal exposures.

RECENT FINDINGS

Large-scale studies and improved exposure assessment technologies, including measurement of airborne allergens and of multiple allergens simultaneously, have extended our understanding of indoor allergen exposures and their impact on allergic disease. Practical, streamlined methods for exposure reduction have shown promise in some settings, and potential protective effects of early-life exposures have been further elucidated through the investigation of specific bacterial taxa. Advances in molecular allergology have yielded novel data on sensitization profiles and cross-reactivity. The role of indoor allergen exposures in allergic disease is complex and remains incompletely understood. Advancing our knowledge of various co-exposures, including the environmental and host microbiome, that interact with allergens in early life will be crucial for the development of efficacious interventions to reduce the substantial economic and social burden of allergic diseases including asthma.

Continuous Inhalation Exposure to Fungal Allergen Particulates Induces Lung Inflammation While Reducing Innate Immune Molecule Expression in the Brainstem

Continuous exposure to aerosolized fine (particle size ≤2.5 µm) and ultrafine (particle size ≤0.1 µm) particulates can trigger innate inflammatory responses in the lung and brain depending on particle composition. Most studies of manmade toxicants use inhalation exposure routes, whereas most studies of allergens use soluble solutions administered via intranasal or injection routes. Here, we tested whether continuous inhalation exposure to aerosolized Alternaria alternata particulates (a common fungal allergen associated with asthma) would induce innate inflammatory responses in the lung and brain. By designing a new environmental chamber able to control particle size distribution and mass concentration, we continuously exposed adult mice to aerosolized ultrafine Alternaria particulates for 96 hr. Despite induction of innate immune responses in the lung, induction of innate immune responses in whole brain samples was not detected by quantitative polymerase chain reaction or flow cytometry. However, exposure did trigger decreases in Arginase 1, inducible nitric oxide synthase, and tumor necrosis factor alpha mRNA in the brainstem samples containing the central nervous system respiratory circuit (the dorsal respiratory group, ventral respiratory group, and the pre-Bötzinger and Bötzinger complexes). In addition, a significant decrease in the percentage of Toll-like receptor 2-expressing brainstem microglia was detected by flow cytometry. Histologic analysis revealed a significant decrease in Iba1 but not glial fibrillary acidic protein immunoreactivity in both the brainstem and the hippocampus. Together these data indicate that inhalation exposure to a natural fungal allergen under conditions sufficient to induce lung inflammation surprisingly causes reductions in baseline expression of select innate immune molecules (similar to that observed during endotoxin tolerance) in the region of the central nervous system controlling respiration.