Clinical effects of air filters in homes of asthmatic adults sensitized and exposed to pet allergens

A systematic review and meta-analysis of field studies of portable air cleaners: Performance, user behavior, and by-product emissions

Indoor air quality is important for the health of building occupants, and public interest in controlling indoor airborne pathogens increased dramatically with the COVID-19 pandemic. Pollutant concentrations can be controlled locally using portable air cleaners (sometimes called air purifiers), which allow occupants to apply air cleaning technology to meet their needs in the location and times that they find appropriate. This paper provides a systematic review of scientific literature that describes field studies of the effectiveness of portable air cleaners. Over 500 papers were considered, and 148 were reviewed in detail, to extract 35 specific research results (e.g., particulate removal performance) or characteristics (e.g., type of building). These were aggregated to provide an overview of results and approaches to this type of research, and to provide meta-analyses of the results. The review includes: descriptions of the geographical location of the research; rate of publications over time; types of buildings and occupants in the field study; types of air cleaner technology being tested; pollutants being measured; resulting pollutant removal effectiveness; patterns of usage and potential barriers to usage by occupants; and the potential for by-product emissions in some air cleaner technologies. An example result is that 83 of the 148 papers measured reductions in fine particulates (PM2.5) and found a mean reduction of 49 % with standard deviation of 20 %. The aggregated results were approximately normally distributed, ranging from finding no significant reduction up to a maximum above 90 % reduction. Sixteen of the 148 papers considered gaseous pollutants, such as volatile organic compounds, nitrogen dioxide, and ozone; 36 papers considered biological pollutants, such as bacteria, viruses, pollen, fungi, etc. An important challenge, common to several studies, is that occupants run the air cleaners for shorter periods and on low airflow rate settings, because of concerns about noise, drafts, and electricity cost, which significantly reduces air cleaning effectiveness.

Environmental allergen reduction in asthma management: an overview

Asthma is a prevalent non-communicable disease that affects both children and adults. Many patients with severe, uncontrolled asthma could not achieve total control despite using anti-asthmatic drugs. There is increasing evidence that allergy to environmental allergens, including both indoor and outdoor allergens, is associated with asthma symptoms and severe asthma. Frequently reported sensitized allergens were dust mites, cockroaches, grass pollens, molds, pets, and rodents in allergic asthma patients, although the patterns of widespread allergens differed from each country. Allergen avoidance is the cornerstone of asthma management, especially in sensitized subjects. This review summarizes environmental allergen avoidance and clarifies their effects on asthma control. Despite contrasting results about the impact of allergen exposure reduction on asthma control, several studies supported the beneficial effects of reducing asthma-related symptoms or risk of exacerbations as a nondrug therapy. Identifying environmental allergens is helpful for asthma patients, and further studies on clinically effective avoidance methods are required.

The efficacy of the Dyson air purifier on asthma control: A single-center, investigator-led, randomized, double-blind, placebo-controlled trial

BACKGROUND

Air pollution is associated with poor asthma outcomes. High-efficiency particulate air air purifiers may reduce air pollution and thus improve asthma outcomes. However, the efficacy of such devices for this purpose remains inconclusive.

OBJECTIVE

To investigate the effects of reducing the levels of pollutants on asthma outcomes in adults, using a novel Dyson high-efficiency particulate air air purifier.

METHODS

In a single-center, double-blinded, randomized controlled trial, participants (N = 50) were randomized at a 1:1 ratio to active filters (intervention) or to dummy filters (placebo) for a total of 78 weeks. The primary outcomes were the changes in Asthma Control Questionnaire 6 (ACQ6) and Asthma-specific Quality of Life Questionnaire (AQLQ) scores from baseline. The secondary outcomes were changes in indoor air pollution and lung function measurements. The coronavirus disease 2019 pandemic limited spirometry measurements to 2 time points and assessment of fractional exhaled nitric oxide and bronchial hyperresponsiveness to baseline only.

RESULTS

Air pollutant levels were significantly lower in the intervention group compared with the placebo group (P = .0003). Both groups had a significant improvement in their ACQ6 and AQLQ. However, there were no significant between-group differences in ACQ6, AQLQ, or spirometry, compared with baseline in multivariable repeated measures models.

CONCLUSION

The Dyson air purifier significantly improved air quality. However, there were no significant improvements in asthma control, quality of life, or measures of lung function in the intervention group compared with the control group despite improvements in indoor air quality. Larger, extended studies are required to confirm or refute these findings, especially given that the coronavirus disease 2019 pandemic prevented the procurement of detailed objective data.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04729530; ttps://clinicaltrials.gov/ct2/show/NCT04729530.

The Efficacy of the Dyson Air Purifier in Improving Asthma Control: Protocol for a Single-Center, Investigator-Led, Randomized, Double-Blind, Placebo-Controlled Trial

Background

Indoor air quality has been shown to influence asthma control and outcomes. Air purifiers and high-efficiency particulate air filtration devices can improve indoor air quality by reducing the indoor levels of air pollution and allergens. However, the influence of this improved indoor air quality on asthma control remains unclear; hence, randomized controlled trials are needed to further elucidate this phenomenon.

Objective

This study aims to investigate the effect of reducing the levels of allergens and pollutants in the bedroom and living room through the use of Dyson air purifiers (Dyson Pure Cool) on asthma control.

Methods

This is an 18-month long, investigator-led, randomized, double-blinded, placebo-controlled, single-center trial. Subjects will be randomized in a 1:1 ratio to active or placebo Dyson filters. The primary outcome is the change in the scores of Asthma Control Questionnaire 6 and Asthma-specific Quality of Life Questionnaire from baseline. Secondary outcomes include changes in lung function (forced expiratory volume in one second, forced expiratory volume in one second/forced vital capacity ratio, and midexpiratory flows), peak expiratory flow measurements, airway hyperresponsiveness (assessed by methacholine bronchial challenge), fractional exhaled nitric oxide, and indoor air pollutant levels. The sample size will be 50 subjects, and all subjects will have a confirmed diagnosis of mild persistent to moderate persistent asthma along with an Asthma Control Questionnaire 6 score of >1.5.

Results

This study was approved by the West Midlands Research Ethics Committee (18/WM/0277). The study results will be published in peer-reviewed scientific journals; presented at relevant scientific conferences; and shared in plain English with participants in our newsletters, in our clinics, and via the David Hide Asthma and Allergy Research Centre website. Our trial began in September 2019 and is expected to end in August 2021.

Conclusions

This is a double-blinded, placebo-controlled, randomized, investigator-led study to investigate the efficacy of a novel air purifier in improving asthma control in adults. The trial period of 18 months will facilitate the collection of robust data and will therefore generate clear signals. However, this extended trial duration may lead to patient withdrawal. Furthermore, this trial is conducted at a single center and in a location with a homogenous cohort of people, which may affect translatability. Nonetheless, it is hoped that the findings of this trial may help further inform clinicians regarding the utility of this novel device as an adjunct in asthma care.

Trial Registration

ClinicalTrials.gov NCT04729530; https://clinicaltrials.gov/ct2/show/NCT04729530

International Registered Report Identifier (IRRID)

DERR1-10.2196/28624

2020 Focused Updates to the Asthma Management Guidelines: A Report from the National Asthma Education and Prevention Program Coordinating Committee Expert Panel Working Group

The 2020 Focused Updates to the Asthma Management Guidelines: A Report from the National Asthma Education and Prevention Program Coordinating Committee Expert Panel Working Group was coordinated and supported by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. It is designed to improve patient care and support informed decision making about asthma management in the clinical setting. This update addresses six priority topic areas as determined by the state of the science at the time of a needs assessment, and input from multiple stakeholders:A rigorous process was undertaken to develop these evidence-based guidelines. The Agency for Healthcare Research and Quality's (AHRQ) Evidence-Based Practice Centers conducted systematic reviews on these topics, which were used by the Expert Panel Working Group as a basis for developing recommendations and guidance. The Expert Panel used GRADE (Grading of Recommendations, Assessment, Development and Evaluation), an internationally accepted framework, in consultation with an experienced methodology team for determining the certainty of evidence and the direction and strength of recommendations based on the evidence. Practical implementation guidance for each recommendation incorporates findings from NHLBI-led patient, caregiver, and clinician focus groups. To assist clincians in implementing these recommendations into patient care, the new recommendations have been integrated into the existing Expert Panel Report-3 (EPR-3) asthma management step diagram format.

Assessing Impact of Household Intervention on Indoor Air Quality and Health of Children with Asthma in the US-Mexico Border: A Pilot Study

Few studies have investigated household interventions to enhance indoor air quality (IAQ) and health outcomes in relatively low-income communities. This study aims to examine the impact of the combined intervention with asthma education and air purifier on IAQ and health outcomes in the US-Mexico border area. An intervention study conducted in McAllen, Texas, between June and November 2019 included 16 households having children with asthma. The particulate matter (PM2.5) levels were monitored in the bedroom, kitchen, and living room to measure the IAQ for 7 days before and after the intervention, respectively. Multiple surveys were applied to evaluate changes in children's health outcomes. The mean PM2.5 levels in each place were significantly improved. Overall, they significantly decreased by 1.91 μg/m3 on average (p < 0.05). All surveys showed better health outcomes; particularly, quality of life for children was significantly improved (p < 0.05). This pilot study suggests that the combined household intervention might improve IAQ in households and health outcomes for children with asthma and reduce health disparities in low-income communities. Future large-scale studies are needed to verify the effectiveness of this household intervention to improve IAQ and asthma management.

Association Between Bedroom Particulate Matter Filtration and Changes in Airway Pathophysiology in Children With Asthma

Importance

Fine particles (particulate matter 2.5 μm [PM2.5]), a ubiquitous air pollutant, can deposit in the small airways that play a vital role in asthma. It appears to be unknown whether the use of a PM2.5 filtration device can improve small airway physiology and respiratory inflammation in children with asthma.

Objective

To discover what pathophysiological changes in the small airways are associated with using a PM2.5-removing device in the bedrooms of children with asthma.

Design, Setting, and Participants

Children with mild or moderate asthma were enrolled in this double-blind, crossover study. The participants used a true filtration device and a sham filtration device in their bedrooms in a random order for 2 weeks each with a 2-week washout interval. The study was conducted in a suburb of Shanghai, China, during a low-ozone season.

Exposures

Ozone and PM2.5 were measured inside bedrooms and outside a window.

Main Outcomes and Measures

Impulse oscillometry, spirometry, and fractional exhaled nitric oxide were measured at the beginning and the end of each intervention. Peak expiratory flow was measured twice daily at home.

Results

Forty-three children (5-13 years old; 26 boys [60%]) participated. Outdoor 24-hour mean PM2.5 concentrations were moderately high, ranging from 28.6 to 69.8 μg/m3 (median, 53 μg/m3). During true filtration, bedroom PM2.5 concentrations were a mean (SD) of 63.4% (35.9%) lower than during sham filtration. Compared with sham filtration, true filtration was significantly associated with improved airway mechanics, reflected in a 24.4% (95% CI, 11.8%-37.1%) reduction in total airway resistance, a 43.5% (95% CI, 13.7%-73.3%) reduction in small airway resistance, a 22.2% (95% CI, 2.2%-42.2%) reduction in resonant frequency, and a 73.1% (95% CI, 0.3%-145.8%) increase in airway reactance. True filtration was also associated with significant improvements in fractional exhaled nitric oxide (a 27.6% [95% CI, 8.9%-42.4%] reduction) and peak expiratory flow (a 1.6% [95% CI, 0.8%-2.5%] increase). These improvements were significantly associated with bedroom PM2.5 reduction. Improvements in small airway function were nonsignificant (8.4% [95% CI, -1.4% to 18.3%]) in all participants but significant (13.2% [95% CI, 1.2%-25.1%]) in participants without eosinophilic airway inflammation at baseline. No improvements were observed for forced vital capacity, forced expiratory volume during the first second, and the ratio of these in all participants or subgroups.

Conclusions and Relevance

Per these results, indoor PM2.5 filtration can be a practical method to improve air flow in an asthmatic lung through improved airway mechanics and function as well as reduced inflammation. This warrants a clinical trial to confirm.

Trial Registration

ClinicalTrials.gov Identifier: NCT03282864.

Effects of the Use of Air Purifier on Indoor Environment and Respiratory System among Healthy Adults

Air purifiers have become popular among ordinary families. However, it remains controversial whether indoor air purification improves the respiratory health of healthy adults. A randomized crossover intervention study was conducted with 32 healthy individuals. The subjects were categorized into two groups. One group continuously used true air purifiers, and the other followed with sham air purifiers for 4 weeks. Following this first intervention, all the subjects underwent a 4-week washout period and continued with the second 4-week intervention with the alternate air purifiers. We collected fine particulate matter (PM) ≤ 2.5 µm in aerodynamic diameter (PM2.5), coarse particulate matter between 2.5 and 10 µm in aerodynamic diameter (PM10–2.5) and ozone (O₃). The subjects’ pulmonary function and fractional exhaled nitric oxide (FeNO) were measured during the study period. The indoor PM2.5 concentrations decreased by 11% with the true air purifiers compared to those with sham air purifiers. However, this decrease was not significant (p = 0.08). The air purification did not significantly improve the pulmonary function of the study subjects. In contrast, an increase in the indoor PM10–2.5 and O₃ concentration led to a significant decrease in the forced expiratory volume in one second (FEV_1.0)/forced vital capacity (FVC) and maximal mid-expiratory flow (MMEF), respectively. In conclusion, air purification slightly improved the indoor PM2.5 concentrations in ordinary homes but had no demonstrable impact on improving health.

Does Air Filtration Work for Cat Allergen Exposure?

PURPOSE OF REVIEW

The goal of this review is to compress all important information and results of the research in reducing cat allergen exposure using air filtration. Fel d 1 is the major allergen responsible for IgE responses in 90 to 95% of patients with cat allergy.

RECENT FINDINGS

Reduction of cat allergen in indoor air with different air filtration systems and portable devices has been demonstrated in the majority of the studies. Recently, early and late asthmatic responses were significantly reduced using portable HEPA air cleaners in an environmental exposure chamber. This review provides a comprehensive overview of the current state of airborne Fel d 1 air filtration targeting the most efficient devices in cat allergen reduction. Novel emerging HEPA filters are targeting reduction of cat indoor asthma trigger so patient can might benefit from efficient solution.

The Role of Home Environments in Allergic Disease

Allergic diseases are surprisingly common, chronic health conditions. The primary location where the vast majority of people are exposed to allergens and other substances is in their home. This means it is important to understand home environments and how a home's systems function and interact-and that how we occupy these spaces plays a crucial role in both environmental exposure and management of allergic disease. This review provides an overview of what is understood about home environmental exposure and its impact on our health, and proposes a systematic process for using a patient's environmental history to develop individualized, manageable and cost-effective recommendations. Once occupant-related information has been gathered, a home environmental exposure assessment should be performed focused on identifying the relationships between any identified sources of contaminants and the housing systems, and conditions that may be contributing to exposure. The results and recommendations from this assessment can then be used to guide exposure-reduction efforts by patients and/or their caregivers in an effort to improve disease management. In this review, we'll discuss three different types of home interventions-active, which must be routinely performed by the patient and/or caregiver, passive, which are interventions that work without routine, direct interaction from the homeowner, and behavioral changes in how the home environment is cleaned and maintained for long-term reduction of allergens. In this review, and others evaluated for this discussion, a significant number of home environmental assessment and intervention programs were shown to be cost effective, with the majority of programs showing a net positive return on investment. It is important to recognize that to be cost effective, the level and intensity of services offered through home visit programs need be stratified, based on the estimated health risks of the patient, in order to tailor the assessment and target the interventions to a patient's needs while maximizing cost effectiveness.

HEPA filtration improves asthma control in children exposed to traffic-related airborne particles

Traffic-related airborne particles are associated with asthma morbidity. The aim of this study was to assess the impact of a high-efficiency particulate air (HEPA) filtration on the concentrations of traffic particles and the resultant effect on children with asthma. Forty-three children with asthma were enrolled in this double-blind, placebo-controlled crossover design. A HEPA air cleaner or a placebo "dummy" was placed in participants' homes for four weeks, interrupted by a one-month washout period, before crossing over to the other treatment arm for four weeks. Air sampling and health outcomes, including asthma control (ACQ) and quality of life (AQLQ) measures, were completed prior to and at the end of each treatment arm. Indoor concentrations of traffic particles were significantly reduced with the HEPA treatment but not with the "dummy" treatment. In participants with poorly controlled asthma and lower quality of life at baseline, ACQ and AQLQ scores were significantly improved (1.3 to 0.9, P = .003 and 4.9 to 5.5, P = .02, respectively) following the HEPA treatment. In this study, HEPA filtration is associated with improved clinical outcomes and quality of life measures in children with uncontrolled asthma.

Efficacy of air cleaners in asthmatics allergic to cat in ALYATEC® environmental exposure chamber

BACKGROUND

Air cleaners have been promoted for respiratory allergic disease prevention, but there is no clear clinical proof of their efficacy in allergic asthma.

OBJECTIVE

To examine the efficacy of a new air cleaner on early and late asthmatic responses in cat-allergic patients.

METHODS

This randomized, cross-over, double-blind placebo-controlled study enrolled 24 cat-asthmatic patients with GINA 1 asthma. At baseline, participants were exposed to 40 ng/m³ of airborne cat allergen for a maximum of 2 hours in ALYATEC^® environmental exposure chamber (EEC). All participants were subsequently randomized into two groups that were exposed to cat allergen, either with active then placebo air cleaners or with placebo then active air cleaners with a 3-week interval in the EEC. This study was registered under number (NCT03928561).

RESULTS

Fewer patients experienced an EAR with active air cleaners (seven patients; 29.17%) than placebo (21 patients; 87.50%). The response incidence was lower with active than with placebo air cleaners. A Cox model demonstrated a significant treatment effect (hazard ratio, 0.10; P = .002). Active air cleaners also prevented late asthmatic response: four patients (16.67%) had a late asthmatic response with active air cleaners compared to 11 patients (45.83%) with placebo (Prescott test P = .002). Active air cleaners also decreased the maximal severity of bronchial response (FEV1 decrease of 17.24% with active vs 25.62% with placebo air cleaners; P = .001).

CONCLUSIONS

Our present results demonstrated that Intense Pure Air XL^® air cleaners significantly prevented early and late asthmatic responses among cat-allergic asthmatics during cat allergen exposure in the ALYATEC^® EEC.

Indoor Environmental Interventions for Furry Pet Allergens, Pest Allergens, and Mold: Looking to the Future

Over the last 2 to 3 decades, significant advances have been made in understanding the role that indoor allergen exposures play with regard to respiratory health. Multiple studies have confirmed that sensitization and exposure to indoor allergens can be a risk factor for asthma morbidity. Environmental interventions targeting key indoor allergens have been evaluated with the aims of examining their causal effects on asthma-related outcomes and identifying clinically efficacious interventions to incorporate into treatment recommendations. Historically, it appeared that the most successful intervention, as performed in the Inner-City Asthma Study, was individually tailored, targeting multiple allergens in a predominantly low-income, minority, and urban pediatric population. Recent studies suggest that single-allergen interventions may be efficacious when targeting the most clinically relevant allergen for a population. In this article, we review recent literature on home environmental interventions and their effects on specific indoor allergen levels and asthma-related outcomes.

Effectiveness of a portable air cleaner in removing aerosol particles in homes close to highways

Outdoor traffic-related airborne particles can infiltrate a building and adversely affect the indoor air quality. Limited information is available on the effectiveness of high efficiency particulate air (HEPA) filtration of traffic-related particles. Here, we investigated the effectiveness of portable HEPA air cleaners in reducing indoor concentrations of traffic-related and other aerosols, including black carbon (BC), PM2.5 , ultraviolet absorbing particulate matter (UVPM) (a marker of tobacco smoke), and fungal spores. This intervention study consisted of a placebo-controlled cross-over design, in which a HEPA cleaner and a placebo "dummy" were placed in homes for 4-weeks each, with 48-hour air sampling conducted prior to and during the end of each treatment period. The concentrations measured for BC, PM2.5 , UVPM, and fungal spores were significantly reduced following HEPA filtration, but not following the dummy period. The indoor fraction of BC/PM2.5 was significantly reduced due to the HEPA cleaner, indicating that black carbon was particularly impacted by HEPA filtration. This study demonstrates that HEPA air purification can result in a significant reduction of traffic-related and other aerosols in diverse residential settings.

Effect of a Novel Photoelectrochemical Oxidation Air Purifier on Nasal and Ocular Allergy Symptoms

Background

Photoelectrochemical oxidation (PECO) is a new air purification technology developed to reduce circulating indoor allergens. PECO removes particles as small as 0.1 nm with the destruction of organic matter otherwise not trapped by a traditional filter and removes volatile organic compounds.

Objective

We hypothesized that with daily use, the device would reduce user nasal and ocular allergy total symptom scores (TSS) within 4 weeks.

Methods

The study was performed among 46 individuals with self-reported allergies using a portable PECO air purifier. Self-reported TSS were calculated at baseline and weekly for 4 weeks following initiation of continuous use of the system. TSS was the sum of total nasal symptom scores (TNSS) and total ocular symptom scores (TOSS) for the week.

Results

There was a statistically significant change in overall TSS from baseline to 4 weeks (10.1 at baseline and 4.35 postintervention) resulting in a mean difference of 5.75 (95% confidence interval [CI] 4.32-7.18; P < .0001). There was a statistically significant change in TNSS from baseline to 4 weeks (6.3 at baseline and 3.04 postintervention) resulting in a mean difference of 3.26 (95% CI 2.33-3.19; P < .0001). There was a statistically significant change in TOSS from baseline to 4 weeks (3.82 at baseline and 1.3 postintervention) resulting in a mean difference of 2.52 (95% CI 1.74-3.3; P < .0001).

Conclusion

With the use of PECO air purification technology, TSS, TNSS, and TOSS decreased significantly. These improvements were consistent over the 4-week course of device use.

Indoor Environmental Interventions and their Effect on Asthma Outcomes

PURPOSE OF REVIEW

The use of environmental interventions to improve outcomes in asthmatics has long been an elusive goal. While numerous interventions have been studied, the results of clinical trials have been mixed. This review aims to identify combinations of interventions that have been proven to be effective and to propose a model for using them in a clinical setting.

RECENT FINDINGS

An NIH workshop emphasized a need for research to identify effective interventions for reducing indoor exposures and improving asthma outcomes. A number of innovative measures were described, though evidence supporting their use was lacking. A recent systematic review described various interventions for which evidence is available. The greatest challenge for this approach is the same as that for the medical approach to treatment: nonadherence. Given evidence for effective interventions, control of environmental exposures should lead to improved asthma outcomes. Methods to improve adherence need to be identified.

Dogs in the Workplace: A Review of the Benefits and Potential Challenges

Pet dogs, therapy dogs, and service dogs can be seen in workplaces with increasing frequency. Although dogs may provide many benefits to employees and employers, their presence may introduce additional hazards and concerns to the work environment. Therefore, decisions to accept dogs in the workplace may include many considerations including the health, safety, and well-being of employees, legal and cultural sensitivities, and animal welfare. The present paper serves to introduce the issue of dogs in the workplace and outline the potential benefits and challenges to their presence. The legal accommodations afforded to certain types of dogs in workplace settings are discussed, and the research findings pertaining to the potential benefits of dogs on human health and well-being are summarized. The paper concludes with considerations for human resource management personnel in the areas of diversity, employee relations, ethics and corporate responsibility, organizational and employee development, safety and security, and legal considerations, as well as suggested topics for future research.

An Experiment with Air Purifiers in Delhi during Winter 2015-2016

Particulate pollution has important consequences for human health, and is an issue of global concern. Outdoor air pollution has become a cause for alarm in India in particular because recent data suggest that ambient pollution levels in Indian cities are some of the highest in the world. We study the number of particles between 0.5μm and 2.5μm indoors while using affordable air purifiers in the highly polluted city of Delhi. Though substantial reductions in indoor number concentrations are observed during air purifier use, indoor air quality while using an air purifier is frequently worse than in cities with moderate pollution, and often worse than levels observed even in polluted cities. When outdoor pollution levels are higher, on average, indoor pollution levels while using an air purifier are also higher. Moreover, the ratio of indoor air quality during air purifier use to two comparison measures of air quality without an air purifier are also positively correlated with outdoor pollution levels, suggesting that as ambient air quality worsens there are diminishing returns to improvements in indoor air quality during air purifier use. The findings of this study indicate that although the most affordable air purifiers currently available are associated with significant improvements in the indoor environment, they are not a replacement for public action in regions like Delhi. Although private solutions may serve as a stopgap, reducing ambient air pollution must be a public health and policy priority in any region where air pollution is as high as Delhi's during the winter.

INTEGRATING HEALTH INTO BUILDINGS OF THE FUTURE

The health and wellbeing of building occupants should be a key priority in the design, building, and operation of new and existing buildings. Buildings can be designed, renovated, and constructed to promote healthy environments and behaviors and mitigate adverse health outcomes. This paper highlights health in terms of the relationship between occupants and buildings, as well as the relationship of buildings to the community. In the context of larger systems, smart buildings and green infrastructure strategies serve to support public health goals. At the level of the individual building, interventions that promote health can also enhance indoor environmental quality and provide opportunities for physical activity. Navigating the various programs that use metrics to measure a building's health impacts reveals that there are multiple co-benefits of a "healthy building," including those related to the economy, environment, society, transportation, planning, and energy efficiency.

Effectiveness of air purifier on health outcomes and indoor particles in homes of children with allergic diseases in Fresno, California: A pilot study

OBJECTIVE

Epidemiologic studies indicate that indoor air pollution is correlated with morbidity caused by allergic diseases. We evaluated the effectiveness of reducing the levels of indoor fine particulate matter <2.5 micrometer diameter (PM_2.5) in Fresno, California using air purifiers on health outcomes in children with asthma and/or allergic rhinitis.

METHODS

The active group (with air purifiers) and the control group consisted of eight houses each. Air purifiers were installed in the living rooms and bedrooms of the subjects in the active group during the entire 12-week study duration. Childhood asthma control test, peak flow rate monitoring, and nasal symptom scores were evaluated at weeks 0, 6, and 12.

RESULTS

At 12 weeks, the active group showed a trend toward an improvement of childhood asthma control test scores and mean evening peak flow rates, whereas the control group showed deterioration in the same measures. Total and daytime nasal symptoms scores significantly reduced in the active group (p = 0.001 and p = 0.011, respectively). The average indoor PM_2.5 concentrations reduced by 43% (7.42 to 4.28 μg/m³) in the active group (p = 0.001).

CONCLUSIONS

Intervention with air purifiers reduces indoor PM_2.5 levels with significant improvements in nasal symptoms in children with allergic rhinitis in Fresno.

Home Environmental Interventions for the Prevention or Control of Allergic and Respiratory Diseases: What Really Works

Home health care workers interventions have been implemented in western countries to improve health status of patients with respiratory diseases especially asthma and allergic illnesses. Twenty-six controlled studies dealing with prevention and control of these diseases through home environmental interventions were reviewed. After a comprehensive description of the characteristics of these studies, the effectiveness of each intervention was then evaluated in terms of participants' compliance with the intervention program, improvement of quality of the indoor environment, and finally improvement of health outcomes, in detailed tables. Limitations and biases of the studies are also discussed. Overall, this review aims at giving a toolbox for home health care workers to target the most appropriate measures to improve health status of the patient depending on his and/or her environment and disease. Only a case-by-case approach with achievable measures will warrant the efficacy of home interventions. This review will also provide to the research community a tool to better identify targets to focus in future evaluation studies of home health care workers action.

Enhancing indoor air quality -The air filter advantage

Air pollution has become the world's single biggest environmental health risk, linked to around 7 million deaths in 2012 according to a recent World Health Organisation (WHO) report. The new data further reveals a stronger link between, indoor and outdoor air pollution exposure and cardiovascular diseases, such as strokes and ischemic heart disease, as well as between air pollution and cancer. The role of air pollution in the development of respiratory diseases, including acute respiratory infections and chronic obstructive pulmonary diseases, is well known. While both indoor and outdoor pollution affect health, recent statistics on the impact of household indoor pollutants (HAP) is alarming. The WHO factsheet on HAP and health states that 3.8 million premature deaths annually - including stroke, ischemic heart disease, chronic obstructive pulmonary disease (COPD) and lung cancer are attributed to exposure to household air pollution. Use of air cleaners and filters are one of the suggested strategies to improve indoor air quality. This review discusses the impact of air pollutants with special focus on indoor air pollutants and the benefits of air filters in improving indoor air quality.

Use of Free-standing Filters in an Asthma Intervention Study

This study characterizes the use of HEPA air filters provided to 89 households participating in an intervention study investigating the respiratory health of children with asthma. Freestanding filters were placed in the child's bedroom and monitored continuously for nearly a year in each household. Filter use was significantly affected by study phase, season and monitoring week. During the "intensive" weeks when a community education worker and a field technician visited the household, the use rate averaged 70±33%. During season-long "non-intensive" periods between seasonal visits, use dropped to 34±30%. Filter use rapidly decreased during the 3 to 4 weeks following each intensive, was slightly higher in spring, summer, and in the evening and at night when the child was likely to be home, although households did not follow consistent diurnal patterns. While participants expressed an understanding of the benefits of filter use and reported good experiences with them, use rates were low, particularly during unobserved non-intensive periods. The provision of freestanding air filters to individuals or households must be considered an active intervention that requires monitoring and evaluation, otherwise unknown and unexpected patterns of filter use may alter and possibly bias results due to exposure misclassification.

Health benefits of particle filtration

The evidence of health benefits of particle filtration in homes and commercial buildings is reviewed. Prior reviews of papers published before 2000 are summarized. The results of 16 more recent intervention studies are compiled and analyzed. Also, reviewed are four studies that modeled health benefits of using filtration to reduce indoor exposures to particles from outdoors. Prior reviews generally concluded that particle filtration is, at best, a source of small improvements in allergy and asthma health effects; however, many early studies had weak designs. A majority of recent intervention studies employed strong designs and more of these studies report statistically significant improvements in health symptoms or objective health outcomes, particularly for subjects with allergies or asthma. The percentage improvement in health outcomes is typically modest, for example, 7% to 25%. Delivery of filtered air to the breathing zone of sleeping allergic or asthmatic persons may be more consistently effective in improving health than room air filtration. Notable are two studies that report statistically significant improvements, with filtration, in markers that predict future adverse coronary events. From modeling, the largest potential benefits of indoor particle filtration may be reductions in morbidity and mortality from reducing indoor exposures to particles from outdoor air.

Effectiveness of air filters and air cleaners in allergic respiratory diseases: a review of the recent literature

Air filtration is frequently recommended as a component of environmental control measures for patients with allergic respiratory disease. Residential air filtration can be provided by whole house filtration via the home’s heating, ventilation, or air conditioning system, by portable room air cleaners, or a combination of the two. Appliances to filter the sleep breathing zone also have been developed. High-efficiency whole house filtration, high-efficiency particulate air sleep zone air filtration, and high-efficiency particulate air room air cleaners all appear to provide various degrees of benefit. Recent studies of various types of filtration, used alone or as part of more comprehensive environmental control measures, are reviewed.

Particle Concentrations and Effectiveness of Free-Standing Air Filters in Bedrooms of Children with Asthma in Detroit, Michigan

Asthma can be exacerbated by environmental factors including airborne particulate matter (PM) and environmental tobacco smoke (ETS). We report on a study designed to characterize PM levels and the effectiveness of filters on pollutant exposures of children with asthma. 126 households with an asthmatic child in Detroit, Michigan, were recruited and randomized into control or treatment groups. Both groups received asthma education; the latter also received a free-standing high efficiency air filter placed in the child's bedroom. Information regarding the home, emission sources, and occupant activities was obtained using surveys administered to the child's caregiver and a household inspection. Over a one-week period, we measured PM, carbon dioxide (CO(2)), environmental tobacco smoke (ETS) tracers, and air exchange rates (AERs). Filters were installed at midweek. Before filter installation, PM concentrations averaged 28 µg m(-3), number concentrations averaged 70,777 and 1,471 L(-1) in 0.3-1.0 and 1-5 µm size ranges, respectively, and the median CO(2) concentration was 1,018 ppm. ETS tracers were detected in 23 of 38 homes where smoking was unrestricted and occupants included smokers and, when detected, PM concentrations were elevated by an average of 15 µg m(-3). Filter use reduced PM concentrations by an average of 69 to 80%. Simulation models representing location conditions show that filter air flow, room volume and AERs are the key parameters affecting PM removal, however, filters can achieve substantial removal in even "worst" case applications. While PM levels in homes with asthmatic children can be high, levels can be dramatically reduced using filters.

Factors associated with furry pet ownership among patients with asthma

BACKGROUND

Exposure to indoor allergens is an established risk factor for poor asthma control. Current guidelines recommend removing pets from the home of patients with asthma.

OBJECTIVES

This cross-sectional study was conducted to determine the prevalence of furry pet ownership in asthmatics compared to non-asthmatics and to identify factors associated with furry pet ownership among those with asthma. Secondary analysis assessed characteristics among asthmatics that might be associated with allowing a furry pet into the bedroom.

METHODS

Using data from The National Asthma Survey collected from 2003 to 2004, we carried out univariate and multiple regression analyses, in 2009, to identify independent predictors of furry pet ownership in asthma sufferers after controlling for potential confounders.

RESULTS

Overall, asthmatics were more likely to own a furry pet than nonasthmatic individuals in the general population (49.9% versus 44.8%, p < .001). Multivariate analysis showed that female sex, older age, white race, and high income were independent predictors of furry pet ownership among asthmatics. Additionally, 68.7% of patients with asthma who own a furry pet allowed them into their bedroom. Higher income and carrying out < or =2 environmental control practices in the home were associated with increased likelihood of allowing a furry pet into the bedroom.

CONCLUSIONS

Furry pet ownership is equally or more common among asthmatics compared to those without asthma. The majority of asthmatics with furry pets allow them into the bedroom. Recognizing and addressing these problems may help decrease asthma morbidity.

Housing interventions and control of asthma-related indoor biologic agents: a review of the evidence

Subject matter experts systematically reviewed evidence on the effectiveness of housing interventions that affect health outcomes, primarily asthma, associated with exposure to moisture, mold, and allergens. Three of the 11 interventions reviewed had sufficient evidence for implementation: multifaceted, in-home, tailored interventions for reducing asthma morbidity; integrated pest management to reduce cockroach allergen; and combined elimination of moisture intrusion and leaks and removal of moldy items to reduce mold and respiratory symptoms. Four interventions needed more field evaluation, 1 needed formative research, and 3 either had no evidence of effectiveness or were ineffective. The 3 interventions with sufficient evidence all applied multiple, integrated strategies. This evidence review shows that selected interventions that improve housing conditions will reduce morbidity from asthma and respiratory allergies.

A systematic review and meta-analysis of interventions used to reduce exposure to house dust and their effect on the development and severity of asthma

We assessed whether any household dust reduction intervention has the effect of increasing or decreasing the development or severity of atopic disease. Electronic searches on household intervention and atopic disease were conducted in 2007 in EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials. We included randomized controlled trials comparing asthma outcomes in a household intervention group with either placebo intervention or no intervention. Meta-analyses on the prevention studies found that the interventions made no difference to the onset of wheeze but made a significant reduction in physician-diagnosed asthma. Meta-analysis of lung function outcomes indicated no improvement due to the interventions but found a reduction in symptom days. Qualitatively, health care was used less in those receiving interventions. However, in one study that compared intervention, placebo, and control arms, the reduction in heath care use was similar in the placebo and intervention arms. This review suggests that there is not sufficient evidence to suggest implementing hygiene measures in an attempt to improve outcomes in existing atopic disease, but interventions from birth in those at high risk of atopy are useful in preventing diagnosed asthma but not parental-reported wheeze.

Asthma in the inner city and the indoor environment

Inner-city residents continue to suffer disproportionate asthma morbidity despite recent progress in reducing asthma morbidity and mortality in other strata of the United States population. Studies over the past decade indicate that the indoor environment is a strong contributor to poor asthma control and asthma-related health care use in inner-city populations. Certain indoor exposures are more common and occur in higher concentrations in inner-city communities than in suburban communities. Identification of "asthmagenic" indoor exposures has paved the way for the development of intervention strategies aimed at reducing asthma morbidity. This article reviews the growing body of evidence that certain indoor environmental exposures contribute to the burden of asthma in the inner city.

Control of asthma triggers in indoor air with air cleaners: a modeling analysis

BACKGROUND

Reducing exposure to environmental agents indoors shown to increase asthma symptoms or lead to asthma exacerbations is an important component of a strategy to manage asthma for individuals. Numerous investigations have demonstrated that portable air cleaning devices can reduce concentrations of asthma triggers in indoor air; however, their benefits for breathing problems have not always been reproducible. The potential exposure benefits of whole house high efficiency in-duct air cleaners for sensitive subpopulations have yet to be evaluated.

METHODS

We used an indoor air quality modeling system (CONTAM) developed by NIST to examine peak and time-integrated concentrations of common asthma triggers present in indoor air over a year as a function of natural ventilation, portable air cleaners, and forced air ventilation equipped with conventional and high efficiency filtration systems. Emission rates for asthma triggers were based on experimental studies published in the scientific literature.

RESULTS

Forced air systems with high efficiency filtration were found to provide the best control of asthma triggers: 30-55% lower cat allergen levels, 90-99% lower risk of respiratory infection through the inhalation route of exposure, 90-98% lower environmental tobacco smoke (ETS) levels, and 50-75% lower fungal spore levels than the other ventilation/filtration systems considered. These results indicate that the use of high efficiency in-duct air cleaners provide an effective means of controlling allergen levels not only in a single room, like a portable air cleaner, but the whole house.

CONCLUSION

These findings are useful for evaluating potential benefits of high efficiency in-duct filtration systems for controlling exposure to asthma triggers indoors and for the design of trials of environmental interventions intended to evaluate their utility in practice.

A systematic review and meta-analysis of interventions used to reduce exposure to house dust and their effect on the development and severity of asthma

OBJECTIVES

We assessed whether any household dust reduction intervention has the effect of increasing or decreasing the development or severity of atopic disease.

DATA SOURCES

Electronic searches on household intervention and atopic disease were conducted in January 2007 in EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials. No date or language restriction was placed on the literature search.

DATA EXTRACTION

We included randomized controlled trials comparing asthma outcomes in a household intervention group with either placebo intervention or no intervention.

DATA SYNTHESIS

Fourteen studies met the inclusion criteria. Eight recruited antenatally and measured development of atopic disease. Six recruited known atopic individuals and measured disease status change. Meta-analyses on the prevention studies found that the interventions made no difference to the onset of wheeze but made a significant reduction in physician-diagnosed asthma. Meta-analysis of lung function outcomes indicated no improvement due to the interventions but found a reduction in symptom days. Qualitatively, health care was used less in those receiving interventions. However, in one study that compared intervention, placebo, and control arms, the reduction in heath care use was similar in the placebo and intervention arms.

CONCLUSIONS

This review suggests that there is not sufficient evidence to suggest implementing hygiene measures in an attempt to improve outcomes in existing atopic disease, but interventions from birth in those at high risk of atopy are useful in preventing diagnosed asthma but not parental-reported wheeze.

Current state of the science: health effects and indoor environmental quality

Our understanding of the relationship between human health and the indoor environment continues to evolve. Previous research on health and indoor environments has tended to concentrate on discrete pollutant sources and exposures and on specific disease processes. Recently, efforts have been made to characterize more fully the complex interactions between the health of occupants and the interior spaces they inhabit. In this article we review recent advances in source characterization, exposure assessment, health effects associated with indoor exposures, and intervention research related to indoor environments. Advances in source characterization include a better understanding of how chemicals are transported and processed within spaces and the role that other factors such as lighting and building design may play in determining health. Efforts are under way to improve our ability to measure exposures, but this remains a challenge, particularly for biological agents. Researchers are also examining the effects of multiple exposures as well as the effects of exposures on vulnerable populations such as children and the elderly. In addition, a number of investigators are also studying the effects of modifying building design, materials, and operations on occupant health. Identification of research priorities should include input from building designers, operators, and the public health community.

Indoor environmental influences on children's asthma

The burden of asthma for children in the United States is substantial and has continued to rise for the past 2 decades. There is growing evidence that the indoor environment may play an important role in the pathogenesis of childhood asthma. This article first reviews the effects of indoor allergen exposure and sensitization on asthma incidence and morbidity, focusing on dust mite, cockroach, pet, and rodent allergens. It then addresses the effects of indoor air pollutants (ozone, particulate matter, nitrogen dioxide, environmental tobacco smoke, sulfur dioxide, and carbon monoxide) on asthma morbidity.

Dust mite allergen avoidance as a preventive and therapeutic strategy

Asthma is a global health problem with genetic and environmental components. Indoor allergens have a major impact on asthma, and exposure in sensitized subjects can compromise lung function. A reduction in allergen exposure would seem a logical facet to treatment. Methods for reducing mite allergen levels that are effective in the laboratory may not work in the home and may not result in a clinical benefit. Six ongoing studies are investigating the effects of environmental control on the primary prevention of asthma and allergies. Although the Isle of Wight and Canadian studies provide encouraging results at age 8 and 7 years, respectively, it will be some time before a definitive public health message emerges. For secondary prevention, there is little evidence to support the use of mite-proof encasings as a single intervention in adults. In children, however, single or multifaceted interventions appear to be of some benefit.

An investigation of the housing environment for persons with asthma and persons without asthma

Asthma is a chronic disease affected by environmental factors that may increase symptoms that impact on a persons' well-being. An important issue in occupational therapy is to improve the relationship between a person's functional capacity and the physical environment. The aim of the study was to compare the housing environment of persons with asthma (cases, n = 49) and persons without asthma (controls, n = 48), with regard to building construction and condition, physical, chemical and biological factors, and cleaning routines. A secondary aim was to compare different types of accommodation within cases and controls. A specialist team, including a construction engineer, a biological scientist, and an occupational therapist, conducted the study. Data were collected using protocols, as well as a number of established technical methods from the field of occupational and environmental medicine. The primary results showed no major differences in the housing environment between the two groups. However, in individual homes environmental factors at levels that could increase symptoms were identified. When single-family houses were compared with multi-family houses, significant differences were found indicating that preventive interventions may be needed in some single-family houses. Further studies are needed to clarify the person-environment relationship for persons with asthma, focusing on their ability to perform daily activities.

Decrease in the allergenicity of Japanese cedar pollen allergen by treatment with positive and negative cluster ions

BACKGROUND

Japanese cedar pollinosis is a severe allergic disease in Japan. The most effective means of decreasing allergic inflammation reactions is still avoidance of the aeroallergen. Recently, a novel air purification system using positively and negatively charged cluster ions was developed to create comfortable living environments. We aimed to assess the ability of existing technology to lower allergenicity of Japanese cedar pollen.

METHODS

A Japanese cedar pollen extract was nebulized from the top of a cylindrical container with 2 or 4 ion-generating devices. The extract in a mist was passed through the space filled with or without plasma cluster ions for 90 s, and the ion-treated or nontreated extract was then collected in a Petri dish at the bottom of the container.

RESULTS

The ion-exposed extract was significantly diminished in its reactivities to anti-Cry j 1 or anti-Cry j 2 antiserum and to human allergic sera IgE on ELISA. SDS-PAGE analysis revealed that ion exposure induced protein degradation in the pollen extract. Similarly, the ion treatment impaired about 80% of the binding to pooled sera IgE from patients allergic to Japanese cedar pollen on ELISA inhibition. Furthermore, intracutaneous and conjunctival reaction tests showed a remarkable diminution in the allergenicity of the ion-irradiated extract.

CONCLUSION

Ion irradiation resulted in a remarkable decrease in in vitro and in vivo allergenicities of atomized Japanese cedar pollen extracts.

A community-based participatory research study of multifaceted in-home environmental interventions for pediatric asthmatics in public housing

Pest infestation is a major problem in urban, low-income housing and may contribute to elevated asthma prevalence and exacerbation rates in such communities. However, there is poor understanding of the effectiveness of integrated pest management (IPM) efforts in controlling pediatric asthma, or of the interactions among various interventions and risk factors in these settings. As part of the Boston-based Healthy Public Housing Initiative, we conducted a longitudinal, single-cohort community-based participatory research intervention study. Fifty asthmatic children aged 4-17 from three public housing developments in Boston, Massachusetts, USA successfully completed interventions and detailed environmental, medical, social, and health outcome data collection. Interventions primarily consisted of IPM and related cleaning and educational efforts, but also included limited case management and support from trained community health advocates. In pre-post analyses, we found significant reductions in a 2-week recall respiratory symptom score (from 2.6 to 1.5 on an 8-point scale, p = 0.0002) and in the frequency of wheeze/cough, slowing down or stopping play, and waking at night. Longitudinal analyses of asthma-related quality of life similarly document significant improvements, with a suggestion of some improvements prior to environmental interventions with an increased rate of improvement subsequent to pest management activities. Analyses of potential explanatory factors demonstrated significant between-development differences in symptom improvements and suggested some potential contributions of allergen reductions, increased peak flow meter usage, and improved social support, but not medication changes. In spite of limitations with pre-post comparisons, our results are consistent with aggressive pest management and other allergen reduction efforts having a positive impact on clinical health outcomes associated with asthma. Our findings reinforce the multifactorial nature of urban asthma and suggest a need for further study of the relative contributions of and possible synergies between environmental and social factors in asthma intervention programs.

New insights in allergen avoidance measures for mite and pet sensitized patients. A critical appraisal

It is widely acknowledged that avoidance of allergens such as those derived from foods, drugs, latex and stinging insects results in a complete disappearance of symptoms. By contrast, although it has been clearly shown that allergens are an important risk factor for the development of respiratory symptoms and that several avoidance measures reduce allergen levels, whether this gives clinical improvement in symptoms is debatable. Many reasons could be invoked to justify this evident discrepancy. Apart from the intrinsic methodological aspects (e.g. single or combined interventions measure, population studied, severity of respiratory symptoms, outcomes, evaluated parameters, etc.), it is important to outline that a successful approach requires that the avoided allergen is the only and real factor responsible for symptoms, the patient's education and the use of a comprehensive protocol to reduce allergen exposure. Other important factors include the involvement of the patient, the relevance of other allergens/non-specific agents, and exposure to sensitizing agents also outside patient's home. It is likely that the clinical phase of allergic airway disease and the degree of bronchial (and also nasal) remodelling, in each individual, represent relevant factors for the clinical outcome of allergen avoidance procedures. Since the management of respiratory allergy is a complex strategy (including drugs, allergen avoidance, immunological and educational interventions), it is difficult in real life to distinguish the efficacy of a single intervention in comparison to the others. A combined strategy is likely to produce better clinical results.

Home environmental intervention in inner-city asthma: a randomized controlled clinical trial

BACKGROUND

Airborne pollutants and indoor allergens increase asthma morbidity in inner-city children; therefore, reducing exposure, if feasible, should improve asthma morbidity.

OBJECTIVE

To conduct a randomized controlled trial of methods to reduce environmental pollutant and allergen exposure in the homes of asthmatic children living in the inner city.

METHODS

After the completion of questionnaires, spirometry and allergen skin tests, home inspection, and measurement of home air pollutant and allergen levels, 100 asthmatic children aged 6 to 12 years were randomized to the treatment group (home-based education, cockroach and rodent extermination, mattress and pillow encasings, and high-efficiency particulate air cleaner) or to the control group (treated at the end of the 1-year trial). Outcomes were evaluated by home evaluations at 6 and 12 months, clinic evaluation at 12 months, and multiple telephone interviews.

RESULTS

In the treatment group, 84% received cockroach extermination and 75% used the air cleaner. Levels of particulate matter 10 microm or smaller declined by up to 39% in the treatment group but increased in the control group (P < .001). Cockroach allergen levels decreased by 51% in the treatment group. Daytime symptoms increased in the control group and decreased in the treatment group (P = .04). Other measures of morbidity, such as spirometry findings, nighttime symptoms, and emergency department use, were not significantly changed.

CONCLUSIONS

A tailored, multifaceted environmental treatment reduced airborne particulate matter and indoor allergen levels in inner-city homes, which, in turn, had a modest effect on morbidity.

The role of allergen avoidance in the secondary prevention of atopic disorders

PURPOSE OF REVIEW

Allergen avoidance is recommended as part of the treatment programme of many patients with allergic diseases in Europe and the USA. However, clinical trials of allergen avoidance tend to be small and the findings inconsistent. Several larger studies have recently been published, making a review of the new literature timely.

RECENT FINDINGS

There have been two large double-blind, placebo-controlled studies on the use of encasings (mattress, pillow and duvet) as a single intervention in adults with asthma. In both studies, participants in the active and the control group showed an improvement in peak flow, but there was no difference between groups over a 12-month period. A further smaller study of encasings reported an improvement in peak flow from 1 week in the active group; this study, however, was only of 9 weeks' duration. In children, the use of encasings was associated with a reduction in asthma medication usage, but not until 6 months into the study. A multifaceted intervention study, with the intervention tailored to the child's sensitization status and home environment (including environmental tobacco smoke), resulted in significant reductions in emergency room visits and symptoms in the active group.

SUMMARY

The evidence suggests that interventions in children (either single or multifaceted) are associated with a meaningful and sustained improvement in asthma control. However, for adults, allergen proof encasings as a single intervention cannot be recommended. There is a need for a large-scale multifaceted intervention study in adults with asthma.

Effect of pet removal on pet allergic asthma

BACKGROUND

Allergen avoidance has been recommended in the management of allergic asthma. Very few studies have assessed the effect of pet removal on pet allergic asthma.

OBJECTIVE

We examined the effect of pet removal from homes on pulmonary function testing, airway hyperresponsiveness, and medication use.

DESIGN

Prospective, nonrandomized, nonblinded observational study.

PATIENTS AND METHODS

Subjects included 20 symptomatic patients with newly diagnosed pet allergic asthma who were keeping domestic animals, including hamsters, cats, dogs, and ferrets, and were sensitized to the animals. They were treated with inhaled corticosteroids or other medications according to recommendations by level of severity of the Global Initiative for Asthma. Methacholine inhalation tests were performed regularly before and after starting medication. Clinical features were compared between the patients who gave away their pets according to recommendations by the clinician (removal group) and the patients who refused to give away their pets (keeping group).

RESULTS

There were 10 patients in both the removal group and the keeping group. After >or= 1 year of follow-up with or without pet removal, a 5.9-fold increase in the provocative concentration of methacholine causing a 20% fall in FEV(1) was observed in the removal group compared with a 2.3-fold increase in the keeping group (p = 0.04). There were no significant differences in the changes in FEV(1) and peak flow variability. Finally, no patient received inhaled corticosteroids in the removal group, whereas all but one of the patients needed beclomethasone dipropionate (mean dose, 600 mug/d) in the keeping group.

CONCLUSION

This study indicates that removal of pets from homes reduces airway responsiveness in patients with pet allergic asthma more than optimal pharmacotherapy alone, thereby enabling a decrease in inhaled corticosteroid doses.

Pet allergen control measures for allergic asthma in children and adults

BACKGROUND

Although pet removal has been recommended in guidelines on the management of allergic asthma, pet ownership remains high in families where one or more members have an allergy to pet dander. Allergen control measures such as air filtration units placed in the homes of pet-allergic asthmatics have been used as a means of reducing allergen exposure.

OBJECTIVES

To determine the clinical efficacy of pet allergen control measures in the homes of people with pet-allergic asthma.

SEARCH STRATEGY

An electronic search of the Cochrane Controlled Trials Register was carried out. No restriction was placed on language of publication.

SELECTION CRITERIA

Randomised controlled trials comparing an active allergen reduction measure with control were considered for analysis. Participants had stable pet-allergic asthma.

DATA COLLECTION AND ANALYSIS

34 references were identified by electronic searching, but only three appeared suitable for potential inclusion in the review. Two met the inclusion criteria for the analysis. Both examined the effectiveness of air filtration units. Two reviewers extracted data independently. A limited amount of data were usable for a meta-analysis.

MAIN RESULTS

Both trials were small (n=22 and n=35). No significant differences were detected between active intervention and control on the primary and secondary outcome measures reported in the studies. Data on absence from school or work were not reported in either study. No meta-analysis could be performed due to lack of common outcomes.

REVIEWER'S CONCLUSIONS

The available trials are too small to provide evidence for or against the use of airfiltration units to reduce allergen levels in the management of pet-allergic asthma. Adequately powered trials are needed. There are no trials of other allergen reduction measures, such as pet washing or possibly pet removal.