Recommendations for allergen avoidance or allergen reduction measures play an important part in the treatment of allergic asthmatic patients. The purpose of this study was to test recently developed air-cleaners with respect to their capacity to capture airborne allergen particles and to improve clinical parameters of asthmatic patients sensitized to aeroallergens. Forty five allergic asthmatic patients were studied in a double-blind procedure for 6 months. The patients were divided into three groups of 15 patients. In Group 1, the intervention consisted of the application of active air-cleaners in living-rooms and bedrooms. In Group 2, placebo air-cleaners were used in combination with allergen-impermeable mattress covers. In Group 3, the same intervention was performed as in Group 2 but with active air-cleaners. Allergen levels in mattress and floor dust were measured before, and 3 and 6 months after the interventions. After 6 months, the air-cleaners were dismantled and the filters were analysed for the amount of dust collected and allergen content. Immunological and lung function parameters were measured before, and 3 and 6 months after the interventions. Considerable amounts of airborne dust and allergenic particles were captured in the filters of the air-cleaners. Up to the 18.9 g of dust, 4,513 ng of house dust mite allergen, Der p 1, and 50,000 mU of cat allergen, Fel d 1, (in houses with cats) were collected by air-cleaners in living-rooms. Only in Group 3 (in which both active air-cleaners and mattress covers were used) was a small (less than 1 doubling dose) but statistically significant improvement of provocative concentration of histamine causing a 20% fall in forced expiratory volume in one second (PC20) observed (from 5.96 to 9.02 mg x mL(-1)). The amount of dust and house dust mite allergen collected in the filters was significantly correlated with an improvement of peak flow variation. In combination with other allergen avoidance measures, the examined air-cleaners can contribute to diminished allergen exposure and improvement of airway hyperresponsiveness in asthmatic patients.

https://erj.ersjournals.com/content/erj/10/6/1217.full.pdf

Allergen reduction measures in houses of allergic asthmatic patients: effects of air-cleaners and allergen-impermeable mattress covers

Filter forensics is a promising indoor air investigation technique involving the analysis of dust which has collected on filters in central forced-air heating, ventilation, and air conditioning (HVAC) or portable systems to determine the presence of indoor particle-bound contaminants. In this study, we summarize past filter forensics research to explore what it reveals about the sampling technique and the indoor environment. There are 60 investigations in the literature that have used this sampling technique for a variety of biotic and abiotic contaminants. Many studies identified differences between contaminant concentrations in different buildings using this technique. Based on this literature review, we identified a lack of quantification as a gap in the past literature. Accordingly, we propose an approach to quantitatively link contaminants extracted from HVAC filter dust to time-averaged integrated air concentrations. This quantitative filter forensics approach has great potential to measure indoor air concentrations of a wide variety of particle-bound contaminants. Future studies directly comparing quantitative filter forensics to alternative sampling techniques are required to fully assess this approach, but analysis of past research suggests the enormous possibility of this approach.

Quantitative filter forensics for indoor particle sampling.

Filter forensics is a promising indoor air investigation technique involving the analysis of dust which has collected on filters. In this thesis, past filter forensics research is synthesized and an approach to quantitatively link filter forensics to average indoor air concentrations is developed. A significant advantage of FF is a large increase in the limit of detection when compared to alternative sampling techniques. In the next chapter, I discuss pre-retrofit comfort and moisture results from an ongoing indoor environmental quality study of post-war multi-unit residential buildings undergoing energy retrofits. A major finding of this study was a high level of discomfort due to overheating and the lack of observed correlations between comfort, moisture and building parameters. I present an application of filter forensics to portable air cleaners deployed in the same study. Preliminary data suggests no significant relationship between particle counts and gravimetric filter results.%%%%M.A.S.%%%%2016-12-28 00:00:00

The Development of Quantitative Filter Forensics for Indoor Air Quality Sampling and a Pre-retrofit Indoor Environmental Quality Assessment of Pre-war Multi-Unit Residential Buildings

VII 0 INTRODUCTION 1 1 TESTING CAUSALITY WITHIN THE COMMUNITY SETTING 15 2 SYSTEMATIC LITERATURE REVIEW 24 2.1 THE SEARCH STRATEGY 25 2.2 RANGE OF STUDY DESIGNS 26 2.2.1 Randomised Controlled Trials 26 2.2.2 Placebo-controlled RCTs 26 2.2.3 Three-way RCTs (Factorial Design) 27 2.2.4 Four-way factorial design 28 2.2.5 Randomised placebo-controlled cross-over design 28 2.2.6 Non-randomised controlled trials 29 2.2.7 Non-controlled, non-randomised, before-and-after studies 29 2.2.8 Blinding 29 2.2.9 Design features to assess potential confounding factors 31 2.2.10 Summary 31 2.3 RANGE OF ALLERGENS THAT WERE TARGETED AND INTERVENTIONS THAT WERE TESTED 32 2.4 OUTCOME MEASURES 32 2.4.1 Allergen-reduction as the primary outcome-measure 33 2.4.2 Personal exposure to allergens 34 2.4.3 Asthma outcome measures 35

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Causal inference and the design of clinical trials in the community environment: a pilot study of allergen-reduction for the amelioration of childhood asthma.

The filtration system investigated in this study uses the thermic convection caused by radiators for the adsorption of airborne particles. The effect of this filtration system on the reduction of clinical symptoms of allergic bronchial asthma was tested as well as its capability in retaining airborne allergens, in particular those of the house dust mite Dermatophagoides pteronyssinus (D. pter.), which are responsible for this special kind of asthma. Dust samples were taken before and after the heating season in households of 36 persons with D. pter. caused asthma. Their mite content was investigated using mite flotation and direct microscopy, their guanine content using the Acarex-test. An allergen extract obtained from the filters was tested on its allergen content by RAST-inhibition. It could be observed that compared to the preceding heating season 55% of the volunteers felt an improvement of their asthmatic symptoms. It was possible to extract allergens of D. pteronyssinus, house dust and mould from the filters. All these results show the capability of the filters to adsorb house dust mite (HDM) allergens.

Petzold D

Papers

Filtration of airborne allergens in various households