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Background: Studies of potential adverse effects of traffic related air pollution (TRAP) on allergic disease have had mixed findings. Nutritional studies to examine whether fish oil supplementation may protect against development of allergic disease through their anti-inflammatory actions have also had mixed findings. Extremely few studies to date have considered whether air pollution and dietary factors such as fish oil intake may interact, which was the rationale for this study., Methods: We conducted a secondary analysis of the Childhood Asthma Prevention Study (CAPS) birth cohort, where children were randomised to fish oil supplementation or placebo from early life to age 5 years. We examined interactions between supplementation and TRAP (using weighted road density at place of residence as our measure of traffic related air pollution exposure) with allergic disease and lung function outcomes at age 5 and 8 years., Results: Outcome information was available on approximately 400 children (~ 70% of the original birth cohort). Statistically significant interactions between fish oil supplementation and TRAP were seen for house dust mite (HDM), inhalant and all-allergen skin prick tests (SPTs) and for HDM-specific interleukin-5 response at age 5. Adjusting for relevant confounders, relative risks (RRs) for positive HDM SPT were RR 1.74 (95% CI 1.22-2.48) per 100 m local road or 33.3 m of motorway within 50 m of the home for those randomised to the control group and 1.03 (0.76-1.41) for those randomised to receive the fish oil supplement. The risk differential was highest in an analysis restricted to those who did not change address between ages 5 and 8 years. In this sub-group, supplementation also protected against the effect of traffic exposure on pre-bronchodilator FEV 1 /FVC ratio., Conclusions: Results suggest that fish oil supplementation may protect against pro-allergic sensitisation effects of TRAP exposure. Strengths of this analysis are that supplementation was randomised and independent of TRAP exposure, however, findings need to be confirmed in a larger experimental study with the interaction investigated as a primary hypothesis, potentially also exploring epigenetic mechanisms. More generally, studies of adverse health effects of air pollution may benefit from considering potential effect modification by diet and other factors., Trial Registration: Australia New Zealand Clinical Trial Registry. www.anzctr.org.au Registration: ACTRN12605000042640 , Date: 26th July 2005. Retrospectively registered, trial commenced prior to registry availability.

Allergic diseases such as asthma and rhinitis are common in many countries. Globally the most common allergen associated with symptoms is produced by house dust mites. Although the bed has often been cited as the main site of exposure to mite allergens, surprisingly this has not yet been directly established by measurement due to a lack of suitable methods. Here we report on the development of novel methods to determine the pattern of personal exposure to mite allergen bioaerosols over 24-hour periods and applied this in a small field study using 10 normal adults. Air was sampled using a miniature time-based air-sampler of in-house design located close to the breathing zone of the participants, co-located with a miniature time-lapse camera. Airborne particles, drawn into the sampler at 2L/min via a narrow slot, were impacted onto the peripheral surface of a disk mounted on the hour-hand of either a 12 or 24 hour clock motor. The impaction surface was either an electret cloth, or an adhesive film; both novel for these purposes. Following a review of the time-lapse images, disks were post-hoc cut into subsamples corresponding to eight predetermined categories of indoor or outdoor location, extracted and analysed for mite allergen Der p 1 by an amplified ELISA. Allergen was detected in 57.2% of the total of 353 subsamples collected during 20 days of sampling. Exposure patterns varied over time. Higher concentrations of airborne mite allergen were typically measured in samples collected from domestic locations in the day and evening. Indoor domestic Der p 1 exposures accounted for 59.5% of total exposure, whereas total in-bed-asleep exposure, which varied 80 fold between individuals, accounted overall for 9.85% of total exposure, suggesting beds are not often the main site of exposure. This study establishes the feasibility of novel methods for determining the time-geography of personal exposure to many bioaerosols and identifies new areas for future technical development and clinical applications.

The role of allergen exposure in the etiology of allergic sensitization and asthma is complex. Advice on strategies to avoid domestic allergens remains contentious because trials of interventions aimed to prevent asthma or reduce symptoms have often failed to demonstrate benefits. Asthma management guidelines differ widely in their recommendations, while Web-based information often claims benefits associated with products. In this rostrum we argue that although many factors have a role in both the etiology and the exacerbation of asthma, allergen exposure probably remains an important contributor to the manifestations of the disease. Currently, there is no evidence-based framework for effective domestic allergen avoidance interventions to reduce chronic aeroallergen exposure. The development of an effective approach to allergen avoidance requires a better understanding of (a) the physical nature of chronic aeroallergen exposure and methods for measuring and reducing this, (b) the interaction between allergen exposure and innate immune modulators at different disease stages, and (c) markers enabling the identification of individuals who would benefit from this. The strategic risk of overemphasizing other novel mechanisms and approaches to asthma management is that we will prematurely abandon and fail to improve an existing approach that could have a significant impact on the development, progression, and symptoms of the disease., (Copyright © 2011 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Airborne fungi are ubiquitous in the environment and human exposure is inevitable. Such fungi differ greatly in their taxonomic, physical, ecological, behavioral, and pathogenic characteristics. Many strategies have evolved to sample, identify and interpret fungal exposure and their choice is determined by the hypotheses involved. While fungi can be sampled directly from surfaces, results do not generally reflect human exposure. For this reason, airborne spores are commonly sampled, by either filtration or impaction, using volumetric air samplers. Identification is commonly performed by either culture on nutrient medium or light microscopy using morphological criteria, although new techniques using DNA probes or characteristic antigens or toxins continue to be developed. Interpretation of such exposure data is both complex and contentious, but while there are numerous recommendations there is no consensus on exposure thresholds. A better understanding of the complex pathogenic roles of fungi and susceptibilities of their hosts will enable refinement of techniques for sampling and interpretation.

Background: Assessment of personal exposure to dust mite allergen has relied on proxy measures. Only recently has a means to directly measure inhaled allergen particle number become available (the intra-nasal air sampler)., Objective: To quantify inspired dust mite group 1 and group 2 allergen-bearing particles in bed in undisturbed conditions prior to sleep by nasal air sampling and to investigate the relationship between inhaled particles and reservoir allergen levels., Methods: Twelve volunteers wore nasal samplers in bed for 6 evenings, nose-breathing in undisturbed conditions. Allergen-bearing particles ('halos') were detected by immunostaining for Der p 1, Der p 2, or Der p 1 and Der p 2 together, and counted by light microscopy. Count data were square root transformed for analysis of variance. Mattress dust samples were assayed for Der p 1 and Der p 2 concentrations., Results: Square root detransformed mean particle counts per 30-min sample were: Der p 1, 4.22; Der p 2, 5.9; Der p 1 + Der p 2, 4.87; and for all samples, 5.01, with no difference between the groups. With replicate samples, halo number correlated significantly with mattress allergen concentrations (Der p 1 r = 0.80, P < 0.01; Der p 2 r = 0.68, P < 0.02)., Conclusion: Nasal air sampling can be used to quantify nocturnal Der p exposure in undisturbed conditions in an area with moderate exposure to mite allergen and can provide a direct measure of inhaled mite allergen. The choice of either Der p 1 or Der p 2 is appropriate for this purpose.

Background: In inland NSW, Australia, allergic sensitization to the fungi Alternaria and Cladosporium and to pollen is common and an important risk factor for asthma., Objective: We report the results of a series of experiments designed to assess the nature of personal exposure to these airborne allergenic particles. We have tested the effect of exposure conditions and level of activity on measurements of the personal exposure., Method: Personal Air Samplers (PAS) and Nasal Air Samplers (NAS) were employed. NAS are fitted just inside the nose and collect inhaled particles by impaction, while the PAS use a pump-operated filter with constant air flow (2 L/min). Thirty-three subjects (adults and children) used both NAS and PAS simultaneously for four one hour periods during which they performed activities or rested, both inside and outside their homes. Samples were analysed by light microscopy. Alternaria spores, Cladosporium spores, grass pollen and nongrass pollen were counted., Results: Both samplers detected substantial variation in exposure between subjects. Between members of the same household, the intrahouse correlation coefficient ranged from < 0 - 0.38. Levels of pollen grains and fungal spores inhaled were higher during periods of activity than during rest, and higher while subjects were outdoors than indoors. During the active outdoor period, the number of Alternaria spores inhaled ranged from 4 to 794 (median 11) spores/hr, Cladosporium from 0 to 396 (median 4) spores/hr, grass pollen from 0 to 81 (median 1) grains/hr and nongrass pollen from 0 to 72 (median 5) grains/hr., Conclusion: This is the first study to quantify individual inhaled levels of allergenic fungal spores and pollen under normal domestic circumstances. Exposure can be substantial and highly variable between individuals. The amount of particles inhaled relates both to location of the individual and activity being performed, independent of age group.

Objective: The object is to design, develop, and test a personal aerosol sampling device consisting of impaction samplers worn just inside the nostrils, driven by the wearer's respiration. The device provides a novel and unique measure of individual exposure to aeroallergens. It was conceived as an integral part of an allergen diagnostic system, in which collected aerosols are immunostained with monoclonal antibodies or the patient's IgE and associated particles positively identified using techniques of image analysis., Methods: Each sampler comprises a slot impactor with a detachable impaction plate covered with either a specially developed medical adhesive or a protein-binding membrane. Sampler performance has been validated by rig tests of aerodynamic resistance and collection efficiency of different sized particles at various flow rates. There have also been field trials with human subjects which show that the sampler can be comfortably worn for periods of up to 4 hours. This is sufficient to gather a representative sample of inhaled allergens in most environments., Results: The sampler collects an increasing proportion of particles in the inhalable range at and above 5 microm. This includes most bioaerosols of interest to allergists. Sampler prototypes have been built by CNC mill and stereolithography. Batches of samplers have been molded in biocompatible materials for field and clinical trials., Conclusions: The device successfully collects aeroallergens from a patient's own respiration. While developed specifically as a vehicle for the allergen diagnostic system, it can be adapted for studies of other aspects of air quality or for prophylactic use.