BackgroundThe GA2LEN chamber has been developed as a novel mobile allergen exposure chamber (AEC) allowing standardized multicenter trials in allergy. Hitherto, subjective nasal symptom scores have been the most often used outcome parameter, but in standardized modern trials objective parameters are preferred. Despite its practicability, the objective parameter peak nasal inspiratory flow (PNIF) has been rarely used for allergy trials in the setting of allergen exposure chambers. This study aims to evaluate PNIF as an outcome parameter for provocation studies in AECs.MethodsIn a randomized controlled blinded setting subjects suffering from allergic rhinitis were exposed to grass pollen, birch pollen, house dust mite and/or placebo in the GA2LEN chamber. Different allergen concentrations were used to evaluate symptom severities. Patients had to perform PNIF before and every 30 min during a challenge using a portable PNIF meter.Results86 subjects participated in 203 challenges, altogether. House dust mite provocations caused the greatest reduction in PNIF values, followed by grass pollen and birch pollen. Provocations with every allergen or pollen concentration led to a significant decrease (p < 0.05) in PNIF compared to baseline. Furthermore, positive correlations were obtained between PNIF and peak expiratory flow, height and weight, and inverse correlations between PNIF and total nasal symptom score, nasal congestion score and visual analog scale of overall subjective symptoms.ConclusionPNIF is a helpful and feasible tool for conducting provocation trials with allergens, especially grass pollen and house dust mite, in an AEC.Electronic supplementary materialThe online version of this article (doi:10.1186/s13601-017-0169-4) contains supplementary material, which is available to authorized users.

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BackgroundAllergenic pollen exposure is mostly seen as an outdoor phenomenon but studies have shown an indoor exposure: different pollen species including birch and grass pollen in houses, schools, and shops are leading to long-lasting symptoms even after the pollen season because pollen settle on surfaces and re-enter the indoor air depending on ventilation. To reduce indoor pollen load, windows need to be closed and devices should be used: as pure wiping and cleaning of surfaces is mostly not sufficient, air cleaners may be helpful in reducing pollen counts in indoor environment.ObjectiveThe efficacy of an air cleaner is usually described by the filtration rate of standard dust particle sizes which is not necessarily related to clinical efficacy.MethodsA novel study design was developed using the technical equipment of a new mobile exposure chamber to investigate participants with allergic rhinitis (individual observational, controlled, prospective, single arm study).ResultsThe tested air cleaner reduced the grass pollen-induced (4000 grass pollen/m3 over 90 min) nasal symptoms (total nasal symptom score) significantly from 6 and 4 points (1st and 2nd exposure in sham run) to less than 1 point when air cleaner was activated.ConclusionsThe novel study protocol is suitable for testing efficacy of air cleaners and the tested air cleaner is effective in reducing clinical symptoms due to grass pollen in an indoor environment.