A novel ambient air sampler for detection of allergens and endotoxin

Current methods for measuring airborne allergen and endotoxin exposure in indoor environments rely on air sampling (using flow rates traditionally lower than 10 L/min) or using settled dust as a proxy, both of which have limitations.

We sought to develop a novel, user-friendly ambient air sampling device (ambient air sampler [AAS]) for accurate and efficient measurement of allergens and endotoxin.

The AAS is a small, quiet, lightweight device that draws air at a high flow rate (>500 L/min) across a filter to collect airborne particles. AAS devices sampled homes across South Wales, UK, and Central Virginia, USA. Devices were run alongside Institute of Occupational Medicine samplers, with both operating for 10 hours. Devices were also operated for 7 days alongside electrostatic dust collectors, which passively sampled the environment for the equivalent time. Following extraction, indoor and food allergens were quantified by multiplex assays and ELISA. Endotoxin was measured using Recombinant Factor C assay.

After 10 hours, the AAS collected 13 allergens from dust mite, cat, dog, mouse, and multiple foods, with positivity rates up to 100%. In comparison, Institute of Occupational Medicine samplers collected 5 allergens in total, with much lower positivity rates. After 7 days, the AAS collected 10 different indoor allergens and 13 different food allergens across UK and US homes. Allergens from cat, dog, milk, egg, and peanut were collected in almost every home. The AAS collected all allergens more frequently and in significantly higher amounts than the electrostatic dust collectors. The AAS also collected airborne endotoxin in every home sampled, from as little as 1-day sampling time.

The AAS developed herein provides a standardizable method for monitoring airborne allergen and endotoxin exposure, with potential applicability to other biological environmental agents.