D2.403 - Controlled exposure to grass and ragweed pollen in an Allergen Exposure Chamber

The EnviroGold™ allergen exposure chamber (AEC) was designed and built to provide controlled exposure to specific aeroallergens for clinical research. Validation testing was performed to test control of temperature, humidity and air exchange, as well as the distribution, stability and repeatability of airborne particle concentrations of both Timothy grass (Phleum pratense) and ragweed pollen (Ambrosia artemisiifolia). 

Pollen was aerosolized and mixed into the chamber (8.4× 7.0× 2.7 m) by a custom allergen dispersion system under controlled environmental conditions (10 air changes per hour of HEPA-filtered fresh air conditioned to 21°C and 40% relative humidity). Pollen concentration was measured using rotational impact samplers positioned throughout the room, sampling hourly over 15-minute intervals. Laser particle counters sampling every minute were used to assess the system response time and ensure that the pollen concentrations were stable over time.

Pollen levels were stable and repeatable for 2 and 4-hour tests with mean (standard deviation) concentrations 3608 (94) p/m³ for grass (N=4) and 3642 (52) p/m³ for ragweed (N=4). Average measurements of grass pollen from 7 locations throughout the chamber were within 10% of the spatial mean, indicating good spatial homogeneity. Temperature and relative humidity were well controlled with averages 21.3°C (range 21.0-21.6°C) and 40% (range 37-46%), respectively.

A new allergen exposure chamber provides excellent environmental control (temperature and humidity) and highly repeatable and stable pollen exposure for both Timothy grass and ragweed. Ongoing work includes clinical validation, as well as development for additional aeroallergens.