Determining Inhalation Exposure Paths to Common Indoor Allergens
 |
Fig. 1. Reservoir Disturbance Due to People Walking. |
Epidemiological evidence indicates exposure to environmental allergens found in building surface reservoirs is strongly associated with the development of bronchial hyper-reactivity (BHR) or asthma. Nearly 50 percent of the population in developed societies, such as North America, Europe and Japan, have some form of developed allergic sensitization, and the rate of increased asthma in developed society populations is epidemic. Although life threatening only rarely, allergic responses and allergy-related diseases such as asthma result in much distress and lost time from school and work. Many allergen-induced respiratory diseases are inhalation sensitized and developed, suggesting the existence of an aerobiological pathway of allergen-containing carrier particles from building reservoir to occupant respiration. Dr. James Freihaut and Carlos Gomes (AE doctoral candidate) joined the AE Department in fall 2002 and have been exploring ever since the influence of human activity, such as walking, on the aerosolization of allergen-containing particles. They have been joined by graduate student Ponkamon Aumpansub and undergraduates Joseph Khapleke, Jessica Baker, Daryl Summerson, Amy Pastor, and Jason Borowski. The objective is to develop quantitative, air-reservoir allergen partitioning models for commonly occurring protein allergens, such as those originating from mites, pets, insects, pests, and molds.
 |
Fig. 2. Allergen Air Suspension via Defined Force Components |
Experiments are being conducted in a chamber designed to deliver defined aerodynamic, mechanical and electrostatic forces to a surface holding a dust of known particle size and allergen composition. For example, floor reservoir perturbation forces associated with human walking (Fig. 1) consists of combinations of walking-induced aerodynamic turbulence superimposed on building resonant floor vibration frequencies. Depending on humidity conditions and tribology characteristics of the floor material, clothing and allergen carrier particles, frictionally introduced electrostatic forces can also be a significant component in allergen aerosolization. Upon delivery of a defined force mix to a reservoir sample, the air above the reservoir is monitored by optical particle counters and samples are collected for a time-resolved assessment of particle size and allergen content classification (Fig. 2).
 |
| Fig. 3. Aerosol Lab American Roaches |
Flooring reservoir samples (carpet, linoleum, tile, hardwood) with cat, dog and cockroach allergen dusts of known particle size and allergen concentration are being prepared. Allergen-producing German and American cockroaches colonies (e.g. Fig. 3)have been established in the Aerosol Laboratory, causing a wave of curiosity in the AE Department (along with alarming a few students and some unsuspecting laboratory visitors!).
The Hybridoma and Cell Culture Laboratory of the Penn State Life Science Consortium is helping to apply immuno-assay (based on immune systems antibody-antigen chemistry) analytical methods to measure allergen contents of samples.
This research will establish partitioning constants for allergens containing particles as a function of allergen type and floor perturbation parameters. It will also establish principal air-suspension pathways of allergens leading to inhalation exposure. Determining air-reservoir partitioning values and air suspension mechanisms will lead to rational indoor allergen mitigation strategies.
This research is being pursued as a focus area of the recently
established Indoor Environment Center |