Factors Impacting Allergen-Containing Particle Resuspension
Open Access
- Author:
- Gomes, Carlos A.S.
- Graduate Program:
- Architectural Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 29, 2007
- Committee Members:
- James Freihaut, Committee Chair/Co-Chair
William P Bahnfleth, Committee Member
Stanley Allan Mumma, Committee Member
James Landis Rosenberger, Committee Member - Keywords:
- Asthma
Bio-aerosol
Indoor Particle Resuspension
Allergen
Dust Production - Abstract:
- An experimental apparatus equipped with a simulated walking-induced floor disturbance system was used to explore the influence of occupant activity on the aerosolization of allergen-containing particles. Controlled air-swirls and field measured vibrations were imposed over floor samples previously loaded with physically and chemically characterized allergen-containing dusts, while timed optical particles counters continuously sampled air for transient, size resolved resuspension rate determination. Different laboratory-produced, allergen-containing dusts (originated in cats, dogs, dust mite and German cockroaches) were compared with an anthrax surrogate (Bacillus thuringiensis) and reference crushed quartz dust in controlled and characterized experiments during which, floor dust load, floor type, humidity level, air swirl and floor vibration intensity were varied. 2k fractional factorial and Box-Behnken statistical designs were created to identify and model environmental factors significantly affecting particle resuspension. Research dusts were obtained in a laboratory by a combination of milling and sieving of allergen-containing parent material, characterized for particle size distribution (optical counter analysis), surface properties (SEM analysis), and allergen content (ELISA analysis). Results indicate aerodynamic disturbances, relative to mechanical, dominated particle resuspension behavior. High dust surface roughness (cat and dog fur dusts) and high floor surface roughness (carpet) facilitated particle aerosolization. Humidity significantly impacted some types of dusts (quartz and dust mite) but not others (cat and dog fur dust). Dust load had an indirect impact on particle resuspension rates, significantly impacting fur-based dusts. Between 0.3 and 7 microns, particle size did not impact particle resuspension. Average resuspension rates and factors ranged, respectively, from 1E-10 to 1E-4 1/min and 1E-10 to 1E-4 1/m, which have phenomenological consistency with previous, large room or chamber investigations.