Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

NIOSHTIC-2 Publications Search

Search Results

Aerosol generation by blower motors as a bias in assessing aerosol penetration into cabin filtration systems.

Authors
Heitbrink-WA; Collingwood-S
Source
J Occup Environ Hyg 2005 Jan; 2(1):45-53
NIOSHTIC No.
20025919
Abstract
In cabin filtration systems, blower motors pressurize a vehicle cabin with clean filtered air and recirculate air through an air-conditioning evaporator coil and a heater core. The exposure reduction offered by these cabins is evaluated by optical particle counters that measure size-dependent aerosol concentration inside and outside the cabin. The ratio of the inside-to-outside concentration is termed penetration. Blower motors use stationary carbon brushes to transmit an electrical current through a rotating armature that abrades the carbon brushes. This creates airborne dust that may affect experimental evaluations of aerosol penetration. To evaluate the magnitude of these dust emissions, blower motors were placed in a test chamber and operated at 12 and 13.5 volts DC. A vacuum cleaner drew 76 m3/hour (45 cfm) of air through HEPA filters, the test chamber, and through a 5 cm diameter pipe by a vacuum cleaner. An optical particle counter drew air through an isokinetic sampling probe and measured the size-dependent particle concentrations from 0.3 to 15 microm. The concentration of blower motor aerosol was between 210(5)and 1.810(6)particles/m3. Aerosol penetration into three stationary vehicles, two pesticide application vehicles and one tractor, were measured at two conditions: low concentration (outside in the winter) and high concentration (inside repair shops and burning incense sticks used as a supplemental aerosol source). For particles smaller than 1microm, the in-cabin concentrations can be explained by the blower motor emissions. For particles larger than 1m, other aerosol sources, such as resuspended dirt, are present. Aerosol generated by the operation of the blower motor and by other sources can bias the exposure reduction measured by optical particle counters.
Keywords
Aerosol-generators; Aerosol-particles; Aerosols; Filtration; Particle-counters; Airborne-dusts; Air-treatment-equipment; Air-contamination; Engineering-controls; Particulate-dust; Particulates; Measurement-equipment; Quality-control; Occupational-exposure
Contact
The University of Iowa, The College of Public Health, Department of Occupational and Environmental Health, 100 Oakdale Campus - 108 IREH, Iowa City, IA 52241
CODEN
JOEHA2
CAS No.
7440-44-0
Publication Date
20050101
Document Type
Journal Article
Email Address
william-heitbrink@uiowa.edu
Funding Amount
1024434
Funding Type
Grant
Fiscal Year
2005
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-T42-CCT-717547; Grant-Number-T42-OH-008414; Grant-Number-T42-OH-008491
Issue of Publication
1
ISSN
1545-9624
Source Name
Journal of Occupational and Environmental Hygiene
State
IA
Performing Organization
The University of Iowa, Iowa City, Iowa
TOP