Nick's research project
involves bioaerosol sampling by means of filtration, to determine
normal background concentrations, of selected bacteria and virus
aerosols in buildings in the United States, at selected locations.
Ventilation filters are removed from air handling units within large
public buildings to be analyzed for harmful bioaerosols. These
filters are basically being used as passive high volume air samplers
for bioaerosol particles. This data is time integrated over 3 month
periods, as we are sampling for each season out of the year. After
the filters have been removed, samples are cut from each filter.
These samples are then eluted to remove any bacteria and/or viruses
from the filter media. The bacteria is cultured on growth plates or
identified by Polymerase Chain Reaction (PCR) methods. The viruses
are analyzed using PCR methods or egg inoculation methods to see if
they are viable. After the bacteria and viruses have been detected,
comparisons will be able to be made between locations and seasons.
The virus and bacteria detection and identification is done by
researchers at the Department of Environmental Health and the
Veterinary Diagnostics Laboratory in St. Paul.
Department of Homeland
Security Research Description:
A recent research project
involved bioaerosol sampling by means of filtration to determine
normal background concentrations of selected bacteria and virus
aerosols in large public buildings in the United States at selected
locations. Ventilation filters were removed from four air handling
units within each building to be analyzed for collected bioaerosols.
Figure 1 shows a typical air handling unit for a commercial
building. The filters were basically being used as passive high
volume air samplers for bioaerosol particles. These data are time
integrated over 3 month periods, as we were sampling for each season
out of the year. After the filters had been removed, samples were
cut from each filter and then eluted to remove any captured bacteria
and/or viruses from the filter media. The bacteria were cultured on
growth plates or identified by Polymerase Chain Reaction (PCR)
methods. The viruses were analyzed using PCR methods or egg
inoculation methods to see if they are viable.
After the bacteria and viruses have been identified, comparisons
will be made between building locations and seasons of the year.
The virus and bacteria detection and identification is performed by
researchers in the Department of Environmental Health and the
Veterinary Diagnostics Laboratory in St. Paul.
Figure 1: Schematic of a Typical Air
Handling Unit for a Commercial Building
Center for Filtration Research Project Description:
A current research project involves measuring total lung
deposited particle surface area with two aerosol instruments to
generate a new Health Index filter efficiency. This method of
aerosol sampling can also be used to determine the effectiveness of
the Nanoparticle Surface Area Monitor (NSAM) compared to a Scanning
Mobility Particle Sizer (SMPS). The NSAM directly measures the
total amount of particle surface area deposited into certain regions
of the human lung. The SMPS is able to measure particle
concentrations of different sizes within a defined size range, but
the SMPS measurements need to be manually integrated to correspond
with the NSAM results. This integration includes correcting the SMPS measurements for the specific region of the lung using
deposition curves for a reference worker, as outlined by ACGIH.
These curves can be seen below in Figure 2. The two regions of the
lung being observed are the Alveolar and Tracheobronchial regions
and are illustrated in Figure 3 below.
An ASHRAE 52.2-1999 Classified Wind Tunnel (see Figure 4) is used
as the test facility for the injected aerosols. The fan speed can
be adjusted to control the aerosol concentration. Three fan speeds
were used to produce three different air flow rates of 500, 1000,
and 2000 cfm. A Constant Output Atomizer (COA) is used to produce a
polydisperse aerosol, which is injected into the wind tunnel.
Different solutions of NaCl are used to produce different
concentrations of particles to be sampled. Silver nanoparticles,
produced by a furnace; and a DOS solution, aerosolized with the COA,
will also be used to test this setup. Sampling is made upstream and
downstream of the filter being tested. These upstream and
downstream concentrations are then used to determine an efficiency
of the test filter based on lung deposited surface area.
Figure 2: Deposition Curves for a
Reference Worker (ACGIH)
Figure 3: Various
Regions of the Human Lung (NSAM Spec
Figure 4: ASHRAE 52.2 ¨C 1999 Classified
Located in Room ME 357
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