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The intent of this study was to evaluate by impartial objective means-the ability of Biological Control’s Microcon™ to filter a simulated human geverated bioaerosol intended to mimic the type of aerosol produced by a human cough or sneeze.

The particulate medium chosen to stimulate the bioaeorsol was Arizona Road Dust. The test dust had a mean diameter of 0.76 microcons. This medium was chosen because it’s aerodynamic properties are within the human respirable range. This medium also permits sufficient residency for consistent and reproducible measurement of airborne concentrations.

In general, the test consisted of generating an airaborne dust concentration in the test room and measuring the change in the perticulate concentration. The internal volume of the test isolation room and regualr patient room were 1,090 ft and 1,612 ft, respectively.

Prior to the start of each test the particulate monitoring equipment was adjusted and a consistent airborne dust concentration generated. After an appropriate period of time to allow for stablilization of dust concentration the Microcon™ was placed in as central location as possible, within the test room, prior to the start of the test.

Once a stable airborne dust concentration was achieved and a baseline established the Microcon™ was then activated. The concentration of airborne dust within the test rooms was monitored using four (4) direct-reading portable aerosol monitors which measured airborne particulate levels at two levels in each of two locations. The monitoring equipment chosen for monitoring particulate levels were battery powered hand-held Haz-Dust™ Particulate Monitors manufactured by Environment Devices Corp. Thae Haz-Dust™ monitor has a digital read out as well as a DC voltage output for data recording.

Four (4) of these monitors were used in each test. Two (2) test stands were used in each test cell and each contained two (2) monitors mounted at different heights. Monitors 1 and 3 were mounted on test stand number 1 with monitors 2 and 4 mounted on test stand number 2. Monitors 1 and 2 were mounted at a height of 66 inches with monitors 3 and 4 mounted at a height of 32 inches. The height of 66 inches was chosen as a representative of the breathing zone height of the average standing adult. The height of 32 inches was chosen as an approximation of the height of a supine patient’s breathing zone. The test stands were located as follows:

1) Test stand #1- (holding monitors 1 and 3) was placed near the front side of the bed approximately 36 inches from the wall near the head of the bed.
2) Test stand # 2 - (holding monitors 2 nad 4 ) was placed in the corner, at the foot of the bed, near the window approximately 24 inches from the corner of the rooms.



The test protocol was designed to address possible increased settling attributable to the greater density of the test dust as compared to that of a bioaerosol. Initially, in an effort to compensate for the lack of air currents necessaary for uniform paticulate dispersion, one (1) 24 inch diameter fan was employed to distribute the test dust and to porduce a more uniform concentration of the test dust within the test room. The primary reasons for the diminution of thetest dust concentrations appeared to be impact losses on fan blades, associated surfaces, and gravity induced settling or drop-out. Another source of loss was the scavenging effect produced by static charges on the room’s interior surfaces.

As a result of scavenging, drop-out and impact losses thequantity of test dust required to produce a stable concentration of 10-20 mg/M in each test room was somewhat greater than calculations indictated. A hand-held air-powered nebulizer was used to disperse the test dust in each test cell. Once the dust loading requirements were met, it took five (5) to seven minutes to achieve a stable and acceptably uniform test dust concentration within the desired range.


-End of Section 2-

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