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Efficiency of an Air Sterilizer manufactured under license of US Patent 5874050 in reducing airborne microbial charge in closed environments

OBJECTIVE
The main objective of this study is was to verify the sir sterilizing device efficiency in reducing airborne bacteria and fungus levels in closed rooms. The study is meant to evaluate the microbial charge in room 1048 of the Industrial Microbiology Laboratory of INETI during the functioning (33 days) of said device manufactured under license of US patent 5874050

METHODOLOGY

Test conditions characterization
The device was plugged in room 1048 of the Industrial Microbiology Laboratory after 14 days of room regular use without any type of cleaning or disinfection. This room area is around 20.5 m2. It is considered as a working office having considerable quantity of bibliographic material. The daily average affluence was of 7 to 9 people.

 

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Test lasted 54 days. Device was connected December 23, 2002 after air samples were collected. All air samples were collected every Monday and Friday. Device was disconnected In January 24, 2003. An air sampler (Merck MAS-100) was utilized. Air samples were always taken in 3 points in the room. For each point 100 litres of air were collected. The suspension airborne microorganism count was made in 9cm diameter Petri dishes.

Culture means utilized in the room airborne microorganism count

Fungus: Malt Extract Agar (MEA) Difco
Bacteria: Trypona Soya Agar (TSA) Oxoid

Incubation Conditions

Fungus: 25ºC 5 to 7 days
Bactéria: 30ºC 3 days
All results for bacteria and fungus were expressed total existent microorganisms per 1 m3 of the room’s air. Each value represents the arithmetic average of 3 samples.

 

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Observing Chart 1 it was verified that the device had influence in reducing airborne bacteria and fungus in the room.
In order to better specify the efficiency of those devices the values and their reduction percentages are at below Tables 1 and 2

Table 1. Initial and final bacterial count values and correspondent percentage reduction for the studied device. For the initial count the four last counts were considered prior to connecting device. For the final count only the last three counts were considered before disconnecting device.
Initial Count (ufc/m3) Final Count (ufc/m3) Reduction
(4 reading average) (3 reading average) (%)
715 90 87

Table 2. Initial and final fungi counts and correspondent device reduction percentage. The procedures for the initial and final counts were the same as for previous Table.
Initial Count (ufc/m3) Final Count (ufc/m3) Reduction
(4 reading average) (3 reading average) (%)
375 7 98

 

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RESULTS
The bactéria and fungus results are in Figure 1 chart.

Chart:
Device plugged in
Bacteria
Fungus
Sampling Days

Figure 1. – Effect of the air sterilizer manufactured under the US Patent 5874050 in maintaining LMI room 1048 airborne bacteria and fungus levels. Each point represents 3 count average. Device was connected in December 23, 2002 after that day air samples were collected and disconnected on January 24th 2003.

 

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The results ratify the great efficiency in reducing bacteria (87%) and fungus (98%)

Lisbon, May 20, 2003

Micology Responsible The LMI Director

(signature) (signature)

Pablo Tavares Pereira José Carlos Roseiro