Laboratory Test Results
Tests by highly reputable and authoritative organisations have shown that SafeAirTM air sterilizing units can destroy* over 99.5% of airborne pathogens.
These organisations have conducted two different types of test that have demonstrated that SafeAirTM UVGI equipment is effective in deactivating pathogens by sampling the air passing directly through the units (Test 1), and also by measuring the dilution of concentrations of pathogens within a given airspace (Tests 2 & 3): -
Test 1 was conducted by the Harvard School of Public Health in the USA.
Test 2 was conducted by the Chinese Ministry of Health
Test 3 was conducted by RTI International in the USA.
It is recognized that these laboratory based tests cannot truly represent the practical application of the SafeAirTM units in a real world situation, as this would necessarily require tests to be carried out within a populated room and whilst the normal congress of day to day activity was taking place. For this reason Viemaster has sponsored a series of Field Trials to provide an assessment of the effectiveness of SafeAirTM equipment in the 'real world' .
Test 1
Why does the air in an enclosed space need to be sterilized?
Starting as early as the 1930s with investigations conducted by William Firth Wells, the Harvard School of Public Health (HSoPH) in the USA has developed expertise in the control of the transmission of airborne diseases by the disinfection of air using ultraviolet energy.
In 2005 HSoPH were commissioned to test the effectiveness of the SafeAirTM equipment in neutralizing airborne pathogens. The test method involved a bacteria being injected into the airstream entering the inlet vent at a precisely controlled rate. The air leaving the unit was then sampled to establish the proportion of bacteria that remained active. In April 2005, Professor Melvin W. First, Professor of Environmental Engineering, Emeritus of the Department of Environmental Health within HSoPH reported that an average of 98.2% of aerosolised bacteria (Serratia Marcescens) passing through the SafeAirTM 1200 unit were destroyed* in in six replicate tests.
Tests 2 and 3
In order to establish how effective SafeAirTM units are at reducing the levels of pathogens in an airspace a second test was conducted in which it was intended to show how effective the units are at diluting the levels of micro-organisms in the air.
The test method involved injecting known pathogens into an airspace within a test chamber of a known volume and then sampling the air in the room at fixed intervals. Given that the initial concentrations of known micro-organisms have natural rates of decay over time, the tests were designed to show the accelerated rates of decay that are attributable to SafeAirTM equipment operating within the test environment.
Note - Whilst this is more comparable with the effectiveness of SafeAirTM equipment operating in a real world environment, it still does not replicate the situation where the concentration of micro-organisms is likely to be balanced by the continual introduction of pathogens into the air by the residents in a room. In such situations, there will be a continuous process of pathogens being inactivated through natural decay and being balanced by viruses or bacteria being continually introduced by residents; a situation that is addressed by Field Trials conducted in the UK.
Test 2: In April 2006, tests carried out by the Chinese Ministry of Health showed that with the SafeAirTM 3500 unit in operation an average of approximately 98.6% of White Staph (8032) bacteria suspended in a 20 m3 airspace were destroyed* over a period of 2 hours
Test 3: In February 2008, R. Keith Esch, Ph.D, Research Microbiologist reported that in tests conducted by RTI International in the USA, results showed that with the SA3500 in operation in a 18.16 m3 test chamber over a period of 2 hours the concentrations of Staphylococcus Epidermidis (a vegetative bacterium) were reduced by 95.8%, Aspergillus Versicolor (a fungus) were reduced by 97.7% and MS2 E. Coli Bacteriophage (a virus) were reduced by 99.5%.
Illustration of Test Chamber
If you require a copy of any of these test reports, then contact us.
* The term 'destroy' means to either kill airborne bacteria, or to remove the ability of airborne bacteria to reproduce.
