Organizations determined the following criteria for the efficient use of ultraviolet germicidal irradiation UVGI system [ระบบ uvgi, which is the term in Thai] system or to protect against tuberculosis:
- UVGI Irradiance as well as Dosage
Elements that must be considered when assessing the ability of an upper-room UVGI system to kill or inactivate airborne microbes consist of the level of sensitivity of the microbes to UVGI as well as the dose of UVGI gotten by a microbe or populace of microorganisms. UVGI dosage is the ultraviolet (UV) irradiance increased by the time of direct exposure and is typically revealed as µW-s/cm2.
A properly designed upper-room UVGI system may work in eliminating or suspending most airborne bead centers having mycobacteria if created to give an average UV fluence rate in the upper space in the series of 30 µW/cm2 to 50 µW/cm2, gave the other elements specified in the standards are fulfilled. In addition, the components should be mounted to give as uniform a UVGI distribution in the upper room as feasible.
- Upper-Room UVGI Solution as well as Mechanical Ventilation
As the mechanical ventilation rate in an area is raised, the overall variety of bacteria eliminated from the space using this system is enhanced. However, when mechanical ventilation is boosted in a room where an upper-room UVGI system has been deployed, the performance of the UVGI system may be minimized because of the house time of the microorganisms in the irradiated area decreases.
Under experimental lab conditions with mechanical air flow rates as much as six air changes per hour or ACH, the rate that microbes are killed or inactivated by UVGI systems seems additive with mechanical ventilation systems in well-mixed spaces.
- Air Mixing
Upper-room UVGI systems count on-air motion in between the lower portion of the space where bead nuclei are created and the upper irradiated part of the space. As soon as in the top portion, bead nuclei consisting of M. consumption might be revealed to an adequate dosage of UVGI to kill or suspend them.