Building Immune Systems in Restaurants

RISK REDUCTION | 29

Far-UV Far-UV, is emerging an option that can provide airborne mitigation in a vertical direction downwards rather than projected horizontally across the upper-air level.

the floor to the bottom of the fixture. The fixture should be mounted so that its UV energy is distributed parallel to the plane of the ceiling. Device construction and placement prevent excessive ultraviolet energy from striking occupants below.

Figure 29. Possible terminal application of far UV (28)

Figure 28. Typical Elevation View showing UVGI energy placed above heads of room occupants (27)

TiO2 PCO or Titanium Dioxide Photocatalytic Oxidation In a titanium dioxide photocatalytic air purifier, ultraviolet light shines onto a titanium catalyst, which converts molecules of pollution into more harmless substances. The big advantage that photocatalytic air purifiers have over other air-cleaning technologies is they completely transform the harmful chemicals and effectively destroy them. While the standard PCO approach does not affect viruses; the ultraviolet light used in the process does (see above).

In areas where there is not a viable opportunity for duct mounted UVC (i.e. spaces with minimal or no ventilation), upper-air UVC is a very promising approach. Even if space is ventilated and has duct mounted UVC, upper-air UVC could provide a “one-two-punch” where floating viruses that remain uncaptured by the HVAC system are inactivated before they can fall into the occupied zone. Ventilation patterns (natural and mechanical) should promote good air mixing in a space equipped with UVC so that infectious microorganisms are drawn through the UVC “kill zone.” In both duct-mounted and unoccupied in-room UVC, the amount of radiation applied can be much higher compared to what can be used for upper-zone UVC, resulting in higher aerosol exposure and quicker inactivation. Duct-mounted UVC can be contrasted to HEPA filtration in the central ventilation system, in that it inactivates the potentially infectious organisms while filtration removes them, and filtration imposes additional load on the fan that UV does not.