Disclaimer:

• Resistance to UV inactivation: bacteria > viruses > fungal spores

• Airborne rate constants tend to be higher in Air, under normal humidity: microbes are more vulnerable in Air, whereas microbes on Surfaces appear to have a certain degree of inherent protection

• It is appropriate to treat Air and Surface UV disinfection together, since airborne microbes are often surface-borne and vice-versa

• The inactivation rates of microbes on surfaces may vary depending on the type of surface. Some metals, like copper or silver, are naturally biocidal (殺生物) effects.

• Water-based UV rate constants are substitutes for airborne rate constants

• Surface rate UV constants may also be used conservatively in place of airborne data

• Contaminated surfaces are often a source of airborne microbes, and airborne microbes often produce surface contamination.

• Bacteria are 5 times (viruses are 3 times) more resistant in water than in air at low humidity. Water absorbs UV, i.e. it requires higher rates of UV dose to disactivate microbes, viruses and fungi.

• Contaminated surfaces are often a source of airborne microbes

• Airborne microbes often produce surface contamination

• The interaction of Air and Surface contamination processes makes the issue of Air vs Surface disinfection almost inseparable:
   

  • Example: the disinfection of cooling coil surfaces removes mold spores from the coils and prevents subsequent aerosolization, thereby helping keep the air clean