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