UV Irradiation Dosage Table

Please note that many variables (air flow, humidity, distance of microorganism to the UV light, irradiation time) take place in a real world environment that make actual calculating of the UV dosage very difficult. However, it is proven that UV light will kill any DNA-based microorganism given enough UV dosage. UV breaks down DNA on a cumulative basis. Therefore, as air circulates through the ductwork of an HVAC system containing an UV light, the UV light continuously disinfects the air. If a microorganism is not effectively deactivated on the first pass through the ductwork, the UV light will continue to break its DNA down on subsequent passes. Microorganisms do not sit in a static environment in HVAC systems except on coils which can be exposed to UV light also. Microorganisms multiply rapidly if not controlled. The UV light helps to reduce airborne microorganisms from the indoor environment.

More about germicidal UV light  UV Definitions 

UV Tests

Tests confirmed that the 14" high output UV lamp used in the American-Lights® units produces 800µW/cm² @ 1' with 534FPM air flow at 55º F. UV dose = UV intensity x time in seconds. To compute time needed to inactivate germs in the following chart at 1' distance  by one American-Lights unit divide the UV dose by 800. 

Example: for 90% kill factor of Bacillus subtilis spores: 11,600 divided by 800 = 14.5 seconds.

The following are incident energies of germicidal ultraviolet radiation at 253.7 nanometers wavelength necessary to inhibit colony formation in microorganisms (90%) and for 2-log reduction (99%):

Energy Dosage of Ultraviolet radiation (UV dose) in µWs/cm2 needed for kill factor

Bacteria 90%
(1 log reduction)
99%
(2 log reduction)
Bacillus anthracis - Anthrax 4,520
8,700
Bacillus anthracis spores - Anthrax spores 24,320 46,200
Bacillus magaterium sp. (spores) 2,730 5,200
Bacillus magaterium sp. (veg.) 1,300 2,500
Bacillus paratyphusus 3,200 6,100
Bacillus subtilis spores 11,600 22,000
Bacillus subtilis 5,800 11,000
Clostridium tetani 13,000 22,000
Corynebacterium diphtheriae 3,370 6,510
Ebertelia typhosa 2,140 4,100
Escherichia coli 3,000 6,600
Leptospiracanicola - infectious Jaundice 3,150 6,000
Microccocus candidus 6,050 12,300
Microccocus sphaeroides 1,000 15,400
Mycobacterium tuberculosis
6,200
10,000
Neisseria catarrhalis 4,400
8,500
Phytomonas tumefaciens 4,400 8,000
Proteus vulgaris 3,000 6,600
Pseudomonas aeruginosa 5,500 10,500
Pseudomonas fluorescens 3,500 6,600
Salmonella enteritidis 4,000 7,600
Salmonela paratyphi - Enteric fever 3,200 6,100
Salmonella typhosa - Typhoid fever 2,150 4,100
Salmonella typhimurium 8,000 15,200
Sarcina lutea 19,700 26,400
Serratia marcescens 2,420 6,160
Shigella dyseteriae - Dysentery 2,200 4,200
Shigella flexneri - Dysentery 1,700 3,400
Shigella paradysenteriae
1,680
3,400
Spirillum rubrum 4,400
6,160
Staphylococcus albus 1,840 5,720
Staphylococcus aureus 2,600 6,600
Staphylococcus hemolyticus 2,160 5,500
Staphylococcus lactis 6,150 8,800
Streptococcus viridans 2,000 3,800
Vibrio comma - Cholera 3,375 6,500
Molds
90%
99%
Aspergillius flavus 60,000
99,000
Aspergillius glaucus 44,000 88,000
Aspergillius niger 132,000 330,000
Mucor racemosus A 17,000 35,200
Mucor racemosus B 17,000 35,200
Oospora lactis 5,000 11,000
Penicillium expansum 13,000 22,000
Penicillium roqueforti 13,000 26,400
Penicillium digitatum 44,000 88,000
Rhisopus nigricans 111,000 220,000
Protozoa
90%
99%
Chlorella Vulgaris 13,000
22,000
Nematode Eggs 45,000 92,000
Paramecium 11,000 20,000
Virus
90%
99%
Bacteriopfage - E. Coli 2,600
6,600
Infectious Hepatitis 5,800 8,000
Influenza 3,400 6,600
Poliovirus - Poliomyelitis 3,150 6,600
Tobacco mosaic 240,000 440,000
Yeast 90%
99%
Brewers yeast 3,300
6,600
Common yeast cake 6,000 13,200
Saccharomyces carevisiae 6,000 13,200
Saccharomyces ellipsoideus 6,000 13,200
Saccharomyces spores 8,000 17,600