Sizing & Performance of UV Home Air Disinfection Systems for the Control of Airborne H1N1 Flu Virus

The sizing of UV systems for residential environments is a straightforward matter. The table below has been adapted from Kowalski et al (2009). For any given floor area and occupancy there is a range of UV wattages that will provide at least an URV 13 rating, the URV 13 rating corresponding to a minimum UV dose of 20 J/m2. The table also shows the estimated number of 30 W UV lamps (such as a G36Homodel) that will meet the URV 13 rating.

The following Figure, also adapted from Kowalski et al (2009) shows the linear relationship between total airflow and required UV wattage for an URV 13 rating. This relationship can be written as:

       UVP = 0.0224 * Q + .0233       (1)

       where UVP = UV power, watts
              Q = airflow, cfm

For example, for a 2000 ft2 area with a total airflow of 2200 cfm, equation (1) provides an estimate of 49.3 W of UV power. Therefore, two 30 W UV lamps should provide adequate air disinfection and meet the minimum URV 13 rating.


Figure (1): Relationship between UV watts and Airflow for an URV 13 UV air disinfection system.

The UV susceptibility of H1N1 flu virus (swine flu) is the same as that for Influenza A, the differences between the virus strains being only their antigenicity factors while their morphology is identical. The D90 value for Influenza is 23 J/m2 or a rate constant of 0.101 m2/J (average based on three data sets per Kowalski et al (2009)). The single-pass inactivation rate (kill rate) for the virus at a dose of 20 J/m2 is computed as follows:

        IR = 1 - (1-0.87)(1-0.87)(1-0.87) = 99.78%      

References

  • Abraham G. 1979. The effect of ultraviolet radiation on the primary transcription of Influenza virus messenger RNAs. Virol 97:177-182.
  • Hollaender A, Oliphant JW. 1944. The inactivating effect of monochromatic ultraviolet radiation on influenza virus. J Bact 48(4):447-454.
  • Jensen MM. 1964. Inactivation of airborne viruses by ultraviolet irradiation. Applied Microbiology 12(5):418-420.
  • Kowalski WJ. 2006. Aerobiological Engineering Handbook: A Guide to Airborne Disease Control Technologies. New York: McGraw-Hill.
  • Kowalski WJ. 2009. Ultraviolet Germicidal Irradiation Handbook: UVGI for Air and Surface Disinfection. New York: Springer.
  • Ross LJN, Wildy P, Cameron KR. 1971. Formation of small plaques by Herpes viruses irradiated with ultraviolet light. Virol 45:808-812.