top of page

Surrogate Aerosol Test

Download Full Test Report Here:

Surrogate Aerosol Test
Download • 411KB

STUDY TITLE Assessment of IONaer 7000 Ion Generator to reduce airborne pathogens: Testing with Cystovirus Phi6 (ATCC 21781-B1) as the challenge

TEST ORGANISM Cystovirus Phi6 (ATCC 21781-B1): Host: Pseudomonas syringae (ATCC 19310).

TEST PRODUCT IDENTITY IONaer 7000 Ion Generator Carrier

TEST Method Air Decontamination Protocol based on US EPA Guidelines OCSPP 810.2500 for Efficacy Test Recommendations on Air Sanitizers

AUTHOR Bahram Zargar, PhD


PERFORMING LABORATORY CREM Co. Labs. Units 1-2, 3403 American Dr., Mississauga, Ontario, Canada L4V 1T4



STUDY DIRECTOR: Bahram. Zargar, PhD



Study Title: Assessment of IONaer 7000 Ion Generator to reduce airborne pathogens: Testing with Cystovirus Phi6 (ATCC 21781-B1) as the challenge

Study Number: CAE200306-01

Sponsor Clean Air EXP

Testing Facility CREM Co Labs Units 1-2, 3403 American Drive, Mississauga, ON, Canada


Test Substance Name: IONaer 7000 Ion Generator


Date Device Received:

Study initiation date: March/03/06

Experimental Start Date: March/03/20

Experimental End Date: April/02/20

Study Completion Date: April/14/20


Indoor air is well-recognized as a vehicle for the direct and indirect spread of a wide variety of human pathogens, and many technologies are used to remove/inactivate such airborne pathogens in healthcare and other settings. In this study, IONaer 7000 Ion Generator was tested to quantitatively assess if it could reduce the contamination of the air by an enveloped bacteriophage (Phi6) as a surrogate for enveloped viruses such as influenza- and coronaviruses. The technology tested is based on the generation of cold plasma to charge indoor air. The device itself is mounted on the HVAC system to take advantage of the air movements in it.


Indoor air can be an important vehicle for a variety of human pathogens and airborne pathogens can contaminate other parts of the environment to give rise to secondary vehicles leading to an airsurface-air nexus with possible transmission to susceptible hosts. Various groups of human pathogens with potential airborne spread include: vegetative bacteria (staphylococci and legionellae), fungi (Aspergillus, Penicillium, and Cladosporium spp. and Stachybotrys chartarum), enteric viruses (noro- and rotaviruses), respiratory viruses (influenza and coronaviruses), mycobacteria (tuberculous and nontuberculous), and bacterial spore-formers (Clostrioides difficile and Bacillus anthracis). Many technologies have been developed to decontaminate indoor air under field-relevant conditions. Furthermore, air decontamination may play a role in reducing the contamination of environmental surfaces and have an impact on interrupting the risk of pathogen spread.


To assess the efficacy of IONaer 7000 Ion Generator for its ability to inactivate enveloped virus (Cystovirus Phi6 (ATCC 21781-B1)) in indoor air under ambient conditions.

Test Device: IONaer 7000 Ion Generator

Room Temperature Relative Humidity (RH): Ambient temperature (22±2ºC) 50±10%

Material and Methods

1. The aerobiology chamber

  • The details of our aerobiology chamber have been published before (Sattar et al., 2016). Briefly, the chamber (26 m3 ) was built to comply with the guidelines from the U.S. Environmental Agency (U.S. EPA 2012). A PVC pipe connected to a nebulizer introduced microbial aerosols into the center of the chamber and another PVC pipe connected to an air sampler collected the airborne microbes directly onto nutrient agar plates inside the sampler. The nebulizer was operated for the desired length of time with air pressure (25 psi) from a compressed air cylinder. A glove-box on one side of the chamber permitted the handling of the required items without breaching the containment barrier. A muffin fan (Nidec Alpha V, TA300, Model AF31022-20; 80 mm X 80 mm, with an output of 0.17 cubic meters/minute) inside the chamber enabled the uniform mixing of the air inside it. Between uses, fresh air was used to flush out the chamber of any residual airborne microbes.

2. Environmental monitoring

  • The air temperature (22±2°C) and RH (50±10%) inside the chamber were measured and recorded using a remote-sensing device (RTR-500 Datalogger).

3. The air sampler

  • A programmable slit-to-agar (STA) sampler (Particle Measuring Systems, Boulder, CO; was used to collect air samples from the aerobiology chamber at the rate of 28.3 L (1 ft3 )/min. The sampler was placed outside the chamber and the sampler’s inlet was connected via a PVC pipe to withdraw air from the aerobiology chamber. A fresh plate (150 mm diameter) with a suitable nutrient agar was used to collect an air sample and the plates incubated for the development of PFU of the test microbes. When collecting airborne phages, the recovery plate was first inoculated with a suspension of their respective bacterial host and placed in the sampler. The air sample collection time varied from 2 to 60 minutes depending on the nature of the experiment.

4. Collison nebulizer

  • A six-jet Collison nebulizer (CH Tech., Westwood, NJ; was used to generate the aerosols of the test microbe for ten minutes. Air from a compressed air cylinder at ~172 kPa (25 psi) was used to operate the nebulizer. The fluid to be nebulized consisted of a suspension of the test microbe in PBS.

5. Test Pathogen

  • Phage Cystovirus Phi6 (ATCC 21781-B1) was grown in its bacterial host P. syringae (ATCC 19310). This phage is a relatively large (about 100 nm in diam.), enveloped virus that is frequently used as a surrogate for human pathogenic viruses. This virus was a gift from the Laval University, Laval, Quebec, Canada.

6. Test Medium

  • The vegetative microbial growth and recovery media in this study were Luria Broth (LB) and Luria Broth Agar (LBA).

7. Preparation of Test Pathogen Suspension

  • To prepare a broth culture of P. syringae, a loopful of the stock culture was streaked on a LB agar and was incubated for 18±2 h at 28±1°C. A colony was inoculated in 25 mL of LB broth and incubated in at 28±1°C. When the optical density (OD) reached around 0.7, the bacterial suspension was used for the test.

8. Preparation of Phage Inocula for aerosolization

  • The test phage suspended in saline and nebulized into the aerobiology chamber (Sattar et al., 2016) using a six-jet Collison nebulizer.

Test Method

1. Experimental Setup

  • Flowchart 1 provides the sequence of steps in a typical experiment for testing the airdecontamination device. As control, the study included testing the natural decay of the test organism over time while the fan of the device was on without turning on the device. Table 1 and Table 2 list the times at which the air samples from the chamber were collected and the duration of sampling for each in control and efficacy test, respectively.

In efficacy, all plates were divided to the sections with 7.5 min sampling period and the PFU in each area was counted and used for calculating the concentration of the bacteriophage in the chamber at the median of that interval.

Experimental Design

Three control tests were performed, with the device OFF, and the muffin fan ON. 150 mm plates with agar and host bacteria were placed in in the STA machine to sample the air. Two multi-challenge efficacy tests were performed. In efficacy test after sampling the baseline, the device turned ON and kept ON until the end of the test.


No product acceptance criterion was specified for this range-finding study.


Testing phage survival:

Any meaningful assessment of air decontamination requires that the aerosolized challenge microorganisms remain viable in the experimentally-contaminated air long enough to allow for proper differentiation between biological decay and inactivation/removal by the technology being tested. Such airborne viability of the microorganism used in this study was tested in the aerobiology chamber with three control tests without turning on the device while muffin fan was ON. The average of the three control tests was used to calculate the efficacy of IONaer 7000 Ion Generator Carrier.

Efficacy test of the IONaer 7000 Ion Generator against Cystovirus Phi6:

This part of the report represents data from the efficacy experiments on the IONaer 7000 Ion Generator against Phi6 at two different RH: 45% and 55%. The raw data are tabulated in Appendix A.

Figure 1 shows the average log10 PFU/m3 recoveries for the three control tests (biological decay) with the corresponding standard deviation at each sampling interval. The concentration of Phage becomes undetectable after 2 hours.

Figure 3 and 4 compares the average log10 PFU/m3 recoveries for the two tests. The average of log10 PFU/m3 recoveries of the transformed control of the three control tests are also shown. ‘Transformed control’ is the curve generated when the log10 PFU data for biological decay were transformed to be compared to the data for the efficacy experiment.

In test #1(Average RH of 53.5%) , the device demonstrate 2.75 Log10 reduction (99.82% reduction) after 33 minutes of introducing the first challenge and demonstrate 4.2 Log10 (99.994% reduction) reduction in 10 minutes after introducing of the second challenge. In the second test (RH of 44%) the device demonstrate 2.6 Log10 reduction (99.75% reduction) after 33 minutes of introducing the first challenge and demonstrate 3 Log10 reduction (99.90% reduction) in 30 minutes after introducing of the second challenge.

Fig. 3. The average of three Stability-in-air tests and the first multi-challenge efficacy experiment on IONaer 7000 Ion Generator device against Phi6 phage with the average RH of 53.5 %

Fig. 3. The average of three Stability-in-air tests and the second multi-challenge efficacy experiment on IONaer 7000 Ion Generator device against Phi6 phage with the average RH of 44 %


  • Aliabadi, A. A., S. N. Rogak, K. H. Bartlett and S. I. Green (2011). "Preventing airborne disease transmission: review of methods for ventilation design in health care facilities." Adv Prev Med 2011: 124064.

  • ASTM International (2013). Standard quantitative disk carrier test method for determining the bactericidal, virucidal, fungicidal, mycobactericidal and sporicidal activities of liquid chemical germicides. 2007 Document #E2197. ASTM International, West Conshohocken, PA.

  • Davies, A., T. Pottage, A. Bennett and J. Walker (2011). "Gaseous and air decontamination technologies for Clostridium difficile in the healthcare environment." J Hosp Infect 77(3): 199- 203.

  • Environ. Protection Agency (Dec. 2012). Air Sanitizers – Efficacy Data Recommendations. OCSPP 810.2500.

  • Eames, I., Shoaib, D., Klettner, C. A. & Taban, V. (2009). Movement of airborne contaminants in a hospital isolation room. J. R. Soc. Interface 6, S757–S766.

  • Eames, I., Tang, J. W., Li, Y. & Wilson, P. (2009) Airborne transmission of disease in hospitals. J. R. Soc. Interface 6, S697–S702

  • Heidelberg, J.F., Shahamat, M., Levin, M., Rahman, I., Stelma, G., Grim, C., Colwell, R.R. (1997). Effect of aerosolization on culturability and viability of gram-negative bacteria. Appl Environ Microbiol. 63:3585-3588.

  • Ijaz, M.K., Brunner, A.H., Sattar, S.A., Nair, R.C. & Johnson-Lussenburg, C.M. (1985a). Survival characteristics of airborne human coronavirus 229E. J. Gen. Virol. 66:2743-2748.

  • Ijaz, M.K., Karim, Y.G., Sattar, S.A. & Johnson-Lussenburg, C.M. (1987). Development of methods to study survival of airborne viruses. J. Virol. Methods. 18:87-106.

  • Ijaz, M.K., Sattar, S.A., Johnson-Lussenburg, C.M. & Springthorpe, V.S. (1984). Comparison of the airborne survival of calf rotavirus & poliovirus type 1 (Sabin) aerosolized as a mixture. Appl. Environ. Microbiol. 49:289-293.

  • Ijaz, M.K., Sattar, S.A., Johnson-Lussenburg, C.M., Springthorpe, V.S. & Nair, R.C. (1985b). Effect of relative humidity, atmospheric temp. & suspending medium on the airborne survival of human rotavirus. Can. J. Microbiol. 31:681-685.

  • Karim, Y.G., Ijaz, M.K., Sattar, S.A. & Johnson-Lussenburg, C.M. (1985). Effect of relative humidity on the airborne survival of rhinovirus-14. Can. J. Microbiol. 31:1058-1061.

  • Mandal, J. and Brandl H. (2011). Bioaerosols in indoor environment - A Review with Special Reference to Residential and Occupational Locations. The Open Environmental & Biological Monitoring Journal 4, 83-96.

  • Mandin, C., Derbez, M., Kitchner, S. (2012). Schools, office buildings, leisure settings: Diversity of indoor air quality issues. Global review of indoor air quality in these settings. Annales Pharmaceutiques Française 70, 204-212.

  • Miles A.A., Misra S.S. (1938). The estimation of the bactericidal power of the blood. J. Hyg. 38: 732– 749.

  • Sattar, S.A. & Ijaz, M.K. (1987). Spread of viral infections by aerosols. CRC Crit. Rev. in Environ. Control. 17:89-131.

  • Sattar, S.A. & Ijaz, M.K. (2007). Airborne viruses. In Manual of Environmental Microbiology, (C. Hurst et al. eds.) 3rd edition, Am. Soc. Microbiol., Washington, DC. Pages 1016-1030.

  • Sattar, S.A. (2002). Viral aerosols. In Encycl. Environ. Microbiol., G. Bitton (ed.), Wiley, New York, NY. Pages 3255-3260.

  • Sattar, S.A., Ijaz, M.K., Johnson-Lussenburg, C.M. & Springthorpe, V.S. (1984). Effect of relative humidity on the airborne survival of rotavirus SA-ll. Appl. Environ. Microbiol. 47:879-881.

  • Sattar, S.A., Synek, E.J., Westwood, J.C.N. & Neals, P. (1972). Hazard inherent in microbial tracers: reduction of risk by the use of Bacillus stearothermophilus spores in aerobiology. Appl. Microbiol. 23:1053-1059.

  • Sattar, S.A., Tetro, J. & Springthorpe, V.S. (1999). Impact of changing societal trends on the spread of infectious diseases in American & Canadian homes. Am. J. Infect. Control 27: S4-S21.

  • Sattar, S.A., Bhardwaj, N., & Ijaz, M.K. (2015). Airborne viruses. In Manual of Environmental Microbiology, (C. Hurst et al. eds.) 4th edition, Am. Soc. Microbiol., Washington, DC. (in press).

  • Springthorpe, V.S. & Sattar, S.A. (2007). Application of a quantitative carrier test to evaluate microbicides against mycobacteria. J. AOAC International 90:817-824.

  • Yang, W and Marr, L. C. (2011) Dynamics of airborne influenza A viruses indoors and dependence on humidity. PLoS One. 2011; 6(6): e21481.


bottom of page