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Far-UVC Cuts Classroom Infection Risk 91% | Airocide Systems Case Study

Roger Williams University Students Model Significant Risk Reduction of Airborne SARS-CoV-2 Transmission with Visium Far-UVC

Airocide Far-222 (Visium) — Airocide Systems is an authorized distributor of Visium by Lit Thinking

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Introduction

Public Health students at Roger Williams University in Bristol, Rhode Island, conducted a year-long study evaluating the impact of Far-UVC technology on reducing airborne pathogen transmission.

Under the direction of Dr. Jacob Bueno de Mesquita, Associate Professor of Public Health, the team assessed Visium Far-UVC fixtures in a 572 sq. ft. classroom. Using the Wells-Riley model, their analysis found a substantial reduction in modeled infection risk when Far-UVC was applied.

Public health professor presenting Far-UVC study findings to a Roger Williams University classroom, with Dr. Bueno de Mesquita holding a Visium Far-UVC light fixture
Visium Far-UVC light fixture with clear Ushio Care222 Kr-Cl Excimer Lamp Module

Visium Far-UVC light fixture with clear Ushio Care222 Kr-Cl Excimer Lamp Module.

The Study

The scenario modeled an 8-hour exposure period in a classroom containing an infectious “super-shedder”—someone emitting a high concentration of viral particles. Four ceiling-mounted Visium fixtures ran continuously throughout the day.

To evaluate occupant exposure to Far-UVC (222 nm), students used colorimetric dosimeters and radiometers.

The Results

Results showed:

  • 90% whole-room inactivation of SARS-CoV-2 in under 4 minutes
  • Infection risk over 8 hours:
    With Far-UVC: 4%
    Without Far-UVC: 45%

Visium fixtures operate silently at just 14 watts each. The four-device setup boosted the classroom's air cleaning capacity from 3 ACH (air changes per hour) to 39 eACH (equivalent air changes per hour):

  • with no added noise
  • virtually no visible light
  • and minimal energy consumption

Operating the four fixtures continuously costs approximately $0.30/day.

Viral Control Effectiveness

Expected rate of air cleaning ⇒ 39 eACH (avg fluence of 0.876μW/cm²)
0.00 0.05 0.10 0.15 0.20 0.25 0 2 4 6 8 Exposure Time (hr) Probability of Infection 45% 16% 4% 3 ACH (7.1 L/s-p) 10 ACH (23.8 L/s-p) 39 eACH (92.9 eq L/s-p)
Fig. infection risk (%) after 8 hr with 1 infectious person shedding 100 ID/hr.
*Using Wells-Riley model
Low (4%) infection risk from a high infection person.
*Risk reduced 41% compared with a decently ventilated space after 8 hr sharing the air.

For reference, the modeled infection risk at each air cleaning rate:

Air Cleaning Rate Infection Risk After 8 Hours
3 ACH (7.1 L/s-p) 45%
10 ACH (23.8 L/s-p) 16%
39 eACH (92.9 eq L/s-p) 4%

Conclusion

Funded by a grant from Rhode Island INBRE for Biomedical Research Excellence, the study concluded that: “Far-UVC mitigates viral transmission at a level unparalleled by [traditional] airflow and filtration methods and should be deployed widely.”

Expert Commentary

“This was an exciting project that demonstrated a significant estimated reduction in airborne infection risk using Visium Far-UVC fixtures,” said Dr. P. Jacob Bueno de Mesquita. “[We have demonstrated] that Visium can transform high-risk indoor environments into safer spaces.”

Airocide Systems is an authorized distributor of Visium, manufactured by Lit Thinking.