Enhancing upper-room UVGI performance through rotating UV source under poorly-mixed ventilation conditions

Area of Science:

• Environmental Health Engineering
• Microbiology
• Public Health

Background:

• Upper-room Ultraviolet Germicidal Irradiation (UVGI) is a key air disinfection strategy.
• Effectiveness is limited by poor air mixing, leading to under-irradiated bioaerosols.
• Rotating lamps are proposed to improve UVGI efficacy, but mechanisms are unclear.

Purpose of the Study:

• To investigate the enhancement effect of rotating lamps on UVGI air disinfection under non-mixing conditions.
• To quantify the improvement in bioaerosol decay rates with rotating versus stationary UVGI lamps.
• To assess the impact of lamp placement and aerosol distribution on disinfection enhancement.

Main Methods:

• Simulated bioaerosol decay in a chamber using UV inactivation alone.
• Examined three rotating lamp placements (X-diagonal, X-middle, Y-middle).
• Considered two bioaerosol distribution patterns based on release locations.

Main Results:

• Rotating lamps increased germicidal irradiance received by bioaerosols compared to stationary lamps.
• Equivalent Air Change Rate (EACH) improved from 2.6-13.7/h to 9.8-17.5/h with rotation.
• Disinfection enhancement ranged from 27.7% to 276.9%.

Conclusions:

• Lamp rotation is a reliable enhancement measure for UVGI air disinfection, particularly under non-mixing conditions.
• The enhancement effect, while diminished by air mixing, remains appreciable.
• Rotating lamps improve the overall effectiveness of UVGI systems in reducing airborne pathogens.