Performance of Ventilation, Filtration, and Upper-Room UVGI in Mitigating PM2.5 and SARS-CoV-2 Levels

Abstract

This study aimed to improve indoor air quality (IAQ) in an existing college building in London by addressing two key pollutants: PM2.5 particles (from indoor and outdoor sources) and SARS-CoV-2 as a biological contaminant. Various mitigation strategies were assessed, including hybrid ventilation that combined CIBSE-recommended rates with partial window and door opening. The effectiveness of HEPA-based air purifiers (APs) and upper-room ultraviolet germicidal irradiation (UVGI) systems with different intensities was also evaluated for reducing viral transmission and the basic reproduction number (R0). To manage PM2.5 in the kitchen, HEPA and in-duct MERV13 filters were integrated into the ventilation system. Results showed that hybrid ventilation outperformed mechanical systems by achieving greater reductions in infection probability (PI) and maintained higher performance as the number of infectors increased, showing only a 2.5–16% drop, compared to 35% with mechanical ventilation. An R0 analysis indicated that UVGI is more suitable in high-risk settings, while APs combined with hybrid ventilation are effective in lower-risk scenarios. The findings also emphasize that combining Supply–Exhaust ventilation with APs or MERV13 filters is crucial for maintaining safe IAQ in kitchens, aligning with the WHO’s short- and long-term exposure limits.