Evaluation of an Air Cleaning Device Equipped with Filtration and UV: Comparison of Removal Efficiency on Particulate Matter and Viable Airborne Bacteria in the Inlet and Treated Air

Abstract

Since the COVID-19 pandemic, improving indoor air quality (IAQ) has become vital for the public as COVID-19 and other infectious diseases can transmit via inhalable aerosols. Air cleaning devices with filtration and targeted pollutant treatment capabilities can help improve IAQ. However, only a few filtration/UV devices have been formally tested for their effectiveness, and little data is publicly available and UV doses comparable. In this research, we upgraded a particulate matter (PM) air filtration prototype by adding UV-C (germicidal) light. We developed realistic UV dose metrics for fast-moving air and selected performance scenarios to quantify the mitigation effect on viable airborne bacteria and PM. The targeted PM included total suspended particulate (TSP) and a coarse-to-fine range sized at PM10, PM4, PM2.5, and PM1. The PM and viable airborne bacteria concentrations were compared between the inlet and outlet of the prototype at 0.5 and 1.0 m3/s (low and high) air flow modes. The upgraded prototype inactivated nearly 100% of viable airborne bacteria and removed up to 97% of TSP, 91% of PM10, 87% of PM4, 87% of PM2.5, and 88% of PM1. The performance in the low flow rate mode was generally better than in the high flow rate mode. The combination of filtration and UV-C treatment provided ‘double-barrier’ assurance for air purification and lowered the risk of spreading infectious micro-organisms.

A Systematic Review on the Application of Ultraviolet Germicidal Irradiation to HVAC Systems

“…Li et al [2] improved air filtration with UV-C lamps to effectively neutralise airborne pathogens, especially SARS-CoV-2. They refined UV-C dose calculations and performed radiation tests.…”

“…Among the experimental studies [1,2,[12][13][14]17,22,23,25,29,31,40,43,44,46,48,49,52,[54][55][56][57][60][61][62][63][64]70,71], three [12,13,23] performed tests in work or everyday living environments, while [1,2,15,29,48,49,54,56,60,70] performed tests in test chambers. Some papers [14,17,25,43,44,52,[62][63][64]…”

“…The risk of airborne transmission is particularly significant indoors, as human occupancy remains one of the primary sources of bioaerosols. Consequently, poor indoor air quality can facilitate the spread of various pathogens present in the atmosphere [1,2]. In addition, antibiotic resistance represents a significant obstacle to healthcare safety.…”

Control technologies to prevent aerosol-based disease transmission in animal agriculture production settings: a review of established and emerging approaches

“…More recently, in light of the COVID-19 pandemic, Qiao et al tested a smaller-scale UV-C duct unit and concluded that the unit can achieve greater than 2-log reduction in viable coronavirus inactivation with a flow rate of 2,439 L min −1 ( 126 ). Since UV-C light itself does not capture or remove pathogens from the fluid stream, it is often used as an additional device to augment current HVAC systems with filters ( 127 ); it is commonly available commercially for this purpose. Importantly, during filter disinfection, the filters still collect pathogens and the time of UV-C exposure is increased for collected pathogens, thus the UV-C intensity can be reduced as compared to that needed for standalone ducted systems.…”

Relative Health Risk Reduction from an Advanced Multi-modal Air Purification System: Evaluation in a Post-surgical Healthcare Setting

“…This is most likely due to the reality that emerging air disinfection techniques have not been yet trialled for their efficiency in real life settings. Recently, here have been advanced prototype investigations into air disinfection using UV-C techniques with providing good results [18] Advanced HVAC-integrated air purification systems have been reported in comparative studies, and these have seen a reduction in hospital stays [19,20]. Arikan et al reported a reduction in surface microbial levels following air treatment in an intensive care unit [21].…”