ABSTRACT
A global survey in December 2020 revealed a preference for surface and air disinfection in automobiles which may have been accelerated by the COVID-19 pandemic. The observed trend towards healthy cars may remain well after the current pandemic. Additionally, new safety features like CO2 gas sensors, antimicrobial fabrics, and enhanced air purifiers have emerged. While automobile air purifiers trap contaminants using cartridge filters, they are not particularly efficient at removing viral particles and create large pressure drops, which must be compensated with larger fans, increasing power requirements and noise in the vehicle cabin. A HVAC system with integrated UVC-LEDs can inactivating viruses, bacteria, and mold. UVC LEDs are desirable because unlike mercury lamps, they do not pose electrical, glass, and chemical hazards. With the recent improvements in UVC LED lifetime and power, UVC LEDs are becoming a better alternative, as highlighted by recent upsurge of successful in air disinfection studies against SARS-CoV-2 and H1N1. In this paper, the KM model is applied to a vehicle, initial testing on 25 L/s shows half log reduction of E. coli, then a model of a disinfection chamber that could fit a vehicle HVAC is created, and finally a full size mock vehicle is disinfected using Phi6 as a surrogate. It's estimated from this that 90#x00025;of SARS-CoV-2 could be eliminated in 5 minutes. This demonstrates the feasibility of UVC LEDs for aerosol disinfection in vehicles. © 2022 SAE International. All Rights Reserved.
ABSTRACT
There is growing evidence that viruses responsible for pandemics, such as Middle East respiratory syndrome and severe acute respiratory syndrome, are mainly spread through aerosols. Recommendations have been introduced to reduce the transmission risks of virulent airborne viral particles by increasing ventilation rates, expressed in air changes per hour (ACHs), effectively improving the dilution of pathogens via mechanical ventilation. However, infrastructural and operational costs associated with upgrades of building heating, ventilation, and air conditioning systems make these solutions expensive. It is well documented that Ultraviolet Subtype C (UVC) disinfection can help lower exposure risks by inactivating viruses and the performance of such solutions can translate into equivalent ventilation. Here, we present the first framework to extract the optimal UVC requirements to improve facility management yet ensuring compliance with ventilation guidelines at lower energy costs. The Kahn-Mariita (KM) model considers the air quality of shared enclosed spaces over time by supplementing the existing mechanical ventilation with localized UVC air treatment and includes variables such as room size, occupancy, existing ventilation, and target equivalent ACH. For example, the model applied to a conference room shows that a UVC chamber with recirculation rates of 160 m(3)/h increases ventilation from an ACH 3 to 7.9 and reduces the room's reset time from 46 to <10 min with as little as 1 W. Recirculation rates of 30 m(3)/h however offer no benefits beyond 200 mW, with an eACH of 3.9 and reset time of 31 min. The first finding is that single-pass disinfection is not an appropriate metric of performance, i.e., low recirculation rates increase single-pass disinfection, and, however, only treats a portion of the space volume within a given time, limiting the overall performance. Conversely, higher recirculation rates decrease single-pass disinfection but treat larger portions of air, potentially multiple times, and are therefore expected to lower the transmission risk faster. The second result is that for fixed amounts of recirculating air flow, increasing UVC power helps with diminishing return, while for a fixed UVC power, increasing the recirculating air flow will always help. This dynamic is particularly important toward optimizing solutions, given the constraints system engineers must work with, and particularly to design for end-user benefits such as increased occupancy, in-dwelling time, or reduction of shared-space reset time.
ABSTRACT
The Covid-19 pandemic, which originated from Wuhan, Hubei province, China, and quickly spread to the rest of the globe is caused by SARS-CoV-2 coronavirus. Preliminary data suggest a relationship between the BCG vaccine and the prevalence of Covid-19. The vaccine is used in the prevention of tuberculosis, a disease that is most prevalent in developing countries. To determine the potential protective role of Bacillus Calmette-Guerin (BCG) vaccination, this study investigated the occurrence of Covid-19 and the relationship between the spread of Covid-19 in countries that offer BCG vaccination and those that do not. To determine if some SARS-CoV-2 strains were more prevalent than others, the study also performed a phylogenetic analysis of the strains from the representative countries. To achieve the objectives, the study utilized publicly available data on population size, vaccination coverage and Covid-19 cases. The study revealed a significant negative trend between countries that offer the BCG vaccine to the general population and the reported cases of Covid-19. The study proposes future molecular and immunological analyses to determine the potential role of BCG vaccination in protection against Covid-19. This will determine if BCG vaccine has antiviral properties, with the possibility of recommending it for widespread use if supported by scientific data.