ABSTRACT
The validity of using CO2 as an indicator of airborne infection probability was studied. Tracer gas measurements were conducted in a field lab with two breathing thermal manikins resembling "infected” and "susceptible” persons seated at desks. The room was ventilated with a mixing air distribution. Experiments were performed at three ventilation rates. CO2 gas was dosed into the air exhaled by the manikins to simulate the metabolic CO2 generation by people. Simultaneously, nitrous oxide (N2O) tracer gas was dosed into the air exhaled by one of the manikins ("infected person”) to simulate the emission of exhaled infectious particles. CO2 and N2O concentrations were measured at several points. The probability of infection was calculated based on the concentration of CO2 and N2O measured in the air inhaled by the exposed manikin ("susceptible person”). The results did not confirm that CO2 can be used as a proxy to assess the infection probability. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.
ABSTRACT
CO2 gas sensors are rapidly growing in importance since they can be easily deployed to assess air quality inside buildings, improving people's life. According to medical studies, we know that exposure to high levels of carbon dioxide on a daily basis poses a risk to people's health with adverse effects at different levels, such as on the neurological, cardiovascular, and respiratory systems. Moreover, the COVID-19 pandemic has shown how important it is to monitor air quality and ensure good ventilation to prevent infection through airborne transmission paths. Some studies estimate the likelihood of indoor airborne infection transmission based on continuous CO2 measurements. This work presents the design of a 32-bit microprocessor based on the RISC-V ISA architecture intended for energy-efficient signal processing in wireless sensor nodes. In particular, the processor is optimized for its application in non-dispersive infrared (NDIR) CO2 sensors. We use asynchronous demodulation to extract the information from the sensor. Therefore, we generate digital quadrature signals for demodulation, requiring the computation of trigonometric functions by the RISC-V processor. We try different strategies to optimize the processor design and the demodulation process to minimize energy consumption while measuring CO2 levels. © 2022 IEEE.
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.