A comprehensive study on respiratory parameters using bluetooth enabled multilayered COVID mask: A preventive measure

Within the contemporary state of affairs we all realize the significance of wearing a masks, though we are wear a mask, in some situations we're affected to Covid. In that case our mask is designed in a way which is multilayered and reusable. The primary gain of our masks is that we're setting a breathing sensor (humidity sensor) within the masks so that any sort of respiratory trouble may be detected in a much simpler way with the use of blue tooth. In order too that respiration troubles of human beings may be quarantined and spreading may be stopped at the primary level itself. The ongoing 2nd wave of Covid 19 pandemics has ended in an global scarcity of face mask and the uncooked chemical compounds that move into them, prompting humans to make their personal mask from of regular items. N95/p2 respiration masks are one of the vital components for decreasing the spread of the Covid 19 virus and shielding frontline humans. With the wearable multi layer air cleanser masks our idea is to replace it with homemade masks worn through many and also which are disposable and reusable ones. The layout also makes it viable to wear the unit with no trouble for hours on give up. This might be made light-weight so that users can utilise it with ease. Further survey has been made among a group of people by wearing our mask and their humidity level has been noted thorough the software developed. © 2023 Author(s).

Can 10× cheaper, lower-efficiency particulate air filters and box fans complement High-Efficiency Particulate Air (HEPA) purifiers to help control the COVID-19 pandemic?

Public health departments such as CDC and California Department of Public Health (CA-DPH) advise HEPA-purifiers to limit transmission of SARS-CoV-2 indoor spaces. CA-DPH recommends air exchanges per hour (ACH) of 4-6 air for rooms with marginal ventilation and 6-12 in classrooms often necessitating multiple HEPA-purifiers per room, unaffordable in under-resourced community settings. Pressure to seek cheap, rapid air filtration resulted in proliferation of lower-cost, Do-It-Yourself (DIY) air purifiers whose performance is not well characterized compared to HEPA-purifiers. Primary metrics are clean air delivery rate (CADR), noise generated (dBA), and affordability ($$). CADR measurement often requires hard-to-replicate laboratory experiments with generated aerosols. We use simplified, low-cost measurement tools of ambient aerosols enabling scalable evaluation of aerosol filtration efficiencies (0.3 to 10 µm), estimated CADR, and noise generation to compare 3 HEPA-purifiers and 9 DIY purifier designs. DIY purifiers consist of one or two box fans coupled to single MERV 13-16 filters (1″-5″ thick) or quad filters in a cube. Accounting for reduced filtration efficiency of MERV 13-16 filters (versus HEPA) at the most penetrating particle size of 0.3 µm, estimated CADR of DIY purifiers using 2″ (67%), 4″ (66%), and 5″ (85%) filters at lowest fan speed was 293 cfm ($35), 322 cfm ($58), and 405 cfm ($120) comparable to best-in-class, low-noise generating HEPA-purifier running at maximum speed with at 282 cfm ($549). Quad filter designs, popularly known Corsi-Rosenthal boxes, achieved gains in estimated CADR below 80% over single filter designs, less than the 100% gain by adding a second DIY purifier. Replacing one of the four filters with a second fan resulted in gains of 125%-150% in estimated CADR. Tested DIY alternatives using lower-efficiency, single filters compare favorably to tested HEPA-purifiers in estimated CADR, noise generated at five to ten times lower cost, enabling cheap, rapid aerosol removal indoors.

Human exposure against airborne pathogens in an office environment

Airborne exposure has been highlighted during the COVID-19 pandemic as a probable infection route. This experimental study investigates different protection methods at an office workstation, where the concentration characteristics are studied under the mixing ventilation conditions. The protection methods were the room air purifier, personal air purifier, face mask, and workstation partition panels. In experiments, the breathing machine, nebulizer, and syringe pump was used to generate an aerosol distribution of paraffin oil into the room. The breathing thermal manikin and the thermal dummy simulated the exposed and infected person, respectively. The concentration characteristics were measured from the manikin breathing zone. The temporal concentration characteristics were measured from zero concentration to steady-state conditions. The study provides insights into the effects of different protection methods for occupational health and safety decision-making for office indoor environments. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Conceptual Design of a UVC-LED Air Purifier to Reduce Airborne Pathogen Transmission—A Feasibility Study

Existing indoor closed ultraviolet-C (UVC) air purifiers (UVC in a box) have faced technological challenges during the COVID-19 breakout, owing to demands of low energy consumption, high flow rates, and high kill rates at the same time. A new conceptual design of a novel UVC-LED (light-emitting diode) air purifier for a low-cost solution to mitigate airborne diseases is proposed. The concept focuses on performance and robustness. It contains a dust-filter assembly, an innovative UVC chamber, and a fan. The low-cost dust filter aims to suppress dust accumulation in the UVC chamber to ensure durability and is conceptually shown to be easily replaced while mitigating any possible contamination. The chamber includes novel turbulence-generating grids and a novel LED arrangement. The turbulent generator promotes air mixing, while the LEDs inactivate the pathogens at a high flow rate and sufficient kill rate. The conceptual design is portable and can fit into ventilation ducts. Computational fluid dynamics and UVC ray methods were used for analysis. The design produces a kill rate above 97% for COVID and tuberculosis and above 92% for influenza A at a flow rate of 100 L/s and power consumption of less than 300 W. An analysis of the dust-filter performance yields the irradiation and flow fields.

The performance evaluation of pleated electret filters enhanced by electrostatic enhanced method

The filtration efficiency deterioration over operating time due to exposure to particles, organic solvents and other factors is an obvious defect of electret filter, especially during the coronavirus pandemic. Electrostatic enhanced method has been proposed as a promising way to improve the filtration efficiency and service time of electret filters without increasing the pressure drop. In this work, the effect of discharge electrode structure and operation mode of the electrostatic enhanced structure(EES) on the filtration efficiency of commercial pleated electret filters were studied firstly, then the EES was installed in a special designed prototype air purifier, two key indicators of air purifiers(clean air delivery rate (CADR) and cumulate clean mass (CCM)) were tested to evaluate the actual performance improvement of electret filters by the electrostatic enhanced method. It was found that the discharge electrode structure had significant influence on the filtration efficiency and multi-wire array electrode was more suitable for the discharge electrode to pleated filter to ground mesh structure used in this paper. The decayed electrostatic charges of pleated electret filter cannot be recharged again through the EES in actual operation condition. The filtration efficiency improvement of the test pleated electret filters was dominantly contributed by particle charging. The filter polarizing induced by the external electric field was helpful in increasing the filtration efficiency when the particles were charged while its effect on uncharged particles was almost negligible. Besides, the actual performance of the prototype air purifier indicated that the EES can alleviate the filtration efficiency deterioration of test electret filters and extend the service life of H11 and H13 filters by more than 3 and 1.5 times respectively according to the CCM test results. © 2023 IOP Publishing Ltd.

Dispersion of droplets due to the use of air purifiers during summer: Focus on the spread of COVID-19.

Coronavirus disease (COVID-19), which emerged in 2019, has induced worldwide chaos. The main cause of COVID-19 mass infection indoors is the spread of virus-containing droplets via indoor airflow, which is affected by air conditioners and purifiers. Here, ten experimental cases were established to analyze how use of air purifiers affects the spread of virus-containing droplets. The experiments were conducted in a school classroom with an air conditioner in summer. In the droplet dispersion experiment, paraffin oil was used as the droplet substance. Two main scenarios were simulated: (1) an infected student was seated in the back of the classroom; and (2) the teacher, standing in the front of the classroom, was infected. The results were expressed using two parameters: peak concentration and loss rate, which reflect the degree of direct and indirect infection (airborne infection), respectively. The air purifier induced a peak concentration decrease of 42% or an increase of 278%, depending on its location in the classroom. Conversely, when the air purifier was operated in the high mode (flow rate = 500 CMH; cubic meters per hour), the loss rate showed that the amount of droplet nuclei only decreased by 39% and the droplet amount decreased by 22%. Thus, the airborne infection degree can be significantly reduced. Finally, the use of air purifiers in the summer may be helpful in preventing group infections by reducing the loss rate and peak concentration if the air purifier is placed in a strategic location, according to the airflow of the corresponding room.

Experimental studies of particle removal and probability of COVID-19 infection in passenger railcars.

A series of experiments in stationary and moving passenger railcars was conducted to measure the removal rates of particles in the size ranges of SARS-CoV-2 viral aerosols, and the air changes per hour provided by the existing and modified air handling systems. The effect of ventilation and air filtration systems on removal rates and their effects on estimated probability (i.e., risk) of infection was evaluated in a range of representative conditions: (1) for two different ratios of recirculated air (RA) to outdoor air (OA) (90:10 RA:OA and 67:33 RA:OA); (2) using minimum efficiency reporting value (MERV) filters with standard (MERV-8) and increased (MERV-13) filtration ratings; and (3) in the presence and absence of a portable high-efficiency particulate-air (HEPA) room air purifier system operated at clean air delivery rate (CADR) of 150 and 550 cfm. The higher-efficiency MERV-13 filters significantly increased particle removal rates on average by 3.8 to 8.4 hr-1 across particle sizes ranging from 0.3 to 10 µm (p < 0.01) compared to MERV-8 filters. The different RA:OA ratios and the use of a portable HEPA air purifier system had little effect on particle removal rates. MERV-13 filters reduced the estimated probability of infection by 42% compared to the MERV-8 filter. The use of a HEPA-air purifier with a MERV-13 filter causes a 50% reduction in the estimated probability of infection. Upgrading the efficiency of HVAC filters from MERV-8 to MERV-13 in public transit vehicles is the most effective exposure control method resulting in a clear reduction in the removal rates of aerosol particles and the estimated probability of infection.

Optimal position of air purifiers in elevator cabins for the improvement of their ventilation effectiveness

Ventilation in confined spaces is essential to reduce the airborne transmission of viruses responsible for respiratory diseases such as COVID-19. Mechanical ventilation using purifiers is an interesting solution for elevator cabins to reduce the risk of infection and improve the air quality. In this work, the optimal position and blowing direction of these devices to maximize ventilation and minimize the residence time of the air inside two cabins (large and small) is studied. Special attention is devoted to idle periods when the cabin is not used by the passengers, in order to keep the cabin ambient safe and clean, avoiding that the trapped air in the cabin (after its use) could suppose a reservoir for contaminants. CFD numerical models of two typical cabin geometries, including the discretization of small slots and grilles for infiltration, have been developed. A full 3D URANS approach with a k-epsilon RNG turbulence model and a non-reactive scalar to compute the mean age of air (MAA) was employed. The CFD results have been also validated with experimental measurements from a home-made 1:4 small-scale mock-up. The optimal position of the purifier is on the larger sidewall of the cabins for a downward blowing direction (case 1 of the database). Flow rates in the range of 0.4–0.6 m3/min, depending on the size of the cabin, are sufficient to assure a correct ventilation. Upward blowing may be preferable only if interaction of the jet core with the ceiling or other flow deflecting elements are found. In general, the contribution of infiltrations (reaching values of up to 10%), and how these secondary flows interact with the main flow pattern driven by the purifier, is relevant and not considered previously in the literature. Though an optimal position can improve ventilation considerably, it has been proven that a good choice of the purification flow rate is more critical to ensure an adequate air renewal. © 2022 The Authors

Design, Fabrication, and Testing of a Solar Powered Air Purifier with UV Sterilization Capability

Rising air pollution is a cause of concern throughout the world. With rapid industrialization, growth of transportation industry, increasing construction activities, all has taken a toll on the air quality. The air quality in most parts of our country remains poor to moderately pollute for maximum part of the year. P.M. 2.5, P.M. 10, NOx, and SOx are the primary pollutants. Along with the poor quality of air, COVID-19 has added to the misery by affecting the respiratory tract and further worsening the condition of a patient. Through this project, we aim to build a economical solar powered air purifier that can be installed in each and every household as well as outdoors, catering to the air quality indoors, and contributing in purification of the air in the surrounding environment. The air purifier would be capable of providing air filtration as well as sterilization be powered by solar energy and be available at an affordable price. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Design of IoT Based Indoor Air Purifier

An IoT-based system for monitoring the quality of the air within a building, which includes a "Smart-Air"air quality sensor on a web server. IoT and cloud storage are used to evaluate the quality of the air at any time and from any place. Smart-Air is a product of the Internet of Things (IoT), a device that uses LTE to broadcast real-time data on air quality to a web server. Today, air pollution is a leading cause of preventable mortality and disease across the world. Pollution has become a major concern all around the globe. The discharge of chemicals or unfriendly compounds has a devastating impact on human, animal, and plant life. This is referred to as pollution. Many studies have been conducted on different air purification techniques because of this. Air purifiers that utilize HEPA filters, activated carbon, and UV light are discussed in this paper. The water and chemicals that an air purifier sprays into the air will spread out contaminants. © 2022 IEEE.

Optimal position of air purifiers in elevator cabins for the improvement of their ventilation effectiveness

Ventilation in confined spaces is essential to reduce the airborne transmission of viruses responsible for respiratory diseases such as COVID-19. Mechanical ventilation using purifiers is an interesting solution for elevator cabins to reduce the risk of infection and improve the air quality. In this work, the optimal position and blowing direction of these devices to maximize ventilation and minimize the residence time of the air inside two cabins (large and small) is studied. Special attention is devoted to idle periods when the cabin is not used by the passengers, in order to keep the cabin ambient safe and clean, avoiding that the trapped air in the cabin (after its use) could suppose a reservoir for contaminants. CFD numerical models of two typical cabin geometries, including the discretization of small slots and grilles for infiltration, have been developed. A full 3D URANS approach with a k-epsilon RNG turbulence model and a non-reactive scalar to compute the mean age of air (MAA) was employed. The CFD results have been also validated with experimental measurements from a home-made 1:4 small-scale mock-up. The optimal position of the purifier is on the larger sidewall of the cabins for a downward blowing direction (case 1 of the database). Flow rates in the range of 0.4–0.6 m3/min, depending on the size of the cabin, are sufficient to assure a correct ventilation. Upward blowing may be preferable only if interaction of the jet core with the ceiling or other flow deflecting elements are found. In general, the contribution of infiltrations (reaching values of up to 10%), and how these secondary flows interact with the main flow pattern driven by the purifier, is relevant and not considered previously in the literature. Though an optimal position can improve ventilation considerably, it has been proven that a good choice of the purification flow rate is more critical to ensure an adequate air renewal.

Natural Ventilation and Air Purification for Effective Removal of Airborne Virus in Classrooms with Heater Operation.

Mass COVID-19 infection cases in indoor spaces have been continuously reported since its global outbreak, generating increasing public interest in reducing the spread of the virus. This study considered a situation in which an infected individual continuously releases the virus into the air in a classroom, simulated by continuous injection of NaCl particles ≤ 5 µm, with heater operation during winter. The effects of applying natural ventilation and operating one or two air purifiers on the removal of virus-containing aerosols were experimentally compared and analyzed based on the spatiotemporal changes in NaCl concentration within the classroom. When a heater was operated with all windows shut, operating one and two air purifiers reduced the amount of the aerosol in indoor air by approximately 50 and 60%, respectively, compared to the case with no air purifier. Additionally, when the heater was operated with one or two air purifiers under natural ventilation, the amount of virus-containing aerosol in the air was reduced by 86-88% compared to the case with neither natural ventilation nor air purifier. Because natural ventilation significantly varies with weather conditions and particulate matter concentrations, combining natural ventilation with air purifiers in classrooms during winter needs to be adjusted appropriately.

Reducing the Effectiveness of Ward Particulate Matter, Bacteria and Influenza Virus by Combining Two Complementary Air Purifiers.

Air purifiers should pay much attention to hospital-associated infections, but the role of a single air purifier is limited. The goal of this study was to evaluate the effectiveness of the combined application of the nonequilibrium positive and negative oxygen ion purifier (PNOI) and the high-efficiency particulate air filter (HEPA) on a complex, polluted environment. Two of the better performing purifiers were selected before the study. The efficacy of their use alone and in combination for purification of cigarette particulate matter (PM), Staphylococcus albicans, and influenza virus were then evaluated under a simulated contaminated ward. PNAI and HEPA alone are deficient. However, when they were combined, they achieved 98.44%, 99.75%, and 100% 30 min purification rates for cigarette PM, S. albus, and influenza virus, respectively. The purification of pollution of various particle sizes and positions was optimized and reduced differentials, and a subset of airborne influenza viruses is inactivated. Furthermore, they were superior to ultraviolet disinfection for microbial purification in air. This work demonstrates the strong purification capability of the combined application of these two air purifiers for complex air pollution, which provides a new idea for infection control in medical institutions.

Water-based air purifier with ventilation fan system: a novel approach for cleaning indoor/outdoor transitional air during the pandemic.

Abstract: This article presents the design and fabrication of an air purifier that uses a water-based technique to clean indoor/outdoor transitional air to provide a low-tech air purifier against the annual smog crisis and the ongoing COVID-19 pandemic. The air purifier was designed and built. All tests were conducted in a closed room as well as a semi-outdoor area. Particle sizes of PM0.3, 0.5, 1.0, 3.0, 5.0, and 10 µm (particle/m3) were measured at an air inlet, air outlet, 2 m from an air inlet, and 4 m from an air outlet after 0, 5, 10, 15, and 20 min of air treatment, respectively, as well as CO2 levels and relative humidity (RH). The average airflow rate was also measured. When compare to 0 min, all parameters, except semi-outdoor PM0.3 and CO2 levels, tend to decrease in both indoor and semi-outdoor conditions. When measure by total airflow specification of a dual ventilation fan, the average airflow rate at an air outlet is reduced by 20 times. Article Highlights: Design and fabrication of a water-based air purifier.A low-tech air purifier helping to protect against the annual smog crisis and the ongoing COVID-19 pandemic.The novel water-based air purifier effectively traps air particles ranging in size from 0.5 to 10 µm.

Identifying behavior of long-distance virus transmission and mitigation performance from a COVID-19 outbreak of a daycare center.

During the last two years, hundreds of millions of people in the world have been infected with SARS-CoV-2 due to recurrent waves and closed spaces. Daycare centers are critical infrastructures that cannot be replaced, even during the COVID-19 period. However, the existing settings in daycare centers may pose risks of inevitable close contact between teachers and children, as well as fomite and airborne transmission during care hours. Therefore, reinforced mitigation strategies have been applied in daycare centers to reduce potential indoor virus transfer in many countries. However, numerous outbreaks of COVID-19 have been reported in daycare centers. Therefore, in this study, researchers focused on the risk and behavior of long-distance virus transmission based on the detected viruses on air purifier filter sampling in a daycare center outbreak in Korea. Various experiments of possible situations were conducted in nursing rooms based on field interviews. The experiments monitored the long-distance transmission behavior of aerosol-sized particles and visualized particle behavior at the daycare center. The results of this study revealed that long-distance virus transmission is possible under the current settings in the daycare center, and flush-out can be an important countermeasure with reinforced ventilation methods to prevent potential airborne spread in the daycare center. The results of air purifiers represented that air purifiers should be properly installed and operated in the daycare center to prevent airborne virus spread by airflow during occupied hours. The findings of this study will contribute to the understanding of airborne virus risk and the development of customized virus measures for daycare centers.

The Myth of Air Purifier in Mitigating the Transmission Risk of SARS-CoV-2 Virus

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly infectious disease that emerged in December of 2019, threatening human health and leading to global public health crises. Airborne transmission via droplets and aerosol has been recently recognized as one of the infection modes for the SARS-CoV-2 virus. Hospitals have deployed/incorporated indoor air purifiers with the hope to minimize the transmission risk of SARS-CoV-2 virus. Nevertheless, the effectiveness of the indoor air purifier in reducing the transmission risk remained unknown. This study uses computational fluid dynamics to model the dispersion of the aerosol particles exhaled from the patient under the influence of an air conditioner, exhaust fans and air purifier. The numerical model showed that airflow from the diffusers, exhaust fans and placement of the air purifier significantly influenced the dispersion pattern of the aerosol particles in the common ward. Multiple air purifiers placed at 1 meter above the floor and next to a patient can increase the total efficiency from 37.14 to 59.91% for weak exhalation and from 36.44% to 48.81% for medium exhalation. No aerosol particles flew out from the door for weak and medium exhalation when multiple air purifiers were deployed in the common ward. Location and matching the clean air delivery rate with the size of the room are the important factors that affect the performance of the air purifier. © The Author(s).

Indoor air purifiers in the effort to reduce the spread of Coronavirus Disease 2019 (COVID-19): The advantage of circumferential outflow diffusers

Aerosol particles containing virions or the ribonucleic acid (RNA) of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) can be airborne. It has been recently hypothesized that the outflow from air purifiers with a directional outlet could entrain SARSCoV-2-containing particles. Because only the case of a directional outflow was examined, here we investigate an indoor air purifier with a circumferential outflow diffuser instead of a directional outflow, the other typical design. We measured the airflow velocity at two different angles to the surface of the circumferential outflow diffuser and two motor-fan speeds. We visualized in scattered light the deflection of a vertical mist spray cone from a sneeze-simulating nebulizer parallel to the side of the air purifier. We found a significant difference in airflow velocities for different angles to the circumferential outflow diffuser: 0.01 m/s – 0.02 m/s for 0° vs. 0.01 m/s – 0.65 m/s for 45° at 1 m distance. We observed no significant deflection of the sneeze-simulating spray cone at the minimum blower speed and a 5 cm deflection at the maximum speed under the experimental conditions. The deflection of the sneeze-simulating spray mist particles by the tested indoor air purifier with the circumferential outflow, under the experimental conditions, is low relative to the recommended safer distances between people in indoor spaces aimed at reducing the spread of COVID-19. Equipping indoor air purifiers with circumferential outflow diffusers has a considerably lower potential to spread infectious aerosols in indoor spaces compared to devices with unidirectional outflow. © 2021 Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA. All rights reserved.

Effects of Air Purifiers on the Spread of Simulated Respiratory Droplet Nuclei and Virus Aggregates.

The present study was performed to quantitatively evaluate the effects of air purifiers on the spread of COVID-19 and to suggest guidelines for their safe use. To simulate respiratory droplet nuclei and nano-sized virus aggregates, deionized water containing 100 nm of polystyrene latex (PSL) particles was sprayed using a vibrating mesh nebulizer, and the changes in the particle number concentration were measured for various locations of the particle source and air purifier in a standard 30 m3 test chamber. The spread of the simulated respiratory droplet nuclei by the air purifier was not significant, but the nano-sized aggregates were significantly affected by the airflow generated by the air purifier. However, due to the removal of the airborne particles by the HEPA filter contained in the air purifier, continuous operation of the air purifier reduced the number concentration of both the simulated respiratory droplet nuclei and nano-sized aggregates in comparison to the experiment without operation of the air purifier. The effect of the airflow generated by the air purifier on the spread of simulated respiratory droplet nuclei and nano-sized aggregates was negligible when the distance between the air purifier and the nebulizer exceeded 1 m.

The effect of an air purifier on aerosol generation measurements during clinical motility testing.

BACKGROUND: Aerosol spread is key to interpret the risk of viral contamination during clinical procedures such as esophageal high-resolution manometry (HRM). Installing an air purifier seems a legitimate strategy, but this has recently been questioned. METHODS: Patients undergoing an HRM procedure at the Leuven University Hospital were included in this clinical study. All subjects had to wear a surgical mask which was only lowered beneath the nose during the placement and removal of the nasogastric catheter. The number of aerosol particles was measured by a Lasair® II Particle Counter to obtain data about different particles sizes: 0.3; 0.5; 1.0; 3.0; 5.0; and 10.0 µm. Measurements were done immediately before the placement and the removal of the HRM catheter, and one and 5 min after. A portable air purifier with high-efficiency particle air filters was installed in the hospital room. KEY RESULTS: Thirteen patients underwent a manometry examination. The amount of 0.3 µm-sized particles was unaffected during the whole procedure. The larger particle sizes (1.0; 3.0; 5.0; and 10.0 µm) decreased when the catheter was positioned, but not 0.5 µm. During the HRM measurements itself, these numbers decreased further. Yet, 1 min after catheter removal a significant elevation of particles was seen, which did not recover within 5 min. CONCLUSIONS & INTERFERENCES: Based on this study, there is no evidence that filtration systems reduce aerosol particles properly during a clinical investigation.

Are photocatalytic processes effective for removal of airborne viruses from indoor air? A narrative review.

A wide variety of methods have been applied in indoor air to reduce the microbial load and reduce the transmission rate of acute respiratory diseases to personnel in healthcare sittings. In recent months, with the occurrence of COVID-19 pandemic, the role of portable ventilation systems in reducing the load of virus in indoor air has received much attention. The present study delineates a comprehensive up-to-date overview of the available photocatalysis technologies that have been applied for inactivating and removing airborne viruses. The detection methods for identifying viral particles in air and the main mechanisms involving in virus inactivation during photocatalysis are described and discussed. The photocatalytic processes could effectively decrease the load of viruses in indoor air. However, a constant viral model may not be generalizable to other airborne viruses. In photocatalytic processes, temperature and humidity play a distinct role in the inactivation of viruses through changing photocatalytic rate. The main mechanisms for inactivation of airborne viruses in the photocatalytic processes included chemical oxidation by the reactive oxygen species (ROS), the toxicity of metal ions released from metal-containing photocatalysts, and morphological damage of viruses.