Airborne health risk has become the topmost air quality concern, ever since the U.S. Center of Disease Control and Prevention declared that the transmission of corona virus occurs more commonly through respiratory droplets. The ‘spreads’ from an infected person to others through respiratory droplets and aerosols is created, when an infected person coughs, sneezes, sings, shouts, or talks. Like, the more people speak and exhale, the more carbon dioxide is produced. Reports of outbreaks with poor ventilation suggest that infectious aerosols are suspended in the air and people inhale the virus, lingering in the air. Hence, air exchange and risk management, facilitated by fit-for-purpose air ventilation, is essential in healthcare.

Air cleaning mechanisms are witnessing sprouting technologies, like UV lights, PCO, air purifiers, micro-filtration etc., focusing to combat pollutants and enhance air quality in the context of health risks. Rise in product extensions, technological innovations and integrating new tech activities, in the HVAC system, air cleaning technologies and air handling upgrades is intensifying. Specifically, close contact and fomite exposure i.e. transmission of infectious disease through objects, play a major role in the transmission of virus. Studies indicate, extended short-range aerosol transmission of the virus is possible in crowded and poorly ventilated enclosures.

Image source: Li et al

Evidence for probable aerosol transmission of virus in a poorly ventilated restaurant suggests, it is crucial to prevent overcrowding and provide good ventilation in buildings and transport cabins for preventing the spread of virus and its development. It’s true; ventilation improves air quality and reduces risk of exposing to airborne bacteria and viruses, thus improving wellbeing.

Ed Gardyne, founder and CEO, Safewell Solutions, says, “My opinion from the outset, based on extensive experience in breathing air risk management was that airborne transmission should be considered as a viable mechanism for CV19 spread. This has been proven by recent research.”

Well-maintained HVAC systems, including air-conditioning units, securely filter large droplets containing virus. It is possible that aerosols containing virus spread through HVAC systems within a building and through stand-alone air-conditioning units – if air is re-circulated. However, the extent to which such potential aerosol route contributes to COVID-19 transmission is unknown. There is limited evidence regarding the effect of stand-alone air filtration and other air cleaning technologies in the transmission of virus.

Doing about ventilation

Air quality and occupant comfort are vital to most buildings. Health-wise, virus aerosols are different than other aerosols like pollution. They float in the air, and their movement depends on their size. Coronavirus spreads through the air, especially in indoor spaces. Scientists now openly acknowledge the role played by the transmission of aerosols –the tiny contagious particles exhaled by an infected person that remain suspended in the air of an indoor environment.

An article in the Science magazine found that there is overwhelming evidence – that airborne transmission is a ‘major transmission route’ for the coronavirus, and the CDC now notes that, under certain conditions, they seem to have infected others, who were more than six feet away. These transmissions occurred within enclosed spaces that had inadequate ventilation. Sometimes the infected person was breathing heavily, for example, while singing or exercising. These super-spreading scenarios increasingly appear to be critical to the development and spread of the pandemic. This implies to have ventilation dealing tools to prevent mass transmission at such events which is a key to controlling it.

Smart HVAC systems to control spread

HVAC systems may have a complementary role in decreasing transmission in closed indoor spaces by increasing the rate of air exchange, decreasing recirculation of air, increasing use of outdoor air, and using adequate filters. Researchers, at the University of Alberta, are looking at how to make heating, ventilation and air conditioning systems smart enough to control the spread of COVID-19.

The core of the project is to design an HVAC system that uses machine learning to react to conditions that would contribute to virus spread. “When you look at the HVAC system that is available in the market, mostly they are designed for cost-effectiveness,” says Yousef Alipouri, an engineering post-doctoral fellow studying smart controls for ventilation systems to safeguard public health. He has received funding to study smarter controls for ventilation systems to combat viruses like COVID-19. They are not designed for infection control at all. Public health organizations including Alberta Health Services have identified that poor HVAC systems may contribute to the spread of disease through airborne transmission.

Image source: Yousef Alipouri, An HVAC system in a University of Alberta laboratory.

UV Ducts with viral load testing  technique

UV ducts invented by scientists in India can kill the virus in the air along with air sampling and viral load testing techniques that can check the viral load in the air. According to the scientists, the UV-C Air Duct Disinfection System is designed as a retrofit into existing air ducts. It consists a slide mechanism, regulated UV light source, and sensors. The device can be fit into ducts by minor modifications. This will aid to prevent spread of the coronavirus at public places.

Air handler systems           

Environmental factors influence the efficacy of airborne disease transmission. The sum of all the factors that influence temperature and humidity conditions, either outdoor or indoor, or other circumstances like wind influencing the spread of droplets containing infectious particles; influence the transmission of airborne diseases. Demands for improved IAQ, low sound, high operating efficiency, and smaller mechanical rooms expect a better technology from today’s air handlers producing AHUS. It must effectively combat air contamination with micro-filtration, bacteria-defeating UV lights, mold-resistant drain pans, and anti-microbial liners to produce a healthier building environment.

Air handler units, as part of HVAC system secure acceptable indoor air quality, they maximize ventilation by drawing as much fresh air as possible from outside to decrease the concentration of aerosols. They control parameters such as temperature, humidity, air movement, air cleanliness, providing free hygienic air. AHU manufacturers should design their products depending upon applications, which have led to emergence of wide array of products suitable for various end-use, in industrial and healthcare applications. Nowadays, AHUs need to focus on advanced ventilation techniques to clean air effectively, combining versatility with economical, dependable performance for heating, cooling, ventilation, and VAV (variable air volume) sensors and hygienic applications.

Customized air handlers for traditional applications find extensive use in hotels, museums, theatres, airports, banks, shops and specific sectors as hospitals, food industry, electronics or pharmaceutical industries, and all the industrial applications, with temperature or controlled-contamination processes. Custom air handling unit is fastest-growing in the application sectors such as pharmaceutical industries, shopping malls, hospitals, data centers and universities and places sensitive for airborne transmission.

The scientists highlight that, depending on the size of the particles, different infection control measures would apply to reduce risk, from opening a window to increasing fresh air delivery through an HVAC system. The demand of improved air exchange – is the need for workspaces. Indoor and outdoor air handler in HVAC systems condition and transport large volumes of air and also, have the potential to contain spread of virus across any space.

Air filtration systems

A properly designed and maintained UV system, often in concert with filtration, humidity control, and airflow management, has been shown to reduce infections from other viruses.

“It is important for people to understand how air-filtration systems are supposed to work,” says Jeffrey Siegel, professor, Department of Civil & Mineral Engineering, University of Toronto and an expert in indoor air quality. “Some may be frightened with the situation we are all facing right now, but the best way to protect ourselves, our families, and our communities is with evidence-based information.”

Similar to building filtration, there is no direct clinical evidence of the benefit of portable air cleaners for reducing infectious disease risk, but some benefit can be reasonably inferred for appropriately sized, maintained, and operated portable HEPA filters. It is suggested to better use MERV 13, 14 or HEPA air filters, if ventilation can’t be increased.

Air cleaners with sanitizers

Air cleaners role with embed sanitizers is increasing. They recycle existing and contaminated air within a room or an internal space using high performance filters and immediately release clean air back into the room or internal space. These types of device filters are used in hospitals.

In this process, 99.95% of all viruses, bacteria and germs are reliably filtered out from the air. Such air cleaners offer a high level of safety against potentially pathogenic micro-organisms in places such as hotel lobby, classroom, restaurant, and fitness room or open-space office. Incidentally, the device also filters fine dust from the room or internal spaces with the same efficiency. Air Cleaning System is far more than an air filter. It’s a one-of-a-kind blend of three technologies: filtration, germ-killing ultraviolet light, and a photocatalytic oxidation (PCO) process.

No less to say for new tech-trends

What is meant by airborne or aerosol transmission can be confusing. It is concluded that droplet transmission gets prompted by air-conditioned ventilation. The key factor is the direction of the airflow. There are now good arguments for promoting measures to reduce inhalation of the smallest droplets by exposed individuals.

In changing times, the new technologies, which combat air contamination to produce a healthier and refreshing building environment, are in rising demand. The growth can be attributed to the growing need in healthcare, food & beverages, pharmaceutical, chemical, and oil & gas industries and continuous advancement in air handling technology. Innovative technologies will continue to rule in the future years, primarily, because of incidences of clean air exchange required in ongoing pandemic times.

Pandemic caused by a microbe less than 0.2 microns in size is affecting every aspect of life globally, including the business sector and markets. Increasing ventilation only is not enough to protect people from risks, though it can be part of a plan to protect all of us, as recommended by the Centers for Disease Control and Prevention. EPA also recommends increasing ventilation with outdoor air and air filtration. Foremost, air cleaning solutions can reduce the virus droplets in home over time. The larger plan includes – using hand sanitizers, social distancing, wearing cloth face coverings or masks, surface cleaning and disinfecting, and other precautions.

Looking into future

An invisible virus risk in air has disrupted the lives of everyone on earth. Resultantly, the hullabaloo in rising demand of air hygiene from healthcare sector – is prompting HVAC manufacturers to improvise technology. Tackling air is taking center stage, as businesses plan for safe reopening of workplaces in 2021. Besides, measures to reduce airborne transmission exposure; other measures include limiting the amount of time people spend in areas, without access to fresh outside air – such as storage rooms or basements. Proper air handling can filter out toxic air pollutants causing various medical ailments and respiratory disorders, including asthma and lung cancer.

Research, innovations and technology advancement are needed to tackle the risk issues. Integration of sensors in HVAC units, UV-C wavelength disinfectant options, use of high rated filters, sanitizer-based conditioning of air etc., to support well-being of occupants is going to be a recurring phenomenon. All of these are important, but even more so is – the efficient ventilation using air handlers. Managing well-being of occupants is going stay as a prolonged happening to manage.

An airborne transmission is disease transmission through small particulates that can be transmitted through the air over time and distance. We are still not so near the beginning of receding pandemic times. As the future focus on clean air is the key for best healthcare, we need to balance an interaction between person, environment and the time, which is the emerging trend.

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