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‘Can’t underestimate the potential of HVAC systems and air filters’

They are vital cogs in the wheel in combatting COVID-19, in light of increasing evidence that SARS-CoV-2 may be transmitted by aerosols, says Dr Iyad Al-Attar, in this free-wheeling interview he gave to Surendar Balakrishnan. Excerpts…

| | Sep 30, 2020 | 1:49 pm
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Dr Iyad Al-Attar

You have often prefaced discussions at webinars with the line, ‘How did we end up here?’ So, how did we?

Scientists believe that urbanisation and global warming could have positioned our atmosphere to be a hospitable sink for viruses and bacteria. Coronaviruses are possibly zoonotic, which suggests that they can transmit from animals to people and from person to a person. Humans are encountering wildlife populations that we have previously never been in contact with, and those populations have new kinds of bacteria and viruses that we may not be ready to confront. Scientists believe that human choices are driving us to witness more outbreaks, owing to the manner in which we are interacting with our planet. We continue to hang our polluted hats on the environment rather than establishing an intrinsic understanding of our human behaviour that seems to be driving our current challenges.

Why are we locked up in our homes, given all the tools and technologies available at our fingertips?

COVID-19 has revealed some real weaknesses in the global health supply chains. If we were perfectly prepared for COVID-19, we could have identified the virus earlier and responded faster to better control its spread. The world’s responses to previous outbreaks have been exceedingly slow and, at times, extraordinarily antiquated – to the extent that unrest has broken out over facemasks and food. With all the advanced technologies available at our fingertips, we are still exposed, and now locked up.

We simply had assumed that the past 60 years of progress in diagnostics, vaccines and supercomputing, and in analytical tools, such as genomics, bioinformatics and scanning electron microscopy would render our preparedness intact. To our surprise, COVID-19 has demonstrated how vulnerable we are, particularly among the immune-compromised patients, new-born, the elderly and the less equipped.

Further, open-ended wars that have left millions of refugees displaced contributed to the soaring cost of health infrastructure and induced difficulties to access populations that are less equipped or ill-prepared, or both. While regulatory frameworks of well-developed countries require refinement to fit emerging realities of recent pandemics, we need to extend a helping hand to countries who are yet to create ones.

How can we regain trust in various applications and indoor spaces, such as airports, shopping malls and schools?

Attention to the role of air filtration in enhancing air quality has been on the wane for the past few decades. HVAC systems have been on a high filtration diet and our respiratory systems have become sick and tired of such air quality. If there are neither marks for enhancing IAQ nor penalties for not doing so, then it is no surprise that no one has spent a penny on improving air quality. Today, we cannot underestimate the potentials of HVAC systems and air filters in combatting COVID-19 in light of increasing evidence that SARS-CoV-2 may be transmitted by aerosols.

Exposure to airborne particulate matter (PM) in urban areas has been a major public health concern. Physical and chemical characterisation of airport-related emissions on air quality is essential in understanding the type of pollutants, their concentration and size distribution and their impact on climate and human health. Considerable attention has been paid recently to the indoor air quality, as a function of airport-related emissions, among other combustion sources of PM in urban areas. Gradually reopening airports and ensuring that the HVAC and filtration systems are capable of capturing and disinfecting the air is a critical topic to the health of passengers, staff and crew members.

We need to redo the math on various aspects of our lifestyles, from personal hygiene to HVAC systems and especially on the kind of air filtration systems we bring to bear to defend our respiratory systems. Long queues in the airport have been a pressing issue for decades but were not tackled. If social distancing is planned to be practised for years to come, it will substantially reduce human occupancy and cause revenue losses. Keep in mind that when budgets were available to provide the latest and greatest HVAC equipment and best air filtration technologies, such tools were not utilised. Today, the excuse could be that economic losses do not allow any sort of improvement and extra spending, and corner-cutting approaches will be the name of the game. We have to be serious about air quality and the underlying parameters of our indoor comfort. We ought to consider the entire physics of the building of interest to ensure that all elements are performing in harmony. These parameters range from air filters selection to HVAC equipment, insulation material, façade, and how green the building is. A similar analogy can be applied for shopping malls and educational facilities, where the facility managers will have to demonstrate to the occupants that yesterday’s choices that got us thus far are no longer an option today.

High-rises have long been seen as the answer to sustainable urbanisation. Green building manuals advocate densely packed communities to avoid long-distance commutes to the workplaces. Is COVID-19, and the mandatory social distancing it has engendered, forcing us to examine that wisdom of densely packed communities and cities?

As a building increases in height, the air temperature outside the building decreases and the wind speed increases, which can
affect the ambient temperatures in the indoor spaces as well as operation of outdoor equipment. The most prominent challenge
in high-rises for HVAC systems, I presume, would be achieving better control on indoor air quality and reducing airborne spread
of bioaerosols. High-rises come with their own package of challenges, including but not limited to stack-effect-induced indoor
airflow, higher infiltration rates at elevated areas through facades and openings, and mechanically induced airflows due to vertical transportation movements within high vertical shafts.

Following the same wisdom, looking at high-rises from a pandemic point of view and the social distancing requirements
should trigger innovative and out-of-the-box approaches to comply with social distance requirements while limiting additional urban
development expansion. These approaches might include rethinking space planning and furnishing design techniques to fit the same
number of people within the same space while keeping social distancing, or revisiting or exploring more flexible or remote work
schedules that allow fewer people to be physically present while delivering the work tasks – for example, a mix of telecommuting
and staggered work schedules. Challenges should trigger innovation rather than limit our options.

High-rises, on their own, are not a solution for long-distance commuting, if they are not part of an overall strategy for sustainable
community, incorporating reduced parking capacity, and for developing residential neighbourhoods that are walking-distance
from workplaces. Further, cities will function better if we provide low- or no-emission alternative transport modes by making more
streets car-free to promote geographical equity, since not all people have or use cars all the time. Bear in mind that at present, we
grant virtually 100% of our streets to cars.

What unique challenges do high-rises pose in the time of COVID-19 and in the event of more such debilitating pandemics? What should we do differently in designing and installing MEP features in high-rises?

MEP systems design and air treatment and air filtration configurations need to take those high-rise-related factors into account while designing those buildings. More accurate modelling techniques should be adopted to predict airflow patterns before deciding on locations and capacities of air treatment equipment.

Moreover, MEP designs and operations in high-riser and other buildings need to plan and adopt an effective strategy for conducting complete building fresh air flush-out operations on a frequent basis, especially before building reopening following any lockdown events. These flush-out operations might require different approaches and retrofits to ventilation systems to ensure effectiveness of these flushes.

One last thought is related to the crucial role of real-time monitoring of air quality – in lieu of one-time air quality tests – inside high-rises in safeguarding building users of any potential risks and building operators of any challenges and operational issues that will require prompt intervention. However, it is important to consider that human occupants can contribute to the spread of the virus when entering or occupying the building through inhaling or exhaling, which can be considered indoor pollution.

How are climate change, air quality and air pollution be interrelated?

The evidence of climate change, owing to human activity, is overwhelming. The signs are all around us: Rising temperatures, melting ice, rising sea levels, more droughts, fires, floods and severe storms. If we do not change our course of action swiftly and sharply, the consequences are going to be terrible. Air pollution and sandstorms add to the complexity of filter performance prediction. Research has proven that polluted air and sandstorms expose the installed filters to high particle concentration, causing pre-mature filter clogging.

From a fossil fuel combustion perspective, what can we change to reduce emissions?

I am not saying never combust fossil fuel, but I am suggesting we should do so responsibly and grant renewables the chance to take a greater share of our energy mix. The energy sector stands as the main contributor to air pollution, where around 6.5 million deaths are attributed to poor air quality; the premature death rate due to this amounts to three million human deaths per year. In fact, poor indoor air quality is considered the world’s fourth-largest threat to human health, with high blood pressure, dietary risks and smoking occupying the top three ranks.

Air quality had taken a backseat for decades without being granted the due attention it deserves. Can we solely rely on air filtration methodologies to confront all contaminants?

Before we embark on enhancing air quality, let’s define what “air quality” is. We ought to regard air filters as an essential element of the HVAC system and not just an accessory. They constitute the sole line of defence for our respiratory system, and their selection should be delegated to filtration experts. Manufacturers have their own fair share of contribution to do in terms of continuous research and development, which could be a collaborative approach among universities, research centres and government entities. We also need to make maintenance teams part of the air quality equation. This could be established through programmes that would involve qualification, training, appropriate examinations and, eventually, enticement through certification and recognition. If we are serious about making a difference in enhancing air quality, we ought to assess air filter performance by efficiency, not filter surface area; by particle-size, not weight, and by real and not ideal loading conditions.

(to be continued)


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