Covid19 and open windows
Many papers have been written on the topic of bio-aerosols and there seems to a general agreement about the airborne transmission of Covid19. We need to deconstruct various facets of this reality to come up with viable solutions.
If you ever happen to visit the countryside on a calm winter evening, it is highly likely that you must have witnessed smoke emerging from the village houses and forming as a static layer, some meters above the ground. Standing still, till a cold winter breeze pushes it towards its salvation.
If you have ever smoked in your life, in a closed room, you would have witnessed an almost static cluster of tobacco smoke hanging in the air. It is so still that a gentle blow of a bored smoker can make a hole through this cloudy mass. Likewise, you may have witnessed smoke emerging from incense sticks build its layered presence inside a closed room.
Ever wondered what is the commonality between these occurrences?
Well, they are all aerosols. Due to their size and weight, they float in the atmosphere. Buoyancy must be keeping them together until a higher force, like wind, disperses them into the atmosphere. Aerosols that comprise of particles of biological origin are called bio-aerosols.
At this point you might be wondering, what has all this got to do with Covid19?
Aerosols are small particles which are less than 5 microns. They are much smaller that droplets, which have a size greater than 5 microns hence, cannot travel far. The recommended Covid19 related social distancing measures are to avoid getting infected from there droplets. It is these droplets which are believed to be the primary cause of surface contamination.
The study Aerodynamic Characteristics and RNA Concentration of SARS-CoV-2 Aerosol in Wuhan Hospitals during COVID-19 Outbreak mentions that the size of bio-aerosols carrying Novel Human Coronavirus at locations of peak concentration in a hospital environment was found to vary from 0.25 to 1.0 micron. Size of tobacco smoke aerosols varies from 0.1 to 1.0 micron. So there is a high chance that these bio-aerosols would also behave like all the other aerosols and hang as a cluster in a still environment.
Does the mention of such an environment sound familiar?
Well, that is the setting of all modern centrally air-conditioned infrastructures. This includes airports, offices, banks, malls… and many homes. Most of the hospitals also boast of similar environment. The Wuhan study also found higher concentration of aerosols in crowd gathering sites, perhaps due to asymptomatic carriers.
The story does not end here. The aerosols eventually land on surfaces. The Wuhan study also mentions that “Our finding has confirmed the aerosol transmission as an important pathway for surface contamination.”
What this means is that apart from being a possible cause of airborne transmission; aerosols are also contributing to surface contamination. Simply put, we cannot ignore their role in spread of Covid19.
How are aerosols released?
Aerosols are released not just by coughing or sneezing but also during breathing and talking. If the smoke logic was to be applied, the aerosols released during breathing and talking seem to be a bigger threat as sneezing and coughing will disperse the aerosols over a wider area which should logically reduce its viral load, i.e. aerosol concentration per unit volume. In the current scenario, people are taking precautions while coughing and sneezing so there is some mitigation of risks there. But the same is not true for breathing and talking.
Imagine an asymptomatic person sitting in an airplane, an airport, an office space or a mall lobby. All these spaces have perfectly still environment with ideal temperature and humidity. Could that be the reason why people in transit brought home the infections while all our friends, even those living at various global hot spots, have largely managed to stay away from the infection? Did these artificial environments amplify the spread of Covid19 across the world?
Can aerosols spread Covid19?
This is a million dollar question which seems to have divided the scientific community. Many papers have been written on the topic and are awaiting peer review. But there seems to a general agreement that the possibility of airborne transmission cannot be ruled out.
A study published in The New England Journal of Medicine found that the Novel Human Coronavirus remained airborne in laboratory conditions for almost 3 hours, though there was over 80% reduction in viral load during this period. But the problem does not end there. These aerosols eventually land on various surfaces and can re-contaminate the air if they get the desired push. Almost behaving like fine dust!
Recent study at University of Nebraska Medical Center found widespread presence of virus in isolation rooms of patients. Positive viral RNA samples were found as far as 6 feet from the patients through the viral activity of these particles could not ascertained.
I was quite intrigued by the fact that the Wuhan study found high concentration on aerosols in the protective apparel removal rooms of healthcare professionals. The study attributes the reason of this high concentration to re-suspension of bio-aerosols from staff apparel due to its higher mobility during changeover. That is why the study recommends surface sanitization of the apparel before they are taken off, to reduce the infection risks for medical staff. The study also mentions that in a hospital environment, aerosols get released in larger quantities during various medical procedures.
While most scientists and doctors are careful with their observations, aerosol scientist Lidia Morawska at the Queensland University of Technology in Brisbane, Australia, minces no words. In an article published by Nature she is quoted saying that “In the mind of scientists working on this, there is absolutely no doubt that the virus spreads in the air. This is a no-brainer.”
To me, her statement makes a lot of sense. Unlike the exposure to surface contamination, aerosol based transmission means that the virus can gain an almost unhindered entry into the lungs. I wonder if that increases the risk of getting the disease even with lesser viral load.
I wonder if one of the key modes of transmission in the Nizamuddin gathering of Tablighi Jaamat was these aerosols. I inquired a friend, who is well versed with the venue and knows the details of how the Jammat functioned during those days. He told me that even though the participants were asked to maintain social distancing while laying the beds, some choose to sleep next to their friends and acquaintances who were not feeling well. Obviously they overlooked the possibility of Covid19, thereby exposing themselves to the risk of contracting the infection. But can we ignore the fact that the venue does not have good ventilation. Even a few asymptomatic and symptomatic patients in such a scenario could have released significant amount of bio-aerosols. If airborne transmission of Covid19 is viable then the numbers that the event eventually threw up is nothing to be surprised about.
The possible solution
Most of the studies suggest that proper ventilation can mitigate the risks of airborne transmission. Isn’t that pretty obvious?
I think it high time we switch off the air conditioners, switch on the fans and opened the windows. Logically this should disperse the aerosols over a wider area thus reducing the atmospheric viral load. Even if these aerosols settle on surfaces, they would settle over a larger area thus reducing the viral load of the surfaces as well.
I think even the hospitals should follow this regime. Due to the lockdown, the air is pretty clean. Luckily, the weather is also nice. What can be better for a patient than a whiff of fresh air? Isn’t that what we always long for?
But if the air conditioners cannot be switched off for any reason then at least the fans can be switched on to ensure good circulation of air. Based on experience, I can say with surety that air conditioning is more effective with the fans on, especially in case of window air conditioners.
As I have already mentioned in a previous article, the threat of aerosols can also be minimized by wearing masks as it would reduce the release and intake of aerosols. An everyone-on-mask regime seems to be the need of the day because it is tough to identify asymptomatic patients. The report Rapid Expert Consultation on the Possibility of Bioaerosol Spread of SARS-CoV-2 for the COVID-19 Pandemic also supports this approach. It mentions that “Surgical masks reduced detection of Coronavirus RNA in both respiratory droplets and aerosols, but only respiratory droplets and not aerosols for influenza virus RNA. These findings suggest that surgical face masks could reduce transmission of human Coronavirus and influenza infections if worn by infected individuals capable of transmitting the infection.”
The conclusions so far clearly suggest that proper ventilation is a must, not just for checking the spread of Covid19 but also for our general well-being.
I strongly feel that once the lock down is eased and people are allowed to slowly return to their normal lives, we should seriously consider the option of dismantling the central air-conditioning systems, pulling down the glass walls and replacing them with windows. These glass chambers make no sense at all. It is high time we realize that sweating is OK. It is just our body trying to cool us down while releasing the toxins. How can we so dislike a natural process designed for our own well-being?
I take this opportunity to also state that I feel strongly about people in suit and tie congregating in an air-conditioned room for meetings. I find it to be one of the big hypocrisies of modern times. Even the so-called climate change champions like Tata Energy Research Institute dishes out papers on climate change from within the confines of a centrally air conditioned environment. Can you beat that? Perhaps yes. Tucking inside a quilt in an air conditioned room is perhaps worse. But nothing can beat the folks who sweat it out in an air conditioned gym. I hope that is not you?
I end this post scriptum monologue by saying sorry for my inability to control that outburst. Could not help speaking my mind! And in spite of the tragedy that we are witnessing, I cannot help but thank the virus for making these questions relevant and bringing them to the fore. It is indeed ironical that we humans need tragedies to build a better world!