While most experts agree that the risk of catching COVID-19 outdoors is very low, it still does not preclude efforts to maintain non-pharmaceutical protocols of checking COVID-19 spread, such as wearing face masks, avoiding large gathering and maintaining social distancing.
This is because there is still the possibility of getting infected when you come too close to someone who is shedding viral loads through coughing or sneezing.
Since Nigeria’s COVID-19 index case of February 27, 2020, breath-holding has become an activity that some of us do almost absent-mindedly.
However, can holding your breath as you walk past someone actually prevent you from catching coronavirus if they happen to be infected?
Experts say the risk is real, but low if you are wearing a good face mask.
Indeed, studies say that holding your breath may actually heighten your risk of COVID-19 infection if you’ve already taken in the air-borne aerosol.
Experts who examine the possibility of contracting COVID-19 when you walk past someone who is coughing or sneezing even warn that holding your breath might do more harm than good. They recommended ways to go about it.
According to a study published online in the American Institute of Physics journal, the transport and deposition of micrometer-sized particles in the lung is the primary mechanism for the spread of aerosol-borne diseases such as COVID-19.
The are of the view that modeling the transport and deposition of drops in human lung bronchioles is of utmost importance to determine their consequences on human health.
The researchers say, contrary to what anyone might think, holding the breath when anyone sneezes or coughs around you may not protect from COVID-19 because the lower breathing frequency or higher breath hold time in-between inhalation and exhalation can increase the threat of virus infection in a crowded place since both of the phenomena increase the deposition in the alveolar region.
This is also upheld by a study by researchers at the Indian Institute of Technology (IIT) Madras, who warn that holding the breath and having low breathing rate can increase the chances of the novel coronavirus-laden droplets being deposited deep in the lungs.
The Indian study, published in the peer-reviewed journal Physics of Fluids, notes that its findings will pave the way for developing better therapies and drugs for respiratory infections, including COVID-19.
The researchers note that several infectious respiratory diseases like COVID-19 that currently threaten the human lives globally, transmit primarily through virus-laden droplets.
“Dramatic respiratory events such as coughs and sneezes that yield a large quantity of droplets play a vital role in aiding such transmission,” says study lead, Prof. Mahesh Panchagnula, from the Department of Applied Mechanics, IIT Madras.
Again, a publication in online journal MIT Medical, states that viral particles disperse quickly in air, and the turbulence caused by two people moving past each other only hastens that process.
“We know that length of exposure is a major factor in virus transmission,” the publication states, noting, however, that fleeting encounters — even relatively close fleeting encounters — carry very little risk, “particularly if both individuals are wearing masks.”
In tracing their findings, the IIT Madras researchers modelled breathing frequency in a laboratory to better understand how the rate of flow of droplet laden with virus determines the deposition of the virus in the lungs.
They found that low breathing frequency increases the time of residence of the virus and therefore it increases the chances of deposition and consequently, the infection.
Prof. Panchagnula says the multiscale lung structure has a significant effect on a person’s susceptibility to COVID-19, hence the ineffectiveness of holding breath after a sneezing or coughing event by someone bearing the virus via the droplets.
That said, holding your breath when you cross someone “might help a little bit in some very infrequent circumstances”, he says. For example, if you cross someone who is shedding a high viral load into aerosols, and their exhaled breath happens to go your way with little dilution.
Stating how to go about it if you choose to hold your breath while airborne-aerosol flies past, honorary Associate Professor and a clinical virologist from the University of Leicester, Dr. Julian Tang, says if you see someone walking towards you, it’s best to take a quick breath in and then you exhale out after you’ve walked past them.
“Holding your breath is good but if you breathe out, it’s even better, because you then blow any virus away,” he says.
Dr. Tang likens it to swimming – you take a big breath, hold, and swim under water. Then when you come up for air, you breathe out. “It’s a physically robust way of avoiding inhaling any aerosols,” he adds.
Again, a professor and emergency room doctor at Delta Hospital, British Columbia, Canada, Prof. Michael Curry, says, “Holding your breath might be marginally beneficial, but unless someone is breathing right in your face or speaking mostly right at you, it is unlikely to spread the virus.
Also speaking, an infectious diseases physician at Trillium Health Partners, Sumon Chakrabarti, says the risk of catching the virus from someone who is briefly walking by is “essentially zero unless they happen to cough or sneeze directly in your face.”
The bottom line: If you are in a public setting with a lot of people around, it is strongly advisable to wear face mask and make sure to practise social distancing.
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