Coughing is a ‘is a potent generator of aerosols’, concludes study

Aerosols are believed to be a significant route of transmission for the virus, and may remain in the air for hours.

Matt Bodell
4 February 2021

The new research has led to calls for PPE guidance to be urgently reviewed.

Coughing is a potent generator or aerosols and a far greater risk than first assumed, according to a new study.


The new research, conducted by the University of Bristol and North Bristol NHS trust, concludes that a patient coughing produces more aerosolised particles than other procedures historically deemed aerosol-generating.

The study compared the aerosols generated by patients breathing, speaking, coughing, high-flow oxygen and using continuous positive airway pressure (CPAP) ventilation.

It concluded that coughing posed the more significant risk with a peak concentration at least 10 times greater the mean concentration generated from speaking or breathing

Only last month healthcare workers were once again denied access to the highest-level of personal protective equipment (PPE), leaving frontline workers caring for confirmed or suspected COVID-19 patients have been wearing nothing more than a thin plastic apron, a standard surgical mask and gloves.


With aerosols being a significant route of transmission for the virus, the highest-level of personal protective equipment (PPE), which includes FF3 masks, long-armed gowns and visors, were reserved for these so-called aerosol-generating procedures (AGPs). Examples of AGPs are; CPR, intubation, NIV, CPAP and any induction of sputum.

A greater risk.

The paper authored by Consultant Senior Lecturer Respiratory Medicine Dr James W. Dodd reads; “Although direct comparisons are complex, cough appears to generate significant aerosols in a size range compatible with airborne transmission of SARS-CoV-2.

“As a consequence, the risk of SARS- CoV-2 aerosolisation is likely to be high in all areas where patients with Covid-19 are coughing. Guidance on personal protective equipment policy should reflect these updated risks.”

Dr Dodd, added; “CPAP is not aerosol-generating – in fact, the aerosols are reduced compared to just normal breathing and speaking. However, cough really is a potent generator of aerosols.”


He added: “[The risk] appears to be far greater than what we would have assumed.”

While the study is awaiting peer review, Dr Chaand Nagpaul, the British Medical Association (BMA) council chair called for greater provision of the most protective PPE.

“We know that staff are still getting sick and having to take time off work to isolate and recover, depriving the NHS and its patients of their expertise at a time when all efforts are being put into defeating Covid-19″, he said.

“Current surgical masks are insufficient to prevent aerosol spread, which is why the BMA is calling for greater provision of enhanced FFP2 and FFP3 masks.”

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