Aerosol boxes increase exposure to airborne particles

A new study shows certain aerosol boxes of a similar type used in UK hospitals in order to protect healthcare workers from Covid-19 can actually increase exposure to airborne particles.

Aerosol box may increase exposure to airborne virus particles

The authors of the Australian research say the danger posed to frontline health workers exposed to infectious coronavirus is significant.

The sickest Covid-19 patients often need to be placed onto a ventilator, which is also when the risk to the health worker of exposure is potentially at its greatest.

This has created a race to manufacture aerosol containment devices including improvised protection strategies and devices for use during tracheal intubation.

It has taken on even greater urgency in the last week, with a global “second wave” becoming more likely, and a recent open letter to the World Health Organisation (WHO) from 239 global scientists in 32 countries warning we have been severely underestimating the amount of Covid-19 spread through fine aerosol droplets over large distances.

On Wednesday, WHO formally acknowledged this emerging evidence regarding potential spread of Covid-19 through these tiny droplets.

Aerosol boxes have been promoted by worldwide news organisations and across social media as not only a quick and simple solution to protecting frontline workers but also an example of private industries stepping up production to support frontline healthcare workers.

However, these devices were produced outside the normal regulatory framework, and thus were never clinically tested or validated for effectiveness and safety.

Yet despite this heavy media promotion, no international guideline on personal protective equipment (PPE) has ever endorsed their use.

The authors say: “We were surprised to find airborne particle contamination of the doctor increased substantially using the aerosol box compared with all other devices and with no device use.

Spikes of airborne particles were clearly seen, coinciding with patient coughing. We believe that these represent particles escaping from the arm access holes in the aerosol box.”

The authors who include Drs Peter Chan, Joanna Simpson and colleagues, Intensive Care and Anaesthesia Specialists at Eastern Health in Melbourne, say: “The race to generate sustainable equipment to protect healthcare workers during intubation procedures in patients with suspected or proven Covid-19, particularly in settings where PPE supply is limited, has flooded the scientific community and social media with a variety of novel devices meant to contain potentially infectious aerosols produced by patients. Evidence for the safety and efficacy of these devices is lacking.”

They conclude: “This study demonstrates devices such as the aerosol box we tested - confer minimal to no benefit in containing aerosols during an aerosol-generating procedure and may increase rather than decrease airborne particle exposure.”

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