Researchers have confirmed the efficacy of a portable particle detector at calculating the concentration of aerosols in public spaces. Hand-held devices may be vital in the fight against the COVID-19 pandemic, given the important role that aerosols play in the transmission of the virus.
Coronavirus particles in aerosol droplets. Image Credit: peterschreiber.media/Shutterstock.com
Aerosol transmission of COVID-19
The latest research has uncovered the fundamental role that aerosols play in the transmission of the COVID-19 virus. Aerosols, produced when humans respire and release water droplets into the immediate environment. These droplets can measure less than 60 μm and can be laden with the COVID-19 virus if expelled into the air by an infected person.
Data has shown that aerosols can persist in public spaces and that the duration that they can linger, along with the concentrations they accumulate in, contribute to the risk of transmission of the virus in different environments.
Obtaining a clearer understanding of what impacts aerosol duration and persistence will help scientists make recommendations on how best to manage shared spaces to prevent the spread of COVID-19.
However, until now, it has been difficult to accurately measure aerosol concentrations, with specialized staff and equipment required to carry out the task. It was this limitation that inspired a team at the Cardiology Centers of the Netherlands and the University of Amsterdam to establish an accurate, portable, and simple to use method of measuring aerosol concentration.
The researchers investigated the efficacy of the Fluke 985, at determining the concentration of aerosols in public spaces. The researchers believe hand-held devices will be useful in determining how suggested measures impact the concentration of potentially virus-laden particles in the environment, thus measuring their potential efficacy at preventing COVID-19 transmission.
Eliminating background dust from aerosol measurements
In a paper published this month in the journal Physics of Fluids, the team describes developed their method using a hand-held particle counter that is capable of overcoming the challenge of separating background dust particles that are prevalent in shared spaces. Previously, it had been difficult for equipment to distinguish particles of interest, such as water droplets produced by breathing, speaking, sneezing, or coughing, from irrelevant dust particles.
The researchers recognized that particles of dust differ in size from that of aerosols. This difference allowed the University of Amsterdam scientists to subtract the signal produced by diet from the signal produced by aerosols. To do this, the team measured the dust for an extended period and monitored how the signal changed as they added aerosols into the mix.
One of the study’s authors, Daniel Bonn, summarizes how the overcame the problem of dust interfering with the signal, “there's a lot of fine dust, so we can't measure aerosols in that range, but there is a reasonably sized range where you can detect the aerosols.” Bonn and the team compared the aerosol concentration calculated via this method to that of laboratory-based techniques, they found that the results were identical.
The study’s findings demonstrate that the Fluke 985, developed to monitor the air and dust quality in clean rooms, can determine the aerosol concentration in a public space. Bonn highlights that the findings aren’t likely to be specific to the Fluke 985, and it is likely that other handheld devices may be just as effective.
While technology cannot measure or detect the presence of infected particles, it provides a useful tool to help scientists understand how particles build up and linger in shared spaces. This data is vital to understanding how virus-laden particles spread and what risk they pose to those using the shared space.
Hand-held devices will likely help to confirm the efficacy of strategies to prevent transmission of COVID-19, such as demonstrating how ventilation can reduce aerosol concentration, as well as help to develop new strategies.