A new COVID-19 article from BioBE has considered various coronavirus related variables. The different factors were examined through a small-scale study. The study involved eleven participants who had been diagnosed with COVID-19.
The participants were studied for three days in a controlled chamber with multiple independent variables. For this, as Microbenet reports, the researchers collected more than 2500 biological samples, particulates, and carbon dioxide levels in the vicinity of each person, with the subjects asked to remain inside controlled chambers so that external environmental sources did not interfere with the collected data.
These samples were taken from two locations, described as ‘near field’ (defined as 1.2 metres) and also ‘far field’ (a distance of 3.5 metres), with these distances assessed for each trial, under controlled airflow conditions. This latter point was necessary because the study took into account variances with ventilation. This is on the basis of decreased aerosol SARS-CoV-2 load with increasing ventilation, both from mechanical and window sources.
To gather the data, each participant conducted a cough test, speak test, and speak loudly test at the beginning of each day. These activities were measured and then sampled. This was followed by routine trials where participants conducted regular office activities under different outdoor air exchange rates, in-room filtration, and relative humidity levels.
The results revealed that an increased viral load in nasal samples is associated with higher viral loads in environmental aerosols and surfaces. This was so in both the near field and far field distances.
Under ambient conditions with effectively zero Air Changes per Hour (ACH), near field measurements showed the highest particulate matter abundance. To highlight the importance of good ventilation (and thus greater air change rates), the study found that increased ventilation and filtration were associated with lower environmental viral loads.
On the topic of humidity, higher relative humidity was found to be associated with lower aerosol viral loads and higher surface viral loads, consistent with an increased rate of particle deposition.
Such findings indicate that building operation practices such as ventilation, filtration, and humidification can substantially reduce the environmental aerosol viral load. In turn, this means a lower inhalation dose.
Lessons can be learned from such data as a means to improve building health and safety, focusing on the key risk aspects designed to create an environment that minimises the risk of viral transmission.
The research paper is titled “Quantifying human and environmental viral load relationships amidst mitigation strategies in a controlled chamber with participants having COVID-19.”
