Dr Bromage completed his PhD at James Cook University and is an associate professor at the University of Massachusetts Dartmouth, where he teaches immunology and infectious disease.
His overview of the research looking at the various causes of infection has been read 17 million times. Dr Bromage penned a follow-on article for The New York Times advising Americans how to safely spend the just-completed Memorial weekend.
He said the key to infection was the amount of virus and the time of exposure.
“Basically, as the work closures are loosened, and we start to venture out more, possibly even resuming in-office activities, you need to look at your environment and make judgments,” Dr Bromage said.
“How many people are here, how much airflow is there around me, and how long will I be in this environment.
“If you are in an open floor-plan office, you really need to critically assess the risk (volume, people, and airflow). If you are in a job that requires face-to-face talking or even worse, yelling, you need to assess the risk.”
Using a conservative measure that 1000 SARS-CoV2 infectious viral particles can cause transmission, Dr Bromage said any workplace that has sneezing (30,000 droplets) and coughing (3000 droplets) were high-risk.
Breathing would not generate enough droplets unless you were close enough to an infected person for 50 minutes. But speaking increases droplets tenfold. This means the virus can be passed within five minutes of being in contact of an infectious person who is speaking.
Referring to a study of an outbreak at a call centre in South Korea, Dr Bromage noted the infection was largely limited to an area where people were speaking and air circulation was limited.
“Interestingly, even though there were considerable interactions between workers on different floors of the building in elevators and the lobby, the outbreak was mostly limited to a single floor. This highlights the importance of exposure and time in the spreading of SARS-CoV2.
“It serves to highlight that being in an enclosed space, sharing the same air for a prolonged period increases your chances of exposure and infection.”
Airflow can be critical. Dr Bromage highlighted Chinese research which showed how in a restaurant 75 per cent of patrons at the table downwind from an infected person had become ill. Other tables away from the main airflow from the air-conditioner were not infected.
Singing was also called out, revealing why officials have been reluctant to open theatres, dance clubs and band venues.
“Singing, to a greater degree than talking, aerosols respiratory droplets extraordinarily well,” Dr Bromage said.
“Deep breathing while singing facilitated those respiratory droplets getting deep into the lungs.”
In a Washington state choir, 60 participants did all the right social distancing and hygiene techniques. But they chose to sing inside an enclosed rehearsal hall roughly the size of a volleyball court for 2½ hours. Over the next four days, two-thirds fell ill with COVID-19, two of them dying.
“The reason to highlight these different outbreaks is to show you the commonality of outbreaks of COVID-19. All these infection events were indoors, with people closely spaced, with lots of talking, singing, or yelling,” Dr Bromage said.
Lifts were earlier considered problematic, with the requirement to maintain a four-square-metre distance meaning that many office blocks would not be workable.
Under pressure from the office block operators, SafeWork Australia last week changed its guidance, dropping the specific requirement.
“However you must still ensure, as far as you reasonably can, that people maintain physical distancing in lifts and lift waiting areas,” SafeWork said.
The secretary of the Victorian Premier’s department, Chris Eccles, on Monday told staff that “working remotely ensures a significant control remains on millions of movements every day within our cities, towns and state.
“This means Victorians who can’t work from home can do so more safely and that restrictions on some business and social activity can be eased.
“With the health and safety of staff at the forefront of our minds, return to the office planning includes how to implement social distancing, cleaning requirements, the use of public transport and simple but important logistics like how to use lifts.”
Other states have relaxed work-from-home orders. NSW, however, has asked people to avoid peak-hour travel on public transport.
Many city-based retailers are pushing for city workforces to return as soon as possible to recover foot traffic and customers, many who have been buying online.
Sydney and Melbourne city councils are also looking for as early a return as is safe, as they continue to see major cuts to their fee and fine revenues.
Planners are unsure what percentage of workforces are likely to return to full-time office work, with private and public sector surveys suggesting many staff want to continue to take advantage of working remotely.
Mr Eccles said surveys of the Victorian Public Service had revealed strong support for more flexible working arrangements.
“Survey data from Departments (which continues to be collated) shows that after the pandemic, nine out of ten staff would like more flexible work arrangements to be an ongoing feature, with the majority suggesting two or three days from home or at a secondary office location would be ideal.
