Airborne diseases are those where germs from a person’s breathe, sneeze or cough can linger in the air and travel because the droplets are very small in size.
Aerosols are so small and can linger in the air for longer and travel further. They include tiny particles like smoke, which can stay airborne for up to eight hours.
There is some compelling evidence to say that SARS-CoV-2 is airborne, despite most of it not being subject to peer review.
The virus can remain in the air ‘for three hours’
Scientists in the US have shown in the laboratory that the virus can survive in an aerosol and remain infectious for at least three hours.
However, at the time the WHO argued the conditions of the experiment were too artificial and did not represent what happens if someone coughs in real life.
The virus spread between diners at a restaurant who had no contact
One study revealed how a cluster of people caught the coronavirus in a restaurant without being in contact with each other.
Nine people in three families in Guangzhou, China, were diagnosed with the virus after eating at the same restaurant as the ‘source’ patient. But the researchers said droplets from coughing and sneezing alone could not explain the spread of the virus.
The team, led by Yuguo Li at The University of Hong Kong, measured the ventilation in the room and concluded that ‘aerosol transmission of SARS-CoV-2 due to poor ventilation may explain the community spread of COVID-19’.
However, the same cluster of cases was studied by a different group who reported their own conclusions in a Centers for Disease Control and Prevention (CDC) journal on April 2.
Jianyun Lu and colleagues from the Guangzhou Center for Disease Control and Prevention said: ‘From our examination of the potential routes of transmission, we concluded that the most likely cause of this outbreak was droplet transmission. However, strong airflow from the air conditioner could have propagated droplets.’
The team admitted droplets from coughing and sneezing alone could not explain the spread of the virus.
The virus can linger in crowded places
In April, Chinese researchers found that the coronavirus can linger in the air of crowded places and published their findings in the journal Nature.
Experts in Wuhan, the Chinese city where the pandemic began, analyzed air samples from 30 sites across the city – in which coronavirus was first reported – including inside hospitals as well as public areas.
Results showed the virus, called SARS-CoV-2, was too low to be detected in all areas except two ‘prone to crowding’.
Viral particles were found floating in the air of hospital toilets, which had very little ventilation.
They also discovered especially high concentrations in the rooms where medical staff put on and took off protective gear.
The latter suggests the virus can latch onto clothing and become airborne again when when masks, gloves and gowns are removed.
Researchers behind the study say the findings highlight the importance of ventilation, limiting crowds and proper disinfection.