Despite experts saying there was no evidence of coronavirus being airborne, it has been detected on particles of air pollution by scientists looking into whether the disease could be carried this way over long distances, a report in The Guardian said. Until now, the virus was believed not to be able to survive in the air. As such, there was little risk of people getting infected through the air.
So far, the World Health Organisation has maintained that coronavirus spreads primarily through droplets generated when an infected person coughs or sneezes, or through droplets of saliva or discharge from the nose.
For the preliminary study, the Italian scientists collected air pollution samples at one urban and one industrial site in Bergamo province and identified a gene highly specific to Covid-19 in multiple samples.
Leonardo Setti at the University of Bologna in Italy, who led the work, said it was important to investigate if the virus could be carried more widely by air pollution.
Setti’s team analysed that higher rates of infection in parts of northern Italy before the lockdown was imposed might be due to higher levels of particle pollution in the region.
Earlier too, studies have shown that air pollution particles harbour microbes and pollution is likely to have carried the viruses causing bird flu, measles and foot-and-mouth disease over considerable distances.
While large coronavirus-laden droplets from infected people’s coughs and sneezes fall to the ground within a metre or two, smaller droplets, less than 5 microns, can remain in the air for minutes to hours and travel further.
However, experts are not sure whether these tiny droplets can cause coronavirus even though the fact that it does survive in the air, even for a short time, could force scientists and health officials to reassess the risk to people, especially to health workers who spend a lot of time near an infected person.
Scientists, affiliated to different laboratories in universities in the United States, found in their experiments that the SARS-CoV-2 virus could survive in air for about three hours, although its ability to infect was severely weakened during this time.
“It is perhaps not surprising that while suspended in air, the small droplets could combine with background urban particles and be carried around,” The Guardian quoted Professor Jonathan Reid at Bristol University as saying. Reid said the virus had been detected in tiny droplets collected indoors in China.
Setti said tiny droplets between 0.1 and 1 micron might travel further when coalesced with pollution particles up to 10 microns than on their own. This is because the combined particle is larger and less dense than the droplet.
“The pollution particle is like a micro-airplane and the passengers are the droplets,” The Guardian quoted Setti as saying.