According to the scientists from the Harvard-MIT Health Sciences and Technology, when people cough or sneeze, the respiratory droplets they exhale can extend over an area of up to 8 meters, which increases the possibility of surface contamination.
This means that the recommendations of social distancing to reduce the risk of COVID-19 transmission are inadequate if we take into consideration for how long and how far the respiratory droplets can travel. So, experts believe that new measures for personal protective equipment should be undertaken.
The Center for Disease Control and Prevention suggests maintaining a 2-meter distance to avoid possible transmission, while the World Health Organization recommends maintaining 1-meter distance from patients who exhibit respiratory infection symptoms. However, health experts emphasize that droplet and airborne transmission are quite different and require undertaking more specific measures.
According to the WHO, airborne transmission refers to the presence of microbes inside the droplet nuclei which are less than 5µm in diameter. This indicates that they can remain in the air for a longer period and can be transmitted to other people over distances greater than two meters.
However, the likelihood of the respiratory droplets to contaminate an area or a person depends on the environment in which they have been coughed up or sneezed, as well as on their size.
For instance, smaller droplets can easily evaporate, while larger ones settle faster and can easily contaminate the surrounding area.
Peak exhalation can reach speeds up to 30 meters per second, so under these conditions, the lifespan of droplets can be extended from seconds into minutes.
Even though the exhalation properties of coronavirus haven’t been studied yet, its droplets contain viruses of various sizes that are created either within or outside the respiratory tract and consequently cause respiratory infections.
Other studies have also suggested that coronavirus can survive the longest in humid and warm conditions. Some people believe that it may die out when the weather warms up, which is normal for the seasonal flu.
But the newest studies have shown that this virus can survive in temperatures up to 41C°. So, unfortunately, it shows no signs of weakening in humid and warm conditions.