Indoor Air and Coronavirus: COVID 19 is an airborne Virus
COVID-19 is thought to spread mainly through close contact from person to person. However, some uncertainty remains about the relative importance of different routes of transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19). Evidence now confirms that this virus can remain airborne for longer times and further distances than originally thought. In addition, to close contact with infected people and contaminated surfaces, the spread of COVID-19 may also occur via airborne particles in indoor environments, in some circumstances beyond the 2 m (about 6 ft) range encouraged by some social distancing recommendations.
Airborne transmission of COVID-19
EPA ‘s [Environmental protection agency] views:
There are straightforward steps that can be taken to reduce the potential for airborne transmission of COVID-19 and the focus of this material is on those measures. The layout and design of a building, as well as occupancy and type of heating, ventilation, and air conditioning (HVAC) system, can all impact the potential airborne spread of the virus. EPA recommends increasing ventilation with outdoor air and air filtration as important components of a larger strategy that includes social distancing, wearing cloth face coverings or masks, surface cleaning and disinfecting, handwashing, and other precautions potentially occur.
CDC’s views [Centre for disease control and prevention]:
Some infections can be spread by exposure to the virus in small droplets and particles that can linger in the air for minutes to hours. These viruses may be able to infect people who are further than 6 feet away from the person who is infected or after that person has left the space.
This kind of spread is referred to as airborne transmission and is an important way that infections like tuberculosis, measles, and chickenpox are spread.
There is evidence that under certain conditions, people with COVID-19 seem to have infected others who were more than 6 feet away. These transmissions occurred within enclosed spaces that had inadequate ventilation. Sometimes the infected person was breathing heavily, for example, while singing or exercising.
Under these circumstances, scientists believe that the amount of infectious smaller droplets and particles produced by the people with COVID-19 became concentrated enough to spread the virus to other people. The people who were infected were in the same space during the same time or shortly after the person with COVID-19 had left.
Available data indicate that it is much more common for the virus that causes COVID-19 to spread through close contact with a person who has COVID-19 than through airborne transmission.
ASHRAE's views:
Limited sampling has established that SARS-CoV-2 is airborne and can expose (but not necessarily infect) occupants well beyond 2 m (7 ft). Recent findings further establish that the virus can circulate through some HVAC systems. While several outbreaks of COVID-19 infection have suggested airborne transmission, these have generally been in areas with poor ventilation.
With present knowledge, both social distancing and wearing masks are equally important. Both together prevent infected respiratory virus loaded droplets from coughing and sneezing travelling from one person and infecting another.