New Delhi: How long can one exercise in an air-conditioned gym during Covid? How many people can safely travel in a car without risk of infection and for how long? A new study by researchers from the Massachusetts Institute of Technology in the US offers answers to many such questions.
The team from MIT created models of airborne disease transmission to develop an indoor safety guideline for Covid. Based on their model, the team has also created an online app that recommends the maximum amount of time people can spend indoors with others in order to minimise the infection risk.
The study also arrived at an important conclusion that in large and poorly-ventilated spaces, masks are more important than social distancing to reduce the risk of transmission.
While distancing, masking and sanitising have been part of Covid safety protocols since early 2020, the past year’s research has shown that virus transmission is most likely to occur through virus-laden aerosols than surfaces.
Furthermore, the six-feet distancing that is recommended is based on the assumption that the virus spreads through large drops ejected from vigorous exhalation events, such as coughing and sneezing.
While the virus does spread through such events, researchers have pointed out that smaller liquid drops expelled through talking and singing also carry the virus.
The MIT study, published in the journal PNAS (Proceedings of the National Academy of Sciences of the United States of America) Tuesday, pointed out that there is now overwhelming evidence that such relatively small, micron-scale aerosol droplets are primarily responsible for the spread of Covid-19, especially indoors.
Infected drops remain suspended in ambient air
The guidelines developed by the researcher, therefore, help determine the maximum amount of time people can spend in an enclosed space without contracting the virus.
According to the study, this depends on a number of factors such as the rates of ventilation and air filtration in the space, dimensions of the room, breathing rate and respiratory activity of the occupants as well as whether the occupants are wearing face masks.
Utilising data from past events where Covid spread through indoor spaces, the study noted that small infected drops may accumulate and remain suspended by the ambient airflow and mixed throughout the room, until they are removed by the ventilation outflow or inhaled.
Therefore, through their online app, people can arrive at the recommended safe time in an indoor space before they are at an increased risk of contracting the infection.
For instance, according to the app, a typical gym of approximately 4,000 square feet area that is air-conditioned and has 10 people exercising without masks would be at risk after 35 minutes.
“Our study makes clear the inadequacy of the Six-Foot Rule in mitigating indoor airborne disease transmission, and offers a rational, physically informed alternative for managing life in the time of Covid-19,” the researchers said.