Dry Indoor Air May Increase COVID-19 Transmission in Coming Winter

The Center of Disease Control and Prevention has issued the Six-Feet Rule to comply to the physical distancing recommendations, based on the assumptions that the large drops ejected from sneezing and coughing are the primary carrier of pathogen transmission.

However, contrary, it was stated that 6 feet distance is not adequate to prevent the transmission, based on a recent report by John Bush and Martin Bazant at MIT. It is speculated that the SARS-CoV-2 will survive the cold weather and thrive resulting in rapid spread at lower temperatures, reduced humidity and drier conditions in inside the breathing airway passage in the winter.


Within the 6 feet vicinity, large droplets may fall to the floor, whereas the small droplets and aerosols   cover larger distance and carried away beyond 10 feet to up to 20 feet in some cases. Therefore, airborne viral transmission will be profound in indoors this winter.

Source: National Jewish Health

Previous reports on influenza and MERS give indication that relative humidity declines from about 40-60% in warm weathers to about 20% in cold weathers increase the chance of infection development. According to another study of a cohort climate modeling at 50 international cities, it was confirmed that as the relative humidity drops to 20%, SARS-CoV-2 is more stable and remains on certain receptors in our airways. This implicates that people are more vulnerable to contract the cold viruses and influenza in colder temperatures.

Numerous factors are involved in the airborne transmission, including ventilation and filtration parameters within indoors such as, space dimension, cumulative exposure time, number of individuals, respiratory rate, face mask use, extent of contagiousness of the respiratory aerosols.

Therefore, study implicates that the physical distancing of any sort in indoors as it was in outdoors and this is one of the majors concerns that will magnify the number of cases and exacerbate the already devastating situation.

Recent data as per the Covid Tracking Project, in last month there has been a continuously increasing trend in  reported cases, hospitalizations, and mortalities in the US. Further, the lead authors of the MIT study, Bazant and Bush also developed new guideline to determine the potential risk of airborne transmission by assessing the size of the indoor space, human activities, exposure time, air filtration, and ventilation.

In early August, Dr. Fauci had warned about the coming fall and winter. “U.S. needs to get daily cases down to 10,000 before fall,” he explained at the time.

Conclusively, study confirms that the SARS-CoV-2 will profoundly survive this winter as it is more stable at the lower temperatures, reduced humidity and drier conditions inside respiratory tract. As the cold weather is getting closer, humidity reduces in air and air gets dry.

When the heating systems are turned on inside the house, it dries the air and the cells and tissues located inside the nasal passage loses the natural mucus, which acts as the integral part of defense mechanism in nasal passage that removes the foreign invaders such as viruses including SARS-CoV-2, other viruses, and bacteria.

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