Low humidity levels at the onset of the new Novel Coronavirus pandemic contributed to its spread. A 1% decrease in air humidity led to a 6% increase in the number of cases of coronavirus.
This was discovered in a joint study by Australian and Chinese scientists from the University of Sydney and Shanghai’s Fujian University School of Public Health.
The researchers said that COVID-19 could potentially take the form of a seasonal disease that would appear during periods when air humidity levels are low.
The results of the study were published in the journal Transboundary and Emerging Diseases.
“The outbreak began in China, Europe and North America during the winter, and we wanted to see the relationship between the weather in Australia in late summer and early autumn and COVID-19,” the researchers said.
“When it comes to the weather, we discovered that it was not the cold temperature but the low humidity in the air that was the main reason for the outbreak, meaning that the disease could increase the risk in the winter,” it added.
When the humidity level in the air decreases, but in the northern hemisphere, countries where the humidity level is low, the risk may be higher even in hot weather.
Why is humidity important?
Researchers say there are biological factors that make moisture important for the spread of such viruses.
When the humidity level is low, the air dries out and the particle volume decreases. When you sneeze and cough, these tiny particles stay in the air for a long time, making other people sick. When the humidity in the air is high, these particles are large and heavy and roar very quickly on the surface.
The study examined 749 patients infected with the coronavirus in Australia between February 26 and March 31.
The research team reviewed the records of meteorological centres near the patient areas and analyzed rainfall, temperature and humidity there from January to March 2020.
The results showed that low humidity in the air increases the rate of cases, ie even a 1% reduction in the rate of humidity can increase the rate of cases of COVID-19 by 6%.
“This means we need to be careful in dry weather,” the researchers said.
A similar study by Yale University in April found similar results.
The study, published in the journal Annual Review of Virology, found that the relationship between the spread of the virus and the weather is being examined in various research reports, and two key factors are environmental parameters and changes in human behaviour.
The study described how cold and dry air could potentially affect the spread of the new coronavirus.