Lower humidity has a link with higher rates of COVID-19 transmission, claims a joint Australian-Chinese study released Tuesday.
Drier air across several different regions of Sydney has been consistently linked to higher numbers of COVID-19 infections, the study found.
But similar links are not true for other weather factors including rain, temperature and wind.
The study was published in the medical journal Transboundary and Emerging Diseases.
It is the second such study by the group on the relationship between weather conditions and COVID-19 in Australia, following a larger study conducted in China earlier this year.
The study estimated that 1 percent drop in humidity could push up COVID-19 cases by 7-8 percent, and for a 10 percent drop, the infections could as much as double.
To conduct the research, epidemiologist Professor Michael Ward from the University of Sydney teamed up with Shuang Xiao and Zhijie Zhang from the partner institution Fudan University School of Public Health in Shanghai.
“The consistency between studies is increasing confidence that humidity is a key factor in the spread of COVID-19,” Ward said. “Dry air appears to favour the spread of COVID-19, meaning time and place become important.”
Further research required
Ward said the result raises the prospect of seasonal disease outbreaks and greatly supports the use of face masks in order to prevent the spread.
He said the result is not entirely unexpected considering that when humidity is lower, the air is drier and it makes aerosols smaller.
“When you sneeze and cough, those smaller infectious aerosols can stay suspended in the air for longer. That increases the exposure for other people,” he elaborated. “When the air is humid and the aerosols are larger and heavier, they fall and hit surfaces quicker.”
The team said further research is required to draw more conclusive ties between humidity and coronavirus transmission and expand on how that can be taken into account to shape the public health response.
The number of globally confirmed coronavirus cases surpassed 2.2 million on Wednesday with more than 781,000 deaths, according to Johns Hopkins University tally.
Coronavirus cases were first reported in China in December last year. In March, the World Health Organisation declared it a pandemic.
Bangladesh confirmed its first cases on March 8 and the first death on March 18. Currently, the country has more than 282,000 officially confirmed cases and over 3,700 deaths.