The Bangladesh weather is far less humid now than normal with the minimum temperature hovering between 16C and 18C at places across the country which might increase the possibility of the novel coronavirus infections.
The minimum night-time temperature mostly remained at 18C and below in Rajshahi, Rangpur, and Mymensingh divisions and parts of Dhaka and Khulna divisions, said the Met Office.
The Met Office forecast that the maximum daytime temperature would remain around 37C, the minimum temperature would continue to hover around 18C at many places in the first week of April.
At the beginning of March researchers indicated that the spread of coronavirus was severe at places where temperatures hovered between 3C and 11C, and they also said that the evidences emerged in the 2nd and the 3rd week of the month that the viral disease spread significantly in countries with 18 C and lower temperatures.
‘The overall situation gives us the message that the time has not come for us to relax,’ BSMMU virology professor Saif Ullah Munshi told New Age.
‘We need to stay careful at least in the first week of April,’ he said.
A study by two scientists of the Massachusetts Institute of Technology recorded a sudden surge in the number of coronavirus cases in regions with temperatures hovering between 16C and 18C, where almost 10,000 new cases were reported from March 10 to 21.
The study published online without peer review described April as a critical month to understand how novel coronavirus acts in warm and humid countries such as India, Pakistan and Bangladesh.
‘The humidity level in Bangladesh air is far less than normal,’ said weather forecaster Abdul Mannan.
The humidity level falls below 30 per cent in the afternoons though it should be around 70 per cent, according to the Met Office.
On Monday, the Met Office recorded 47 per cent humidity at 6:00am.
‘The flow of wet wind from the Bay of Bengal has been less than usual,’ said Mannan.
‘Low humidity is holding the temperature from climbing up,’ he said.
Though a heat wave is sweeping in parts of Bangladesh at the moment the maximum temperature has not reached as predicted for the current month’s long-range weather forecast.
The temperature was predicted to reach 40C at the end of March.
Mannan predicted the weather would remain almost unchanged over the next week.
According to the MIT study, 90 per cent of COVID-19 cases were so far reported from the regions having absolute humidity ranging between three to nine grams per cubic metre.
Mannan said that the average humidity of Bangladesh air at the moment was 15 gram per cubic metre, far less than the normal 27 gram per cubic metre.
More humidity means more water collected in the nasal cavity which increases the temperature inside the body, Saif said.
‘Increased temperature acts against viral growth,’ he said.
The MIT study says that higher absolute humidity reduces the chances of indirect transmission of viral disease transmitted through the air.
It says that higher humidity makes it difficult for virus to stay in the air for long.
On March 9, four Chinese scientists published a study that reveals that relative humidity has a stronger significance than the temperature in limiting the spread of the novel coronavirus infection.
After studying COVID-19 cases in 100 Chinese cities, they revealed that if the temperature increased by 1C and humidity increased by 1 per cent the severity of infection could reduce by 0.0383 per cent and 0.0224 per cent respectively.
The humidity level in Bangladesh air is likely to increase as the rainy season approaches in the country.
Different studies already predicted that with the onset of monsoon the spread of the novel coronavirus would slow down in many Asian countries.
Monsoon in Bangladesh spans from June to October.
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