Scientists recommend at least 40% humidity in public buildings to curb COVID-19 spread
New Delhi: In addition to measures like social distancing and wearing masks, an Indian-German team of scientists recommend controlling indoor humidity conditions to contain the spread of the novel coronavirus which causes COVID-19.
The researchers, including those from CSIR National Physical Laboratory in New Delhi, said in order to contain the pandemic, it is extremely important to implement standards for indoor air humidity in rooms with many people, such as hospitals, open-plan offices, or public transport.
In their review of studies, published in the journal Aerosol and Air Quality Research, the scientists specifically drew focus on relative humidity, which is a measure of water vapour in the air compared to the total saturation of vapour that can exist in the air at its current temperature.
According to the study, a relative humidity of 40 to 60 percent could reduce the spread of viruses and their absorption through the nasal mucous membrane.
The scientists said tiny drops of five micrometres in diameter, such as those produced when speaking, can float in the air for up to nine minutes.
"In aerosol research, it has long been known that air humidity plays a major role -- The more humid the air is, the more water adheres to the particles and so they can grow faster. So, we were curious -- what studies have already been conducted on this," explained Ajit Ahlawat, a co-author of the study from the Leibniz Institute for Tropospheric Research (TROPOS) in Germany.
According to the scientists, humidity affects the behaviour of microorganisms within the virus droplets, and the survival or inactivation of the virus on the surfaces.
They said it also influences the role of dry indoor air in the airborne transmission of viruses.
"If the relative humidity of indoor air is below 40 per cent, the particles emitted by infected people absorb less water, remain lighter, fly further through the room and are more likely to be inhaled by healthy people," Ahlawat explained.
"In addition, dry air also makes the mucous membranes in our noses dry and more permeable to viruses," he said.
The scientists believe the new findings are particularly important for the upcoming winter season in the northern hemisphere, when millions of people will be staying in heated rooms.
"Heating the fresh air also ensures that it dries. In cold and temperate climate zones, therefore, the indoor climate is usually very dry during the heating season. This could encourage the spread of coronaviruses," said study co-author Alfred Wiedensohler of TROPOS.
At a higher humidity, the scientists said droplets grow faster, fall to the ground earlier, and can be inhaled less by healthy people.
"A humidity level of at least 40 per cent in public buildings and local transport would therefore not only reduce the effects of COVID-19, but also of other viral diseases such as seasonal flu. Authorities should include the humidity factor in future indoor guidelines," added study co-author Sumit Kumar Mishra of CSIR - National Physical Laboratory in New Delhi.
For countries in cool climates, the scientists recommend a minimum indoor humidity.
They said countries in tropical and hot climates, on the other hand, should take care that indoor rooms are not extremely undercooled by air conditioning systems.
When air is extremely cooled, it dries out the air and the particles in it, making people inside the room feel comfortable, but the dry particles will remain in the air for longer duration, the researchers warned.
They added that the measures already known, such as social distancing, having as few people per room as possible, and wearing masks should also be practised to lower the risk of infection.
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World saw valour, courage of Indian armed forces through Operation Sindoor: President
New Delhi (PTI): President Droupadi Murmu on Wednesday said the world saw the valour of Indian armed forces through Operation Sindoor when they destroyed terror camps on the strength of their own resources and asserted that any terror act will be responded with decisive action.
"India has proved that power can be used with responsibility and wisdom. The world has seen the valour and courage of Indian armed forces through Operation Sindoor," Murmu said in her address to both Houses of Parliament, marking the beginning of the Budget Session.
"Our nation, on the strength of our own resources, destroyed terror camps. My government sent a message that any act of terror will be responded to with resolute and decisive action," the President said, amid thumping of desks by Prime Minister Narendra Modi and other parliamentarians.
Murmu said the suspension of the Indus Water Treaty was part of India's fight against terror.
"We are also working on Mission Sudarshan Chakra to further strengthen national security," the President said, adding that security forces have also taken decisive action against Maoist terror.
Following Operation Sindoor, she said, the trust on Indian defence platforms has increased.
Murmu further said her government was committed to social justice in the country.
In the third term of the government, she said, work is being done to further empower the poor, and social security benefits are available to nearly 95 crore citizens now.
"My government is committed to true social justice," she said, adding that 25 crore Indians moved out of poverty in the last 10 years.
The President also said the government has been successful in tackling corruption and scams, and ensuring proper use of public funds.
"For India, the end of the first 25 years of this century has been filled with several successes, proud achievements and extraordinary experiences. In the last 10-11 years, India has strengthened its foundation in every sector," she said.
Lauding India's celebration of the 350th martyrdom day of the ninth Sikh guru, Guru Tegh Bahadur, and the country's tribute to revered tribal leader and freedom fighter Birsa Munda on his 150th birth anniversary, Murmu said, "when the country remembers the contribution of its ancestors, the new generation gets inspiration, which further speeds up our journey towards Viksit Bharat (Developed India)."
"The country celebrated the 350th Shaheedi Diwas of Sri Guru Tegh Bahadur Ji. During the 150th birth anniversary of Birsa Munda, the entire country paid him tribute and remembered his contribution to the tribal community," the President said.
"The events related to the 150th birth anniversary of Sardar Vallabhbhai Patel further strengthened the sense of Ek Bharat, Shresht Bharat (One India, Best India). The entire country became witness to how Bharat Ratna Bhupen Hazarika's birth anniversary celebrations filled the country with music and a sense of unity," Murmu said.
The President's mention of the Viksit Bharat – Guarantee for Rozgar and Ajeevika Mission (Gramin) (VB-G RAM G) scheme was met with loud protests from the Opposition benches.
Murmu said the VB-G RAM G initiative would provide guarantee for 125 days of work, would stop corruption and leakages, and provide a new impetus to rural development.
The Opposition members raised slogans demanding its rollback, even as the treasury benches thumped their desk in support of the scheme.
The President had to take a brief pause amid opposition cries of "vapas lo" (roll back) against the Act that replaced the Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA).
The Opposition parties have been demanding withdrawal of the VB-G RAM G Act and restoration of MGNREGA as a rights-based law in its original form, the right to work and the authority of panchayats.
The government has, meanwhile, claimed that the new Act will further strengthen the guarantee for rural employment.
