Deaths of children: Careless Yogi should step down as CM, says U T Khader

The coronavirus can stay aloft for hours in tiny droplets in stagnant air, infecting people as they inhale, mounting scientific evidence suggests.

This risk is highest in crowded indoor spaces with poor ventilation, and may help explain superspreading events reported in meatpacking plants, churches and restaurants.

It’s unclear how often the virus is spread via these tiny droplets, or aerosols, compared with larger droplets that are expelled when a sick person coughs or sneezes, or transmitted through contact with contaminated surfaces, said Linsey Marr, an aerosol expert at Virginia Tech.

Follow latest updates on the Covid-19 pandemic here

Aerosols are released even when a person without symptoms exhales, talks or sings, according to Marr and more than 200 other experts, who have outlined the evidence in an open letter to the World Health Organization.

What is clear, they said, is that people should consider minimizing time indoors with people outside their families. Schools, nursing homes and businesses should consider adding powerful new air filters and ultraviolet lights that can kill airborne viruses.

What does it mean for a virus to be airborne?

For a virus to be airborne means that it can be carried through the air in a viable form. For most pathogens, this is a yes-no scenario. HIV, too delicate to survive outside the body, is not airborne. Measles is airborne, and dangerously so: It can survive in the air for up to two hours.

For the coronavirus, the definition has been more complicated. Experts agree that the virus does not travel long distances or remain viable outdoors. But evidence suggests it can traverse the length of a room and, in one set of experimental conditions, remain viable for perhaps three hours.

How are aerosols different from droplets?

Aerosols are droplets, droplets are aerosols — they do not differ except in size. Scientists sometimes refer to droplets fewer than 5 microns in diameter as aerosols. (By comparison, a red blood cell is about 5 microns in diameter; a human hair is about 50 microns wide.)

From the start of the pandemic, the WHO and other public health organizations have focused on the virus’s ability to spread through large droplets that are expelled when a symptomatic person coughs or sneezes.

These droplets are heavy, relatively speaking, and fall quickly to the floor or onto a surface that others might touch. This is why public health agencies have recommended maintaining a distance of at least 6 feet from others, and frequent hand washing.

But some experts have said for months that infected people also are releasing aerosols when they cough and sneeze. More important, they expel aerosols even when they breathe, talk or sing, especially with some exertion.

Scientists know now that people can spread the virus even in the absence of symptoms — without coughing or sneezing — and aerosols might explain that phenomenon.

Because aerosols are smaller, they contain much less virus than droplets do. But because they are lighter, they can linger in the air for hours, especially in the absence of fresh air. In a crowded indoor space, a single infected person can release enough aerosolized virus over time to infect many people, perhaps seeding a superspreader event.

For droplets to be responsible for that kind of spread, a single person would have to be within a few feet of all the other people, or to have contaminated an object that everyone else touched. All that seems unlikely to many experts: “I have to do too many mental gymnastics to explain those other routes of transmission compared to aerosol transmission, which is much simpler,” Marr said.

Can I stop worrying about physical distancing and washing my hands?

Physical distancing is still very important. The closer you are to an infected person, the more aerosols and droplets you may be exposed to. Washing your hands often is still a good idea.

What’s new is that those two things may not be enough. “We should be placing as much emphasis on masks and ventilation as we do with hand washing,” Marr said. “As far as we can tell, this is equally important, if not more important.”

Should I begin wearing a hospital-grade mask indoors? And how long is too long to stay indoors?

Health care workers may all need to wear N95 masks, which filter out most aerosols. At the moment, they are advised to do so only when engaged in certain medical procedures that are thought to produce aerosols.

For the rest of us, cloth face masks will still greatly reduce risk, as long as most people wear them. At home, when you’re with your own family or with roommates you know to be careful, masks are still not necessary. But it is a good idea to wear them in other indoor spaces, experts said.

As for how long is safe, that is frustratingly tough to answer. A lot depends on whether the room is too crowded to allow for a safe distance from others and whether there is fresh air circulating through the room.

What does airborne transmission mean for reopening schools and colleges?

This is a matter of intense debate. Many schools are poorly ventilated and are too poorly funded to invest in new filtration systems. “There is a huge vulnerability to infection transmission via aerosols in schools,” said Don Milton, an aerosol expert at the University of Maryland.

Most children younger than 12 seem to have only mild symptoms, if any, so elementary schools may get by. “So far, we don’t have evidence that elementary schools will be a problem, but the upper grades, I think, would be more likely to be a problem,” Milton said.

College dorms and classrooms are also cause for concern.

Milton said the government should think of long-term solutions for these problems. Having public schools closed “clogs up the whole economy, and it’s a major vulnerability,” he said.

“Until we understand how this is part of our national defense, and fund it appropriately, we’re going to remain extremely vulnerable to these kinds of biological threats.”

What are some things I can do to minimize the risks?

Do as much as you can outdoors. Despite the many photos of people at beaches, even a somewhat crowded beach, especially on a breezy day, is likely to be safer than a pub or an indoor restaurant with recycled air.

But even outdoors, wear a mask if you are likely to be close to others for an extended period.

When indoors, one simple thing people can do is to “open their windows and doors whenever possible,” Marr said. You can also upgrade the filters in your home air-conditioning systems, or adjust the settings to use more outdoor air rather than recirculated air.

Public buildings and businesses may want to invest in air purifiers and ultraviolet lights that can kill the virus. Despite their reputation, elevators may not be a big risk, Milton said, compared with public bathrooms or offices with stagnant air where you may spend a long time.

If none of those things are possible, try to minimize the time you spend in an indoor space, especially without a mask. The longer you spend inside, the greater the dose of virus you might inhale.

Bengaluru, May 30: People travelling to Bengaluru by flight or train must pay to get their Covid-19 tests done at designated private labs.

This is being done to improve the participation of private labs that have been approved by the Indian Council of Medical Research to do testing. Many of these labs are running at sub-optimal levels.

The new rule will also help the special categories of passengers and their attendants to leave early for home quarantine after giving the sample once the swab collection centres are established at airports and railway stations. The nodal officers at these places will coordinate in establishing the swab collection centres.

Each test will cost Rs 650 per sample. XCyton Diagnostics will cater to air passengers. Rail passengers will be tested at Neuberg Anand Reference Laboratory, Cancyte Technologies Pvt Ltd, Aster Labs, Narayana Hrudayalaya, Vydehi Hospital and Syngene International Ltd.

Bengaluru, Mar 18: Karnataka Chief Minister B S Yeddyurappa on Wednesday said that the lockdown in the state will continue till March 31st. However restaurants and hotels will remain open.

Speaking to reporters here, Yediyurappa had said, "...we need to take more stringent measures, when the US President has recommended avoiding gatherings ofmore than 10 people in his country. We will discuss in the cabinet and take all necessary measures."

Two more coronavirus cases have been registered in Bengaluru on Wednesday, 18 March, taking the total infected cases to 13, ANI reported quoting state Health Minister B Sriramulu.

Meanwhile, Dental clinics in Bengaluru have shut shop after order from Indian Dental Association and Karnataka State Denta Council. The doctors have been advised to treat the patients only if there is an emergency.

In Udupit distrcit, Section 144(3) have been imposed across the district by DC G Jagadish.

No religious events allowed, devotees should not enter temples, churches or Masjid's in groups. Tourist locations closed. Students in PGs and Hostels asked to return home.

While, schools and colleges remained shut, IT professionals and other professionals working in air- conditioned places were advised to work from home. Till Tuesday evening, 13 COVID-19 positive cases have been reported in Karnataka, including one death.

The State government had on March 13 leapt into action announcing lock-down of malls, cinema theatres, pubs and night clubs for a week.

Instructions were also given to stop all kinds of exhibitions, summer camps, conferences, fairs, marriages, sports and engagement events and birthday parties state-wide for a week from Saturday.

While, schools and colleges remained shut, IT professionals and other professionals working in air- conditioned places were advised to work from home. Till Tuesday evening, 11 COVID-19 positive cases have been reported in Karnataka, including one death.

The Ministry of External Affairs confirmed that there are 276 coronavirus infected Indians abroad - 255 in Iran, 12 in UAE, five in Italy, one each in Sri Lanka, Hong Kong SAR, Kuwait, and Rwanda.

Earlier in the day, the total number of confirmed COVID-19 cases in India neared 150, according to the Health Ministry data.