Pollution has shrunk Indian newborns

Melbourne, Jul 24: Home-made cloth face masks may need a minimum of two layers, and preferably three, to prevent the dispersal of viral droplets associated with Covid-19, according to a study.

Researchers, including those from the University of New South Wales in Australia, noted that viral droplets are generated by those infected with the novel coronavirus when they cough, sneeze, or speak.

As face masks have been proven to protect healthy people from inhaling infectious droplets as well as reducing the spread from those who are already infected, several types of material have been suggested for these, but based on little or no evidence of how well they work, the scientists said.

In the current study, published in the journal Thorax, the researchers compared the effectiveness of single and double-layer cloth face coverings with a surgical face mask (Bao Thach) at reducing droplet spread.

They said the single layer covering was made from a folded piece of cotton T shirt and hair ties, and the double layer covering was made using the sew method described by the US Centers for Disease Control and Prevention (CDC).

The scientists used a tailored LED lighting system and a high-speed camera to film the dispersal of airborne droplets produced by a healthy person with no respiratory infection, during speaking, coughing, and sneezing while wearing each type of mask.

Their analysis showed that the surgical face mask was the most effective at reducing airborne droplet dispersal, although even a single layer cloth face covering reduced the droplet spread from speaking.

But the study noted that a double layer covering was better than a single layer in reducing the droplet spread from coughing and sneezing.

According to the researchers, the effectiveness of cloth face masks is dependent on the number of layers of the covering, the type of material used, design, fit as well as the frequency of washing.

Based on their observations, they said a home made cloth mask with at least two layers is preferable to a single layer mask.

"Guidelines on home-made cloth masks should stipulate multiple layers," the scientists said, adding that there is a need for more research to inform safer cloth mask design.

Consumer watchdog Which? has claimed that more than one billion Android phones and tablets are vulnerable to hackers as they no longer supported by security updates.

According to the research report, the most at-risk phones are any that run Android 4 or older and those smartphones running Android 7.0 which can not be updated are also at risk.

Based on data from Google analysed by Which?, two in five android device users around the world are no longer receiving the important updates. Currently, those devices are unlikely to have issues, but the lack of security leaves them open to attack.

"It is very concerning that expensive Android devices have such a short shelf life before they lose security support, leaving millions of users at risk of serious consequences if they fall victim to hackers," Kate Bevan editor Which? said in a statement.

"Google and phone manufacturers need to be upfront about security updates with clear information about how long they will last and what customers should do when they run out. The government must also push ahead with planned legislation to ensure manufacturers are far more transparent about security updates for smart devices and their impact on consumers," Kate added.

Android phone released around 2012 or earlier, including popular models like the Samsung Galaxy S3 and Sony Xperia S, are particularly at risk to hackers.

Which? has made suggestions to Android users on what to consider if they have an older phone that may be at risk.

Any Android device which is more than two years old, check whether it can be updated to a newer version of the operating system. If it is on an earlier version than Android 7.0 Nougat, try to update via Settings> System>Advanced System update.

In case a user is not able tto update the phone, the device could be at risk of being hacked if it is running a version of Android 4 or lower.

A user also need to be careful about downloading apps outside the Google Play store and should also install a mobile anti-virus via an app.