To slow the spread of covid-19 caused by the new coronavirus, health regulators have given a set of combined measures, namely, wash hands frequently, wear masks, and maintain social alienation. After the air transmission ability has been confirmed, people should pay attention to avoid long-term, close contact, which may cause transmission when taChinaing, sneezing or coughing. Based on this, wearing a mask has become a seemingly simple but effective droplet / aerosol blocking measure.
In a new study, the University of New South Wales team in Australia has compared the droplet / aerosol blocking effects of different types and layers of mask fabrics. If it is difficult for you to buy personal protective equipment that meets the standard, you can also refer to it when making it.
With LED lighting and a high-speed camera at 1000 frames per second, researchers were able to assess the spread range of droplets emitted during coughing / sneezing before and after wearing masks, as well as the effect gap when wearing single, double and three-layer masks.
According to the early recommendations of multi-national health agencies, the standard three-layer medical masks on the market are enough for ordinary people. As for the more effective N95 mask, it's better not to buy the version with breathing valve, which is confirmed by the new study.
Face coverings to minimise droplet dispersion and aerosolisation（ via ）
The researchers came to the following conclusions:
First of all, a single face mask is better than not wearing any personal protective equipment.
Second, although a single layer of covering reduces the amount of droplets emitted when speaking, the double layer fabric can better reduce the diffusion of liquid during coughing and sneezing.
Finally, the three-layer medical mask is the most effective way to prevent the discharge of droplets.
Details of the study have been published in the recently published British Journal of Medicine (BMJ)
《Face coverings and mask to minimise droplet dispersion and aerosolisation: a video case study》
In order to more intuitively show the protective effects of the three types of masks, interested friends can click to watch the slow photography video attached to the new study.
[source: cnBeta.COM ]