VOA慢速英语--戴不戴口罩？

Experts seem to agree: If you are not a health care worker, do not buy N95 masks, long considered the best of protective masks.

They will not help you much, and they are in extremely short supply for the people who need them most: health care workers trying to protect themselves from COVID-19 while saving lives.

However, there is still debate over whether everyone should wear some kind of face covering when they leave their homes.

Staying home and limiting contact with groups of people remain the best ways to stop the spread of the new coronavirus.

But some experts suggest that some kind of face covering may help, too -- not by protecting the wearer from infection, but by protecting others from the wearer.

There is growing evidence that people can spread the disease without having signs of sickness themselves. Two studies have linked 6 percent to 13 percent of infections to people who were not showing any signs of infections themselves.

The new coronavirus, which causes COVID-19, spreads mostly through small drops of liquid that infected people expel from their mouths. That happens when they cough or sneeze. But it can also happen when they talk or sing.

If virus-infected drops of liquid land on surfaces, people who touch the surface get the drops on their hands. From the hands, it is a short trip to the eyes, nose or mouth. Masks may help by blocking at least some of those droplets².

"I don't think it's going to be the most effective tool in our toolbox, but I think it might help," said Tim Schacker. He is vice³ dean for research at the University of Minnesota Medical School.

However, he added, "this is a tough question because like all things COVID, we lack data."

There is not much definitive⁴ research on how well face masks of any kind work to prevent any disease, and even less research for a new disease like COVID-19.

N95 masks generally are best for preventing someone from catching⁵ a virus. When used correctly, they fit closely onto the face and block more particles than most other masks.

However, many people do not use them correctly. They often do not get a tight enough fit, which largely defeats the purpose of the masks.

Dr. Chongfei Jin works at Patient First in the state of Virginia. He said there are many videos available online that show how to wear the mask the right way.

He said, "I just want to remind the public three things: Avoid inside out. Avoid upside down. And cover your nose as well."

Health care workers are facing serious shortages in part because the panicked public has bought N95 masks for themselves.

"If they run out of masks, then it's very difficult for them to stay healthy to take care of you and me when we get sick," said Jon Andrus, a professor of global health at George Washington University in Washington, D.C.

Surgical⁶ masks are another popular choice. But experts say they provide limited protection from the coronavirus since they do not fit as closely to the face. They may help prevent the wearer from infecting others. But again, the masks should be saved for health care workers.

Some cloth masks may also help protect the public too. But it is not clear how much protection different kinds of fabric⁷ provide.

Some efforts have aimed to ask the public to sew fabric masks for health care workers facing extreme shortages. But, these homemade masks do not provide the usual level of protection.

One study from 2013 states, "A homemade mask should only be considered as a last resort to prevent droplet¹ transmission from infected individuals." The researchers added, "But it would be better than no protection."

Jin, the Virginia doctor, said a "homemade mask, I believe that is the last resort. If you have a surgical mask, please use the surgical mask [as] that's much better."

Andrus, the global health professor, is worried that masks will give wearers a false sense of security. Wearing a mask of any kind is no substitute for social distancing, he said.

But, "This is a war," he added. "Anything we can do to minimize risk is critically important."

Words in This Story

droplet - n. a very small drop of liquid

tough - adj. very difficult to do or deal with

tight - adj. difficult to move : fastened, attached, or held in a position that is not easy to move

surgical - adj. of or relating to the process of performing a medical operation

global - adj. involving the whole world

1 droplet   

n.小滴，飞沫

参考例句：

• The rate of droplet growth under different conditions can be evaluated.可以计算在不同条件下的云滴增长率。
• The test results showed that increasing droplet size was associated with better stability.试验结果表明，增加液滴尺寸将使稳定性提高。

2 droplets   

n.小滴( droplet的名词复数 )

参考例句：

• Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
• In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反，从人嘴里呼出的烟则包含相当大的水滴，所以呈白色。 来自辞典例句

3 vice   

n.坏事；恶习；[pl.]台钳，老虎钳；adj.副的

参考例句：

• He guarded himself against vice.他避免染上坏习惯。
• They are sunk in the depth of vice.他们堕入了罪恶的深渊。

4 definitive   

adj.确切的，权威性的；最后的，决定性的

参考例句：

• This book is the definitive guide to world cuisine.这本书是世界美食的权威指南。
• No one has come up with a definitive answer as to why this should be so.至于为什么该这样，还没有人给出明确的答复。

5 catching   

adj.易传染的，有魅力的，迷人的，接住

参考例句：

• There are those who think eczema is catching.有人就是认为湿疹会传染。
• Enthusiasm is very catching.热情非常富有感染力。

6 surgical   

adj.外科的，外科医生的，手术上的

参考例句：

• He performs the surgical operations at the Red Cross Hospital.他在红十字会医院做外科手术。
• All surgical instruments must be sterilised before use.所有的外科手术器械在使用之前，必须消毒。

7 fabric   

n.织物，织品，布；构造，结构，组织

参考例句：

• The fabric will spot easily.这种织品很容易玷污。
• I don't like the pattern on the fabric.我不喜欢那块布料上的图案。