Danish study finds face masks provide limited protection



ORIGINAL POST
Posted by Ed 6 days ago
https://hongkong.asiaxpat.com/Utility/GetImage.ashx?ImageID=8e3c4f4e-2410-47ec-acdb-6cff49a35afb&refreshStamp=0 
COPENHAGEN (Reuters) - A Danish study released on Wednesday found face masks provide the wearer with only limited protection against COVID-19 infection, but said this should not be used to argue against their widespread use to prevent people infecting others.
 

In the study, which was carried out in April and May when Danish authorities did not recommend wearing face masks, 6,024 adults were divided into two groups, one wearing face masks and one control group.
 
After one month, 1.8% of the people wearing masks had been infected, while 2.1% of the people in the control group had tested positive, Copenhagen University Hospital said in a press release.
 
“The study does not confirm the expected halving of the risk of infection for people wearing face masks,” it said. “The results could indicate a more moderate degree of protection of 15-20%, however, the study could not rule out that face masks do not provide any protection.”
 
 
The findings are consistent with previous research. Health experts have long said a mask provides only limited protection for the person wearing it, but can dramatically reduce the risk to others if the wearer is infected.
 
Preventing the spread to others is known as source control.
 
The study’s findings “should not be used to conclude that a recommendation for everyone to wear masks in the community would not be effective in reducing SARS-CoV-2 infections, because the trial did not test the role of masks in source control of SARS-CoV-2 infection,” the authors wrote.
 

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COMMENTS
Ed 6 days ago
Comment:
 

6 hours ago

I was trained as a chemist. A large part of my professional career was working in various parts of the filtration industry. I developed a line of mixed esters of cellulose membrane filters. Millipore type filters, that were used to sterilize flu vaccines for Merck Sharp and Dohme as well as other medical products companies.
 
I developed respiratory protection products for Wilson Safety Products used in the mining industry. I worked for Baxter developing medical / IV filters. I have patents on three IV filters I invented. Baxter sold more than 5 million of one of those every year for most of a decade. I know a little bit about filters.

Surgical masks were not designed as filters and were not intended to be used as filters. Surgical masks were designed to be used by surgeons standing face down over an operating table holding a patient with an open wound. The surgeon wearing the mask would be able to talk to others in the room without discharging spittle droplets into the patient's wound. Spittle droplets are large and can cause infection.

I witnessed a test of surgical masks. Small plaster particles were generated in a room. They were visible as a white dust in the air. A man was properly fitted with a surgical mask and spent a short time in the room. When he came out the mask was removed.
 
A camera was focused on the man’s face. The entire area that had been covered by the mask was coated by the white dust. The camera showed that his nostrils and his mouth had been penetrated by the white dust. The dust particles were measured and found to be around 40 micrometers in diameter. The particles that penetrated the mask were the same diameter.

Covid-19 virus molecules are about 0.1 micrometers in diameter. That is 400 times smaller than the plaster particles that penetrated the mask.

Surgical masks will not prevent the wearer from inhaling or exhaling viruses or bacteria. They provide absolutely no protection for either the wearer or anyone nearby. 

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