Why should we wear masks?
The virus doesn't respond to bravery and isn't impressed that you won't be intimidated by it. It has no feelings, no goals, no interest in whether you're afraid of it or not. Why not take advantage of the easiest defense strategy you can find?
If that's not enough, here are much more detailed arguments.
Masks work to reduce the spread of COVID-19
Masks are perhaps the cheapest and most effective weapon we have to fight this viral pandemic - and any other airborne disease.
A recent paper places the economic value of a single mask at $3-6,000:

- "People infected with the SARS-COV-2 virus can have minimal symptoms or can be completely asymptomatic. Thus, seemingly healthy people, including young people, are spreading the virus by transmitting it to others."
- "Masks, including cloth masks and surgical masks, have measurable efficacy at preventing infected people from transmitting viruses to others."
Read more in this Twitter thread by one of the paper's authors.
While most people are by now aware that SARS-COV-2 is transmitted through droplets in the air, it may not be obvious what that means in reality. Those droplets travel far and linger long after being expelled by an infected person.

Chinese scientists discovered infections occurring at a distance of 4.5 meters (almost 15 feet), with infected droplets lingering in the air for half an hour.

Asymptomatic transmission
We've already established that masks reduce spread of COVID-19 partly due to the incredible numbers of carriers who show no symptoms.
This is such an incredible and increasingly researched area that we've split this section off into its own article.
Masks protect your community
We all have someone we care about in a vulnerable class. That includes far more people than you might imagine: besides the elderly, anyone with respiratory problems like asthma, a heart condition (which are often undiagnosed), Parkinson's, diabetes, cancer treatment, suffering from autoimmune conditions or simply overweight (that factor alone accounts for 70 million people in the United States), is vulnerable.
Even if you're not convinced that masks will protect you from infection, they could save others from yours. It's simply selfish and irresponsible not to wear a mask, prolonging the economic downturn for everyone.
Besides you wearing a mask yourself for the benefit of others, you can distribute masks to those who don't have them or can't afford them.
If you're in the United States, the PPE Coalition lists ways you can help with supply.
Other places to donate:
- Donate masks via mail (USA)
- Directory of donation options (International)
- Find the Masks (USA)
- A document with many more places to donate (USA)
If you can afford to, give them away to essential workers: besides nurses and doctors, consider the underpaid cashiers, delivery drivers and technicians who never signed up for this kind of risk that they're now absorbing to keep the rest of our lives running comfortably indoors. Their level of exposure is high. You'll be safer if they're safer (we've been giving delivery drivers masks on top of their tips).
Give them to family and friends who are skeptical about the benefits of mask wearing; they'll be grateful to have some on hand when they do eventually come around.
Models: how it looks if many people wear masks
Models show that, with widespread mask wearing, the spread can be slowed dramatically.


Mask wearing reduces other infections so hospitals are less strained
Another interesting effect of mask wearing has been observed in Hong Kong: the rate of all other infectious diseases has been reduced, lessening the strain on hospitals. Mask wearing in Hong Kong, which was heavily impacted by SARS, became nearly universal during this pandemic, despite the government insisting it wasn't necessary.

Mask wearing is a true community effort
The great thing about masks is that you don't need permission to wear them (in most places). You don't have to wait for incompetent government officials to reach a consensus or take action.You don't even have to buy them: making your own mask is far better than nothing. The more people who wear them, the more the stigma against masks is reduced: a positive feedback loop. As one official said in the 1918 Spanish Flu pandemic, "Better be ridiculous then dead."
Your own safety depends on others being safe. Just as you aren't in traffic - you are the traffic - you are someone's "other" as they are yours.

Masks protect you
And not only against COVID-19. Masks protect you against air pollution and, notably, many infectious diseases.
Masks keep you from touching your face, a common way for the infection to spread. The "virus is viable for up to 72 hours on plastics, 48 hours on stainless steel, 24 hours on cardboard, and 4 hours on copper. It is also detectable in the air for three hours."

The dose makes the poison
Even if the mask fails to prevent infection, it's likely to reduce the viral load - that is, the amount of the virus you're exposed to.
A study on SARS (another novel Coronavirus) concluded that initial viral load was a factor in the severity of the illness:

There was a fascinating study on the spread of SARS within an apartment building where early cases were detected. For a research paper, it's a pretty gripping read. Cases nearer to the initial (index) patient on block E7 had a higher viral load: In E7, patients who resided within a few stories of the 16th floor had higher viral loads. For cases in neighboring E8, the distribution of patients and viral loads was random.
![Viral Load Distribution in SARS Outbreak [Figure left] Viral Load Distribution in SARS Outbreak [Figure left]](/assets/amoy-1.png)
![Viral Load Distribution in SARS Outbreak [Figure right] Viral Load Distribution in SARS Outbreak [Figure right]](/assets/amoy-2.png)
The death rate for patients near the source of transmission were much higher.
The overall case death rate among the 79 patients was 24.1%. The highest rate was in block E, which accounted for 79% of all deaths, while the death rate in patients living in E7 (the same block as the index patient) was 70% (7patients). This rate is significantly higher than in other units (p = 0.001 by χ2 test). The index patient was one of the few patients from E7 who survived the disease.
The method of transmission with the block was never fully determined. Like any good horror film, it left an opening for the sequel, SARS 2.
![Viral Load Distribution in SARS Outbreak [transmission source] Viral Load Distribution in SARS Outbreak [transmission source]](/assets/amoy-3.png)
Another paper concludes that the culprit was an exhaust fan driving air through the sewage system into neighboring apartments.
This isn't the case only with SARS. Studies on HIV reached similar conclusions:

And the flu:
Here’s a paper demonstrating correlation of flu dose with severity of subsequent infection in mice
Almost everyone has come around on masks
Most countries, scientists, and news organizations have reached the conclusion that the closer we get to universal mask wearing, the better. Everyone but the WHO. Who knows why. Though even they're now re-evaluating their position.
There are fewer and fewer #antimaskers by the day.
Below is a partial list of converted mask skeptics, taking the example of mask-wearing countries where the pandemic is best controlled - South Korea, Hong Kong, Taiwan, and others.
- Sweden changed their stance on masks, citing new information (this is actually very old information).
- Canada
- Germany is now recommending mask wearing.
- Peru has been handling the crisis effectively and mask wearing is now mandatory in public.
- Austria has made mask wearing mandatory, but much of the population remains skeptical.
- Now mandatory in Bulgaria.
- Israelis required to wear masks.
- The South African Minister of Health made a somewhat contrite statement in support of masks.
Case study: Czechia and Austria
A telling, but not conclusive, case study is the contrast between Czechia and Austria.
On March 16th, both Austria and Czechia started nationwide quarantines. One difference was that Czechia's quarantine included masks. Compared to Austria, the growth of Czechia's new daily cases #Covid_19 has relatively slowed.

Case study: Prato, Italy
Another instructive case is of the Chinese community in Prato; Italy's largest. Among Chinese resident in Prato there isn’t even one case of COVID contagion
because they, in contrast to their Italian counterparts, took early, strict adoption of infection-control measures.


United States
As late as February 27th, Dr. Robert Redfield, the Director of the U.S. Centers for Disease Control and Prevention was asked, "should you wear a mask if you're healthy?"

To which he replied:
"No... because I do see people feeling the need to go buy masks... there's no role for these masks in the community"
Thankfully, the United States will be recommending mask wearing, though with a signature twist, as President Trump insists that scarves are superior to masks (scarves are thicker).
This is a welcome reversal after the US Surgeon General recommended against universal mask wearing:

Mainstream publications named and shamed celebrities for wearing masks. Others went as far as to say that wearing masks "could put you at greater risk for coronavirus."
Now California is fining residents $1,000 for failing to wear masks outdoors, much as it did in the 1918 epidemic:

The boffins at Vox recanted their jibes after initially coming out against masks, and are firmly pro mask.

Everyone eventually comes around to the same realization.
Case study: Singapore vs. Hong Kong
Warning: this is all speculation
Contrary what you may have seen on social media, Singapore is not a mask-wearing country. Their success in combating spread has come from diligent quarantine, testing and some of the best tracking and tracing in the world.

A recent survey (February 26 to March 11, pending publication) found that only 6% of Singaporeans wear masks every day and 58% hadn't worn one in a week. But still better than in the West: 82.6% say they wear one when they're knowingly sick.
While Singapore has gone from recommending against universal wearing to handing masks out to its citizens due to concern over asymptomatic transmission, compliance is not at Hong Kong levels and the lag time has potentially revealed a marked difference in new case counts between the two.


Other factors endemic to Singapore are the large number of migrant workers who are suffering in crowded dormitories (of the 942 new cases reported on the April 18th, 95% were among migrant workers in these dormitories) and the daily influx of commuters from neighboring and much more heavily afflicted Malaysia.
Advice from China
Gao Fu, director general of the Chinese Centre for Disease Control and Prevention, is clear on the necessity for mask wearing. He says:
"The big mistake in the US and Europe, in my opinion, is that people aren’t wearing masks... This virus is transmitted by droplets and close contact... you’ve got to wear a mask, because when you speak, there are always droplets coming out of your mouth... Many people have asymptomatic or pre-symptomatic infections... If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others."
Here's a study from China on the size and distribution of droplets from coughing. The amount of distribution (that is, how far the droplets spread) is so much greater without a mask that the scale of the charts are completely different: without masks (left), the y-axis goes from 0 to 6000 droplets/cm3. With masks (right), it maxes out at 800 droplets/cm3.


Upcoming case study: Turkmenistan
Some countries are trying bold, alternative strategies. We'll check back in with them later to see how they do.

Scientific consensus
Study after study after study confirms that masks work. Not 100% of the time. But enough to save many lives and, with full compliance, even the global economy. An partial list of studies and white papers follows (the most thorough and conclusive is highlighted in red):
Study | Conclusion |
---|---|
Physical Interventions to Interrupt or Reduce the Spread of Respiratory Viruses: Systematic Review | From 2008, wearing a N95 mask is a 91% effective intervention to prevent SARS infection (beats 10x daily hand-washing) |
Rational use of face masks in the COVID-19 pandemic (Lancet) | "As evidence suggests COVID-19 could be transmitted before symptom onset, community transmission might be reduced if everyone, including people who have been infected but are asymptomatic and contagious, wear face masks." |
Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? | "Our findings suggest that a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection" |
Respiratory virus shedding in exhaled breath and efficacy of face masks | 5 year study "Our results indicate that surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals." More so for coronaviruses! |
Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers | Surgical masks and N95 respirators work comparably well to reduce flu infection |
Mathematical Modeling of the Effectiveness of Facemasks in Reducing the Spread of Novel Influenza A (H1N1) | "Facemasks and hand hygiene were correlated with a 35–51% reduction in influenza-like illness." (Figure A) |
Economic Analysis of the Use of Facemasks During Pandemic (H1N1) 2009 | Simulation showing that 25% mask compliance could lead to under 1m cases instead of over 100m (Figure B); if 50% use masks = $573b losses averted. |
Modeling the Effectiveness of Respiratory Protective Devices in Reducing Influenza Outbreak | Model: "80% compliance rate essentially eliminated the influenza outbreak." |
Could SARS-CoV-2 be transmitted via speech droplets? | All speech generates thousands of droplets. "A damp homemade cloth face mask dramatically reduced droplet excretion, with none of the spoken words causing a droplet rise above the background." |
The Case for Universal Cloth Mask Adoption and Policies to Increase Supply of Medical Masks for Health Workers | "...each cloth facemask generates thousands of dollars in value from reduced mortality risk. Each medical mask, when used by a healthcare worker, may generate millions of dollars in value" |
Further reading
Many more studies can be found in the Masks4All Google Doc.

For less scientific reading, a list of articles in mainstream publications:
- More Americans Should Probably Wear Masks for Protection (New York Times)
- Should I Wear a Face Mask? Coronavirus Advice Is Confusing (Bloomberg)
- U.S. Reviews Guidance on Masks to Fight Coronavirus as Europe Embraces Their Use (The Wall Street Journal)
- Would everyone wearing face masks help us slow the pandemic? (Science)
- Not wearing masks to protect against coronavirus is a ‘big mistake,’ top Chinese scientist says (Science)
- Simple DIY masks could help flatten the curve. We should all wear them in public. (Washington Post)
- Covid-19 Why We Should All Wear Masks - There is New Scientific Rationale (Medium)
- Why Telling People They Don’t Need Masks Backfired (New York Times)