Coronavirus: Face mask, face shield, FFP2 mask, N95, KN95 – what′s the difference? | Science| In-depth reporting on science and technology | DW

Since the onset of the coronavirus pandemic, most countries in the world have introduced mandatory mask use in public spaces, on local transport and in stores. In Germany, too, everyone must wear some sort of mask when shopping, entering public buildings and offices, riding in trains, buses or cabs.

Still, infection figures continue to rise despite tighter lockdown measures. This has probably been triggered by mutated virus variants. Therefore, Bavaria is now the first German state to go one step further – the state government has decided that a simple mask is no longer enough. In the future, it must be a so-called FFP2 mask – the equivalent to a KN95, N95 or P2 mask in other parts of the world.  Here, we explain what the different standards mean. 

Simple face mask

The current regulation in Germany requires a simple face mask to be worn as a minimum requirement in most public areas. This is a piece of cloth that completely covers the mouth and nose. Even a bandana, or a scarf would qualify. When you exhale, it inhibits the flow of air and therefore the distance possible germs can travel. And this already significantly reduces the risk of infection for other people.

The purpose of wearing such a face mask is not to protect those wearing the mask from infection. It is the other way around – everyone else is protected from the germs the person wearing the mask may have. Because infected people can infect others even before the onset of symptoms,  virtually everyone is considered a potential virus carrier.

The logic behind the mask requirement is therefore: if everyone complies, the overall risk of infection in society will fall.

Cloth masks should be changed frequently and washed in hot water to prevent viruses from surviving. 

Surgical masks 

Such medical face masks  are the professional equivalent of the cloth mask. They consist of thin disposable tissue and fleece and were formerly used almost exclusively in operating theaters. 

Doctors and assistants wear this mouthguard primarily to prevent their patients on the operating table from being infected with germs and pathogens. If the wearer of the mask coughs or sneezes, for example, most of the droplets from the mouth and throat get caught in the mask. 

In the long run, however, this only works if the mask is changed regularly and disposed of hygienically and safely. In surgery, doctors must change their mask at least every two hours. If, on the other hand, a mask of this type is worn repeatedly, it quickly loses its effectiveness. 

However, during this pandemic, doctors and nurses hardly ever wear simple surgical masks. Higher-quality masks with better filtration  have become the standard practically everywhere in the medical profession. 

How much protection does the mask provide?

The wearer of the mask can protect himself against droplet and smear infections, but only to a very limited extent. Although the virus usually enters the body through the mouth or eyes — if there are no open wounds — the hands play the most important role in transporting the virus.

If you decide to wear a mask, you should probably also opt for protective goggles. The surgical masks, albeit less effective in keeping the viruses out, merely function as a constant reminder not to touch your nose with your hands when it itches. Neither should you rub your eyes.

FFP Half masks offer better protection

In addition to surgical masks, which look more like multi-layer disposable kitchen towels, there are also half masks with a real filter effect. These are more familiar to those who work in dusty environments or with aerosols. They are available either as disposable masks, usually made of strong pressed cellulose with a filter element and an exhalation valve, or as plastic masks in which a suitable filter is then inserted. 

A woman, wearing a FFP 3 protective mask.

Only a FFP 3-grade mask will filter out enzymes and viruses.

In the European Union these types of masks are divided into threeFFP protection classes (filtering face piece).

FFP1 

Although masks of protection level FFP1 are still better than surgical masks, they do not offer the desired protection against viruses. They are intended for carpenters, for example, who work at a band saw with an vacuum extraction system. Workmen may wear them to catch the coarser dust, which the vacuum cleaner is unable to catch. Or a bricklayer can put them on before mixing cement with a trowel, kicking up some dust.

FFP2 

FFP2 masks (equivalent to other international standards known as N95, KN95 and P2 masks) are becoming more and more prevalent for elderly care and nursing in these times of the coronavirus. They provide a certain level of protection against viruses to the wearer, but should not be used when in contact with highly infectious patients.

Given the temporary shortage of hygiene materials during the first COVID-19 wave in 2020, Germany’s Robert Koch Institute said at the time that medical staff could wear FFP2 masks rather than the standard FFP3 masks in infectious medical situations, if FFP3s weren’t available. However, this was controversial among physicians. Now there is no longer a shortage of high-quality masks for such critical workers. 

FFP3 

Only FFP-3 class masks (roughly equivalent to other international standards like N99, EN149 and P3) effectively protect the wearer from droplet aerosols, protein molecules, viruses, bacteria, fungi and spores, and even from highly dangerous dusts such as asbestos fibres.  Such high-quality filter masks can protect the wearer – unlike simple surgical masks – from infection due to their design. In other words, also from a highly infectious pathogen such as measles or tuberculosis. 

A Polish military officer, wearing a complete body suit and a military gas mask is caring for patients, who arrived in Wroclaw from Wuhan.

Effective but not suitable for just everybody: Military gas mask and complete body protection.

If a mask is needed – then it needs to be the right one 

But here too, protection only works if many other protective measures are taken at the same time: Strict hygiene when putting on a mask, protective goggles, gloves and plastic apron or overall, proper disposal of possibly contaminated disposable items and regular hand washing. In addition, the surroundings must always be systematically disinfected. 

These masks – together with all other protective clothing – are therefore used in quarantine stations, for example, where patients who are already infected are cared for. The medical staff has to put on and take off all the protective clothing, including the protective mask, at considerable expense.

For travelling in public transport or working at a keyboard at alternating workstations, which happen to be among the worst germinators of all, this effort would be completely disproportionate. 

Other approaches for better masks 

In addition to the three certified FFP mask types, there are other concepts for masks that have an antiviral effect. However, these would not meet formal regulatory requirements if FFP2 masks becomes obligatory in public spaces. Even if they were found to be effective, they would lack necessary certification.

One such idea is to take advantage of the germicidal effect of copper.  This is also used by hospitals, where you can find copper door handles,  for example, to minimize infections. One manufacturer produces masks with a fine copper mesh as filter material.

Another approach for home use, is to spray citric acid on a face mask. Phil Sadler, a mechanical engineering expert at the Arizona Controlled Environment Agricultural Center,  promotes this idea  in the accompanying YouTube video.

It has been known for some time that citric acid can protect against noroviruses,  which cause stomach and intestinal diseases. For example, using lemon juice when eating mussels can protect a person from a norovirus infection.

U.S. hygiene products manufacturer Kimberly-Clark  experimented with citric acid-based antiviral facial tissues in the 1980s and 1990s with the intention to counter seasonal colds and flus. Forty-one years ago, Sadler had also participated as a volunteer in a related research project at McMurdo Antarctic Station, he told DW.  Over the past 30 years, citric acid has also been used to some extent in N95 standard masks produced in the U.S. as an antiviral agent. 

Best protection: Don’t forget to wash your hands

All masks and goggles are of little use if the most important hygienic principles are neglected. For example, if you come home after a long bus or train ride, where you touched handrails and handles, take off the mask and scratch your nose, You could have left out the protective mask just as well.

It’s the same at work: if you have been typing on the computer keyboard all morning and then go to lunch without washing your hands first, you take a considerable risk. Then, wearing a mask at the computer workstation would have been of little use either. 

Proteste in Hongkong

Only the man in the center has effective protection against tear gas.

And what about tear gas?

Demonstrators often also wear a variety of different protective masks – from simple surgical masks to half masks with filters.

Surgical masks are probably only effective in conceiling the demonstrators’ identity. However, when the police fire tear gas grenades that spray an aerosol, only FFP-3 filters can provide some protection. To prevent the tear gas from getting into the eyes, airtight protective goggles are absolutely necessary. 

However, occupational safety filters from the hardware store do not offer any real protection. A proper full face gas mask with a military NBC filter would do the job.

And of course this also provides good protection against viruses. But in everyday life nobody wants to walk around like this.

This article was last updated on January 14, 2021.




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