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How long does it take to catch coronavirus depending on the type of mask you’re wearing? | Society


A recent study carried out by the American Conference of Governmental Industrial Hygienists (ACGIH), based on data provided by the US Centers for Disease Control and Prevention (CDC), estimates different timeframes for coronavirus contagion depending on the type of face mask a person is using. These range from 27 minutes for somebody wearing a cloth mask to up to 25 hours for someone wearing a perfectly adjusted N95 mask (the US equivalent of an FFP2 in Europe).


In a closed space, without ventilation and no masks, an infected person can pass the virus to another in 15 minutes.

A well-fitted N95 mask lets a maximum of 10% unfiltered air through. If two people are using them, infection is unlikely.

*All infection times in this infographic have been calculated in an enclosed, unventilated space with a distance of two meters between the two people.

In a closed space, without ventilation and no masks, an infected person can pass the virus to another in 15 minutes.

A well-fitted N95 mask lets a maximum of 10% unfiltered air through. If two people are using them, infection is unlikely.

*All infection times in this infographic have been calculated in an enclosed, unventilated space with a distance of two meters between the two people.

In a closed space, without ventilation and no masks, an infected person can pass the virus to another in 15 minutes.

A well-fitted N95 mask lets a maximum of 10% unfiltered air through. If two people are using them, infection is unlikely.

*All infection times in this infographic have been calculated in an enclosed, unventilated space with a distance of two meters between the two people.

In a closed space, without ventilation and no masks, an infected person can pass the virus to another in 15 minutes.

A well-fitted N95 mask lets a maximum of 10% unfiltered air through. If two people are using them, infection is unlikely.

*All infection times in this infographic have been calculated in an enclosed, unventilated space with a distance of two meters between the two people.

These masks were in short supply in the early days of the pandemic, but now that they are commonplace, scientists and health authorities have been stressing the importance of using this kind of effective protection against coronavirus, pointing out that masks made of cloth and surgical masks are not equipped with a facial seal and are loose-fitting, thereby allowing a large quantity of aerosols to escape.

In the United States, the Joe Biden administration announced in January it would distribute 400 million N95 face masks to people across the country free of charge as part of the president’s strategy to combat the spread of the more-contagious omicron variant of the coronavirus. Since December, anybody wishing to attend the theater or a concert or use public transport in Italy has been obliged to wear a face mask of this grade to be granted access. In Spain, sales of FFP2 and FFP3 masks rose by 642% between November 2021 and January 2022 according to medical material distributor Cofares, while some Spanish regions such as Andalusia and Catalonia have asked that the wearing of this type of mask be made obligatory on public transport and during visits to senior homes.

The lack of protection against Covid-19 afforded by surgical masks is due to their loose-fitting design. Masks of this type are used to contain splashes on both sides of the fabric. During a surgical procedure, for example, they prevent the patient from being contaminated by drops of saliva from the mouths of the surgeons when they are talking, while also protecting the medical personnel from blood and other fluids from the patient. Furthermore, the filters in these masks only trap particles of between three and seven microns in size. This means that bacteria and other large aerosols are retained by the mask, but other finer aerosols, such as those that transmit the coronavirus, are able to get through.


Their loose design allows for up to 50% of the air (and aerosols) that we breathe to enter and escape.

These are designed specifically to stop infectious droplets that we emit when we speak, cough and sneeze, but not to trap the air nor the possible infectious aerosols.

During their production and professional use, tests are not carried out on the fit, only on the filtering material.

*Micron: a thousandth of a millimeter

Most of the aerosols that we breathe are smaller than 3 microns. Surgical masks do not trap these, but well-fitted N95 masks do.

Their loose design allows for up to 50% of the air (and aerosols) that we breathe to enter and escape.

These are designed specifically to stop infectious droplets that we emit when we speak, cough and sneeze, but not to trap the air nor the possible infectious aerosols.

During their production and professional use, tests are not carried out on the fit, only on the filtering material.

*Micron: a thousandth of a millimeter

Most of the aerosols that we breathe are smaller than 3 microns. Surgical masks do not trap these, but well-fitted N95 masks do.

Their loose design allows for up to 50% of the air (and aerosols) that we breathe to enter and escape.

These are designed specifically to stop infectious droplets that we emit when we speak, cough and sneeze, but not to trap the air nor the possible infectious aerosols.

During their production and professional use, tests are not carried out on the fit, only on the filtering material.

Most of the aerosols that we breathe are smaller than 3 microns. Surgical masks do not trap these, but well-fitted N95 masks do.

*Micron: a thousandth of a millimeter

These are designed specifically to stop infectious droplets that we emit when we speak, cough and sneeze, but not to trap the air nor the possible infectious aerosols.

Their loose design allows for up to 50% of the air (and aerosols) that we breathe to enter and escape.

*Micron: a thousandth

of a millimeter

During their production and professional use, tests are not carried out on the fit, only on the filtering material.

Most of the aerosols that we breathe are smaller than 3 microns. Surgical masks do not trap these, but well-fitted N95 masks do.

The N95, which is considered a high-protection mask and used in the prevention of respiratory diseases, is designed to retain fine aerosols. To achieve this, such masks are better adjusted to the contours of the face and have a filter capable of trapping up to 95% of particles measuring three microns (94% in the case of the FFP2). “For an FFP2 mask to meet all the regulations you have to perform 15 or 20 different tests. In the case of surgical masks, only four are carried out: filtration of bacteria, respirability, whether or not they contaminated and if they are splash-resistant,” explains José María Lagarón, a researcher at the Spanish National Research Council (CSIC).

The fit of a mask and its seal are more important than the filtration efficacy of its component materials when it comes to reducing leakage on the inside of the fabric. Ensuring an optimal fit is also important with these masks, as a gap between mask and face equivalent to as little as 2% of the mask’s surface would allow up to 50% of air to pass through unfiltered.


Recommendations for a good fit

Beards can

impede a

good fit

The best filtration and facial seal are offered by an N95 mask (N95 in Europe) that is well fitted around the head and the neck.

A knot tied in the bands of the mask improves the fit and reduces the entry and exit of aerosols.

The best recommendation to ensure a good facial seal of a surgical mask is to use a silicone mask fitter.

Recommendations for a good fit

Beards can

impede a

good fit

The best filtration and facial seal are offered by an N95 mask (N95 in Europe) that is well fitted around the head and the neck.

A knot tied in the bands of the mask improves the fit and reduces the entry and exit of aerosols.

The best recommendation to ensure a good facial seal of a surgical mask is to use a silicone mask fitter.

Recommendations for a good fit

The best filtration and facial seal are offered by an N95 mask (N95 in Europe) that is well fitted around the head and the neck.

Beards can

impede a

good fit

A knot tied in the bands of the mask improves the fit and reduces the entry and exit of aerosols.

The best recommendation to ensure a good facial seal of a surgical mask is to use a silicone mask fitter.

Recommendations for a good fit

Beards can

impede a

good fit

A knot tied in the bands of the mask improves the fit and reduces the entry and exit of aerosols.

The best recommendation to ensure a good facial seal of a surgical mask is to use a silicone mask fitter.

The best filtration and facial seal are offered by an N95 mask (N95 in Europe) that is well fitted around the head and the neck.

Tests to measure the concentration of aerosols on the interior and exterior of masks establish the minimum fit factor required to provide effective protection at 100. “A good FFP2 mask has a fit factor of over 200; a surgical mask can be as low as two,” explains Santos Huertas, director of research and innovation at Spanish occupational accidents and diseases insurer Asepeyo.

The type of fastening a mask has, the researcher explains, is key to ensuring an optimal fit. Masks that fit around the ears have much lower fit factors than those that are attached around the nape of the neck and the crown of the head. However, the fit of masks that use ear supports can be improved by a cardboard or plastic hook that links both straps behind the head. Whichever type of fastening is employed, it is essential to ensure that the nose piece is correctly shaped to the wearer’s requirement and that the mask fits the overall shape of the user’s face.

N95 masks are more durable than surgical masks, which lose their efficacy after around four hours of use. A disposable mask has a useful life span of around eight hours, while reusable models can last for 30 hours. Between uses, it is important to ensure that the mask is allowed to dry out, while also checking that it is in good condition, has not been damaged in any way and that its fastenings retain their elasticity.


The maximum usage time for a reusable N95 mask is up to 40 hours, but according to the exposure to the virus, experts consulted say that they can last up to 20 days.

Low exposure to the virus

Ventilated spaces and

with few people.

* Provided that the mask remains dry

and is properly fitted.

High exposure to the virus

Hospitals and areas with high amounts

of people.

Tests carried out with high levels of virus showed that it can remain active up to 72 hours in an N95. Four N95 masks alternated every 72 hours could last up to 20 days.

The maximum usage time for a reusable N95 mask is up to 40 hours, but according to the exposure to the virus, experts consulted say that they can last up to 20 days.

Low exposure to the virus

Ventilated spaces and

with few people.

* Provided that the mask remains dry

and is properly fitted.

High exposure to the virus

Hospitals and areas with high amounts

of people.

Tests carried out with high levels of virus showed that it can remain active up to 72 hours in an N95. Four N95 masks alternated every 72 hours could last up to 20 days.

The maximum usage time for a reusable N95 mask is up to 40 hours, but according to the exposure to the virus, experts consulted say that they can last up to 20 days.

Low exposure to the virus

Ventilated spaces and

with few people.

* Provided that the mask remains dry

and is properly fitted.

High exposure to the virus

Hospitals and areas with high amounts of people.

Four N95 masks alternated every 72 hours could last up to 20 days.

Tests carried out with high levels of virus showed that it can remain active up to 72 hours in an N95.

The maximum usage time for a reusable N95 mask is up to 40 hours, but according to the exposure to the virus, experts consulted say that they can last up to 20 days.

Low exposure to the virus

Ventilated spaces and

with few people.

High exposure to the virus

Hospitals and areas with high amounts of people.

Four N95 masks alternated every 72 hours could last up to 20 days.

Tests carried out with high levels of virus showed that it can remain active up to 72 hours in an N95.

* Provided that the mask remains dry

and is properly fitted.

Methodology: Contagion times based on the type of mask used come from a study carried out by ACGIH, using as a reference point the 15 minutes that it takes two people not wearing masks to become infected with the coronavirus, then estimating the remainder of the timeframes based on the performance of the various different types of masks.

Sources: José María Lagarón (CSIC), José Luis Jiménez (University of Colorado), Elena Plaza (nurse and teacher), Santos Huertas (Asepeyo), Pablo Medina (risk-prevention technician), US Centers for Disease Control and Prevention (CDC), European Centre for Disease Prevention and Control (ECDC), Spanish Health Ministry.



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