Ad-hoc Simple Washable Respiratory Mask From Household Material

A simple washable mask, made locally out of a cotton T-shirt and (used) inner tube, may be a last resort in settings where commercial masks are not available.

Jakob Möhring (Berlin, Germany)

April 2020     ( updated: 2020-04-25 18:40:14.417 )

Correspondence to:


The US Centers for Disease Control and Prevention (CDC) recommended the use of homemade masks in settings where commercial facemasks are not available as last resort to protect against COVID-19 infection.1 Researchers described cotton T-shirt as a suitable household material for handmade masks, showing that simple masks may prevent droplet transmission from infected individuals and might even provide a measurable level of protection from a challenge aerosol depending on the design of the mask. Eliminating leakage around the mask will reduce exposure to infectious bioaerosols.

The following instructions show how to fold a T-shirt (dish-towel or bandana) to use it as a respiratory filter and wear it as a tight fitted and fairly well sealed respiratory mask using cut-up inner tube. Both low-cost materials are readily available and can be sterilized in low resource settings. The only tool needed is a knife or a pair of scissors.

Meta analysis of research indicates that a mask of this type can not only provide a physical barrier, but should achieve a reasonable fit factor, and therefor MAY reduce exposure to infectious particles.

Ad-hoc Simple Respiratory Mask

The use of this mask in place of a properly fitted commercial respirator is NOT advocated.

Persons with respiratory compromise of any type should NOT use this mask.

Ad-hoc mask from T-Shirt and cut-up inner tube

Facemasks reduce exposure to infectious particles and aerosol by a combination of the filtering action of the fabric and the seal between the mask and the face. While surgical masks can provide measurable reduction in exposure, properly fitted respirators will provide significantly higher reduction a study published by the UK Health and Safety Executive (HSE) reported.2

Cotton T-shirt and dish-towel have been described by researchers as a suitable household materials for handmade face-masks.3 Depending on its design even a simple respiratory mask made of several layers of cotton T-shirt can provide a measurable level of protection.4 Eliminating leakage around the mask is critical for reducing exposure to infectious bioaerosols.5

For this ad-hoc mask a cotton T-shirt is folded and used as the respiratory filter. Two straps from cut-up inner tube tightly fit and seal the mask to the face to reduce leakage. Since the straps are cut out of a torus (donut-shape) they are slightly rounded and maintain a surface curvature which will contribute to a better fit and seal. The rubber straps provide enough friction to hold the mask in place with simple half knots.

Inner tubes are made of butyl rubber (IIR), a robust elastomer (which is also used for seals in gas masks, other protective clothing, cars and windows). Butyl rubber maintains stability at working temperatures up to +120C (+248F).

Both cotton T-shirts and inner tubes are cheap and readily available. They can be sterilized with detergent and hot water, even in low resource settings.

The only tool needed to make this ad-hoc mask is a knife or a pair of scissors to cut the inner tube into straps.

Cutting the inner tube

Two rubber straps are needed, long enough to reach around the head and to easily tie a simple half knot at the ends: one from the nose to the back of the head, the other from under the chin to the top of the head. Any length short of one meter (or three feet) should be practical. The strap that will go over the nose should have a minimum width of 3 to 4 centimeters (around 1+1/2 inch) to maintain a reasonable width when folded in half in cross direction. A main feature of this mask is to fairly close the gap between the nose and the cheekbones (as far as possible) by the twists resulting from such a fold on the nasal ridge.

Inner tubes are made for bicycles, motorscooters, and motorcycles, as well as for heavy vehicles and old pneumatic tires. Smaller tube radius and smaller diameter both contribute to a better fit because the cut-out straps will feature a more pronounced cross and longitudinal curvature.

The first step to make the straps out of an inner tube is to cut out the valve. The remaining tube is cut into segments of the desired length: short of one meter (or three feet). Thinking of the torus shape of the original tube these segment are then horizontally (in toroidal direction) cut in two as one would slice a bagel, preserving as much of the circular bend (longitudinal curvature) of the original tube while making sure that at least one part has a minimum width of 3 to 4 centimeters (around 1+1/2 inch). Segments from wider tubes can be sliced lengthwise into straps of the desired width. The produced straps are slightly bent with an arched cross profile. They should be washed before use.

A regular bicycle tube (26" or 28“) has a roll length (torodial circumference) of about 200 cm (6 to 7 feet) and a (polodial) tube circumference of 5 to 10 cm (2 to 4 inch), a regular motor-scooter tube (10”) is 130 cm (4 feet) by 20 cm (8 inch). It should be possible to cut two pairs of straps from both such inner tubes.

For this demonstration a racing bicycle inner tube was cut into two pairs of straps, 88 centimeters (34 inch) in length, 35 and 20 millimeters (1+3/8 and 3/4 inch) in width.

Only one pair of straps is needed per mask.

Cutting the rubber straps from inner tube

Folding the T-shirt

A folded cotton T-shirt (dish-towel or bandana) is used as the respiratory filter. The filtering action depends on the number of layers and on the characteristics of the fabric, which should be tightly woven and hot washed to provide a higher degree of density. Individual ad-hoc masks of this type will differ in filtration efficiency because of variations in the material.

To increase the filtering action an extra layer of non-woven fabric can be added, such as single-use common household materials like paper-tissue, paper-towel, or coffee-filter-bag (which should always be new and not reused). With an increasing degree of density, breathing may become difficult.

The T-shirt or fabric may be of any size, as long as the resulting filter sufficiently covers the face. It is more easy easier to put the mask on if the fabric or shirt is long enough to be tied around the head (for instance, with its sleeves).

When rolling or double-folding the top of a T-shirt from the back of the neckline downwards to the shoulders, the contour of the rolled-up neckline (with a dent in the middle between two bulges) fairly matches the facial contour of the nose to the cheekbones, contributing to a better fit. The effect is similar if the T-shirt is first folded in half horizontally by placing the two bottom corners on the two shoulders (resulting in 4 layers of cotton).

For this demonstration a cotton T-shirt (size XL) was folded into to a triangular shape (with two diagonal folds, resulting in 6 to 8 layers of cotton in the center): the lower right-hand corner of the shirt is placed to the upper left side of the neckline, the lower left-hand corner is placed on the upper right side of the neckline, forming a V-shaped space within the neckline. The T-shirt is then double-folded from the back of the neckline downwards closing the open the V-shape and creating the advantageous bulges and dent.

A dish-towel or bandana can be folded in a similar manner.

Folding a T-shirt, dish-towel or bandana to be used as respiratory filter

Wearing the mask

The folded filter is put on the face like a bandit’s mask, with the folds on the inside. Placing the dent in the center of the long edge on the nasal ridge (dorsum) the two bulges are padding the spaces left and right between the nose and the cheekbones. If possible, the filter is provisionally tied behind the neck.

The rubber strap with the preferable width of 3 to 4 centimeters (around 1+1/2 inch) seals the filter to the face. It should overlap the filter one-half its width from the nose to under the ears, and being tied with a simple half knot at the back of the head.

On the ridge of the nose the strap is folded in half crosswise, bending the upper edge inwards around the edge of the fabric. The resulting twists to the left and right of the nose will fairly close the gaps between the nose and the cheekbones.

A second rubber strap is tied from under the chin to the top of the head to hold the filter in place and to support a tight fit of the mask.

Wearing this mask might restrict the ability of turning the head sideways. With long-term wear, comfort might decrease. After making sure that the ad-hoc mask is capable of accommodating the breathing demands, the wearer should follow general safety recommendations:

T-shirt and rubber straps can be hot washed to sterilize, but must be completely dried before reuse.

While testers wore ad-hoc masks made from different T-shirt and fabric for an hour without difficulty (during household routines and outdoor activity, riding the bicycle, commuting, shopping, plastering or grinding works), no comment on its utility during strenuous work or adverse environmental conditions can be made.

Rational for using this mask

The use of a mask alone is insufficient to provide the adequate level of protection and other equally relevant measures should be adopted. If masks are to be used, this measure must be combined with hand hygiene and other infection prevention and control (IPC) measures.6 Masks should ideally be used in combination with a face shield that covers the entire front (that extends to the chin or below) and sides of the face.

An improvised face mask should only be viewed as the last resort in settings where commercial masks are not available.7 8

Meta analysis of research indicates that a mask of this type can not only provide a physical barrier, but should achieve a reasonable fit factor, and therefor MAY reduce exposure to infectious particles. Individual ad-hoc masks of this type might be less effective because of variations in material, assembly, facial structure, practices, and handling. Because of the ad-hoc nature of this mask no definitive test can demonstrate the effectiveness before each use.

However, to people in low resource settings, who are advised to protect against infectious disease by using handmade masks or otherwise covering their mouth and nose with cloth or a scarf9, this instruction demonstrates how to effectively make a simple washable respiratory mask from household material readily available.

  1. Centers for Disease Control and Prevention (CDC). Strategies for Optimizing the Supply of Facemasks (Crisis Capacity Strategies). Page last reviewed: March 17, 2020 .↩︎

  2. Gawn, J.M., Clayton, M., Makison, C., & Crook, B. (2008). Evaluating the protection afforded by surgical masks against influenza bioaerosols Gross protection of surgical masks compared to filtering facepiece respirators.↩︎

  3. Davies, Anna & Thompson, Katy-Anne & Giri, Karthika & Kafatos, George & Walker, James & Bennett, Allan. (2013). Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?. Disaster medicine and public health preparedness. 7. 413-418. 10.1017/dmp.2013.43.↩︎

  4. Dato, V. M., Hostler, D., & Hahn, M. E. (2006). Simple Respiratory Mask. Emerging Infectious Diseases, 12(6), 1033-1034.↩︎

  5. Booth, C & Clayton, M & Crook, Brian & Gawn, Jonathan. (2013). Effectiveness of surgical masks against influenza bioaerosols. The Journal of hospital infection. 84. 10.1016/j.jhin.2013.02.007.↩︎

  6. World Health Organization (WHO). Advice on the use of masks the community, during home care and in health care settings in the context of the novel coronavirus (2019-nCoV) outbreak Interim guidance 29 January 2020, WHO/nCov/IPC_Masks/2020.1↩︎

  7. MacIntyre CR, Seale H, Dung TC, et al. A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open 2015;5:e006577. doi: 10.1136/bmjopen-2014-006577.↩︎

  8. World Health Organization (WHO). Rational use of personal protective equipment for coronavirus disease (COVID-19) and considerations during severe shortages. Interim guidance 6 April 2020. WHO reference number: WHO/2019-nCov/IPC_PPE_use/2020.3↩︎

  9. World Health Organization (WHO). Pandemic influenza preparedness and mitigation in refugee and displaced populations. WHO guidelines for humanitarian agencies, Second edition; Geneva, 2008.↩︎