Why Wear A Mask?


This article is written for the benefit of the end user to be able to differentiate between one mask and another and the essential features required for a mask to work properly in filtering out urban pollution.

POINT 1 – Does it seal effectively?


The single most important point:

For a mask to work properly, it has to seal the area of nose and mouth from the external environment. The inhaled air has to pass through the filter material in order to remove pollution by physically trapping or adsorbing (different from absorption) gas or vapour molecules. A nose clip of some fashion, usually a strip of aluminum to bend between the bridge of the nose and the cheekbone is a vital component required to assist in making an effective seal.

Failure to create an effective seal will allow unfiltered air to pass around the sides of the mask and into the respiratory system. This is known as Inward Leakage.

A ‘one size fits all’ mask will invariably offer a poor fit and an ineffective seal and will place the mask squarely in the useless product bin. Like shoe sizing, one size does not fit all.

POINT 2 – Is the filter material up to spec?

Filter materials come in two categories:

The first is the ability to remove particulate matter. Typically that would be diesel particulates and pollen. The type of filter is usually a non-woven material made from zillions of fibres bonded together. They are electrostatically charged, both positively and negatively (like combing your hair makes a charge), so that particles, which are passing through the filter structure, are attracted and physically held in the matrix of the material. The smaller the particle, the greater the attractive force, which means that materials which are electrostatically charged can readily trap fine respirable dusts that over populate the air in our towns and cities.

Having first been developed by the Defence Establishment in the UK, these types of filter materials are not cheap. So if you are purchasing a product which appears to be ‘cheap’ and it says ‘removes particles down to 0.3 microns’, then the chances are that it might stop one or two particles but not the millions that are actually passing through. Watch out! If the material cannot be backed up by industrial test data then it probably doesn’t do the job effectively.

The second type of filter is Activated Charcoal material. It has the ability to filter (adsorb) gases and vapours. Well, like everything, if it’s cheap, then the chances are that the material is either black cloth appearing to look like Activated Charcoal (Far Eastern copy products are known for this) or a cloth that is impregnated with carbon powder. There is a big difference between the filtering capacity of a carbon powder impregnated cloth and a piece of Charcoal Cloth that is 100% Activated Charcoal.

Carbon powder impregnated cloths are used in the industry for cheap nuisance odour type products, like ‘odour eaters’ ; you know the things you put in your husband/wife or girlfriend/boyfriend’s trainers/shoes because his/her trainers stink after a while. These are good for air that is not moving i.e. static air, but of little use when air is travelling like when you are inhaling air into your lungs. For urban pollution, the best  material  to use would be what’s known as DACC™ (Dynamic Activated Charcoal Cloth). This material is 100% Activated Charcoal Cloth, which can absorb gases and vapours on a molecular level and very quickly too. It is manufactured under licence and is another decedent of the UK Defence Establishment. It has been tested on a range of gases and vapours that are listed on our website.

POINT 3 – Comfort

The ideal mask would be one that you forget that you have it on:

Well that isn’t quite going to happen. The best we can do is to ensure that the levels of discomfort are kept to a minimum.  Materials need to be soft not hard, edges need to be curved not cornered.

Exhaled breath contains three components that are not good to re-inhale and only increase discomfort.  On exhalation, heat, water vapour and carbon dioxide are all produced and need to be expelled before inhaling again. So rather than these components passing through the filter, it is best to channel them out through exhalation valves.   These are valves that open one way only. They close automatically when you inhale and open when you exhale. They are simple but effective parts of a mask and do not need to be replaced. The reason why we want the air to travel out through the valves is so they don’t saturate the filter with water vapour as it makes it harder to breathe in again and the relative back pressure of the speed of exhaled air including heat and water vapour, will hit you back in the nose and mouth area like hot air when getting off a plane at an airport in a really hot climate.

Comfort is important and if the mask is not comfortable for the duration of your journey you probably will give up on it. So choose your mask with the following points in mind:

1.     Covers both nose and mouth.

2.     Provides an effective seal

3.     Quality filter materials

4.     Exhalation valve or valves

[The mask in the picture is the Respro® Allergy™ Mask, available on www.respro.com]

Copyright© Respro® June 2012

16 Responses to Why Wear A Mask?

  1. Tamika Tucker says:

    My husband works at a plant that packages chemicals for tires and need a mask how good will this one be for that use

    • Hi Tamika,
      Sounds like your husband needs an occupational mask and should get in touch with the companies health and safety officer to do a risk assessment to determine what PPE would be suitable for the levels of chemicals your husband is being exposed to.

      Our sports masks are used for urban pollution. The dusts and chemicals that he may be exposed could well be toxic and life threatening so this is something that we recommend to all occupational enquiries of this type and would be irresponsible if we not to advise you of this procedure.

      I hope this is of assistance and please feel free to ask any further advice.

      Kind regards
      Harrison |Team Respro® Customer services

  2. Shirley carter says:

    I am swamped with information to the point of no longer knowing what is best to buy for a person with COPD trying to avoid infection and germs on a heavily congested London commuter train.


    • Hi Shirley,

      We differentiate mask use primarily into two camps. The first camp being users who do not have a respiratory problem but want to minimize exposure to pollution and those who have a respiratory disorder and are looking for a solution that will assist them in minimizing the resultant physiological effects of exposure. You fall into the second camp and we would only recommend the standard Respro® Allergy mask with Hepa-Type filter.

      The Respro® Allergy mask (click here) has a sub-micron particle filter for the removal of pollen, animal dander and most particulates in an urban environment with poor air quality. It has a breathable material comes in 4 sizes and is made from materials that are not considered to be allergenic. The important point about any mask is that it fits correctly and seals out the environment whilst allowing filtered air to pass.

      Our product can be ordered directly from our website, you get free shipping and we offer a fast, efficient, secure whilst we have stock.


      It is important that a mask fits correctly otherwise air will just pass through the gaps and not function how it is intended. Even if it has the best filter; if it is a poor fit it will reduce its ability to filter out the pollutants.

      If you do use our website service, we strongly recommend that you send in your details to confirm your sizing. We ask this so that we can ensure you have the correct size and that the mask will be of benefit to you or those who are using it. It is also important for any sizing issues that may arise so we are able to assess and resolve any problems.

      Our policy on returns:
      If we have advised you of the size for your mask and it is subsequently found to be an incorrect size, then we will exchange the mask.

      If you choose to make the decision on the size of the mask and purchase the wrong size, then we are not at liberty to exchange the mask as it is considered a personal item. Under the Consumer Contracts Regulations June 2014 if the item has been used or the seal broken then we are not liable to refund or exchange the item as this poses a contamination and subsequent product liability issue and therefore we are unable to resell the item.

      Please see the following link for sizing assistance and supply the following measurements so we can confirm your size: http://respro.com/pg/faqs/mask-sizing-guide



      Neck size:

      Head size:

      Eye to chin length:

      (most people know their height)

      (most people know their weight)

      Neck Size:
      Using piece of cotton or string, measure the circumference around the neck. use a ruler to determine the length of string. This is the neck circumference. Easier still check your shirt size.

      Head size (AKA Hat Size):
      Using piece of cotton or string, measure the circumference around the head. use a ruler to determine the length of string. This is the head or hat size circumference.

      Eye to Chin:
      Take a piece of string and place it between the eyes on the top of the nose bridge, run the string over the tip of your nose and down to just under the chin. This is the eye to chin length. Please note the curved line and the point to point distance. If you are in doubt then a Passport image would also be useful.

      Please use the illustrations to accurately provide your biometrics. http://respro.com/pg/faqs/mask-sizing-guide

      I look forward to receiving your information and confirming your size.

      Harrison | Respro® UK Customer services

  3. Deepak says:

    Some querys

    1. Does valves bypass air only from inside? Doesn’t air get pass through valves fom outside including pollution?

    2. What is the usage life/Expiry of the mask? If i wear it for 6 hours a day, for how many days it can be used?

    3. I am from India. How can i purchase it from here?

    • Hi Deepak

      1. The valves are one way exhalation valves, ie on exhalation air passes through them, on inhalation they close.

      2. The mask is washable and the filter in replaced. Depending on the environment and the activity and the time used, we normally recommend replacement after one month.

      3. At this moment in time we are working on distribution in India but do not have our masks available direct from India.

      To India it takes about 10-14 days using Royal Mail (tracked out of the UK) which is a free shipping service. We do offer FEDEX/UPS services, these are available at the Checkout and are charged at cost.

      Best regards
      Harrison | Respro® UK Customer services

    • we have respro mask available with us in India BVM MEDITECH PRIVATE LIMITED, NEW DELHI, http://www.bvmmkt.com

  4. ben says:

    i wear a mask alot since gastro has been going around my town

  5. DEAR SIR,

    • Respro UK Ltd says:

      Hi Nasir,

      We only supply our products through our website
      respro.com and only accept Mastercard or Visa

      Kind Regards

      Team Respro®

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