Size Guide & Mask Usage Information

This article covers the following topics:

Sizing Guide

To ensure the mask is the right size. Please first, measure from the middle of your nose to about a little over an inch under your chin, this is the reference for the first number on our size chart. For the second number, measure from the outer edge of your left cheekbone to the outer edge of your right cheekbone (about an inch below your temples) to find the correct width for your mask. Make sure to add a couple of millimeters to your measurement to avoid the mask being too small.

And check when you inhale there are no gaps between the mask and the face which could allow air to enter. The mask is probably too small if it is pulling your ears forward or rising above your chin. We base the size on body weight.



Washing Guide

The masks are washable, but cleaning them only cleans the external surfaces, not the pollution trapped inside the filter. The mask needs to be replaced after extended use to ensure proper filtration. 

You can find the washing instructions on the back of the tin. Wash the mask by gently massaging in/with warm water mixed with washing soda. This will remove dirt, makeup, and dust, however, it will not extend the life of the filters. Once you washed it, you can then leave the mask to hang dry.

Storage Guide

Our PRO masks are packaged in eco-friendly packaging, with plastic zip-lock bags which also act as a safe storage compartment for your mask when not being used. 

Please ensure the mask is dry before storing, particularly in warm environments. 

Infant Mask - Extra Small

We do not  offer masks for babies under 1.5 years both due to the choking risks and because babies' lungs aren't able to overcome the resistance to draw air properly through our filter materials. A healthy child from this age onwards should be able to overcome the resistance to airflow due to the mask and therefore would not have their oxygen intake limited. Depending on the reason for the use of the mask from this age up it may be beneficial to use a mask rather than expose such a young child to high levels of pollution. Any respirator should only be worn by children under close adult supervision and should only be worn when required. 

As the extra small size is indeed very small, and really designed for toddlers or very small children. The adjustable apparatuses; toggles and nose clip are too big for the mask and therefore we do not produce these at the moment. You may also notice the XS size does not come with a valve for the same reason. This does not usually create any issues as smaller children do not need to exhale as much air as adults. 

How do the valves work?

The valve works in a way that it opens when you exhale and closes when you inhale. The easiest way to see this would be to look in the mirror and see how it works.  

We have made improvements to the valve to adjust the thickness of the inner membrane to allow for ease of opening and closing at the exact time of exhaling and inhaling.  


Note that most health and safety organizations recommend no facial hair be worn when using a mask, as it may have an effect on seal/fit. We have had a number of customers report good feedback when wearing the masks with a beard, however, we cannot formally recommend it. 

A thick beard can create difficulties for a good seal, but the ribbing of the mask should still be able to get close to the skin to form a seal. You may consider ordering up a size if you are near the top of our sizing boundaries.


Sunglasses and glasses tend to fog when the mask is slightly too big and the air can escape through the top of the mask when exhaling only.  

You will have tried adjusting the nose clip and maybe altering the straps slightly. These are the two main methods. Some customers have attached our head-strap, tightening the fit. Alternatively, we have developed a nose foam that will come with your PRO mask or you may purchase it on our website. You can attach that to your nose clip of the mask.


Wearing a motorcycle helmet over the Cambridge Mask might create a problem. There is currently no PPE on the market that would fit under a helmet and be comfortable. This leaves the "buff" type bandanas which offer little in the way of protection from pollution. You may be able to find one that filters PM.2.5. 

However, we strongly recommend you check the background of the manufacturer to confirm those claims. Due to the nature of the filters required for filtration below PM2.5, it is unlikely any bandana-type mask will have that. Anything which is just cotton and with no filter within is unlikely to offer any protection from pollution. 

Rest assured, we are working hard to improve the mask and create new products that are better suited to certain activities.


The mask should be sealed snugly on the face so as not to be too tight to restrict facial movement, and not too loose to allow external air in through gaps. The valve ensures the exhaled air is expelled quickly. When inhaling this valve shuts and the air is forced through the filters. You may feel a slight resistance sensation at first, but it should become largely unnoticeable once accustomed to wearing the mask.


If you have further questions, please contact us by email at or Chat button on our sites to connect with our Customer Service Team.