Respiratory Protection in Asia – Principles of Protection
Last year the World Health Organisation (WHO) reported that sufficient evidence now demonstrates air pollution to be the world’s single largest environmental health risk, contributing to 1 in every 8 deaths globally (approx 7 million people per year).
I have been working in Asia for some months now and have certainly noticed the significant environmental pollution. The other thing I have noticed is the “face masks” worn by the Asian population.
With all due respect, I do have some concern regarding the “masks” I have witnessed in use, particularly as the general perception is they will protect against dusts, chemicals and other biological hazards.
This blog is intended to simply explain how a “mask” works and how it actually protects you from all of the bad stuff in the air!
Let me provide you with a simple explanation of how clean air gets into your lungs and how bad air can be kept out.
Now, imagine billions of tiny little pollution particles that continue to float around in the air. Under a microscope, they usually look like this little creature
Now the aim of protection is to stop these little creatures from getting into your lungs
Sounds easy enough, right? Well, let me tell you it’s not!
You see when you wear a protective mask there will be a myriad of things that influence whether or not those little creatures will get into your lungs. Fundamentally to provide you with protection, the mask must:
— remove creatures of all sizes;
— remove creatures of all chemical states (gas, solid or liquid); and
— fit your face.
Let’s have a look at these more closely.
Whoever said size doesn’t matter was wrong! You see the tiny creatures that get into your lungs and hurt you are typically not visible to the naked eye, that is you won’t be able to see them!
Dust (or “particulate matter” as occupational hygiene nerds like to call it) comes in many sizes. The fact that it is floating in the air demonstrates how small it really is, you see the heavy particles will fall out of the air leaving us to deal with the small ones.
Now here’s two facts for you to consider:
1. the smaller the creature, the deeper it will go into your lungs
2. the deeper the creature goes into your lungs the less likely it will be for the creature to ever come out
Well, how small does it have to be you ask?
Let’s look at the pictures below. For us to even breathe in a creature it would have to be around about 10μm (AKA PM10), for a creature to get deep into our lungs it will need to be around 2.5μm (AKA PM2.5). Now let’s compare these sizes to the size of a human hair.
The microscopic image of the hair on the left below demonstrates the diameter of a human hair to be 60μm. Now looking at the diagram on the right we can compare the size of each creature to the cross section of human hair. Pretty small right?
So for a mask to even work it would need to include filter media that would capture even the smallest particle.
CHEMICAL STATE (GAS, SOLID OR LIQUID):
Creatures that “float around” in the air don’t just include particulates. Creatures come in many different forms and include liquids (think of vapours coming from a petrol tank) and gases. It is important to understand how the mask will actually adsorb the creatures made up of liquids or gases so that they don’t pass through and travel into your lungs. The discussion above regarding size continues to be relevant even when discussing the chemical state of each creature.
Think of the protection you need in the form of an umbrella that you were standing underneath. Your goal is not to get wet! If your umbrella was made of cotton (similar to the shirt on your back) and it started raining, would you get wet? Have a think about it.
It’s important to understand what you are protecting yourself from, whether it be a gas, solid (particulate) or vapour (liquid) so you know that the mask you are wearing is actually not going to let the little creatures travel across to the other side so they can get into your lungs. This is the very reason why different filters are used to capture different types of creatures. It is also important to note that sometimes no matter how good your mask is there are just some creatures that cannot be captured with a filter, for example, carbon monoxide (CO).
Sometimes people say to me that they don’t like wearing a mask because it makes their glasses fog up. Well, I can tell you there is only one reason for that – – – – the mask actually doesn’t fit!
So your still a little confused when I talk about a mask “fitting” you? Well it is simple, the mask you wear is designed to cover both your mouth and nose as these are the two locations air will go in and out of your body (other than farting of course!). We know that all of the air needs to pass through a filter to remove all of the bad creatures, therefore if there is a gap between your mask and your face, then bad air will enter your lungs, its that simple!
Mask seal against the wearer’s face
What’s not simple is actually getting a seal between the mask and your face, that is getting your mask to fit! Remember the picture showing the tiny size of the creatures in comparison to a human hair? Well, the picture below demonstrates how something as simple as facial hair will create a gap between a mask and a person’s face resulting in a broken seal. Once this seal is broken it is easy for the little particles to travel through the gap and into the lungs.
— the material the mask is made from;
— the shape of the persons face;
— features such as a persons nose;
— the size of the mask; and even
— chewing and talking!
So what do I need to remember?
The only thing I want you to remember from this blog is never assume a mask will protect you.
A mask will only protect you when all of the air that goes into your lungs passes through a filter that removes all of the bad creatures. To achieve this two fundamental things need to occur:
1. the filter media has to be designed and tested to prove that the creature you are protecting yourself from will be removed from the air; and
2. all of the air has to pass though the filter before it reaches your lungs – that is, no bad air is can pass though the filter or travel though any gap.
Don’t miss the next blog in this 5 part series where we take a look at and apply the above principles to the following three types of respiratory protection or “masks” commonly used in Asia to protect against all sorts of airborne health hazards.