A bit on respirators: This will start with describing the careful introspection and thought that must take place BEFORE you cinch up that respirator to your face.
In industry, OSHA requires this process: engineering controls, administrative controls and last PPE. This means first you must try and engineer out the threat. If that can't be done use control of exposure by rotating the people to reduce each s exposure (Share the pain, not used in my shops) and lastly PPE or Personal Protection Equipment. So if you can eliminate the risk by dust capture you are required to do so. This is the best way in our shops as well
In industry, the wear of respiratory protection REQUIRES a roughly 120 question questionnaire that is filled in and taken to the Doctor who does the respirator exam. And the reason for the exam is to see that your Cardio-pulmonary system is healthy enough to wear a respirator without causing harm to you. Now wait you ask, I want to wear a respirator to protect my...When you put a half or full face filtering respirator on your face your body has to work harder to pull air into your lungs. It has to overcome the restriction of the filters to get air in. This added stress can cause a heart attack in people with existing health issues. The doc will listen to your heart, listen to your lungs as you breathe and will perform a pulmonary function test in which the air volume of your lungs is measured. This becomes the base line and each year after it will again be measured to watch for changes. Most Doc's do a baseline lung X-ray as well.
So with that said if you will choose to wear a respirator, and not get that Doc's advice, you must really consider your own health. Do you have any issues in your cardio-pulmonary system. Consider well!
Once that first step is out of the way, there are many factors to now consider. A simple air purifying half face respirator is cheap and fairly effective. If you consider that a paper dust mask is not even considered a respirator in industry as they provide no real protection but are only allowed for nuisance dust, how do you know what respirator to choose?
First one should know the hierarchy of protection;
1. Paper dust mask=for nuisance dust IE dust that is not toxic
2. Half face air purifying respirator.
3. full face air purifying respirator
4. Supplied air respirator
As you go down that list the protection increases as does the cost. A supplied air respirator requires a special compressor or filter system, since a regular shop air compressor often generates Carbon monoxide in the process of compressing the air. Scary thought, lets fill my face mask with carbon monoxide!
Most folks go for the half face, air purifying respirator so I will be referring to that style form here on out. First thing, do not buy a respirator from a big box store if at all possible. Go to your local safety supply house and see if they have someone on staff who can train and fit you. Masks come in a huge assortment of sizes, materials and styles. The number of possible filters is scary big. A trained person to help you on the spot is of great value. And once you have found that person make them you best friend with a blacksmiths gift and they can often wholesale price all your safety needs, and boy will wholesale pricing be better then big box or online.
In short you need a mask that fits your face size, and no everybody is not the same. Got a beard? willing to shave? cause a regular face mask will not seal against facial hair. There are some solutions for a beard if you are willing to mortgage the house.
Once you have found the mask size material and size, now what filter? Here many people go wrong. For weld fume, you need a particulate filter. For paint vapor an Organic vapor cartridge. Many folks like to stack them and get protection from both. UNLESS you have both at the same time, don't do this, as it greatly increases the difficulty in pulling air in and increases your cardio-pulmonary stress.
Lets talk about fume vs vapor. In the safety world vapor is the term for a chemical that has changed state from a liquid to a gas, IE solvent in the paint evaporates and becomes a vapor that presents danger. Fume is from the French and is smoke. When you weld you make the metal liquid and some droplets become airborne and are so small that even when the cool and become solid they are small enough to be aerosols, of will stay in the air waiting to be breathed in.So the filters are very different for these two very different threats.
For weld fume and dust a particulate filter is used and these are rated by their efficiency in capturing what goes through them. HEPA is the term used in asbestos abatement that is now basically meaningless since every vacuum cleaner in the market starting referring to themselves as HEPA rated. That is patently false but I digress.
For a blacksmith, facing dust from grinding and fume from welding a N-95, P-95 or N-100 or P-100 filter is needed. These numbers mean N=not permissible. P=Permissible and the number is efficiency rating IE 95=95% of the particulate is captured, So what is the permissible part? It refers to is oil mist permitted when wearing against dust/fume. So if you have a dusty and oil misty shop you need the P rated. Please note that very few of us have a oil misty blacksmith shop, but if you do this P rating greatly increases the cost of the filter.
So what you ask do you wear in your shop against weld fume and dust? I always try for cross ventilation at the welding table. this removes the fume before it reaches my breathing zone. I have aquired and will install duct control at my grinders this winter. But when I am wearing protect against dust now, I wear a half face mask, with N-100 pancake filters because it fits under my weld helmet. The pancake filters have more surface area and allow easier breathing, and are a bit less expensive. Mine are labeled as protecting against particulate Radionuclides and are the old HEPA rated and are good for asbestos abatement. I always Seal check my mask. I also clean my mask often.
Respirators need to be cared for as does any equipment. The air you exhale is laden with moisture and thus the inside of the mask gets coated in your bodies lung secretions. This will begin to grow mold and the like very quickly in my Midwest location, and I suspect most of the world is no different. When one buys a good respirator the device comes with disassembly instructions and cleaning instructions. Some of the lower cost half face respirators are disposable and are not intended to be cleaned. these are often used in industry for coatings applications where a worker ends his shift, and tosses the entire respirator instead of disassembling cleaning drying installing new filters and storing the unit. A bit expensive for the blacksmith shop. Follow the instructions provided. A couple of tips, the thin rubber disks that serve as inhalation and exhalation valves tear very easily so use caution to not tear. Use the cleaning agent as listed in the instructions, the rubbers used in the face mask body can be ruined by some chemicals.
If your shop is like mine, wasps, mud daubers and spider are pretty common. Either carefully examine the mask for critters before use or store in a Tupperware type container that has a very positive seal. Nothing quite like getting your mask on and seal checked only to discover that you are sharing you mask with an eight legged friend.
What is a seal check you ask? After you have the mask on and the straps adjusted, one covers the exhaust valves with palms, and breathes out. The mask should inflate a bit and then some air should escape. If air just blows out then you need to adjust the mask to get a better seal. Then you cover the inhalation valve and suck in a breath and the mask should collapse a little and you should be able to feel that it is sucked against your face. These 2 checks tell you that you are pulling your air through the filters and cleaning it instead of breathing air that bypassed the filters.
Filters do not last forever. Any damage to the filter is an obvious change moment. With dust filters you can have them actually blank off from dust and you can't get air thru. But that is rare and when to change is a bit harder o tell. When you see an obvious "Cake" or layer of dust, time to change. Never blow out filters with air, this damages them and you no longer get protected. Organic vapor filters are done when you get ANY solvent smell coming through.
Written by Jeff Reinhardt