Industrial Hygiene in Construction

Question: During mixing of portland cement bags of material (or similar types), am I overexposed?

Maybe, likely. But, probably not to silica. Most manmade, off the shelf products do not contain free-silica, or respirable fraction of the dangerous parts of silica. However, there is overexposure to respirable and total dust. But, be forewarned, if the product has rocks in the material, these may contain silica and if you cut the cured product- you can release respirable silica.

So, best practice is to:

• Use a product without silica (look for the warning on the SDS/MSDS, or bag)
• Eliminate any visible dust by water control methods (misting) or use local exhaust ventilation
• Don’t be dumb; stay upwind. Or, at least do the mixing away from others
• Wear a respirator
  • N95, aka paper dust maks is ok** (but, I’ve got a strong opinion of these)
  • 1/2 face tight fitting respirator with P100 (HEPA) filter is best

**You really do not know which respirator to wear unless you have performed airborne exposure monitoring**

The latest push from NIOSH is ridiculous, in a bad way. It’s titled, “Recognizing N95 Day” on September 5. I’ve written about these types of respirators before.

Let’s start with:

• NIOSH estimates 20 million workers exposed to airborne health risks
• N95 (s) are the most commonly used respirator
• NIOSH certifies all respirators. And, OSHA requires all respirators to be certified by NIOSH
• All certified respirators must have an “assigned protection factor”, which is a level of protection they are able to achieve
• N95 respirators are certified to provide a protection factor of “up to” 5 times the exposure limit

For the record, I am not disputing how NIOSH certifies respirators, or if these respirators can achieve a protection factor of 5 (5x the exposure limit). I will also add that in the healthcare setting (hospitals) these might have a useful role.

Here’s the problem:

• If you need a respirator, you would NOT choose a N95. They are terrible fitting.
  • To put it another way: if you had to work in an environment which had a dangerous airborne hazard, would you CHOOSE this respirator?
  • Or another way: “There is a chance this N95 respirator might protect you, wear this just in case”. (?)
• If you have fit tested these types, you know they are hard to fit, and at best, mediocre in their protection. At times it is hard to fit test a tight fitting 1/2 face respirator on someone who is clean shaven.
• N95 respirators are handed out (like candy) at construction sites for any task which “may be hazardous”.
• Let’s be honest:
  • these are “comfort” masks. AKA:  peace of mind, not for protection.
  • these are cheap. That is why most employers buy them.
• And, let’s mention:
  • exposure levels can vary (have you measured the worst case scenario?)
  • change out schedule? Do your workers wear the same respirators every day? Do they change them when they start getting hard to breathe?
  • facial hair (no one who is on a jobsite has this, right?)
  • there are knock-off N95 respirators which actually aren’t certified (they’re fake)

In this instance I wish NIOSH would spend money on training people to use the correct type of respirator. Or, how to adequately measure the hazards found at various sites.

As a quick review. If you need to wear a respirator, here are the proper steps.

There is a lot of confusion about N95 paper dust masks. And, it is confusing. The reason is because NIOSH has rated this type of equipment as a respirator. Prior to this, it was called a “comfort mask”. This name sounded better than calling it, “a worthless false sense of protection”. It is now called a, “dust mask”, or a “filtering face-piece”.

Here is what is required by OSHA if you wear this type of respirator (N95, or similar):

• Employees must read and sign Appendix D (of the OSHA respirator standard)
• Employees must clean, inspect, and store their dust mask

That’s it.

UNLESS you are wearing this because:

• Your employer requires it
• You have overexposures
• or, nobody “wouldn’t wear it”. (meaning: it’s an industry practice, and when when we do this XXX task, everyone wears this type of respirator– this is the same as your employer requiring it)

If  any of the above statements are true, then you have more to do. Here are links for more information:

Voluntary Use of respirators

Getting ready to wear a respirator

Professionally I do not recommend these type of respirators. Email me if you’d like to know why.

‘Tis the season for silica (here, and here too).

I had four observations about this picture,

1. paper dust masks are totally inadequate for this task, and
2. why isn’t there any engineering controls (water?, vacuum?), and
3. why is the observer standing in the dust plume?, and
4. what does the employees do with their clothes after work?

Please be safe out there.

There is much confusion over the requirements and best practices of employees using respirators voluntarily.

Let me first clarify. You must do air monitoring (or have other verifiable information) that employees are not REQUIRED to wear respirators (if they are overexposed to something, you must protect them). Also, they cannot voluntarily wear a respirators if there is a known hazard above the exposure limit (the employee cannot opt-out of wearing a respirator and be overexposed).

Some points about voluntary use:

• Assuming the above statement (s) is true, firstly, you do not have to allow them to wear respirators. I am sure this is arguable from a human resources/PR/legal stance. However, if you have documented no overexposure and have not provided a respirator, they should not need to wear one.
• Next, the employees need to be educated and you need to prove it. Having them sign Appendix D of the OSHA respiratory rule is a minimum. Training them would be better.
• What respirator are they wearing? A paper dust mask (N95, P100, or similar) is a respirator. If they are wearing anything other than this type of mask they need a medical evaluation (Appendix C of respiratory standard).
• If they are wearing a 1/2 face tight fitting negative pressure respirators (or more protective ones) the company needs to have a written respiratory program.
• Fit testing is not required to be performed
• Maintenance, inspection, storage, and training should always be done. Can you verify that the employee does this?

I personally do not recommend the paper dust masks (N95, or similar) for this simple reason. Why would you wear this type of respirator if you could have a 1/2 face, tight fitting one with the correct cartridge? The cost difference is negligible, the protection is better, and you can be assured of a better fit. If you’re going to do it, do it right.

I have done a bunch of respirable silica dust air monitoring during drywall sanding activities. I have found varying results from the data (meaning overexposures & within the exposure limits). I have found silica in the drywall mud (or possibly the drywall itself).  I have also found that most drywall sanders wear a paper dust mask. In recent years I have not found any airborne silica in my samples. However! I have found airborne (total) dust levels higher than five times the exposure limits during sanding. What does this mean?

Well, the issue is that most drywall sanders use paper dust masks, or equivalent N95 or P100. Like this.

NIOSH has rated these masks for a protection factor of 5. Meaning that you are “allowed” to be exposed up to 5 times the exposure limit. IMO there are many things wrong with these masks. For starters, their fit on your face is really a guess. There are no “tried-and-true” methods for assuring these masks fit.*  Second, if you admit that you need to wear a respirator (meaning: you need to protect yourself) why would you choose an inferior product? I could go on…

Therefore, or finally, we come to my recommendations:

• if you’re drywall sanding:  wear a 1/2 face tight fitting respirator with HEPA cartridges. It will protect you (given a proper fit) and based on my findings, you can rest assured you won’t be overexposed.

Besides who wants to look like this at the end of the day?

*Quantitative fit testing is a reliable fit test method, but for these types of masks, I find it to be totally useless in the real-world