At this point, the OSHA silica rules are forthcoming, what should you be doing to prepare?

  • Read the OSHA Small Entity Guide. Initially it is daunting – 103 pages, but much of it is specific to tasks from Table 1 and the full rules are within it, as well. Plus, they have pictures!
  • Identify tasks which could have silica exposures silica-grinding
  • Train employees, identify your “competent person(s)” – my suggestion is: Superintendents/Project Managers
    • Warn those on your projects: NO VISIBLE DUST on any tasks (cutting, finishing, dry sweeping, etc.)
  • Document activities with airborne silica exposures below 25 ug/m3
  • Identify possible solutions for overexposures
    • Verify airborne levels with personal air sampling
  • Start a process to log the number of days with (any) exposure – >30 is inclusion into medical
  • Find a medical provider that can have medical screen performed & with a B reader

*Thanks Andrew for the photos*


OSHA has recently announced the final time frame for the proposed silica rule. February 1, 2015 is their anticipated rule promulgation. However, we will see if anyone protests this new information, and if the date for final rule “sticks”.

AIHA broke the news (at least to me) and you can see their summary here. If this is the first you’ve heard about this new rule, then it’s time to do some research, and I might recommend starting here. There are quite a few new requirements, including a lower permissible exposure limit (PEL).

dust exposure

These pictures will come as no surprise. But, silica dust exposures (and nuisance dust) is an ongoing issue. Bottom line: if you have dust, you need to add some controls.

Platform of rock crusher (photo courtesy BP)
silica 5

Crusher operations (photo courtesy BP)silica 6

Grinding asphalt with a Bobcat (photo courtesy AH) silica 7

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

mixing cement

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

NIOSH (and with the help from some other groups) released a document this last week titled, “Best Practice Engineering Control Guidelines to Control Worker Exposure to Respirable Crystalline Silica during Asphalt Pavement Milling”cold milling machine

The issue: These machines are used to remove asphalt roads. They have a drum with teeth on them that essentially chew up the road and asphalt. A lot of respirable silica is generated (based upon the amount of silica in the rocks). The drums get really hot so water is used to cool it.  However, it does not control the respirable silica dust.  I’ve written (or, maybe complained) about the issue here, in 2010. And, I was informed, some good people were working on it.

The solution: The quick summary is: add more water and ventilation. Not rocket science, right? However, after reading this document, it might be. There’s a lot of information and specifics on what worked, and what didn’t. It was almost too much detail, but I suppose if you have a $200k+ machine, it is worth the time to figure it out. Below are some details:

  • Case studies – adding water and increasing the pressure flow decreased airborne dust
  • Tracer gas studies for ventilation effectiveness
  • Checklists and flow rate controls
  • Diagrams for where to direct water

Another benefit was the documentation of other’s work. There are numerous references  (5 pages!) to scientific articles. I did not notice any cost to implement the recommended changes, and I am curious to know what adding the ventilation system might run. Overall the document is good.

Finally, if you hold-on and continue reading to Appendix C, let me know what that all-means.  🙂



I was asked to summarize my thoughts on the OSHA proposed silica rule (which is currently pending). I’ve done it before, but since it was for the ASSE’s Industrial Hygiene Practice Specialty, it seemed fitting to post it on this site as well.

Wondering what is happening with the OSHA crystalline silica rule? In aviation terms it’s called a holding pattern. This airplane may-or may not-land. And, it is anyone’s guess.

If you haven’t heard, Federal OSHA is proposing to reduce the airborne silica permissible exposure limit (PEL) to 50 µg/m³. It is difficult to say how much lower this new rule will be, since the current standard relies on a calculated formula to obtain the exposure limit. However, for rounding purposes, let’s just say it’s a 50% reduction in the PEL. This limit is the same at the NIOSH Recommended Limit but still above the ACGIH (2006) Threshold Limit Value of 25 µg/m³.

Over the last year my views on this rule haven’t changed much: It’s a mixed-bag. There are still overexposures to silica. However, will the new rule change behavior?

To show some of the contrast, let me explain. Overexposures to airborne crystalline silica are still occurring. However, silica deaths have continued to decrease over the recent past (without the new rule). But, will the small employers comply? Or just wait to be cited? There is rarely a perfect solution for all situations. I’d like to provide a perspective balance to both sides of the rule.

The obvious benefit to lowering the silica exposure limit will be to protect overexposures to silica. I believe the rule will accomplish this in a number of ways. Any new rule will generate increased awareness for the subject of silica. The new rule will drive OSHA compliance by both lowering the PEL and by compliance with their additional controls. This will drive changes and modification to industries. Innovation will be spurned for controls and the need to comply.  In turn, this will create more discussions on the topic, the solutions, and overall awareness.

The new rule will get closer to the ACGIH TLV and update the health standards. The original rule was from the 1970s. And, OSHA is on the prowl for ways to update their current PELs.

Health and safety consultants will have an occasion for additional revenue in training, air monitoring, recommending controls, and other opportunities.

The new rule allows for alternatives to sampling. Rather than air sampling, you can choose to “over protect” and assure employees are controlling silica exposures.  This is a great solution for short duration tasks where exposure monitoring is prohibitive (see Table 1 from OSHA’s Fact Sheet). They emphasize control measures for silica.

There are very few new products and control measures for mitigating silica exposure in industry. Technology has somewhat sidestepped innovating products for dust capture and control for concrete work. Hopefully new products will be created to control silica. If nothing else, maybe we will see frequent job safety analysis (JSA, JHA) as a common practice to control exposures.


However, there are notable weaknesses to the proposed rule. The obvious downside is employers are expected to spend money. This will be an additional cost to doing business. Money will be spent on citations, controls for silica, labor during the activities, and for consultants to verify exposures are below the PEL.

This new rule will also allow OSHA to issue citations easier.  There are many items in the new rule which are beyond merely lowering the exposure limit. I imagine compliance officers will cite for failure to implement controls, or other technical aspects, rather than measuring the airborne dust and finding overexposure. Look for more drive-by citations.

And, there will be more confusion. Remember explaining to people how to calculate the current PEL? Well, in the short term, it won’t get easier. Although the PEL will be a fixed amount, there will be other things to explain. And, remember all the OSHA rules for leaded paint? The new rule is similar in how it allows you to provide adequate PPE and controls for “interim” work without measuring airborne levels.  Imagine you are a smaller contractor employer. This will be confusing and a lot of background work in order to use a jackhammer for one small project.

And, analytically, the airborne levels attempting to be achieved are so low, they are at the laboratory detection limits. With laboratory I currently use, to reach the detectable minimum PEL you will need to sample for at least 80 minutes (200 Liters). There is some newer sampling equipment which makes these levels easier to achieve. But, guess what? That will cost more money.  In addition, contained in the rule are mention of specific medical evaluations and facilities for those with continued overexposures. There are not enough medical facilities to support the number of people who need them.


Overall, I believe the new silica rules will help reduce overexposures to silica. The increase in awareness across the US will bring more attention to the danger. Employers who are doing absolutely nothing to control silica will get caught, punished, and hopefully change their ways. For employers already in compliance, there will be a small, but manageable, learning curve. I also see many contractors using interim controls (Table 1) as a guide to easily protect employees on short tasks with high silica exposures.

To stay ahead of the curve, the AIHA has released (2013) a white paper for guidelines on skills & competencies in silica specific to construction. It is a great outline for training your employees. Another great resource for awareness and silica control measures is As a reminder, pre-task planning is still one of the best methods for health and safety.

 Here’s my sampling outfit.

my silica bag


Sorry for the delay in writing. I have had some personal and professional projects taking a lot of my spare time. I have been preparing to present at a couple local conferences on Industrial Hygiene in Construction. It is a good exercise for me to ponder what I should say to these audiences. Here are some takeaways:


My latest guess (subject to change, by even tomorrow) is the Federal OSHA rule for silica will be enacted.

“Why”, you say? …well:

  • Current administration would love to push it through
  • Yes. It’s still an issue in the construction world. Have you driven by a construction site lately?
  • Federal OSHA is also talking about updating the PELs…and this one (silica) is an easy one
  • When?  No idea.

Falls in Construction:

This one is huge. In a bad way. If you look at what kills the most in construction, it’s falls (inclusive of scaffolding, ladders, fall protection, etc.) They cost a lot too. Not just in the number of people killed, but the claims & recovery cost are high. And, near misses in construction are VERY common. For example, just two weeks ago: An 18 year old roofer apprentice was working on a roof.  He stepped onto a piece of drywall and would have fallen to a concrete slab 25 feet below. Luckily someone had moved a piece of equipment directly under where he fell. He only fell four feet and had no injuries.

Hierarchy of Controls:

Is anyone working with these anymore? Just kidding, sort of. But, we can do a better job in construction of:

  1. Engineering Controls first. Can we eliminate this hazard? Has anyone asked to substitute this product for a safer one?
  2. Administrative Controls second. There are ways and methods which we do things in construction. These are usually passed down from journeyman to apprentice. Overall, this is awesome. For example, we need to rethink why we place the rebar on the ground? Can we use saw horses? Better material handling would save a lot of injuries.
  3. PPE third. And as a last resort.

Personal Protective Equipment:

Oh boy. There is a lot of room for improvement here. The wrong equipment, worn incorrectly, not used enough, and damaged. I don’t have the answer for this, except we should create and encourage the best safety culture possible.  I think this helps construction to take pride in their work, and their (and their friend’s) safety.

Here’s my top 5 gifts for Christmas in the (my) occupational hygiene world of construction:

  1. A new carbon monoxide monitor.
    • Not just a “normal” $40 model. A Nest Protect Fire & Carbon Monoxide monitor, which is in the $100 range. This thing is sweet. Talks to you, sends you a text message. Here’s a review from Cool Tools. Or, just buy it here.
  2. High flow air pump, Gast model.
    • I have some other flow rate pumps up to 5 liters per minute (LPM), but this one is great for flow rates 10-up to 28 LPM (depending on the model). Good for high volume area type samples and vacuum wipe sampling. You must have 110 power available, but once calibrated, it’s a done-deal. They can be bought for under $250. Grab a rotometer too, if you don’t have one.gast pump
  3. Wireless response system to use during training.
    • Attendees have a wireless response keypad and the trainer can ask a multiple choice question. It allows the audience to reply. The results then show up on the screen. Great for anonymous responses, or a general overview from your audience. There are several vendors, here’s an example, and the leader in the industry is Turning Point. I think these are in the $500-$1,000 range.
  4. A bulk asbestos example kit.
    • A bunch of “typical” building materials which are asbestos containing. In sealed glass jars, of course. I don’t know where you’d buy this sort of thing. I wish I would have kept all of my samples over the years.
  5. A dedicated short term silica sampling kit.
    • SKC has a new sampler which can sample at a higher flow rate  of 8 LPM, compared with the usual 2.5, or 1.8 LPM. (which, if you think through the math; allows you to achieve a detection limit with a lower sample volume, and a shorter time duration) Unfortunately, you must purchase a new SKC Leland pump/charger, PPI sampler, calibration junk. Total cost is probably in the $2,000 range.


If you haven’t heard, Federal OSHA is proposing to reduce the airborne silica permissible exposure limit (PEL) to 50 µg/m³. It is difficult to say how much lower this new rule will be, since the current standard relies on a calculated formula to obtain the exposure limit. However, to make this easier, let’s just say it’s a 50% reduction in the PEL. This limit is the same at the NIOSH Recommended Limit and above the ACGIH Threshold Value of 25 µg/m³. Before I offer my opinion, you can state yours to OSHA here, and I’d recommend you do.


OSHA helps


  • Increase awareness by everyone (any news is good news for silica awareness)
  • Further protect employees from overexposures
  • Update the health standards. The original rule was from the 1970s.
  • New products for the industry will be created to control silica, like this.
  • Pretask planning (JSA, JHA) will become more common
  • Consultant hygienists will get more $ to: train, air monitor, etc.
  • Alternatives to sampling. This is written in the proposed rule.
    • Rather than air sampling, you can choose to “over protect” and assure employees have adequate PPE
    • This is great for short duration tasks where exposure monitoring is prohibitive (see Table 1. below from OSHA’s Fact Sheet)

OSHA lead table 1



  • Employers will spend additional money:
    • on controls for silica
    • on labor during the activities
    • on consultants to verify you’re below the PEL
  • OSHA will cite you easier
    • (my guess) is compliance officers will cite you for failure to implement controls, rather than measuring the airborne dust and finding overexposure
    • driveby citations. Look at some of my “caught on cameraoverexposures. It is easy to see why this will be easy for OSHA to cite.
  • More confusion
    • remember how you felt when you started working with leaded paint? Picture that again.
    • smaller contractors might be confused with the changes
  • I’ve heard: the airborne levels trying to be achieved are so low, they are at the laboratory detection limits. (this is a bit beyond me, honestly, but it has to do with chemistry & analytical methods)

Overall, I think lowering the limit will reduce employee overexposures to silica. The increase in awareness across the US will bring more attention to the danger. Contractor employers who are doing absolutely nothing to control silica will get caught, punished, and hopefully change. For good-contractors out there, this will make it easier to explain to your subcontractors who are a little behind. I can see many contractors using Table 1 as a guide to easily protect employees on short tasks with high silica exposures.

Your thoughts? I’d love to hear them. Here is a NY Times Article perspective.

I was visiting a friend and in their neighborhood all of the curbs were cut for driveways (they were not poured for the cutouts). curb1

This might have saved some time for the carpenters forming & pouring the concrete. But it created additional work for the concrete cutters and the finishing of the driveways.

This lack of pre-planning created:

  • additional time to cut the curb,
  • dust (and silica, for sure),
  • the use of additional water (hopefully) to control the dust,
  • respirators (& cartridge filters),
  • exposure to noise, dust, silica

I don’t know the circumstances why this occurred, but I wonder if the person planning the development thought of the exposures to other human beings?


ps. Sorry for my blogging absence. Have been on vacation! (for some of it)

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