Engineering Controls

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*


For 100% selfish reasons, I debated about sharing this link.

Do you have an awesome idea for noise controls that uses technology?  NIOSH would like to hear about it. They make no promises, other than they will keep it a secret. But, this may be an opportunity to make your idea come to fruition.

I think the key to this “noise challenge“is to combine new technology for use in education, limiting exposure, or noise metercontrolling exposures. Personally, I think construction has a lot of room for improvement. Unfortunately there is no money to the winner, but I think this may be a good thing, so as it promotes and attracts the people who want to do it for the right reasons. Here are some of my inferior ideas:

  • make a low cost audiometric exam workers could do pre/post work to measure temporary hearing loss
  • ask Google and Apple to install the sound level meter app in everyone’s phone. Then based on Big Data create “noise maps” so people will know how loud it is wherever they are going
  • crease a device which produces acoustical waves which can be calibrated and set for stationary equipment. Once calibrated, it produces acoustical waves in the opposite direction – thereby cancelling the noise. (yea, I know, far fetched)

A new idea, SmartSite, which may spark some interest is a wireless health & safety monitoring system for construction sites similar to the residential “Nest” systems. They have a monitoring system set up on a tripod with a laser particle counter and noise level meter. The information is able to measured in real-time.

So working people, be challenged! Submit your idea by September 30, 2016. Email me if you do, and I will accept your challenge, and throw mine in the hat with you.

I live in a moderate climate, but we had some 102 degree weather and it reminded me of how important it is to have a heat stress program and educate our workers.

Here are some tips and suggestions for keeping this hazard under control:

  • Mandatory rest/water breaks (time between work & break dependent on heat) in shade
  • Monitor/measure water consumption (& urine, if extreme)
  • Educate employees on symptoms and factors which might contribute (medications, were you drinking last night?= deydration)
  • Always work with a partner
  • Flexible work schedule (start early, leave when conditions get unbearable)
  • Increase ventilation
  • Consider the space (attics can be worse than conditions outside)
  • Provide easy access to emergency services
  • One of the coolest (pun intended) ways is a “smart” vest with a downloadable app – workers wear this safety vest and it will alert people when symptoms/conditions get bad (heart rate, temperature, etc). Developed in Australia by RMIT University in Melbourne.



If you are in the United States, you have probably been hearing issues with lead (Pb) exposures. The main focus lately has been in Flint, Michigan and their (new) source of water, which contains high levels of the metal. Wiki here.

So, who is to blame?

The NY Times suggests we should blame HUD for the millions of pounds of lead in paint. However, I’m not so sure we can cast all of the blame on them, the legislators, or manufactures. But, we are going to be dealing with lead exposures in the future.

I do not know the depth and extent to which lead poisoning is occurring throughout the US. I’m not sure anyone really does. But, there are MANY sources of lead exposure. For example: leaded gasoline (tetraethyl lead) was used in the past, aviation fuel (av gas low lead) still is, lead in paint, lead in copper pipe solder, lead in fishing weights, lead in ammo, lead in sheet rock, lead in Chineese toys…I could go on.

Bottom line though, if you (or your kids) have elevated lead levels,…there is a source. So, What To Do? Here’s my takeaways:

  • Test you & your kids for their blood lead levels.
    • It is a very established method, but isn’t an exact science. Don’t freak out if they are above “background” levels. Just do what you can.
    • The CDC recently lowered their recommended blood lead threshold to 5 ug/dl of blood.
    • Don’t do chelation therapy, unless the blood lead level is REALLY high. How high? I’m not a doctor.
    • DO eat lots of vegetables and fruit. These have found to lower lead levels the best (but maybe not the fastest).
  • Find the source.
    • Keep looking, there might be more than one. School, work, hobbies, nearby businesses, daily activities.
    • Measure: dirt, water, paint, your workplace.
    • Consider how small an amount is dangerous. 5 micrograms in 1 deciliter of blood. 5 micrograms is 5 millionth of a gram. A fruit fly weighs about 200 micrograms. So, cut a fruit fly into 200 pieces, take 5 of them…you get the idea.
  • Tell others.
    • Recommend that others investigate for themselves.

lead paint

There are pieces of equipment used in construction which are VERY difficult to control their noise generation; open cabs of equipment, drilling machines, impact drivers/drills, and some mechanical devices are the first to come to mind.

Modifying equipment to control the noise is better than handing out ear plugs. But, before you modify the equipment, does your company have a “Buy Quiet” program? NIOSH & CPWR released some info graphics which can help start you down this road to considering noise levels when purchasing new equipment.

Before modifying equipment to control noise consider:

  • Does the manufacturer have a “factory approved” modification already available?
  • Are there any liability considerations if you make this change?
  • Have you discussed the modifications with:
    • The manufacturer? Engineers?
    • Operator?
    • Mechanics?
    • Scope of work?
  • How much noise reduction are you hoping to achieve?
    • remember noise is logarithmic, so a reduction of  1 dB is achieving a lot…
    • but not much practical difference in regards to operations
  • Measure noise before and after, both static and dynamic

noise engineering control

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**

There is a lot of confusion over confined spaces in construction. OSHA is enforcing these rules since Aug 3, 2015, but has given a 60 day postponement (effective Oct 2, 2015). Right now you need to make “good faith efforts” to comply. For those in construction, you need to get up to speed, and even more importantly, get confident. Unfortunately, this information isn’t going to get you 100% there.

The reason confined spaces (and the rules) are so complicated is because every space is different. It’s not a minimum height guard rail, or fall arrest system. There are just too many factors, including: death by honey

  • the size (or smallness)
  • the ventilation (or lack of)
  • access (or lack of)
  • the work activity (what you introduce)
  • the hazards (before you enter, and what you introduce)
  • the people inside (people are different, and work different)

To begin getting educated, here are my suggestions:

  • Know the definition of (and when it’s) a confined space (hint: 3 things)
  • Know the location(s) of your confined spaces (AND mark them as such)
  • Train your employees and yourself
  • Buy a multi-gas meter
    • And, know how to use it, bump it, and calibrate it
    • And, train others
  • Know: host employer, controlling contractor, sub contractor, mobile worker. It may not be obvious.
  • Know: ventilation. When you can use it,  what changes, and how much you need
  • Understand “rescue”.  And, the answer is not calling 911.

When an accident happens in a confined space, there’s a high likelihood it’s a fatality.

If you have confidence in the rules, and, more importantly, in the hazards & controls, confined spaces can be safe.

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.  🙂



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.

Next Page »