Industrial Hygiene in Construction

I get the best questions from employees as I’m setting them up to wear a dosimeter. (FYI- this does not really apply to sound level readings, only dosimetry)

• Why do I have to wear the monitor (dosimeter)? Can’t we just place it in the middle of the area?

Ideally we want the dosimeter to measure the individual exposure. Many factors influence the average noise level, including work practices, location (sound bouncing & dampening), height, proximity to others, equipment, etc.

• What is the dosimeter actually measuring?

A dosimeter measure the sound pressure level, measured in decibels A-weighted, dBA (usually). It can record this level and average it (usually) for every 1 minute period. The amount of information it gathers is staggering…and confusing.

• What if we work a longer shift (more than 8 hours) will the results of the noise monitoring be the same?

Yes, the results are (usually) given as an average. So, in theory, if you measure the noise for 15 minutes and it is the same for the next 7.75 hours, it should be the same. However, if you work more than 8-hours a day OSHA actually decreases the amount of noise you can be exposed to. They have a table (G-16)  that attempts to explain it.  If you know the average level of noise (say it’s an average of 95 dBA 8-hour TWA), then you can determine the time you are allowed (answer: 4 hours).

• How often should noise monitoring be performed?

There is not a specific rule from OSHA on how often you must monitor. However, the guideline is yearly.  Or if/when significant changes occur “which might effect the results of this testing” (I always use this statement in my reports).

• Which individual employees should have their noise level measured?

It is best to let the industrial hygienist make this determination (there are several good reasons). If you are just starting out, they will often choose an average, or those who might have the highest noise level exposures.

• I’m wearing hearing protection, why don’t they take that into account when they determine the average readings?

Your exposure is determined without regard to the specific type of hearing protection used. If you are wearing the wrong type of hearing protection, or if it is worn incorrectly, you could still have this exposure.

Construction and exposure to Hepatitis B (or C or HIV) doesn’t arise very often since construction workers are usually not around blood, bodily fluids, or patients. There are times when construction must occur at wastewater treatment facilities, municipals, or in active sewers. Occasionally exposure can come from illegal drug use or the remnants of it (think of a project underneath a downtown bridge).

Currently there is not a specific rule for bloodborne pathogens in construction (1926). However, if it is reasonably anticipated that an employee might have exposure, you should take precaution.

What are the dangers? First, you must have occupational exposure to skin, eye, or mucous membrane with contact to blood or infected material.  Exposure may then cause the employee the diseases of Hepatitis B, C and HIV. Occasionally construction companies want to know if they need to offer their employees the Hep B vaccine.

The real-threat is contact with blood. Here is a question to ask… Do you anticipate seeing any blood on the jobsite? If the answer is NO…then you probably are under what is called the COLLATERAL DUTY clause. In this case, the hepatitis B vaccination does not need to be given…until the presence of blood. Once this happens (and employees must be trained beforehand) you have certain steps to take in order to offer the Hep B vaccination. Oregon OSHA (and others) have adopted this stance.

If you have probable exposures you must:

• make an exposure control plan
• train your employees
• universal precautions – google it…there’s a lot to know
• protect your employees (engineering controls, work practices)
• housekeeping – cleanup
• label
• keep records

Oregon OSHA has some good info here.

Here in the Northwest, rock crushing definately has a season…and that season is now. Road crews are getting set up and now is the time to make sure you get everything is in order…before the MSHA inspector shows up.

Below is my safety punch-list, specific to industrial hygiene:

• Training – I know it’s required for MSHA sites, but double check. Does everyone have it? What about contractors onsite?
• Water controls working & in place? The dust isn’t bad, yet.
• Air monitoring for silica – done it yet? Are you at a new location? New part of the quarry? Better do it again.
• Miner’s hearing checked (audiogram taken?). Anyone with a threshold shift? Make sure you follow up with another test.
• Are the air conditioning units working in the vehicles? – if they’re not= the windows will be down = noise levels WILL be up.
• Noise monitoring (dosimetry) performed 8-hour time weighted averages? If you don’t do it, MSHA will (maybe will be citation too).
• Is your shop done hardfacing the equipment? see my earlier post here.
• Paperwork in order?

Be safe out there!

If you hardface on construction equipment (or anything) you *probably* have overexposure to airborne hexavalent chromium. There are always exceptions, but if you are using a hardfacing wire/stick with any amount of chromium in it, the process (heat) generates hexavalent chromium. For how this happens, go here.

In construction it is quite common to have buckets and equipment with hardfacing applied to the surfaces in order to protect the equipment from excess wear and deterioration. The grid pattern varies, but it can look like this.

I realize that the application of the hardfacing procedure doesn’t occur very often. However, when it does, there is usually high levels airborne hexavalent chromium generated. So, what to do?

• Use some type of ventilation system (I know, I know, it messes with the shield gas, but do something!)
• Wear (at least) a 1/2 face tight fitting respirator with P100 (HEPA) filters (honestly, I’d buy a powered air purifying welding hood if I was doing it..and money was not an object)
• Cover any exposed skin (it can be absorbed by your skin)
• Designate the area as hazardous and limit the activities in this area (no eating!)
• Perform air monitoring to verify airborne levels are below limits (and get an IH out to evaluate it)

These suggestions really only scratch the surface of what you should do. Doing all of the above will not even meet the OSHA rules…but it will help protect you from exposure. Here is the OSHA Fact Sheet.  Another article from Welding Design & Fabrication.

In  the trainings I perform for employers, I try to explain to them that there IS overexposure to silica on their jobsite. I tell them that if I could be at their site everyday, and be ready to perform air monitoring at a moments notice, I could find overexposures.

Here is an example of a road crew cutting asphalt with a concrete saw. I’m sure it was a small cut (since they were not a concrete cutting subcontractor, and it was a tiny little saw). But the haze you see is the dust plume from the cutting.

I just happened to drive by and be stopped at a red light when this occurred. I know, I probably shouldn’t have touched my phone (while in my car) to take a picture…but I couldn’t resist. And, with that same train of thought, the road construction crew probably thought, “it’s just a small cut and it will only take 5 minutes”. So, neither of us are innocent

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We, in the US, hardly need a reason to celebrate. However, here’s another one.

Most of the time my job feels like a cross between a persuasive speech, an attorney at a deposition, a lab rat, and a mechanic working on a VW. However, once in awhile  you feel like you helped someone live a little better life, or changed things for the better. For those of you doing it…good job!

And, if you feel the urge, share the love! 🙂