Industrial Hygiene in Construction

I’m easily impressed with welding and welders. Welding looks so simple, yet hard, dangerous and permanent.

When interviewing your welder, here are some questions to ask:

• What type of welding are you doing?
• What type of metal do you weld on? (mild steel, stainless, galvanized)
• Is there any coating on the metal?
• What type of flux is used?
• Where do you weld?, and then, “Where else?”
• Is there any ventilation in the area you weld?
• Are there any flammables in the area?
• Do you wear any PPE when welding? (ear plugs, respirator, leather)
• When do you use fall protection?
• Do you have & use welding shields?

What makes welding so difficult is the number of variables involved. The welding variables can change by the minute. Educate your employees on these dangers.

After the above questions, if the employee is agreeable, I ask some additional questions. These are the ones that provoke the best stories:

• What is the strangest things you’ve welded?
• Have you ever welding in a really small (confined) area?
• Have you ever welded with exotic metals? fluxes?
• What’s the worst thing you’ve welded on?
• Have you ever gotten sick from welding?

There are many, many more questions to be asked depending on the answers. The authority on this subject, Michael Harris, has written an excellent book on this subject, “Welding Health and Safety“(ISBN 978-1-931504-28-7). It is available from AIHA. It is VERY detailed, and money well spent if you do welding. I have taken his short course (all day) and I learned more than I ever thought possible, and I still can’t even weld!

Hair growth for your ears! This type of hair growth is different than the hairs which grow longer as you get older… 

The problem with most types of hearing aids, cochlear implants, and other types of enhancements is that they only amplify the body’s ability to hear. I talked about a type of pill we someday might be able to take that helps, here.

Research has found a way to regrow the hairs in your ear…well, at this point, only in mice. But, in theory, you could put these hair growth cells in the part of your ear where you have the most damage…and, well, it might help!

The summary article is here. The original article is here. And, to nerd-out, here is the research paper.

As you might be aware, there is a loudness of noise which your ears cannot be protected against. Your body’s system of preventing the sound waves from entering your ear are just too much for it to handle. As the noise (sound pressure) hits your inner ear the bones convert the physical energy (noise) into a chemical & neurological process so you are able to hear. Ear plugs and ear muffs are not sufficient enough to protect against the amount of noise exposure.

However! Sometime in the future we might have a pill to prevent this type of hearing loss.

Researchers have found that the chemicals, D-methionine, ebselen & N-acetylcysteine, battle chemical stress on your ears.  We are still a long way from being able to take a pill to avoid hearing loss. They must go through more testing and the FDA approvals.

But, isn’t that cool!?

If you operate a ready-mix plant and have concrete trucks, you are aware of this process. Once a year (hopefully, only once) a person must climb into the drum of the ready-mix truck and chip off excess concrete. What happen during regular use, is that some concrete hardens, which usually sets-up over and around the blades. Access into the drum is by either the 3×4 hole in the side, or down the chute.

Yes, it is a confined space (def’n: 1. large enough to enter, 2. not designed for occupancy, and 3. limited entry/egress).

Here are a list of the possible hazards:

• silica dust (from chipping concrete)
• noise exposure
• hazardous atmosphere (curing concrete uses up oxygen, which we DO need BTW)
• slipping hazard (drum is round inside)
• heat stress (if you’re trying to do this activity in the summer)
• eye hazard (chipping)
• electrical hazard (if you’re using water & have an electric hammer)
• lock out / tag out (if the truck drives away, or if the barrel starts turning)

There are many resources available (see below). Some things to keep in mind; ventilation (fans, etc) to control the airborne silica dust are usually not effective (too much dust versus exhaust). Water controls are best, but you must limit the amount of water and the direction of the sprayer. I suggest looking at what others have done.

Keep in mind, if you perform this activity you will need (as a company):

• respiratory program (medical, fit test, written plan)
• confined space program (multi gas meter, written program, attendant?)
• lock out /tag out policy or procedures
• training (for each of the above, and for this specific activity)

At this point I know what my contractor-friends are thinking…I will subcontract this out!   ha. If you do, please make sure your sub is doing it right.

Resources:

Georgia Tech – good presentation & guidance

Georgia Tech/OSHA – Safe Work Practices (in Spanish too!)

Teamsters H&S hazards & controls

Illinois DCEO – Consultation on ready mix cleaning

As I have said in an earlier post, some OSHA, EPA, and MSHA rules are a good fit. They blend well with health research, scientific technology, good practices, and a low-cost-of-compliance for employers. Other rules are just bad. They are  totally out of date, not protective enough, or just not feasible/practical. Here’s my plug for a good safety manager/industrial hygienist – A good one will know which rules/guidelines to follow.

The New York Times (July 19, 2012, Cara Buckley) recently wrote an article on the US noise standards which are not protective enough for employees. In construction we also have three additional problems.

1. hearing loss is expected (or at least assumed in certain fields – carpenters, sheetmetal, ironworkers, etc.) and,
2. work shifts are usually over 8-hours. Noise exposure is usually calculated on an 8-hour time weighted average. During the busy months, an 8-hour work day is rare. It’s at least 10, maybe 12-14 hours. This doesn’t allow your ears to “rest” between shifts. For more information on extended work shifts go here.
3. extracurricular activities contribute to overall hearing loss – my point is that most construction workers don’t sit at home at the end of their shift. Almost everyone I know in construction is involved in one of these activities: hunting, shooting, motorcycles, water sports, yard work, cars, wood working/cutting, concerts, music, etc. Each of these activities contribute to their overall hearing loss, and again, doesn’t allow your ears to “rest”.

…which reminds me that I need to keep a set of ear plugs in my motorcycle jacket.

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.

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!

This is a big distinction when evaluating a workplace.

If you find an overexposure (or simply a real-exposure), then it is prudent, and expected, to look for employees with possible symptoms.

If employees have symptoms (especially those nondescript ones, like; nausea, dizzyness, and fatigue) it is much harder to say they have an exposure. You really can’t make that assumption without more information.

For example, if you have cancer, do you assume it is from all the bad food you ate during your lifetime? or, is from multiple factors? On the flip side, if you are a pile driver for 30 years and at the age of 60 you find that you have hearing loss, everyone assumes it’s from your job.

However, a lot of industrial hygiene work comes from “my employees have these symptoms”. The hard part is taking that information and determining if there is concern in the workplace.

Most welders wear ear plugs. Why? Because of noise, sure, but also because of slag entering into their ear canal and harming the ear drum.

The average noise levels can vary throughout the day – depending on the project. During the day of this survey, welders were tacking and fabricating stairs and handrails. However, their typical business is large tanks. Do you think the noise levels might vary depending on what they’re making? I do.

I’d also bet that air monitoring during these events would vary. If the welder is inside a large tank performing welding for a few hours, I’d worry about more than just welding fumes. (some might be: welding gases displacing oxygen, electrical hazards, heat exposure, UV, and also the welding metal and rods).

Be safe out there!