Industrial Hygiene in Construction

Stainless steel welding is a great way to generate hexavalent chromium (Cr6). There is chromium in all types of stainless steel. When heating up stainless steel, chromium goes from chromium 3 to it’s hexavalent state (chromium 6).  Look to my other post for the health effect summary.

At this site, we measured just hexavalent chromium for the two welders and the two helpers on site. It is helpful to take wipe samples around the area to see if the material is migrating. If I am really worried about hygiene, I’ll take samples in the shop bathroom or in people’s truck (steering wheels, floor boards).

In general TIG welding does not generate a lot of hexavalent chromium. I’m sure there’s a good reason for this, but I have not heard exactly why. Probably the lower heat, not as much metal used, etc. However, as in all welding, it depends.  One welder was working inside a three foot diameter duct, which is entirely different than welding in an open shop.

Well, every time this year I start seeing Radon in the news. I probably have an altered view, and no one else sees these…, but it is a good time to think about you & your family’s radon exposure. For those that don’t know. Radon is a odorless, tasteless, colorless gas that occurs naturally in some areas. The real trouble is that the only way to know – is to test. Home testing is simple and I REALLY recommend it. Seriously.

There are plenty of good sites about this subject, and on testing. For a quick overview try:  EHS Today’s article

Click here for the radon awareness link on wordpress.

EPA’s website always has reliable information.

Finally,  I have used the testing from radon.com and found it to be useful and helpful. However, buyer beware, I have had some results with mixed information.

Many bridges and elevated highways have leaded paint. Lead and cadmium was (and sometimes still) added to paint for durability. Nowadays other heavy metals are used for durability. This particular bridge was near the coast and had already been repainted sometime in the past. Repainting requires the removal of the existing paint by sandblasting.  Since the bridge was previously  repainted with a non-leaded paint, in theory, there should not be any airborne levels of lead, or cadmium. However, I always find airborne levels of lead. Why?

The possibilities are:

• not all of the leaded paint was removed
• recycled blasting agent has trace amounts of lead
• and possibly there are still levels of lead in the new paint that is supposedly “non-lead”

I always ask the laboratory to analyze my air sample for lead, and cadmium. Lead is usually the main contaminant, but occasionally I find cadmium. I will sometimes also have the lab check for zinc and chromium.  The sandblasters wear hooded powered air supply respirators, coveralls, and ear protection while blasting. Some other time I’ll talk about the noise from that activity (it’s LOUD!) and the fall protection issues they face.

Lead is a hazard in two forms: 1. airborne and 2. ingestion- from the transfer of contaminated hands/clothing to being eaten. Hygiene on a lead project is essential to preventing these exposures. A good safety practice, by which to verify that lead is not being transferred is to obtain wipe samples at random (or not-so-random) locations. Lunchrooms, shower/change areas, and pickup trucks are some of my favorite “random” locations.

The views around the area weren’t bad either…

It’s still dry here in the Northwest and the crusher operations have been in full swing. This mobile, 2 cone crusher was just moved to the coast for about a six week project. We performed airborne respirable dust monitoring and noise dosimetry on the crushing crew. We use a 37mm aluminum cyclone to obtain the respirable fraction. If you run the pump at 2.5 Liters per minute you get a balanced sample across each size in the curve -5 um (microns) and smaller. I analyze for respirable dust, crystalline quartz and cristobalite. We’ve never found trydimite in this area.

There was visible dust coming from the crusher. However exposure might be a non-issue since everyone was either in the cabs of their equipment, or in the operator’s booth.  Silica exposure is nothing to take lightly. Here is a MSHA video on the subject titled, “What Does Silica Mean to You“. (windows media)

For MSHA noise dosimetry is done very similar to the OSHA methods. There are only slight difference between the two. MSHA has a nice fact-sheet here.

You can see one of the cones in the picture below (before it was running).

To summarize,  there is no real quick-fix to this type of industrial hygiene assessment. Depending on what type of spray finishing you are performing- will depend on how to proceed. Here are some things to look during your assessments of these areas:

• air flow across the face of the spray area should be at least 100 feet per minute
• review the MSDS for the products you spray, and the solvents, thinners, and A+B parts-everything.
• check the filters – are there scheduled changes? a manometer in place and used?
• no flammables should be inside the booth area
• watch the flow of work- usually there can be improvements- as well as lessons to learn
• is the employees’ skin protected during spraying? (obviously not in the picture-right)
• where does the waste (left over) spray product go?
• ask employees about concerns and health issues

Typically respirators are worn in the spray finish areas. This list is not complete, but for starter, check:

• what type of respirators are being worn? Are they protective enough?
• what type of cartridges are used? Are they changed regularly?
• are there scheduled change out times for their cartridges? where is that posted?
• where are their respirators stored?

I know, the title is wrong.  It should read:  “How to prevent hearing loss“.

Here’s the problem (IMO).  I think most people know how to prevent hearing loss- and in America we can all afford to buy ear plugs. I have also heard of hearing loss claims that are unfounded and totally unrelated to their current work activity.  Even just a one time loud event can cause permanent hearing loss.

Construction companies hand out ear plugs like candy and say, “wear them when it’s loud”. Then, these same construction workers go home buck-up a cord of wood, ride their motorcycle, shoot their gun, and then after dinner go to a rock concert.

So, to avoid a claim, here is my advice:

1. Measure the noise (by dosimetry) at your job site- and do it annually.
2. Start a “hearing conservation program” or, in the simplest words, have your employees’ hearing checked annually.
3. Educate (train) your employees in hearing conservation
4. Give them choices in hearing protection (different brands of plugs, muffs, etc.).
5. Manage their hearing- (see below)

If you notice a loss in their hearing- do something! To manage possible hearing loss, I suggest these additional steps:

1. Retest their hearing. On a Monday, before work.  (To avoid a possible temporary threshold shift)
2. Have another company test their hearing. (sometimes the equipment is out of calibration)
3. Remind your manager to enforce the employee’s use of ear plugs on the job site.
4. Offer to give them ear plugs to take home.
5. Have an Industrial Hygienist (IH) perform noise monitoring at the job site for the full shift (dosimetry).
6. Retest their hearing again a month or two later.
7. Have an audiologist review their audiogram & your noise sampling data and ask for an opinion.