Industrial Hygiene in Construction

Hypothetically (and allegedly):

• You receive a project as a subcontractor.
• You are verbally told no asbestos or lead onsite. Only that’s not true.
• There is asbestos, and you, and multiple other subs, have disturbed it.
• The prime contractor says, “oops”. Has the materials tested, and then blames the owner for not letting them know.
• OSHA is called and citations are issued to the owner and GC for not testing and telling people.
• A year goes by and now both the owner and GC are being sued by 5 employees for $10,000,000 (yep $10 million, that’s the max BTW).
  • As a footnote: this incidentally is not a worker compensation case (yet) since they are not suing their employer (they are suing the GC and owner)

Even if the employees don’t win $10m, are you prepared for: the headache, loss of client-relationship, trust breaking? Here’s a similar hypothetical article about such a situation.

On the flip side, here are some positive things you can do:

• get a written copy of the building survey (lead & asbestos) ALWAYS. (you might also ask for cadmium, radon, other possible hazardous substances)
• Train your employees about asbestos prior to having to deal with it.
• Give employees the power to “stop work” if they are suspicious of possible asbestos containing material (PACM).
• When handing out a building survey to your subs, get their acknowledgment (in writing, of course)
• Fight your OSHA citations. Go to your informal conference. Present your evidence and, at the very least, beg for forgiveness.

When performing air monitoring it can be useful to take multiple samples on the same individual throughout the day. Here are some reasons to change out the filters:

• build up of dust on filter – can cause overloading
• break-out the exposure data. Morning versus afternoon, or by job tasks, or the physical area the employee is working in, controls vs. no-controls, etc.
• if you question the employees motives. If you think the employee might skew the results, multiple samples might give you better control- or at least tell you if one is way-out-of-line.

Once you have your data results, how do you combine them?

If you’re taking particulate (dust, lead, cadmium, silica, etc) and you have the concentrations (from the lab) here is what to do.

1. note the time (in minutes!) and the concentration results (mg/m3, ug/m3, etc) for each sample
2. multiply the time and concentration for each – then add each number together
3. finally, divide the above number by the total number of minutes sampled. This is your time weighted average (TWA).

Simple?! Yes. …And it’s really easy to make a mistake too. Check your math, and then eyeball the results and see if they make sense logically.

Here’s an example:

Andrew took three samples during one shift while Shelley was rivet busting through leaded paint. The first sample (118 minutes) was reported as 6.8 ug/m3 of lead, the second was for 245 minutes and had a concentration of 18 ug/m3. The last sample was taken for 88 minutes and was reported a level of 29 ug/m3. The overall results is 17.2 ug/m3 for the total time sampled. (Side: if you sampled for their entire exposure, and they worked longer hours, you could add those hours (assuming zero exposure) into the final time-in step three)

See the math below:

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…