One of my pet-peeves is reporting industrial hygiene results with absolutely no explanation of what happened (or the conditions) on the day of the survey. The results will never be reproducible, verifiable, or really ever used again. If you are going to perform the exposure assessment, tell us what happened. We all know that an “average day” is rarely ever the average.

Sometimes you are not able to choose the time when you are able to perform air sampling or monitoring. But, that is a very important part of the overall picture of the exposure. When sampling I very frequently hear, “You should have been here yesterday”, or “Today is really slow”, or “Can you come back next week when we are doing XXX activity?”.

Those phrases and employee interviews are almost as critical as the air sampling results. They tell you what you DIDN’T see, or capture in your exposure monitoring.

At a minimum you should tell a story about:

  • what engineering controls are in place
  • what administrative controls are used
  • what are the employees doing
  • how often does this occur
  • is this a worst-case scenario, or just average day
  • what happens during set up and clean up
  • what products are they using (MSDS)
  • what PPE are they using


When performing spray finishing activities with any product that contains isocyanates (diisocyanates, HDI, MDI, TDI) the minimum respiratory protection to be worn is a powered air supply respirator.

The reasoning is simple: isocyanates DO NOT have good warning properties.

Painters can usually tell when their cartridges are wearing-out, or getting “break through”. However, with isocyanates, the odor threshold is much too high to detect (it can be detected, but only at harmful levels).

In addition, isocyanates have a skin-notation, meaning that if the product gets onto the skin, it can be absorbed. As you can see, this employee was not wearing the proper PPE (personal protective equipment). However, when you’re a consultant, you have temper your comments. We did educate him and also told the general manager of our concerns and the reasoning.

On the plus-side, they had a manometer that was used and the employee knew when to change out the filters.  How this simple meter works is this:  A manometer measures the pressure differential between two different areas. In a paint booth it measures the pressure between each side of the air filters for the air coming into the booth. If the pressure gets too high, then the filters are clogged (or built-up). Notice the arrows on the bottom of the gauge to see when to service the filters. When the manometer (in this case) reads above 0.045 either the fan has to work harder, or the air escapes by the filter (in various ways- more information for another time)



As a guy, I must admit… these tools are really cool. They’re loud, look like a space-age pistol, and have loaded bullets.  They use a .22 or .27 round casing  to drive the nail through the wood (or steel) stud (or bracket) and into the concrete.  It is really fast and …essentially a gun.

Powder actuated tools (sometimes confused with power, but it’s not) are typically used as  a quick method to anchor into concrete. There are a few types of these tools (Hilti, Simpson, Ramset) and there are specific safety precautions and controls that must be in place during use. However, I will focus on the newer hazard that was brought to my attention:  airborne lead exposure during their use.

I have seen these in use for many years, and at one point it was brought to my attention that lead was listed in the MSDS in section 2 Hazardous Ingredients (lead styphnate) and some of the manufactures caution the extended use of the tool. I actually dismissed the concern for airborne releases.   Well, I was corrected.

A study done by Liberty Mutual’s Mark Wiggins, CIH, CSP, ARM found that when as few as 50 to 90 loads are used per shift, the OSHA Action Limit can be exceeded.  It depends upon the type of load, where work is being done (location), and the type of work (overhead, etc).  He also suggests that the airborne exposure can be estimated based upon the number of rounds.

There are many alternatives to minimizing this exposure including: using battery-operated, or pneumatic anchoring tools, loads without lead, decreasing the frequency of use, and finally- respirators. A half-face, tight fitting negative pressure respirator is suggested to be adequate.

Leave me a comment if you would like the more information about this study.

This post will be an attempt to describe the hazard of the heavy metal, hexavalent chromiumThe subject is confusing. It’s a technical subject, and I will try to make it simple to understand.  If you have questions you can contact Julia Roberts,  from the movie Erin Brockovich.  (This was the one of the contaminants in the water in that movie/documentary)

Chromium is a metal found as chromium-3 (it’s valence) – and…if you remember from chemistry, the valence is the number of positive charged ions.  The point: when chromium is heated, it “becomes” chromium-6, or hexavalent chromium.  Hexavalent chromium will eventually go back to chromium-3. I believe the half-life is about 17 days (it takes 17 days for half of the material to convert back from cr6 to cr3).  Here’s the confusing part:  Chromium-6 isn’t harmful, but it is VERY able to be absorbed by your body (skin & membranes).  Chromium-3 is harmful, but isn’t able to be absorbed by your skin.

So, here’s what happens:

  1. you have a material (or a product, ie. stainless steel, or look at your MSDS) with chromium-3 in it.
  2. you heat it up
  3. it turns into chromium-6 (hexavalent chromium)
  4. it absorbs into your body (breathe, drink, touch)
  5. it goes back to chromium-3
  6. you develop symptoms/disease

Symptoms might include:   irritation or damage to nose/throat/lung, chrome ulcers (gross, huh?), lung cancer (if breathed), eye damage, allergic response (including dermatitis).

In construction we typically see exposures in these activities:

  • Welding
  • Stainless steel metal-work
  • Painting- (as a pigment) or an anti-corrosion agent
  • Hardfacing – applying weld-beads to the sides of loader buckets (see picture)

The risk of high exposure varies due to many factors including, type of work, ventilation, amount of chromium in the product, etc.

The CDC has some good information here.

Controls:  As usual, it depends. However, as a general rule you should try and eliminate the hazard (use non-chrome materials, or add ventilation). If it is still of concern, use administrative controls (limit the time, make sure employees are following protocols). And, finally, personal protective equipment to control exposures. Proper respirators (with HEPA cartridges) and don’t forget skin protection (gloves, tyvek, etc.).

Some workers were performing MIG (gas metal arc) welding and subarc welding. This is a daily task and their employer requested that we measure the air – as a general assessment tool. In other words, employee’s weren’t concerned, and no one was complaining, but they wanted to explore further into this aspect of their employee’s health and wellness.

We performed air monitoring and analyzed as a welding fume profile which is a number of commonly found welding metals including:

  • Antimony
  • Beryllium
  • Cadmium
  • Chromium
  • Cobalt
  • Copper
  • Iron Oxide
  • Lead
  • Manganese
  • Molybdenum
  • Nickle
  • Vanadium
  • Zinc Oxide

Along with the welding fumes, we ran a sample for hexavalent chromium using OSHA Method ID215.

Nowhere in the MSDS (material safety data sheet) did it list “chromium” in the material make-up. However, knowing that it could be a trace metal it might be an issue. MIG welding (in general) isn’t typically of high concern for this hazard. And, as it turns out, the results were found to be below their respective limits.

Employees were not welding the entire day.  At least half of the time was spent fitting, moving, tacking, remeasuring, and gathering materials. Noise was a big issue as well. Most of the day it was quiet, but when the steel would drop, or an “adjustment” to the metal was needed…it was usually followed by a hammer-bang.  Honestly, without the ear plugs, it scared me.

« Previous Page