Industrial Hygiene in Construction

How much information should be contained in your written safety programs? There isn’t a right answer, but here are my suggestions and thoughts.

Have two “levels” of programs.

Corporate Safety Programs –

• This type should contain the general overview of the safety at the company. It should speak to the concern that the company has to the safety of the employees.  ie. “we don’t want you to get hurt, so…”
• No details. For example,  an Asbestos Policy statement – “As a company we anticipate that we may encounter asbestos onsite. We train our employees in identifying suspected asbestos containing material (ACM) and subcontract any work where we may disturb potential ACM. “
• Employees should be trained from the Corporate Safety Policies (initially, annually, or periodically thereafter).
• Establishing these programs should take a lot of thought, consideration, and buy-in from management and leadership.
• Do NOT make a policy that you do not plan on keeping. If you are going to occasionally do something which is a direct contradiction to your policy – don’t make it a policy. I know, simple in theory, but…

Site Specific Programs

• These types of programs should contain the details. Who, what, when, where, how.
• Only include the policies that you have at the jobsite- otherwise don’t have this policy on file in the trailer.
• Cut and paste the policies you need for this specific job – from your corporate program list.
• Another example, from the asbestos policy, “on XXX project we have identified asbestos in the blue and green 9×9″ floor tiles to contain 5%asbestos. ABC Abatement Company will abate and remove any asbestos found. If additional materials of this size, shape, color are found, please notify the superintendent immediately”.
• Perform tool-box talks from your site specific programs. These programs should have enough detail that your Project Engineer could read it to the employees and have enough information.

During mild steel welding I very rarely see respirators being worn. I believe this to be “standard practice” (the act of NOT wearing a respirator). However, is this a good idea?

The correct answer is:  It depends.

Explanation:

• I actually think during common mild steel welding, respirators should not usually be required. My experience in air monitoring has demonstrated that most “average” levels are well within occupational exposure levels (OELs).  While sampling under the hood (placing the filterpiece inside the welding hood), the flash hood protects from a lot of exposure. Most of the particulate that is seen-visually is iron.

Caveats:

• “average” welding changes everyday. What is average at one fabrication shop may be totally different from another. Each project may have different welding exposures. Welding inside a 36 inch tube is different than in an open field. You should roughly know what airborne levels you have at your site.
• If the welding contains metals other than what is in typical mild steel (and many times there are other stuff), the air levels can vary. Steel nowadays is so much recycled metal that there is a huge variability in the makeup of new product. Exotics (stainless steel, etc)  and known contaminants (leaded paint, coatings, oils, etc) should be treated very different.
• Long term exposures from metals might be a real health concern. There aren’t many metals in mild steel that you need to inhale.

Finally:

To wear respirators is a good decision. Conditions change and, in construction, this might be every hour. When the project needs to be completed quickly, most welders will not run to the store for a respirator. It is nice to be prepared.

My advice is to issue half-face tight fitting respirators with HEPA (high efficiency particulate air) filters. Train employees WHEN to use them and, if you have safety culture that permits it, trust them to use it when conditions warrant their use.

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

If you are taking multiple samples employees to get an average total time weighted average (TWA), here is how you calculate TWAs.

First take the first concentration (mg/m3 or ug/m3, etc.) and multiply it by the time (in minutes). Do this again for each sample. Add each of these calculated amounts together.

Then, divide by the total minutes sampled.

Or, alternatively, by the total time in the work shift (480 minutes for an 8-hour day). You would only do this if you captured all of their exposure and the rest of the day was (in theory) zero additional exposure.

Look at the number. It should make sense and be logical. If not, look at your math, especially the units for each.

If you like math, here’s the formula: