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!

You already knew it. There is a lot to do in industrial hygiene. At times this occupation feels like a safety middleman trying to keep people out of trouble. Occasionally I’m rewarded with really helping someone. In the United States, there is still a lot of occupational hygiene issues and concerns. Overseas, particularly in developing countries, there is even more.

It is hard to obtain accurate exposure data, or illness rates, from these underdeveloped countries. (How does a village of 1,000 people in Kenya report that they’ve had lead exposure to battery recycling?) How these exposures are brought to light is by either a massive death (# of people, quickly) or, someone with a camera able to actually photograph the pollution. As we know, what it looks like doesn’t necessarily correlate with hazardous levels of exposure. But, in some cases, it’s pretty obvious.

I ran across this photo story on pollution (The Guardian, UK). They estimate 125 million people are exposed to industrial pollutants (generic term, I know). This makes occupational related exposures a health risk as big as TB and Malaria! The article is based upon a report from the Blacksmith Institute which included this map of the worst pollution with associated disease.

How does this apply to construction? The worst offenders are lead (Pb) (and other metals), and asbestos.

What can you do? Here’s their recommendation, from the report (p50):

Developing countries need the support of the international community
to design and implement clean up efforts, improve pollution control technologies, and provide educational
trainings to industry workers and the surrounding community

Another NPR article about lead poisoning can be found here.

If you use heavy equipment and need to move dirt, rocks or soil, look closely at the buckets. Many times they will be coated with a material called hardfacing. It is a durable (consumable) welding bead laid out in a pattern. This pattern (from what I am told) helps to extend the life of the bucket. Apparently the cost of putting this product on the buckets is well below the cost of replacing the bucket (or teeth, or whatever).

The hazard is really on during the application of hardfacing. See my earlier post here. Hardfacing contains stainless steel (approximately 25%?, but it varies). Heating the stainless steel releases chromium in it’s hexavalent form (Cr6).

If your buckets have this on their exterior, your employees are probably exposed to hexavalent chromium at some point in the year.

However, the pattern is an art & science. Look closely at the side of this bucket…I think I know where this welder got his inspiration.

An agricultural sprinkler and pipe fitting company would not be first on my list for hexavalent chromium exposures. However, they hired a great manager who happens to keep up on safety concerns. He identified the hazard before any work had started.

This company makes custom fittings and pipe for municipals and agricultural systems. The most durable pipes are made of stainless steel. An employee was performing TIG welding for elbows and joints for a new system. In the past I have found that TIG welding produces the least amount of airborne hexavalent chromium (Cr6), so I was not too worried about the airborne levels that might be measured. (keep in mind that there is still a dermal concern, more info here).

However, after interviewing the employee for awhile, he said that plasma cutting and stick welding also occur. Unfortunately air monitoring during TIG welding does not compare with plasma cutting or stick (arc) welding. Additional air monitoring during those activities will have to be performed.

Background: We arrived at the welding /fabrication shop where they were working on stainless steel. We were the first to arrive and found this next to the project.

I found 3 things that were blatant “no-no’s”. Want to guess? (see my answers below) You might find more.

1. respirator sitting out -not put away in box (actually sitting next to it!)
2. grinder without a guard
3. eating/drinking in the work area (gum, drinking cup)

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.

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.