Industrial Hygiene in Construction

It was recently declared that diesel exhaust is a carcinogen by the World Health Organization’s (WHO) International Agency for Research on Cancer (link to the press release). As you know, a carcinogen is a substance known to cause cancer. The most well known carcinogens are cigarette smoke, benzene, and asbestos.

If you are in construction you probably know how many pieces of equipment use diesel…LOTS. In fact, heavy highway and large commercial construction use it almost exclusively. And, if you have ever traveled out of the US, you realize that diesel is used a lot more than gas. Don’t forget trains and commercial trucks.

So, if you think you have possible exposures to diesel exhaust on a regular basis…you should do something. Here are some ideas:

• tune-up (lower emissions, better efficiency)
• direct exhaust away from people/HVAC intake
• exhaust equipment outside
• increase dilution ventilation (usually not recommended for carcinogens)
• make sure the scrubber works
• measure exposures to employees (ask me in 20 years why this is a good idea)
• switch to biodiesel (I actually DO NOT know if this is a safe-alternative, but it does smell better)

Here is another article on it.

As you may know, sometimes tin knockers (aka sheetmetal workers)  use sheet lead, or lead soldering, to make flashing on roof vents. Here is a picture of what these commonly look like (if there is (?) a common one).

The lead iron is heated up. Lead solder, or sometimes lead/zinc solder is used. Muratic acid (or similar) is used to clean the stainless steel. The iron is used to heat up the solder and drip it on the stainless surface. Anyways, the process creates lead fumes. This is dangerous both from airborne inhalables to the contact surfaces surrounding the area.

The surfaces around these areas are usually very high in lead content. There is not a OSHA standard for lead wipe tests. However, in the past OSHA has used the HUD standards and cited employers under the general duty clause. If you are performing these tasks, please make sure you are doing everything you can to limit the airborne, dermal, and ingestion exposure.

• Follow OSHA Lead Standard (1926.62).
• Train your employees.
• Ventilation (downdraft is best). This is the best way to control the fumes.
• Post signs in the area “lead work and hazardous”.
• Perform air monitoring. I have found levels both above, and below, the exposure limits.
• Wear a respirator (1/2 face negative air with HEPA).
• Do not: eat, drink or smoke in this area.
• Good hygiene. Wash after doing these activities.
• Use a plastic sheeting on all surfaces. This makes it 100x easier to clean up.

in other words, don’t do what is in this picture below:

Occasionally I hear of certain (construction) trades having to touch asbestos. Usually it is an electrician, sheetmetal worker, carpenter, or plumber.

How it usually happens is that they have a small remodel/install/repair. They must cut through the asbestos to install the item (duct work, electrical, plumbing). Be careful. If you look at OSHA’s definition you may not be able to perform this type of work without specific training. In some cases, 16 hours of asbestos-specific training!

If you work with any type of asbestos (or, are even near it) you must have Class IV (4) training. This is a 2-hour training which is defined as, “…contact, but DO NOT disturb asbestos…”. As a contractor, you want to make sure you fall under this type of training. The alternative is,

Class III (3) training. This type of training where employees are, “likely to disturb” asbestos.  If you think you disturbed asbestos in your activities, you REALLY should prevent it. Here are some suggestions for making sure you never disturb asbestos.

• Always, always get (in writing) a building survey for asbestos (and leaded paint) before performing work
• Train your employees in how to recognize asbestos, etc. (Class IV training as a minimum. See my earlier post)
• Establish procedures for how you will prevent contact with asbestos

If you must touch (and possibly disturb it) asbestos then also,

• Have specific procedures for how you prevent exposure
• Have PPE (including respirators)
• Obtain air monitoring data while you are performing your activities – document that you DO NOT disturb the asbestos
• Dispose of the material properly

Asbestos is one of those hazards you can’t ignore. If you are not doing the correct procedures, it will bite you (a claim, a citation, a lawsuit, horrible PR, or someone getting ill!).

I find many construction-related companies who operate a spray booth at their shop. Many are used irregularity, depending on the project. As with most things that are used occasionally, they aren’t always in tip-top shape. Below are a few suggestions and questions for construction firms with these types of equipment.

• Measure the airflow of your booth (there are various ways) but it should be 100 feet per minute. If it isn’t, you need to change something. The filter? the fan size? the exhaust duct size? the make up air (add more)? Please get someone to help you with this. Increasing the motor size is usually the knee-jerk reaction, but NOT usually the solution.
• Make sure your manometer works. Is there a range written on the gauge for “operational”? see arrows at bottom of picture

• Do your employees actually spray inside the booth? (seems like an obvious question but….)
• Are your MSDS nearby?
• Where do the employees mix the paint? (hopefully in a ventilated area)
• Do the employees wear the correct PPE? What about during mixing? When the items are drying?
• Are they covering their necks & arms when spraying? Do they need to? (check the MSDS)
• What product do they clean their spray guns with?
• What product do they thin the paint with?
• Is there a functional eyewash station nearby?
• Do you know the airborne level of exposures to employees?

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.

January is Radon awareness month. I posted this same topic last year.

As a reminder, if you have not measured the radon in your home, do it. Winter is the perfect time (since there is less airflow with the house buttoned up- and you’ll get a worst-case reading).

If your neighbor said he took readings and they came back fine, it doesn’t necessarily mean your home is ok. Check it!

Also, if your kids stay at a daycare, grandparents, or other place for a long period of the day/evening…you might also check the levels there.

You know those lead testing kits from the hardware store?  They seem extremely handy, however, they are a bit misleading.

LEAD CHECK ™ and LEAD ALERT ™ use a chemical (rodizonate-based) to instantly tell you if you have lead in your paint. If you use this kit, and the color changes, you have lead present.

They are quick and easy, but have a few HUGE downsides.

• OSHA has stated in a letter of interpretation (7/2003) that these should not be used for determining if lead isn’t present. In other words, you can’t rely on a test that says, “no lead!”
• These kits only check the “top layer” of paint – not the coat of paint below the one you are testing. You must test each layer.
• These kits will not tell you how much lead you have (what percentage). You knew these kits didn’t do this already, but this is useful information!
• Some chemicals may interfere with these type of kits. If you have chromium in your paint, the kit may say there is no lead present, but in fact, the chromium has interfered with the true results.

The biggest issue is that you need to have objective air monitoring to prove that your airborne levels of lead are not overexposing your employees.  A true bulk test (of paint) gives you great information. It tells you the percentage of lead in the paint. This, and your air sampling data, can be used again for future projects. It will also tell you which colors of paint have the highest lead.  Be safe out there!

I recently heard a very good summary of when (or alternatively when-you-DON’T) need to perform air monitoring when working with lead in construction.

Is there leaded-paint (lead based paint) in your project?

• Then you MUST comply with the OSHA lead in construction rules.

On what occasion do I NOT have to perform air monitoring?

• if you don’t have lead (see the first question)
• if you want to provide the minimum required protection for all of your exposed employees (respirators, blood lead monitoring, etc. etc.)
• if you have historical air monitoring data (from another project) that supports the methods you are using

Otherwise (in summary):

• Take a bulk sample of the paint
• Set up all engineering & administrative controls for controlling dust
• Train your employees
• Perform air monitoring during the FIRST day of actual work
• Continue with all controls through the project
• Notify everyone onsite of results
• Require that all subcontractor do the same process

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