If you are in the United States, you have probably been hearing issues with lead (Pb) exposures. The main focus lately has been in Flint, Michigan and their (new) source of water, which contains high levels of the metal. Wiki here.

So, who is to blame?

The NY Times suggests we should blame HUD for the millions of pounds of lead in paint. However, I’m not so sure we can cast all of the blame on them, the legislators, or manufactures. But, we are going to be dealing with lead exposures in the future.

I do not know the depth and extent to which lead poisoning is occurring throughout the US. I’m not sure anyone really does. But, there are MANY sources of lead exposure. For example: leaded gasoline (tetraethyl lead) was used in the past, aviation fuel (av gas low lead) still is, lead in paint, lead in copper pipe solder, lead in fishing weights, lead in ammo, lead in sheet rock, lead in Chineese toys…I could go on.

Bottom line though, if you (or your kids) have elevated lead levels,…there is a source. So, What To Do? Here’s my takeaways:

  • Test you & your kids for their blood lead levels.
    • It is a very established method, but isn’t an exact science. Don’t freak out if they are above “background” levels. Just do what you can.
    • The CDC recently lowered their recommended blood lead threshold to 5 ug/dl of blood.
    • Don’t do chelation therapy, unless the blood lead level is REALLY high. How high? I’m not a doctor.
    • DO eat lots of vegetables and fruit. These have found to lower lead levels the best (but maybe not the fastest).
  • Find the source.
    • Keep looking, there might be more than one. School, work, hobbies, nearby businesses, daily activities.
    • Measure: dirt, water, paint, your workplace.
    • Consider how small an amount is dangerous. 5 micrograms in 1 deciliter of blood. 5 micrograms is 5 millionth of a gram. A fruit fly weighs about 200 micrograms. So, cut a fruit fly into 200 pieces, take 5 of them…you get the idea.
  • Tell others.
    • Recommend that others investigate for themselves.

lead paint

Here’s my top 5 gifts for Christmas in the (my) occupational hygiene world of construction:

  1. A new carbon monoxide monitor.
    • Not just a “normal” $40 model. A Nest Protect Fire & Carbon Monoxide monitor, which is in the $100 range. This thing is sweet. Talks to you, sends you a text message. Here’s a review from Cool Tools. Or, just buy it here.
  2. High flow air pump, Gast model.
    • I have some other flow rate pumps up to 5 liters per minute (LPM), but this one is great for flow rates 10-up to 28 LPM (depending on the model). Good for high volume area type samples and vacuum wipe sampling. You must have 110 power available, but once calibrated, it’s a done-deal. They can be bought for under $250. Grab a rotometer too, if you don’t have one.gast pump
  3. Wireless response system to use during training.
    • Attendees have a wireless response keypad and the trainer can ask a multiple choice question. It allows the audience to reply. The results then show up on the screen. Great for anonymous responses, or a general overview from your audience. There are several vendors, here’s an example, and the leader in the industry is Turning Point. I think these are in the $500-$1,000 range.
  4. A bulk asbestos example kit.
    • A bunch of “typical” building materials which are asbestos containing. In sealed glass jars, of course. I don’t know where you’d buy this sort of thing. I wish I would have kept all of my samples over the years.
  5. A dedicated short term silica sampling kit.
    • SKC has a new sampler which can sample at a higher flow rate  of 8 LPM, compared with the usual 2.5, or 1.8 LPM. (which, if you think through the math; allows you to achieve a detection limit with a lower sample volume, and a shorter time duration) Unfortunately, you must purchase a new SKC Leland pump/charger, PPI sampler, calibration junk. Total cost is probably in the $2,000 range.


This hazard is somewhat difficult to understand. There are number of reasons for the confusion, but the easiest way to explain it is to realize that:


Diesel exhaust = Diesel particulate matter (DPM) = lots of different chemicals & particulates

AND: There is not a perfect way to measure the exact exposure.

The Long Story:

The term ‘diesel particulates‘ includes the following (not a comprehensive list):

  • elemental carbon (the most reliable method for testing occupational exposure to exhaust, Birch & Cary 1996)
  • organic carbon
  • carbon monoxide (CO)
  • carbon dioxide (CO2)
  • hydrocarbons (PAH)
  • formaldehyde
  • oxides of sulfur & nitrogen

You can quickly see that these are very different substances, and to make it more confusing, you can change the amounts by:

  • the fuel (on road/off, low emission fuel, biodiesel)
  • the motor type
  • the tuning of the motor (& dynamic versus idle), new motor restrictions
  • scrubbers, etc.

In addition, there are not any well-established occupational exposure limits specifically for diesel exhaust. However, the International Agency for Research on Cancer has classified “whole diesel engine exhaust” as a carcinogen (cancer causing), so there is reason for concern. Most of the research and rules are in the mining industry, which uses a lot of diesel equipment and the exhaust really has no where to go.

  • OSHA = none, but they have a hazard bulletin, and of course, some of the components have exposure limits
  • MSHA = 0.4 mg/m3 for total hydrocarbons and 0.3 mg/m3 for elemental carbon
  • Canada (CANMET) for respirable combustible dust (66% of respirable dust in mines is from diesel exhaust) = 1.5 mg/m3
  • ACGIH = none (for now)
    • 1995 proposed 0.15 mg/m3 (for diesel particulate matter)
    • 1996 proposed lowering it to 0.05 mg/m3 (for diesel particulate matter)
    • 2001 proposed a different limit of 0.02 mg/m3,
      • but for elemental carbon and
      • said it was a suspected carcinogen
    • 2003 withdrew proposed limit- citing not enough scientific information

Bottom line:

  • control the exhaust & where it goes (better fuel, better mechanical, scrubbers, ventilation).
  • most exposures to diesel are below the (now retracted) ACGIH TLV of 0.02 mg/m3 (or 20 ug/m3) (Seshagiri & Burton, 2003).
  • If you have a confined area, unusual concerns, or a particularly stinky situation; measure for multiple parameters (CO, CO2, elemental carbon and maybe NOx, and SOx). Compare these to their respective limits and classify the exposure (describe the conditions)

Do you smell dirty clothes in your indoor building? Do you suspect your heating ventilation and air conditioning system of causing the smells?

It might be what’s called, “Dirty sock syndrome”. Typically found in high humidity locations. A brief video overview can be found here (You Tube 2:03)

Lawrence Berkeley National Laboratory has good information on indoor air quality and how it affects people as they work. They also have some scientific information about how improving the indoor space (by ventilation, temperature, particles, etc) can create a better environment.

AIHA has a “Position Statement on Mold and Dampness in the Built Environment” (March, 2013).  It lays out the reasons to control moisture in a building, and some basic steps for remedy (spoiler: air sampling doesn’t usually help).

Bottom line: Check your coils before replacing your entire system. Replacing these might be cheaper. Or, sometimes they can be cleaned, but it is a strict protocol. One possible solution is here (I do not endorsement, or recommend this particular product/brand. Do your own research).

Unfortunately I have no problem finding an appropriate picture for this blog on Ebay. People are weird. Yuk.

dirty sock

If you really have an indoor air quality and mold/fungus issue, it usually stems from moisture. I’ve talked about it before, here. The simplest answer is to find the water. Control the moisture and you inevitable will control the future indoor air quality concerns. Once you have found (and controlled) the water, then it is time to repair the damage and lingering water (which can’t evaporate).

The issue is: where does moisture come from? Well, it ‘can’ come from almost any direction:

EPA moisture control

  • from above (rain, roof vents, skylights)
  • from below (moisture in flooring, concrete)
  • walls (penetrations into the exterior, or windows and flashing)
  • out of thin air (relative humidity)

The EPA has written a new document titled, “Moisture Control Guidance for Building, Design, Construction and Maintenance“. As a contractor, how do you know when the clean up is too much to handle? I’ve written a bit more about it here.

The best time to clean up a moisture issue was yesterday, but the second best time to clean it up is today. Don’t let it sit, it usually doesn’t get any better.

Yep. Polychlorobiphenyls (PCB) are found in caulking. Typically buildings before 1979 have this caulk. (EPA Facts about PCB in Caulk) The only way to know is to test. BUT, wait!


  • Assume you have it and renovate with caution. Or,
  • Have the air tested for PCBs in the air.

Do not have a bulk sample taken. You should ask for an exposure assessment to be performed (air monitoring) by a qualified industrial hygienist. The reason is two-fold.

  1. The potential for the hazard is airborne. In most instances, people aren’t getting exposure from any other method.
  2. By measuring the air, you account for any other sources of PCBs (paint, ballasts, oils, ceiling tiles).

Most of this caulk is found in outdoor uses (high grade) in older buildings up to around 1980-ish. If an airborne exposure assessment finds levels below the acceptable rules & recommendations (depends on age & location), you may continue with your project. Of course, you would take appropriate precautions, like these recommendations from the EPA. They also have a very nice flow chart. Just like a choose-your-adventure book, make sure you don’t fall into the “Abatement” box!

EPA PCB Caulk flow chart

Let me first say that I am still learning about this hazard and why it is so dangerous.

Polyurethane foam is used as an insulating material. More info on it’s uses here. The danger is when you spray it (think: expandable type), or apply it, or cut/remove it after it’s cured. The danger is in the off-gassing.

There are two main considerations:spray foam

  • the process of applying the foam
    • spray type
    • quantity?,
    • ventilation?
  • the type (manufacturer/brand/type) of foam
    • curing rate,
    • type of hazard, etc.

What we know is that there is a hazard. AND, this hazard may not effect everyone, OR, it may not effect you until some time has gone by. But, some of the chemicals in these types of products include:

There is a huge potential for work related asthma when using these types of products. And, even contact with the skin can trigger an allergic response/asthma attack. If you have employees working around this type of product and have ANY respiratory symptoms (or asthma), please have them checked by an occupational medicine doctor.

Control of this hazard should include:

  • PPE for employees (respiratory, eye, & skin protection)
  • ventilation during application
  • ventilation during off-gassing & curing (can be 72 hours)
  • control plan for spills, cutting & demo
  • control plan for employee/occupants with asthma

The EPA has a quick reference card here (hat tip to Tom), and more detail from the EPA on how to control the hazard here. The Spray Polyurethane Foam Alliance has free training here (haven’t checked it out though), and be mindful that anyone can be an instructor (good & bad).

Many times an IH is called upon to determine the cause of a person’s ailing symptoms. For example, an employee might complain of congestion, irritability, bloody nose, etc. Someone has decided it might be from their exposure at work.homer sick

The practice of industrial hygiene is difficult to apply to an individual. What I mean is, this field of study was developed due to serious health concerns over a population of people at work. This is essentially how science works, you take a population, study it, find the differences, then make conclusions.

Trouble occurs when you try this backwards. If the same person (as example above) complains of congestion, irritability, bloody nose- can we assume they must have exposure to lead dust? Not usually. We must obtain other clues.

What industrial hygienists try to do in these instances is rule-out the possible over-exposures. Sometimes we can measure for chemical exposures to see if it might be of concern. But even then, it’s not fool proof. Below are a few issues which make it complicated.

  • exposure at work? job? extracurricular activities? home?
  • person might have autoimmune disease and gets sick easier
  • sampling is not feasible
  • sampling is somehow screwed up (by IH, lab, mail carrier)
  • exposure is through food, clothing, etc.

Even with these fallacies, there are things an individual can do to narrow down their ailments:

  • create a log. time, type of symptoms, pain scale, others experience/smell, food eaten
  • change things and see if it improves/makes it worse
  • research – but do it right. Look at the items you use, check the SDS


As continued from my earlier post, and, a little more to the point…What do you ACTUALLY do when you think you have mold?

Test the air! Perform air monitoring for as many different things as you possibly can. Just kidding. Actually, DON”T do this. (caveat: if you plan legal action-then you might do this)

If there is visible mold/fungus. The first step is to find the water.  In order for mold to grow it must have moisture and a place to grow. There are many places to look including; the roof, windows, seams, ANY penetrations into the building envelope, from below (seeping up), water lines, A/C units, condensation, etc. You absolutely cannot fix the damage or test the air until you stop all sources of water.

Second step, assess the damage. The general rule of thumb is if the damage has altered the substrate (ie, the wood is damaged) then you need to replace it. If it is only on the surface, it may be possible to just clean, dry and seal it. If it is more than 10 square feet of damage, consider hiring a qualified specialist.

Thirdly, repair & replace any concerned areas.

Fourthly, dry it thoroughly, then seal it. Look into methods to increase the ventilation into this area.

Fifthly, inspect and finish. A good visual inspection is far better than air monitoring. If you can still see mold growing, you’re not done.

Finally, clean the ducting & surrounding areas. Please choose a qualified inspector. For some reason this industry attracts lots of bogus contractors.

Air sampling vary rarely gives you any information that will assist you in these steps. Some other good information about indoor air quality and mold from California can be found here.

I have never (as of yet, knock on wood) heard a construction worker say, “you know, Mr. IH,  the air around this construction site is moldy, dirty, full of fungus, and smells. I’m not sure I can work here”. Never heard it. It’s probably because these guys (& girls) are so tough! Right?

More commonly what I hear in construction is:

  • I’ve got a client who has some water leaks, what should we so?, or 
  • What can we do to help them?
  • How much mold can my employees remove?
  • Is it OK for my employees to remove moldy building materials?

The most important thing is: make a decision about what you will allow (as a company) your employees to do? What business are you in? Will you let an employee take out a sheet of moldy wallboard? Will you allow them to demo an entire bathroom with black fungi all over the walls?  There are some guidelines (page 2) and here. OSHA does not have specific rules for this type of work. However, OSHA (and you) will be concerned if your employees are exposed to this type of activity. They will cite you under the general duty clause.

So, the next decision is what level of protection (level A? full face respirator? paper dust mask?) will my employees need to wear? again, it depends (see link above). But as a general rule and in most scenarios, a full face respirator with HEPA filters is perfect. A half-face is fine, at times, but the eye protection during construction is easier (less fog on your safety glasses) if you are wearing a full-face.

Finally, decide if you will either:

  • clean it (guidelines here)
  • replace it (tear it out, and build new)
  • subcontract it (please, use a remediation contractor, not your brother in law)

This will depending on many factors including; size of damage, where the damage occurred, access, available workforce, etc.

Stay close, I will attempt to blog more about this topic in the coming weeks.

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