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Instead of explaining how to calculate safe levels of chemical mixtures, this will be a reminder.

The American Conference of Governmental Industrial Hygienists (ACGIH) in their Threshold Limit Values (2014), has an excellent explanation of how to calculate a safe level of exposure. However, in summary, if separate chemicals have the same health effects (effect the body in the same way), they may do three things:

  1. Additivity – the sum of their exposure & health effect is A+B. More on this below.
  2. Synergy – the sum of their exposure is MORE than A+B. This is bad, and hard to calculate.
    • Similar in principle to smoking and asbestos. If you smoke and have asbestos exposure, you are worse than just the additive.
  3. Antagonism – the mixed chemicals cancel each other out. It usually never works this way.
    • But, as a terrible example, it would be like acid rain dissolving styrofoam. (I don’t think that’s true, BTW)

Back to Additive (Additivity):additive

If two chemicals (or more) in a mixture have similar health effects (central nervous system, or effect the kidneys, for example), then, until you know otherwise, you should assume they have additive effects. Have your favorite Industrial Hygienist use your air monitoring data to calculate the additive effects using the ACGIH Additive Mixture Formula.

This is useful for combining both full shift air monitoring data, short term, and ceiling exposures. Extreme caution should be used if the chemicals are carcinogenic (as low as reasonably achievable (ALARA) is best here), or if they are complex mixtures (diesel exhaust).

It’s a bit confusing, but worthy of reminding ourselves of chemical mixtures.

I’m slow to the game, and frankly, not that good at it. So, excuse my stumbling.

I’ll be posting on this site, as well as pictures on Instagram (user: Alden Strealy, #IHConstruction)instagram

and Facebook.

Facebook

 

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:

Summary:

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

I regret I don’t have the energy to post every question and situation on this site.

However, occasionally there are very unique questions. I won’t say how I answered them, but I will offer some considerations. Here’s are my two favorites from the recent past:

  1. My construction crew is working on a “special TI (tenant improvement)”, alongside an elephant who has Turberculosis (TB). What personal protective equipment (PPE) do my workers need to wear?
    • Is the TB active
    • Does TB transfer from people to animal, and/or vice versa
    • How much contact (distance, time, amount of touching, etc) will the workers have with animal?
    • Will you offer prophylactic shots? (to the employees, of course)
  1. We are going to be excavating the carcasses of dead sheep. What type of PPE will my excavator operators need to wear while performing these tasks?
    • How large of an area (2-3 football fields)
    • How long have the carcasses been in this area
    • Any additives to the soil/area
    • Will workers be in contact with dead animals?
    • Will workers need to enter the excavation?
    • Will you use a multigas meter (4 gas)?

elephant

I’d love to hear your best (or worst) questions.


This topic is not industrial hygiene specific. However, it is a construction safety/cost issue. A lot of contractors do a poor  job at modified duty (light duty) for injured employees. There are a few reasons for this:

  • temporary worker (disposable employee)
  • no “light duty” for the hard work needing done
  • the superintendent doesn’t want them back
    • doesn’t like him
    • can find someone else to do job
    • job is over

One of the best methods to reduce your return to work costs (aka workers compensation costs) is to return employees back to (some kind of) work as soon as possible. Keeping these injured employees on the project where the superintendent was responsible not only impact’s their projects bottom line, it reminds them of the injured employee.

Here is a list of some light duty jobs from Safety Awakenings.

Also, psychologically, how do you treat your injured employees? I have a brother, when younger, who would cry over a little tiny scrape. However, when he was actually hurt, he would firm-up, not shed a tear, and act as tough as possible. Employees are no different. Their reaction really varies, and your response might also need to change. There is probably not a one-size fits-all approach, but being professional is a good start.

Do you:

  • Shame them (make fun of them because of their injury?)
  • Encourage their injury (baby those who get hurt?)
  • Highlight it (bring it up in meetings?)
  • Discourage the behavior? or the act of unsafe behavior?

As you know, sometimes it’s hard to find light duty in construction.mixing1

It is officially summer and construction road crews & roofing is in full swing. Some projects require the use and application of coal tar pitch. Not only is it stinky, it is is hazardous.

Here’s some info:

  • Uses
    • Roofing
    • Asphalt seal coating
    • Pharmaceutical treatment for psoriasis (scalp/skin condition)
    • Graphite industry (in the production of graphite)
  • General
    • Coal tar pitch is actually a make-up of a bunch of different substances (maybe even 10,000 of them)
    • Contains lots of polycyclic aromatic hydrocarbons (PAHs) and other chemicals including: benzene, pyrene, benzo(a)pyrene, phenanthrene, anthracene
  • Exposure
    • can be exposed by inhalation, ingestion (is this likely?), or exposure to skin, eyes
    • considered a carcinogen if the product contains more than 5% of coal tar
    • cancers include: skin, scrotal, lungs, bladder, kidney & digestive
    • increases your sensitivity to sunlight (easier to sunburn)
  • Safety
    • Pick a sealant/coating that does not contain coal tar. A list of some can be found here.
    • Avoid inhalation & skin/eye contact
    • Train your employees. A sample safety SDS (MSDS) can be found here.
    • Wear the correct PPE.
    • Air sample to determine exposures. OSHA has a method (58).
  • Resources

asphalt

This question gets asked a lot, and in many different ways. Such as:asbestos iron

  • Will I get hurt if I touch asbestos? (aka: How long can I be exposed?)
  • What if I have done siding removal/cutting pipe/removed TSI (etc) on an asbestos containing product, am I safe?
  • If I am only doing going to do touch asbestos for 20 minutes (or ___ time), will I still be in compliance?
  • I am disturbing less than 3 square feet of asbestos, I can do this legally, right?

The answer is:   it depends.

Or, an alternative answer: if you think you are disturbing asbestos; you’d better verify (by performing an air sample).

Nowadays there is no excuse for exposing employees, tenants, neighbors to asbestos. And, really, if you are working with asbestos, you need to be extra diligent to inform everyone about the hazard. The worst situation isn’t from a single exposure to asbestos, or an OSHA fine. The worst situation is this:  when you don’t pre-plan, and then verify your exposure levels. Because, someone will make up a worst case scenario, and at that point, you are already behind.

 

 

Construction workers falling is the number 1 cause of death in this industry (residential & commercial).

NIOSH has published a prevention through design (PtD) document for those who design parapets to prevent falls. This document is new. But the principle of it has been around since Moses’ time: “When you build a new house, make a parapet around your roof so that you may not bring the guilt of bloodshed on your house if someone falls from the roof.” Deuteronony 22:8. 

Another good resource: Stop Construction Falls .com. They even have an interesting map which shows where they occur.

The CPWR obtained a NIOSH grant and has some free videos here.

map of falls

Spring is when the work picks up, be safe out there.

Let’s clarify: You are a working adult. You are feeling symptoms (of some sort). And, you think it’s from something your exposed to while at work (in construction). This could include, but will not, the flu-bug. Below is a list of the most common construction illnesses.

Most Common Construction Illnesses:

  1. Upper respiratory
    • could be from silica, drywall, dust, asbestos, nuisance dust, chemicals (I won’t even try to list all of them)
  2. Skin (dermal, dermatitis) damage –
    • From: concrete, abrasion, chemicals
  3. Eyes
    • mostly from things that get into the eye.
  4. Cumulative trauma (ergonomics) or inflammation
    • repetitive motion, over a day hurts, imagine this for years
  5. Burn (heat or chemicals)
    • Usually around hot work like welding, but this can occur when using certian chemicals
  6. Hearing loss
    • cumulative trama to the ears when exposure is above about 85 decibels for any extended period of time.
  7. Poisoning– General or systemic
    • From: poison ivy, stinging needles, dog bites, bees, etc.

This list may vary depending on many things including what type of construction you are in; GC, heavy, civil, specialty, etc.  I put this list together to get a picture of where we see illnesses. However, as previously mentioned, and, everyone knows, the FOCUS FOUR is really where most injuries occur in construction.

We have seen the most prevention of illness due to one single device:

back supportthe back support.   ha. just kidding, of course.

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