Dust


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:

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)

I titled this post, “hazards of drywall”, but it encompassing most of the common hazards of plaster, mud, gypsum, wall-hangers, tapers, and acoustic employees.

  1. Corrosive drywall.

    I have not dealt with this subject on a personal level. However, AIHA has a new guidance document titled, “Assessment and Remediation of Corrosive Drywall: An AIHA Guidance Document“, which is a clarification of an earlier white paper document from 2000, titled, “Corrosive Drywall“. The danger is from a specific type of drywall which was imported from China. After installation it is known to emit sulfide vapors, which corrode copper (electrical wires), and can give off a sulfur smell (HT to JeffH in Ohio).

  2. Asbestos in mud/plaster.

    Be aware, some older buildings (pre 1980s) may have asbestos in the mud compound or plaster (not as common). This will be a concern if you are performing demo on these walls. Info here.

  3. Silica (dust) in joint (mud) compound.

    Some types of silica I have found to have silica. This can be an issue when sanding. AND, if you install drywall like me…you do a lot of sanding. More information from an earlier post can be found here. NIOSH has some suggestions too.

  4. Leaded sheetrock. If you are installing (or demo) leaded sheetrock, you NEED to protect yourself. Airborne levels of lead can approach the exposure limits, even during installation. More info here.
  5. Lead in paint. If you’re tying into existing plaster/drywall and there’s paint, you need to know if there’s lead in it. Sanding on the paint is a good way to be exposed. More info here.
  6. Ergonomics. Hanging the wallboard takes a toll on your body after 20 years (or less). Not to mention sanding. Washington OSHA (L&I) has a good demo.
  7. Noise. Cutting steel studs, powder actuated tools (there’s lead exposure too, you know).
  8. Skin hazards. Cutting, but also dermatitis from prolonged exposure to dust.
  9. Eye hazards. Dust, carpentry, etc. Working overhead is an easy way to get falling items in your eyes.
  10. Falls. Last on my list, but certainly not the least. Scaffolding, working from ladders, and using stilts, to name a few.

For better, or worse, the silica rule has been delayed, again. This delay is for an extension of the public comment period, which goes until December 12, 2013. Public hearings are set to begin on March 4, 2014.

Find OSHA here, with links to my previous post. A NPR story from February, 2013.

My views on this rule haven’t changed much: It’s still a mixed-bag. There are still overexposures to silica (see my pictures from the last 3 weeks). However, will the new rule change the behavior?

  • Overexposures are still happeningsilica street2
  • Silica deaths have decreased over the past (without the new rule)
  • Will the small employers (the ones who typically offend the most) comply? Or just wait to be cited?

But, my overwhelming thought is this:

  • Any new rule will generate “noise” for the subject of silica. And, that’s a good-thing.
  • This will drive:
    • compliance
    • changes
    • innovation
    • discussions
    • awareness

silica street1

If you haven’t heard, Federal OSHA is proposing to reduce the airborne silica permissible exposure limit (PEL) to 50 µg/m³. It is difficult to say how much lower this new rule will be, since the current standard relies on a calculated formula to obtain the exposure limit. However, to make this easier, let’s just say it’s a 50% reduction in the PEL. This limit is the same at the NIOSH Recommended Limit and above the ACGIH Threshold Value of 25 µg/m³. Before I offer my opinion, you can state yours to OSHA here, and I’d recommend you do.

 

OSHA helps

Benefits:

  • Increase awareness by everyone (any news is good news for silica awareness)
  • Further protect employees from overexposures
  • Update the health standards. The original rule was from the 1970s.
  • New products for the industry will be created to control silica, like this.
  • Pretask planning (JSA, JHA) will become more common
  • Consultant hygienists will get more $ to: train, air monitor, etc.
  • Alternatives to sampling. This is written in the proposed rule.
    • Rather than air sampling, you can choose to “over protect” and assure employees have adequate PPE
    • This is great for short duration tasks where exposure monitoring is prohibitive (see Table 1. below from OSHA’s Fact Sheet)

OSHA lead table 1

 

Weakness:

  • Employers will spend additional money:
    • on controls for silica
    • on labor during the activities
    • on consultants to verify you’re below the PEL
  • OSHA will cite you easier
    • (my guess) is compliance officers will cite you for failure to implement controls, rather than measuring the airborne dust and finding overexposure
    • driveby citations. Look at some of my “caught on cameraoverexposures. It is easy to see why this will be easy for OSHA to cite.
  • More confusion
    • remember how you felt when you started working with leaded paint? Picture that again.
    • smaller contractors might be confused with the changes
  • I’ve heard: the airborne levels trying to be achieved are so low, they are at the laboratory detection limits. (this is a bit beyond me, honestly, but it has to do with chemistry & analytical methods)

Overall, I think lowering the limit will reduce employee overexposures to silica. The increase in awareness across the US will bring more attention to the danger. Contractor employers who are doing absolutely nothing to control silica will get caught, punished, and hopefully change. For good-contractors out there, this will make it easier to explain to your subcontractors who are a little behind. I can see many contractors using Table 1 as a guide to easily protect employees on short tasks with high silica exposures.

Your thoughts? I’d love to hear them. Here is a NY Times Article perspective.

I was visiting a friend and in their neighborhood all of the curbs were cut for driveways (they were not poured for the cutouts). curb1

This might have saved some time for the carpenters forming & pouring the concrete. But it created additional work for the concrete cutters and the finishing of the driveways.

This lack of pre-planning created:

  • additional time to cut the curb,
  • dust (and silica, for sure),
  • the use of additional water (hopefully) to control the dust,
  • respirators (& cartridge filters),
  • exposure to noise, dust, silica

I don’t know the circumstances why this occurred, but I wonder if the person planning the development thought of the exposures to other human beings?

curb2

ps. Sorry for my blogging absence. Have been on vacation! (for some of it)

It’s always fun to hear about new/different situations especially when the contractor handles it properly.

Vermiculite

During the start of a demolition on a 1989 structure, the first swing of the hammer produced a pile of vermiculite sand.

 

 

 

After some discussion on “what in the world is this doing inside a wall cavity“. The contractor stopped work, had an asbestos test performed and quarantined the area. The bulk sampling for asbestos came back with the report of “asbestos containing, but less than 1%“. Well, as you know (and as I have mentioned earlier) it may not be safe to treat this product like every other demolition project. In this case, the asbestos was very friable and by opening the wall cavity, it had definitely been disturbed.  The contractor quickly set up some procedures. Here they are:

  • Stop work in area. Quarantine area and place warning on doors.
  • Train employees & subcontractors onsite to hazard (asbestos).
  • Abatement contractor will remove wall & vermiculite
  • Abatement contractor will treat the material as if it is asbestos containing
  • Once the area is abated. An aggressive clearance test will be performed to assure no airborne levels of asbestos are present.

But why in the world was it in there in the first place? The best guess is it was added as a sound proofing / noise dampening for a air conditioning unit (actually a liebert unit) located on the adjacent wall. No other wall cavities contained the material.

There is a lot of confusion about N95 paper dust masks. And, it is confusing. The reason is because NIOSH has rated this type of equipment as a respirator. Prior to this, it was called a “comfort mask”. This name sounded better than calling it, “a worthless false sense of protection”. It is now called a, “dust mask”, or a “filtering face-piece”.

Here is what is required by OSHA if you wear this type of respirator (N95, or similar):n95

  • Employees must read and sign Appendix D (of the OSHA respirator standard)
  • Employees must clean, inspect, and store their dust mask

That’s it.

UNLESS you are wearing this because:

  • Your employer requires it
  • You have overexposures
  • or, nobody “wouldn’t wear it”. (meaning: it’s an industry practice, and when when we do this XXX task, everyone wears this type of respirator– this is the same as your employer requiring it)

If  any of the above statements are true, then you have more to do. Here are links for more information:

Voluntary Use of respirators

Fit testing

Getting ready to wear a respirator

Professionally I do not recommend these type of respirators. Email me if you’d like to know why.

Controlling most of these types of exposures is really simple. If you know the job- and you know it will generate airborne silica = Pre Task Plan!

I wish Superintendents would enforce their project managers, or project engineers, to make a pre-task plan for every concrete/silica producing task. Then, (please don’t stop yet), review the plan once the project starts!

Below are two examples with different outcomes:wet saw

1. Cutting concrete block.

The pretask plan called for a garden hose with attachment(s) to wet the cutting area. Everything was perfect until the water was shut off. But, they improvised and found an electric water pump with bucket and recycled the water. It was a great outcome. What if the power went out? They could have used a Hudson sprayer.

2. Grinding plaster off a brick wall.

They built an enclosure and containment. They had a negative air machine with HEPA filters. They had a vacuum with HEPA filters, tyvek, 1/2 face respirator, eye protection, etc. But, as they worked the vacuum couldn’t keep up with the amount of dust generated by the 7 inch Bosch grinder. It was really dusty. They worked like this for days. No one onsite saw them because they were in containment. Unfortunately  the project is almost over and it could have been better. A simple shroud to the grinder, like this one (no endorcement) might have controlled the dust & silica. Sure, it might have been troublesome to find the exact one, and get a vacuum attachment, and have the extra weight, and ….

 

dustless shroud

So, let’s talk to people about silica, talk about solutions, and then check to see if they’re effective.

You must follow both. (I’ve mentioned this before)

OSHA’s rules are very detailed and apply to any amount of lead in paint (even less than 0.5%) if you are disturbing it. The only time OSHA rules do not apply is:

  • if you are working as a sole-proprietor (no employees), or
  • if you are in some other country.

EPA’s rules are just a start. They apply to any residential facility where there are kids under the age of 6. OSHA’s rules are much more comprehensive and protective. (in some instances, overkill)

To EPA’s credit, they have done a great job of marketing and letting contractors know they insist on compliance. OSHA, on the other hand, only inspects 2% of businesses/year and does virtually no marketing. The chances of OSHA showing up on any given jobsite, is nearly 0%.

OSHA’s rules are very complete and comprehensive. You WILL need air monitoring, blood monitoring, PPE, change areas, water/sanitation, and training. The worst thing you can do is NOT follow the OSHA rules, find overexposures, and then try to “make up” for it. From my experience this scenario is a bad place to be, and happens all the time.

« Previous PageNext Page »