Tue 16 Nov 2010

Drywall Sanding – silica & dust exposures

Posted by admin under Drywall, Paper Dust Masks, Personal Protective Equip (PPE), Respirators, Silica
[3] Comments

I have done a bunch of respirable silica dust air monitoring during drywall sanding activities. I have found varying results from the data (meaning overexposures & within the exposure limits). I have found silica in the drywall mud (or possibly the drywall itself).  I have also found that most drywall sanders wear a paper dust mask. In recent years I have not found any airborne silica in my samples. However! I have found airborne (total) dust levels higher than five times the exposure limits during sanding. What does this mean?

Well, the issue is that most drywall sanders use paper dust masks, or equivalent N95 or P100. Like this.

NIOSH has rated these masks for a protection factor of 5. Meaning that you are “allowed” to be exposed up to 5 times the exposure limit. IMO there are many things wrong with these masks. For starters, their fit on your face is really a guess. There are no “tried-and-true” methods for assuring these masks fit.*  Second, if you admit that you need to wear a respirator (meaning: you need to protect yourself) why would you choose an inferior product? I could go on…

Therefore, or finally, we come to my recommendations:

  • if you’re drywall sanding:  wear a 1/2 face tight fitting respirator with HEPA cartridges. It will protect you (given a proper fit) and based on my findings, you can rest assured you won’t be overexposed.

Besides who wants to look like this at the end of the day?

*Quantitative fit testing is a reliable fit test method, but for these types of masks, I find it to be totally useless in the real-world

Tags:

 

Wed 10 Nov 2010

Asbestos Training

Posted by admin under Asbestos, Training
[5] Comments

Who needs it? And what are the requirements?

IMO every contractor who works on buildings built before 1985 needs it. I know, the rules say buildings 1980 and earlier, but asbestos has been found in buildings built after 1980.  So what kind of training do you need? Well, that depends.

If you work on buildings built before 1985 you will need at least Class IV training. The definition (by OSHA) of Class IV activity is “maintenance and custodial activities during which employees contact but do not disturb asbestos containing materials and activities to clean up dust, waste and debris resulting from Class I, II and III activities“. I believe this includes all construction activities where there might be asbestos present.  Even if the plan is to stop-work, and call the abatement company.

Class III definition is, “– means repair and maintenance operations, where asbestos containing material, including thermal system insulation and surfacing asbestos containing material is likely to be disturbed“.  I can think of many instances where contractors touch and disturb asbestos including, HVAC (Mechanical), Plumbers, Electricians and others.

Classes I and II are strictly abatement activities and, for our purposes, we will not define, or get into.

Comparing Class III and Class IV, we see the real difference is if there is: 1. contact or 2. disturbance.

  • Class III – Contact and LIKELY to be disturbed
  • Class IV – Contact but DO NOT disturb

Depending on the construction activities  on the structure- will determine which class you’re in…and will determine what type of training you will need.

Class III Training- 16 hours in length, and includes hands on use. Also, as a side- you must also register your project with EPA, depending on the size and type of activity.

Class IV Training- 2 hours in length, and must cover certain assigned topics.

Tags:

 

Fri 5 Nov 2010

Asphalt milling machines – a big silica problem

Posted by admin under Engineering Controls, Noise, Respirators, Silica
[3] Comments

Asphalt milling machines are used to remove road asphalt in wide sections. It has been awhile since I’ve had the opportunity to perform air monitoring for silica on these operations. However, my experience in the past tells me that they can produce a lot of respirable silica dust. I snapped this picture while I was driving (I was going slow, but yea- probably not safe) on a road crew working.  I didn’t capture the cloud of dust hitting the sunlight, but it was a beautiful/scary sight.

The drums on the asphalt machines have many sharp teeth. The drum is lowered onto the asphalt surface and basically chews up the asphalt while carrying it to a belt. As you can imagine, the drum gets really hot. Water is kept on board the milling machine to cool the drum.  The theory is that the drum is wet, so the silica issue must be at a minimum.  I have found really high exposures to airborne respirable silica during this process. I believe due to the water NOT being directed at the cutting teeth.

The solution? Unfortunately, I don’t have an easy one. For starters, I’d make sure the water is directed at the point of cutting (which can vary from day to day). Respirator are not really an option. The road crew must communicate with each other and doing this with a respirator is extremely hard. The noise from these operations is also very high and most crews have ear muffs with communication head-sets.

I would love to hear your comments on engineering solutions to this issue. I don’t believe there is much research going into this issue.

Tags:

 

Thu 4 Nov 2010

Rock crushing – silica & noise

Posted by admin under Mines, MSHA, Noise, Silica
1 Comment

I was at another rock crushing site this week. This company has a mobile crusher that can crush some nice sized rocks. Which, by the way, is unique, since most crushers that can handle these size rocks take various cones, belts and screens.  Air sampling conditions were definitely not “worst case” due to morning mist and cloudy conditions for almost the entire day. However, any dust that was generated was most likely from the crusher- not gravel trucks, haul trucks, or wind. We did perform airborne silica monitoring and noise dosimetry on the crushing crew.

I did emphasize some easy, but usually overlooked, tips for the crew:

  • keep the doors closed! (this reduces dust and noise)
  • keep the radio and CB turned down as low as you can
  • backup alarms should point to the back (not at the cab)
  • wear hearing protection in high noise areas (around generators)

Tags:

 

Thu 28 Oct 2010

Stainless Steel Welding

Posted by admin under Hexavalent chromium, Stainless Steel, Welding
1 Comment

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.

Tags:

 

Mon 18 Oct 2010

Radon Awareness Week

Posted by admin under EPA, odor thresholds, radon
[4] Comments

Well, every time this year I start seeing Radon in the news. I probably have an altered view, and no one else sees these…, but it is a good time to think about you & your family’s radon exposure. For those that don’t know. Radon is a odorless, tasteless, colorless gas that occurs naturally in some areas. The real trouble is that the only way to know – is to test. Home testing is simple and I REALLY recommend it. Seriously.

There are plenty of good sites about this subject, and on testing. For a quick overview try:  EHS Today’s article

Click here for the radon awareness link on wordpress.

EPA’s website always has reliable information.

Finally,  I have used the testing from radon.com and found it to be useful and helpful. However, buyer beware, I have had some results with mixed information.

Tags:

 

Fri 15 Oct 2010

Sandblasting Bridge Repaint – lead & cadmium air monitoring

Posted by admin under Admin Controls, Cadmium, Lead, Personal Protective Equip (PPE), Respirators, Sandblasting
[10] Comments

Many bridges and elevated highways have leaded paint. Lead and cadmium was (and sometimes still) added to paint for durability. Nowadays other heavy metals are used for durability. This particular bridge was near the coast and had already been repainted sometime in the past. Repainting requires the removal of the existing paint by sandblasting.  Since the bridge was previously  repainted with a non-leaded paint, in theory, there should not be any airborne levels of lead, or cadmium. However, I always find airborne levels of lead. Why?

The possibilities are:

  • not all of the leaded paint was removed
  • recycled blasting agent has trace amounts of lead
  • and possibly there are still levels of lead in the new paint that is supposedly “non-lead”

I always ask the laboratory to analyze my air sample for lead, and cadmium. Lead is usually the main contaminant, but occasionally I find cadmium. I will sometimes also have the lab check for zinc and chromium.  The sandblasters wear hooded powered air supply respirators, coveralls, and ear protection while blasting. Some other time I’ll talk about the noise from that activity (it’s LOUD!) and the fall protection issues they face.

Lead is a hazard in two forms: 1. airborne and 2. ingestion- from the transfer of contaminated hands/clothing to being eaten. Hygiene on a lead project is essential to preventing these exposures. A good safety practice, by which to verify that lead is not being transferred is to obtain wipe samples at random (or not-so-random) locations. Lunchrooms, shower/change areas, and pickup trucks are some of my favorite “random” locations.

The views around the area weren’t bad either…

Tags:

 

Thu 14 Oct 2010

Surface Mine Rock Crusher -Air & Noise Monitoring

Posted by admin under Mines, MSHA, Noise, Silica
1 Comment

It’s still dry here in the Northwest and the crusher operations have been in full swing. This mobile, 2 cone crusher was just moved to the coast for about a six week project. We performed airborne respirable dust monitoring and noise dosimetry on the crushing crew. We use a 37mm aluminum cyclone to obtain the respirable fraction. If you run the pump at 2.5 Liters per minute you get a balanced sample across each size in the curve -5 um (microns) and smaller. I analyze for respirable dust, crystalline quartz and cristobalite. We’ve never found trydimite in this area.

There was visible dust coming from the crusher. However exposure might be a non-issue since everyone was either in the cabs of their equipment, or in the operator’s booth.  Silica exposure is nothing to take lightly. Here is a MSHA video on the subject titled, “What Does Silica Mean to You“. (windows media)

For MSHA noise dosimetry is done very similar to the OSHA methods. There are only slight difference between the two. MSHA has a nice fact-sheet here.

You can see one of the cones in the picture below (before it was running).

Tags:

 

Fri 8 Oct 2010

Spray Finish Air Monitoring

Posted by admin under Admin Controls, Engineering Controls, Personal Protective Equip (PPE), Respirators, Spray Finishing
Comments Off on Spray Finish Air Monitoring

To summarize,  there is no real quick-fix to this type of industrial hygiene assessment. Depending on what type of spray finishing you are performing- will depend on how to proceed. Here are some things to look during your assessments of these areas:

  • air flow across the face of the spray area should be at least 100 feet per minute
  • review the MSDS for the products you spray, and the solvents, thinners, and A+B parts-everything.
  • check the filters – are there scheduled changes? a manometer in place and used?
  • no flammables should be inside the booth area
  • watch the flow of work- usually there can be improvements- as well as lessons to learn
  • is the employees’ skin protected during spraying? (obviously not in the picture-right)
  • where does the waste (left over) spray product go?
  • ask employees about concerns and health issues

Typically respirators are worn in the spray finish areas. This list is not complete, but for starter, check:

  • what type of respirators are being worn? Are they protective enough?
  • what type of cartridges are used? Are they changed regularly?
  • are there scheduled change out times for their cartridges? where is that posted?
  • where are their respirators stored?

Tags:

 

Tue 5 Oct 2010

How to prevent a hearing loss claim

Posted by admin under Admin Controls, Hearing Conservation, Management, Noise, Personal Protective Equip (PPE)
[2] Comments

I know, the title is wrong.  It should read:  “How to prevent hearing loss“.

Here’s the problem (IMO).  I think most people know how to prevent hearing loss- and in America we can all afford to buy ear plugs. I have also heard of hearing loss claims that are unfounded and totally unrelated to their current work activity.  Even just a one time loud event can cause permanent hearing loss.

Construction companies hand out ear plugs like candy and say, “wear them when it’s loud”. Then, these same construction workers go home buck-up a cord of wood, ride their motorcycle, shoot their gun, and then after dinner go to a rock concert.

So, to avoid a claim, here is my advice:

  1. Measure the noise (by dosimetry) at your job site- and do it annually.
  2. Start a “hearing conservation program” or, in the simplest words, have your employees’ hearing checked annually.
  3. Educate (train) your employees in hearing conservation
  4. Give them choices in hearing protection (different brands of plugs, muffs, etc.).
  5. Manage their hearing- (see below)

If you notice a loss in their hearing- do something! To manage possible hearing loss, I suggest these additional steps:

  1. Retest their hearing. On a Monday, before work.  (To avoid a possible temporary threshold shift)
  2. Have another company test their hearing. (sometimes the equipment is out of calibration)
  3. Remind your manager to enforce the employee’s use of ear plugs on the job site.
  4. Offer to give them ear plugs to take home.
  5. Have an Industrial Hygienist (IH) perform noise monitoring at the job site for the full shift (dosimetry).
  6. Retest their hearing again a month or two later.
  7. Have an audiologist review their audiogram & your noise sampling data and ask for an opinion.

Tags:

 

« Previous Page — Next Page »