Air Monitoring


Confession: I missed the assessment of this hazard the first time.

Awhile back I performed air sampling during aluminum welding. The welders were cordial and let me crawl over their welding equipment, poke around old boxes of wire and metal stock. I did not think there were any “real” hazards. We did find some airborne levels of various metals. From the picture can you tell who did the most welding?

welding mce

After I had performed the sampling and the report was sent, I was asked if I had checked for ozone (O3)? I admitted I hadn’t and asked if it was an issue? Well, apparently it is (or rather, might be).

I went back to the shop, begged for another chance, and performed ozone sampling. It wasn’t difficult, but eating crow was the hardest part.

More information on the subject can be found at: NIOSHUK- HSE. Ozone is formed when the UV radiation hits oxygen. The ACGIH TLV is variable (see table below)ozone acgih, and the OSHA PEL is 0.1 ppm.

Health: Ozone, O3, can cause lots of different respiratory illnesses. These can include a decrease in lung function, aggravation of asthma, throat irritation/cough, chest pain, shortness of breath, inflammation of lungs, and a higher susceptibility to respiratory illnesses. ACGIH classifies it as an A4, or not a suspected carcinogen.

Luckily the results were found to be non-detectable (“IH talk” for none-found). Which only means I didn’t find it, not that it is not there. I sampled for a long time (530 minutes) because they were working 10 hour shifts. But, they only welded for a total of approximately 1.5 hours during that time.

If welders are in a confined area, or a small space with limited ventilation, the results might be significantly different.

 

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 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.

The latest push from NIOSH is ridiculous, in a bad way. It’s titled, “Recognizing N95 Day” on September 5. I’ve written about these types of respirators before.

Let’s start with:n95 box

  • NIOSH estimates 20 million workers exposed to airborne health risks
  • N95 (s) are the most commonly used respirator
  • NIOSH certifies all respirators. And, OSHA requires all respirators to be certified by NIOSH
  • All certified respirators must have an “assigned protection factor”, which is a level of protection they are able to achieve
  • N95 respirators are certified to provide a protection factor of “up to” 5 times the exposure limit

For the record, I am not disputing how NIOSH certifies respirators, or if these respirators can achieve a protection factor of 5 (5x the exposure limit). I will also add that in the healthcare setting (hospitals) these might have a useful role.

Here’s the problem:

  • If you need a respirator, you would NOT choose a N95. They are terrible fitting.
    • To put it another way: if you had to work in an environment which had a dangerous airborne hazard, would you CHOOSE this respirator?
    • Or another way: “There is a chance this N95 respirator might protect you, wear this just in case”. (?)
  • If you have fit tested these types, you know they are hard to fit, and at best, mediocre in their protection. At times it is hard to fit test a tight fitting 1/2 face respirator on someone who is clean shaven.
  • N95 respirators are handed out (like candy) at construction sites for any task which “may be hazardous”.
  • Let’s be honest:
    • these are “comfort” masks. AKA:  peace of mind, not for protection.
    • these are cheap. That is why most employers buy them.
  • And, let’s mention:
    • exposure levels can vary (have you measured the worst case scenario?)
    • change out schedule? Do your workers wear the same respirators every day? Do they change them when they start getting hard to breathe?
    • facial hair (no one who is on a jobsite has this, right?)
    • there are knock-off N95 respirators which actually aren’t certified (they’re fake)

In this instance I wish NIOSH would spend money on training people to use the correct type of respirator. Or, how to adequately measure the hazards found at various sites.

As a quick review. If you need to wear a respirator, here are the proper steps.

n95 box2

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.

 

 

Can we measure an exposure accurately with just one sample? (statistically, no.) Also consider: Can we measure a “worst case” scenario and be OK for the rest of the project? (again, hypothetical question)

There was a blog post, here by Mike Jayjock, which reminded me of how silly our data points (aka industrial hygiene sample results) are in the big picture of statistics.  I’m slowly reading a book titled, “Control Banding” by David Zalk who is with Lawrence Livermore National Labs. The CDC also has a section on control banding here.

Another side of this is a common practice we all perform called Risk Analysis. There is much on the subject, but essentially it’s similar to triage at an emergency room. What is the easiest, best thing you can do: given what you have available and what you are able to muster?safety triangle

Too often (myself included) we perform air monitoring for a specific situation and use that information as the gospel-truth. Well, this might be like living in the United States and never traveling. We meet a very nice person from the Ukraine. They seem very typical Eastern European and have a thick accent, but are they really like everyone in Russia? Is this person typical? Are they exactly like every other person from Russia?

This type of stereotyping is the same as taking one sample and drawing conclusions about all exposures. You might be right, BUT…you might be wrong.

There is a fun app you can download called, IH DIG by Adam Geitgey (Apple & Android).  This app illustrates the importance of using statistical tools, rather than guessing. (It’s a game)

Sorry I do not have many answers in this post, just a lot of questions.

This has to be one of the coolest types of cutting. Raw obliteration of metal.

As you know, hexavalent chromium (Cr6) is generated when the metal, chromium, is heated. Cutting this metal with a plasma torch is an easy way to heat it up quickly.  We performed air monitoring on one employee performing plasma cutting on #304 stainless. Luckily the employee was wearing a 1/2 face tight fitting respirator (and skin protection due to the body readily absorbing Cr6) and we found exposures at 36% of the exposure limits (they were within the acceptable limits). This employee was able to stand away from the cutting due to the machine he was using. He did not do this task all day and no engineering controls (ventilation) was used. 

****Caveat: Please do your own air sampling. Conditions and environment may not be similar to your environment, and they can change rapidly. One sampling event rarely indicates all conditions. We’re talking about people’s health!****Keep in mind welding safety

plasma cutting

And a close up of the cutting machine without the motor & tracks:

cutting bevel

I previously wrote about a worst-case scenario in which asbestos was not discovered till after it was disturbed.TSI asbestos

Recently I heard a story of the opposite:

A general contractor hired a company to remove various pieces of asbestos. They had obtained an asbestos building survey, which clearly stated where the  asbestos was located. A boiler with surrounding insulation was identified as non-asbestos containing (asbestos-free). The employee was using a bobcat to demolish the boiler. As he started to tear into the insulation surrounding the boiler (disturb it), he paused. He checked the building survey again, and it had clearly stated it was “asbestos free” (actually 5 samples had been taken of the insulation around the boiler). Then, he did what most other people would not do: HE REFUSED to demo the insulation. He told the General Contractor and owner he thought it was asbestos containing and wanted it tested, AGAIN.

Guess what they found? Yep. Asbestos WAS contained inside the insulation around the boiler.

There was obviously some break-down in communication with the report, inspector, and possibly the lab.  However, this employee is to be commended and, really, the safety culture at this company should be congratulated. You never know where you will find asbestos.  The employee had enough guts to speak up for his safety (and for the others).

Measuring good-safety behavior is the type of thing we should reward. In the past (and still today) many safety-people measure losses ( ie. how many injuries). This is backwards thinking. We should be rewarding good behavior and encouraging people to speak up for safety.

For example; what do you say to this guy?

scaffold ladder

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.

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