***Q. The problem I always hear about respirators (besides being uncomfortable) is that they don't work for men with beards. That must include about half the men in Alaska. Is there equipment for this situation or should male workers that may deal with hazardous material limit themselves to little or no beard?
A. If you work with hazardous materials that require a "negative pressure respirator," your employer needs a formal "respiratory protection program" that will have lots of details. An annual respirator "fit test" is always required (every six months is better). The program will always say that you cannot have any facial hair on the "sealing surfaces" of the respirator. I have had a full beard for 27 years, but I shaved those surfaces for my fit test. Yes, I looked very funny for a few weeks. The option is use some sort of PAPR. When I was in that situation, I bought my own PAPR with a hood. My employer only supplied the negative pressure respirators. I do not recommend the hood for people that actually have to work with respirators for extended times. Hoods are more uncomfortable, they come loose easily, and you can't wear a hard hat with the type I had. But I only needed the respirator briefly, so it was OK.
***Q. The UEL and LEL are a bit confusing to understand for a first timer. I think they should be more self explanatory. Both are limits when the gas explodes but due to different reasons. In one the flame has to be present while in the other flame has to be absent. I think they should be treated differently since they showcase different scenarios. It seems like these two limits (LEL & UEL) are upper and lower limits for totally different effects but they are grouped as one.
A. Not quite. Both require a spark or other ignition source. The LEL is intuitive. There are concentrations so low they will not explode, even with a spark. The UEL is not intuitive. There are concentrations so high that they will not exploded either, even with a spark. In a gasoline engine we refer to such mixtures as being "too rich" or the engine as being "choked"
***Q. [Difference between reactivity and flammability] I cannot understand the reason why my quiz points are decreased for 2nd question considering reactivity of styrene
In the web site you gave in the module it is clearly indicated that the reactivity rating in the yellow region is from 0 to 4. http://safety.science.tamu.edu/nfpa.html
A. Since there is a different part of the diamond for flammability, the reactivity refers to non fire-type events. A fire is an oxidation by heat and oxygen from air. An explosion is very rapid expansion of heat and gas due to a chemical reaction that may not involve air at all. Further, some of these do not require any flame or high heat to explode. That is what the reactivity part of the diamond is all about. http://safety.science.tamu.edu/definexplosive.html
***Q.I have looked at several MSDS sheets that give exposure levels in mg/m^3 with the notation "(skin)" following. Listed below is the example of one of the MSDS web sites. I assume this is the maximum concentration of contaminate in the air that can be in contact with bare skin? No. But good question. Above that concentration do you have to wear PPE to avoid dermal contact with the contaminated air? If so, what type of protection is good enough and for how long?
A. The notation "skin" means that skin is a significant exposure route and exposures via the skin may contribute to overall systemic exposure. It generally refers to liquids on the skin. It is difficult to quantify, but exposures via the skin can be eliminated with proper clothing and if the 'skin' notation is present, the substance should be kept off the skin altogether.
***Q. I was confused about the difference between a PAPR [Powered Air Purifying Respirator] and a supplied air respirator.
A. A PAPR has a little air pump with a battery, while a supplied air has an airline or SCBA tanks.
**Q. The part about worker asphyxiation threw me…
A. Any gas will displace oxygen and thus asphyxiate.
**Q. I work for the XXXX. In our safety manual it mentions that State Response Personnel may not use a PAPR. Unfortunately this section was written by an unknown individual and with high staff turn-over, no one working here remembers why this was written. Do you know of any state or federal regulation, or safety issue that would favor an APR over a PAPR?
A. No, quite the opposite. An APR requires the wearer to work harder at breathing, while the PAPR does not. The PAPR always has a higher protection factor because the pressure inside the mask is mostly positive. Sounds like someone needs to review your safety program.
** Q. The confusing part was about the PPE. When chemicals can react with air or moisture or other gases in atmosphere and they can form some unexpected chemicals. So the PPE clothing is designed differently for different chemicals or they just do it with the material they think is best worst conditions.
A. You need to know which chemicals you are dealing with. In most industrial settings that is not such a problem, an industry knows what chemicals it produces and what happens to them. At hazardous waste sites, especially during the initial phases, the chemicals are not known, and the worst must be expected.
* Q. So Stoddard Solvent accounts for <40% of GoJo [A waterless hand cleaner] which is designed for use on the hands (that's what I got from the MSDS sheet, although the 40% might refer to the fraction of the exposure limit imparted), but Stoddard Solvent is listed as a skin irritant? I don't get it. There is typically no listed exposure level (concentration) for skin contact which makes skin irritation a difficult symptom to quantify (and rank as an indication of exposure).
A. Yes, the assumption is that you can eliminate all the skin exposure. It is difficult to quantify.
*Q. Also, I didn't read the closure module until after finishing the rest of the homework, but I took the part b question to be one of forced PPE use. Also, is there a formal source on the listing of PPE use as a last resort, or is it a Dr. Perkins rule of thumb?
A. That is Industrial Hygiene Bible. First engineering controls, then administrative controls, and lastly PPE.
*Q. I have a little problem with the Fire Marshall situation. It seems a little backwards in that while the Fire Marshall is allowed to inspect, it is unlikely that the building will be inspected. The danger for the firefighters attending the scene should supercede costs. Is this only an Alaska situation or is it present throughout the US? Plus, in smaller towns, it in unlikely, in my opinion, that all safety officers will be diligent to report what is actually being stored in their warehouse and the associated risks. Is this a reoccurring issue in Alaska, in that more people are requesting more regulation with chemicals?
A. There are few fires and explosions in Ak because we are non-industrial state. In general, big industries are pretty good about reporting such things and coordination with the local fire department. Oil companies in the US are hyper diligent. It is the smaller industries that fly under the radar, and these have the problems.
* Q. Are all engineers employed in the company supposed to undergo training in the PPE so that whenever required they can be sent to the accident site. If this is not the case when there has to be some specific people in the company who have been trained for this purpose. Can only they be sent ? Can anybody volunteer for such training ?
A. Depends on the company. The company must train any who will be exposed to hazardous substances - the law requires that. Training of others is optional.
Q. The best people to ask for advice [about a respirator] is usually the vendor itself.
A. Often you are talking to a salesman in some sort of intermediate position, perhaps with an industrial supply firm. The manufactures have exact data; they needed this when they got the equipment certified. But even if you are talking to the right people, they do not know your particular situation, and will be relying on exactly what you tell them. Again, the right person would question you and you would realize if more information was needed for the right decision.
Q. The response to my posting for the previous assignment (earplugs, etc.) makes more sense after completing this assignment. Still, when you send a guy out in the woods to cut down a tree, you give him earplugs and a chainsaw (among other things), not an axe as an administrative control.
A. Substituting the axe would be an "engineering control."
Q. Also, isn't the pipeline example sort of a natural fumehood? Even without wind, the horizontal mixing from the jet and the vertical convection should dilute the hell out of the volatile components in the mixture.
A. For the gross oil, it will drop out. For the vapors, as I said in the module, they might not settle very quickly, if at all.
Q. Flammability and crude inhalation seem far more important from a risk standpoint.
A. Yes. Microdroplets of oil are also a problem.
Q. The distinctions between types of controls on page 5B_1 is counterintuitive I think. I would think eliminating the hazard would be an administrative control and that reducing the exposure would be an engineering control. Typo or is my brain wired backwards?
A. It could be confusing, but that is the correct terminology.
Q. I was confused by the explanation of how the LEL and UEL relate to worker health – is it that the LEL-UEL levels don't mean any specific thing for health, they merely indicate at what percent concentration a combustion reaction could occur?
A. They are not directly related to health at all. Fire is a “safety” hazard, not a “health” hazard. Many substances that are both toxic and flammable are toxic at levels that are orders of magnitude lower than the LEL.
Q. I am also confused about why PPE is required by many employers when adequate engineering and administrative controls would work. It seems to me (just in my experience) that many employers have the “more PPE is better” approach, and don't really think about the situations where workers are asked to use a specific piece of protective equipment. Just an observation, although I'm curious about your opinion on this.
A. Your observation is correct. Overprotection is sloppy industrial hygiene, or, usually, no industrial hygiene at all.
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