***Three Comments on the Quiz

  1. Styrene is not an "oxidizer" but the instructions say to keep styrene away from things that are oxidizers, such as chlorine. Here is a site with information on oxidizers: Besides supplying oxygen, many oxidizer release heat.
  2. I wanted you to cruise around the exposure limits, note how there were different. What is odd about styrene is the TLV is lower than the RELs. NIOSH, who make the RELs is noted for being very conservative, that is, making recommendations that are very protective of worker health (and perhaps overprotective.) For styrene, the TLV is lower than the REL. But, since the TLVs are proprietary, the NIOSH booklet cannot publish them. The MSDS can quote the TLVs for the one substance the MSDS sheet covers, so you need to go to the MSDS. There you find that the TLV is lower.
  3. Flammable gases. The term "flash point" refers to temperature at which explosive vapors are generated over the liquid. It is not used for gases, but UEL and LEL are used and are very important. Most LEL detectors are used that pull the atmosphere over a hot wire, the flammable gas is oxidized and ions formed during oxidation cause a current that can be metered. Those meters only work if there is sufficient oxygen. These meters report % LEL. You should not work above 10% LEL. The meters are calibrated with a standard gas, often methane. The LEL of interest is that of the specific gas your are concerned about. However there are tables and protocols that enable you to adjust, if you know the gas you are concerned with. All the notions discussed above might be topsy-turvy when you are dealing with a spray aerosol. Also, the "local" environment might vary from under the LEL to over the UEL in a few feet.

***Here's my answer to the Mineral Sprits in Garage question:
The very best way to handle this situation is with Engineering Controls, that is eliminate the hazard. In this case tell your boss to buy you some nontoxic cleaner. You might treat this with ventilation, although the problem implied you couldn't, you might think about it. If you did, you would want local ventilation to exhaust where you are working. Only after these do we go to PPE. One exposure, 200 ppm is under the OSHA PEL and is therefore legal, but over the ACGIH TLV and therefore not recommended. I would wear a half-face mask with an organic vapor cartridge. That has a protection factor of 10, so I would be breathing about 20 PPM, well under the TLV. The other scenario was 3000 PPM, which is very high, near the IDHL level. The NIOSH book recommends a supplied air respirator for this exposure. [I would not work anywhere near the IDHL levels regardless of protection unless it was to rescue someone.] You would explore the LEL for solvent. That is tough because this, like many petroleum products, is a mixture of variable composition. At 3000 ppm, which is 0.3% it is unlikely to be explosive, most LELs are over 1%, but that is just guesswork. With a lot of splashing associated with washing, I would be very caution about fire.

** Q. One thing I found foggy was trying to keep straight all the different entities have a say in the regulation of hazardous materials (DOT, NFPA, OSHA, NIOSH, etc.). At times it feels like I get too much info to process. Yes. I guess it's important to realize that different entities have to regulate different aspects of hazardous materials, unfortunately there is no one organization that covers all.
A. True. Often you want to default to the most conservative, but often that would be prohibitively expensive and there is no scientific data to drive the stricter standards.

** Q. Who regulates each company to make sure that they are protecting their workers to the adequate level required? I know that adequate protection equal money out of the employers pocket, which they would tend to skip corners on if they thought it was worth the risk. I know that OSHA can set the standards, but do they also have some sort of person that comes by and rechecks concentrations and makes sure that everything is up to code? I assume they do, I just was curious about the details of it all.
A. Yes. OSHA inspects work places. In Alaska, the OSHA function is performed by the ADOL (Department of Labor) and they do inspect, cite, and fine employers. OSHA/ADOL is very short staffed and it takes a lot of paperwork to actually issue a fine. OSHA typically is responding to a worker complaint rather than making a random inspection, although they do not admit this.

Q. [From homework] Styrene is considered a flammable liquid so the firefighters can expect a flame below 100 F.
A. The temperature of the flames will be thousands of degrees.

Q. Interesting: is interesting that someone could store steel beams or TNT in a warehouse and that doesn't make any difference to any regulators around here.
A. Right, except the fire marshal. If you planned a public building with TNT, you would need to account for that in your design of the building. But once it is built, there is no real control. I believe the fire marshal could demand an inspection, but they would probably need a court order to do that.

Q. I don't really understand why, when dealing with the same chemical (CAS #), that searches for MSDS sheets result in finding various characteristics and OSHA, NIOSH requirements. It would seem that some information is either not known by the person or company doing a MSDS sheet simply omits this data. Why are they different? Isn't there any regulation on reporting an MSDS sheet?
A. We discuss this some in the module on MSDS, the OSHA requirements are very general, and many variations are possible. They must report the PEL, if there is one. There are only PELs (and TLVs) for 400 or 500 chemicals out of the 33,000 chemicals in industrial use. The manufactures or suppliers have to provide what data they have, but it may be nothing.

Q. As for something new, I have worked with mineral spirits before and never even really thought about the consequences or dangers involved with it. I guess you really can't trust anything manmade.
A. Or trust anything "natural " either, if you have too much of it. We'll talk about this later in module 9, but if I told you to work with "Stoddard Solvent" you might be concerned and check the MSDS sheet. If I told you to work with "Mineral Sprits" a substance you are familiar with, you probably would not question it.

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