Hazardous Materials

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Course Learning Outcomes for Unit II

Upon completion of this unit, students should be able to:

3. Explain the chemistry of common substances 3.1 Explain the chemical characteristics, production methods, uses and associated unique hazards

of oxygen, hydrogen, chlorine, phosphorus, sulfur, or carbon as related to the safety of an environmental health and safety (EHS) and fire science (FS) professional.

3.2 Identify associated workplace regulations of oxygen, hydrogen, or chlorine.

5. Classify hazardous materials according to Department of Transportation (DOT) classification and warning systems. 5.1 Identify the labels, markings, and placards that DOT requires when transporting oxygen,

hydrogen, chlorine, phosphorus, sulfur, or carbon. 5.2 Describe DOT recommended response actions to releases of oxygen, hydrogen, chlorine,

phosphorus, sulfur, or carbon.

8. Apply information resources commonly used in emergency response operations. 8.1 Describe how the Emergency Response Guidebook (ERG) as is used in initial response

actions to hazardous materials incidents.

Course/Unit Learning Outcomes

Learning Activity

3.1 Unit II Lesson Chapter 7 Reading Unit II Assessment

3.2 Unit II Lesson Chapter 7 Reading Unit II Assessment

5.1 Unit II Lesson Chapter 7 Reading Unit II Assessment

5.2 Unit II Lesson Chapter 7 Reading Unit II Assessment

8.1 Unit II Lesson Chapter 6 Reading Unit II Assessment

Reading Assignment

Chapter 6: Use of the DOT Hazardous Materials Regulations by Emergency Responders, pp. 179-217

Chapter 7: Chemistry of Some Common Elements, pp. 227-267

Unit Lesson

In this unit, we examine the chemical properties of six elements that possess hazardous features that an environmental health and safety (EHS) and fire service (FS) professional should be aware of. These elements

UNIT II STUDY GUIDE

Chemistry of Some Common Elements

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are widely used, which increases the likelihood that they could be involved in unauthorized release incidents requiring emergency response and/or mitigation efforts. Workplace regulations involving these elements and Department of Transportation (DOT) labeling and placarding requirements for their transportation are also covered. These topics are the focus of Chapter 7. We also briefly look at the Emergency Response Guidebook (ERG) since this is still the most popular reference used for hazardous materials emergency responses. If you need more background information on DOT regulations, you are encouraged to read all of Chapter 6 and Appendix C.

Oxygen: When somebody mentions oxygen, the first thing that most people associate it with is air. Normal air as we all know consists of 21% oxygen and 78% nitrogen by volume. The other 1% consists of argon, with small trace amounts of inert gases found in the early Earth’s atmosphere, such as helium (Ackerman & Knox, 2011). This oxygen concentration is what supports life as we know it. When the concentration drops to below 19.5%, supplied air or a self-contained breathing apparatus (SCBA) is required. Normally, when humans breathe out, oxygen levels are in the range of 19%, which is why you can resuscitate an unconscious person through the means of artificial respiration. OSHA defines an atmosphere containing more than 23.5% as an oxygen enriched atmosphere, and an oxygen-deficient atmosphere has oxygen content less than 19.5% (Occupational Safety and Health Administration, n.d.).

Trivia: Although atmospheric oxygen (O2) is constantly being used up by living organisms, oxygen is replenished by photosynthesis. Scientists estimate that the world’s supply of atmospheric oxygen is generated by the life process of plants, especially the trees within the huge span of the Amazonian rainforest in South America (Meyer, 2014).

At ambient temperatures, oxygen is a colorless, odorless, and tasteless gas. Oxygen is commercially available as compressed gas, cryogenic liquid, or liquid oxygen (LOX). When LOX vaporizes, it becomes gaseous oxygen, sometimes called GOX.

Oxygen also supports the process of combustion. If the concentration of oxygen is very high, its reaction with other substances could lead to explosions or detonations. Therefore, great care should be taken in the storage and handling of gases with high oxygen concentrations. Exposure of an ignitable substance to LOX increases its rate of combustion. When shippers offer LOX or GOX to be transported, the DOT has certain labeling and packaging requirements as well as recommendations for responding to a transportation mishap (Meyer, 2014).

Ozone (O3), an allotrope of oxygen, is a powerful oxidation agent—considerably more powerful than oxygen. It is used commercially for several purposes such as a microbiocide at drinking water and wastewater plants. This ozone is produced on purpose by ozone generators. Please note that ozone is also formed (not on purpose) by the chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. This ozone is commonly known as ground-level ozone or the “bad ozone” as inhaling it can trigger or exacerbate a variety of health problems like asthma. Although the presence of ground level ozone (tropospheric) can be a problem, the presence of ozone in the stratosphere benefits earth’s inhabitants by reducing the amount of ultraviolet radiation that can reach the earth’s surface.

Hydrogen: Elemental hydrogen (H2) is an odorless, colorless, tasteless, and non-toxic substance. It is commercially available as both a compressed gas and as a cryogenic liquid. Liquid hydrogen is a good rocket fuel. In the mid-2000s, compressed hydrogen was being touted as a viable fuel alternative for powering automobiles, thereby, decreasing dependence on foreign oil for fuel.

When released indoors or into an enclosure where the gas can accumulate, the presence of hydrogen poses a risk for fire and explosion. For example, hydrogen is released when charging acid-lead batteries indoors. When released outdoors in a manner that enables the hydrogen to readily dissipate, the likelihood of forming a flammable mixture is decreased.

Just like oxygen, the DOT has requirements when hydrogen is being transported that shippers have to follow. When there is an incident involving hydrogen gas, the practical side of responding generally involves permitting the fire to burn itself out. However, the fire should be monitored to prevent the spread of the fire. OSHA regulates hydrogen storage locations (Meyer, 2014). They also have placarding requirements.

Chlorine: Elemental chlorine (Cl2) is not found naturally, but chlorine is found on earth to the extent of 0.19% by mass in a variety of compounds such as sodium chloride, potassium chloride, calcium chloride, and

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magnesium chloride. In ambient conditions, chlorine exists as a yellow-green gas with a characteristic penetrating and irritating odor. It is encountered as a gas or a liquefied compressed gas. Chlorine is about 21⁄2 times heavier than air and is highly poisonous when inhaled. This means that a chlorine release will accumulate in low-lying areas.

Exposure initially causes coughing, dizziness, nausea, headache, and severe inflammation of the eyes, nose, and throat. Prolonged exposure (> 1 hr) to moderate concentrations could cause the onset of pulmonary edema, which is the excessive accumulation of fluid within the lungs. OSHA requires employers to limit employee exposure to a maximum concentration of 1 ppm averaged over an eight-hour workday (Meyer, 2014).

Chlorine is a powerful oxidizing agent and supports combustion of certain elements and organic compounds. On the positive side, chlorine is used in the production of a wide range of solvents, pesticides, dyes, bleaching agents, plastics, and other products. Because chlorine poses an inhalation hazard and is very toxic, the use of proper protective equipment is very important when responding to incidents involving chlorine. Just like oxygen and hydrogen, shippers have to follow DOT requirements when offering chlorine for transportation.

Phosphorus: Elemental phosphorus has several allotropes. Two especially important allotropes are white phosphorus and red phosphorus. Both allotropes are used to manufacture special alloys, rodenticides, fireworks, matches, phosphoric acids, and metallic phosphides. In the past, both were also used as the active agents in incendiary bombs.

White phosphorus is a waxy, translucent solid at ambient temperature that has an autoignition temperature of 86° F (Meyer, 2014). Body heat is enough to cause an ignition. Red phosphorus is a dark-red solid consisting of long chains of P4 tetrahedra, each having an undefined length. Compared to white phosphorus, this red allotrope is not as reactive. Red phosphorus is not poisonous but could react with water to form the poisonous gas phosphine.

Sulfur: Sulfur is found in meteorites and also occurs naturally in the vicinity of volcanos and hot springs (Burke, 2003). Pure sulfur is an odorless solid. Sulfur is one of the world’s most important raw materials and has a broad use in its elemental form (S) or as one of its compounds in all sectors of the chemical industry. It is used to produce gunpowder, matches, fireworks, and products manufactured from vulcanized rubber. Sulfur readily melts under normal fire conditions, thereby, flowing into areas where it can initiate secondary fires.

For the next unit, we will combine the study of two hazard classes, corrosive and water-reactive/air reactive materials, so that we can cover all the major hazard classes in this course.

References

Ackerman, S. A., & Knox, J. A. (2011). Meteorology: Understanding the atmosphere (3rd ed.). MA: Jones & Bartlett Learning.

Burke, R. (2003). Hazardous materials chemistry for emergency responders (2nd ed.). NY: Lewis.

Meyer, E. (2014). Chemistry of hazardous materials (6th ed.). Upper Saddle River, NJ: Pearson.

Occupational Safety and Health Administration. (n.d.). Confined spaces. Retrieved from https://www.osha.gov/dte/grant_materials/fy09/sh-18796-09/confinedspace.pdf