PTAC 1308 Chapter 4 Gases, Vapors, Particulates, and Toxic Metals

Overview Physical and health hazards associated with gases, vapors, particulates, toxic metals. Poisonous metals and the hazards associated with them. List the metals that are fire hazards Hazards associated with toxic metals and their compounds. Hazards associated with compressed gas cylinders. Flammable gases. Hazards associated with dust explosions. Precautions used when working with particulates, dust, and gases. Discuss the Du Pont Virginia vapor release incident. Working safely with asbestos.

Physical Hazards of gases Compressed gas—has a gauge pressure of 40 psig at 70°F (21.1°C). Explosive—a chemical characterized by the sudden release of pressure, gas, and heat when it is exposed to pressure, high temperature, or sudden shock. Flammable gas—forms a flammable mixture with air at ambient temperature. Oxidizer—a chemical that promotes combustion in other materials through the rapid release of oxygen, usually resulting in a fire. Pyrophoric—a chemical that ignites spontaneously with air at temperatures below 130°F (54.4°C). Unstable—a chemical that will react (condense, decompose, polymerize, or become self reactive) when it is exposed to temperature, pressure, or shock.

Asphyxiants These are gases that can interfere with oxygen supply to the body. Simple asphyxiant – gases that displace the oxygen content in the air. Inert gases- N2, He, H2, CO2, CH4. Chemical asphyxiant – Gases that prevent cells from using oxygen or prevent the blood from supplying oxygen- CO and hydrogen cyanide (HCN)

Anesthetic gases – Have a numbing effect and will cause the loss of sensation and unconsciousness. Symptoms include dizziness, coordination lose and falling asleep due to the central nervous system becoming chemically depressed. Systemic poisons: Formed when toxic gases enter the blood through lungs and move to other body organs and tissues. 1. Arsine – blood cells and liver 2. Benzene – bone marrow 3. Hydrogen sulfide – respiratory system 4. Mercury – nervous system, kidneys, glands

Health Hazards Carcinogens – are known cancer causers Mutagen – a chemical that is suspected to have the properties required to change or alter the genetic structure of a living cell. Teratogen – a substance that is suspected to have an adverse effect on the development of a human fetus. reproductive toxins, asphyxiation, anesthetic, neurotoxic, allergic response, irritant, sensitizer, corrosive, toxic, highly toxic, and target organ effects.

Poisonous metals Mercury- Dental amalgams, Vaccines, Lead-Found in lead-based paints, leaded gasoline, lead contaminated water, manufacture of lead batteries, rubber products, glass among others. Aluminum- Associated with Alzheimer’s disease. Arsenic- Used mainly as pesticides or to preserve wood. Exposure through smoke or drinking water. Long term exposure may cause various cancers while short term may result in nausea, decreased red blood cells production and abnormal heart rhythm. Cadmium-Found in food, water and cigarette smoke. It harms the DNA directly and disturbs a DNA repair system that helps in preventing cancer.

Poisonous metals- asbestos When an abrasive, irritating, asbestos fiber enters the human lung it activates the natural body defense system by encapsulating it. This process creates scar tissue on the lungs. Over time, the lungs lose their ability to move oxygen in and out of the lungs and supply oxygen to the blood stream, a condition called asbestosis. Because asbestos is classified as a cancer-causing agent, asbestosis is considered serious.

Fire hazards calcium cerium cesium lithium lutetium magnesium and magnesium alloys neodymium phosphorus potassium potassium-sodium alloys rubidium sodium strontium aluminum (powder) beryllium (powder) nickel catalyst (Raney) titanium (powder) zinc (powder) zirconium (powder)

Compressed Gas Cylinders When cylinders are heated up the compressed gases expand rapidly, increasing pressures. Direct flames will weaken the exposed side of the cylinder. Gas cylinders can rupture with catastrophic effects. The cylinder head or hoses could be damaged or knocked off, releasing the contents of the cylinder.

Flammable gases Acetylene, H2, Propane are flammable gases. They mix with air/O2, the mixture is subject to explosion or ignition if exposed to an ignition source.

Du Pont West Virginia Incidents January 2010 Release of methyl chloride Oleum release Phosgene release- highly toxic chemical. Damages lung tissue 3 incidents in sequence. The company had a history a good safety reputation.

Du Pont mistakes:

Particulates Small liquid or solid particles dispersed through the air. Various concentrations will have differing effects. Coal dust caused Black Lung.

Dust and Gases Any type of dust can be potentially dangerous if sufficient quantities are inhaled. Two types of respiratory protection programs: air purifying and air supplying.

Dust explosions Occur when particle concentrations are detonated from a single spark. Almost anything will burn if broken down into small enough parts. Dust acts as fuel in Fire Triangle.

Figure 4-5 Examples of Gaseous Hazards

Figure 4-6 Harmful Effects of Toxic Metals

Metallic compounds can be as dangerous as the purer form if not more dangerous depending on how the chemical is introduced into the human system. Class D fires involve fires caused by metals. The proper fire extinguishers must be used for these types of fires.