Hazard and Risk Assessment: Exposures and Identifying Hazardous Materials

Exposures in Hazard and Risk Assessment

• Potential exposures include:

  • People

  • Environment

  • Property

  • $\text{Figure 24.69}$, Potential exposures include people, the environment, and property.

Harm

• Harm is defined as injury or damage caused by exposure to a hazardous material.

• Three mechanisms of harm in hazardous materials incidents:-

  • Energy release (thermal, mechanical, chemical, pressure, electrical, radiological)

  • Corrosivity

  • Toxicity

Seven Clues to the Presence of Hazardous Materials

• Awareness level personnel and first responders must be able to analyze incidents to detect and identify hazardous materials.

• Incidents involving hazmat can be controlled only when personnel have sufficient information to make informed decisions.

• Identifying contents of buildings, vehicles, and containers results in greater safety for first responders and the community.

• Historically, failure to recognize hazardous materials at accidents, fires, spills, and other emergencies has caused unnecessary injuries and deaths.

• Once hazmat is detected, first responders can use resources to identify it and its potential hazards.

• With information, first responders can initiate appropriate response actions and perform them confidently.

• Some hazmat identification clues are easily visible at a distance, while others require responders to be much closer.

• The closer you need to be to identify the material, the greater your chances of being in an area where you could be exposed to its harmful effects.

• In general, distance often equates to safety when hazmat is involved.

• The following are the seven clues to the presence of hazardous materials:

  1. Occupancy types, locations, and preincident surveys

  2. Container shapes

  3. Transportation placards, labels, and markings

  4. Other markings and colors (nontransportation)

  5. Written resources

  6. Senses

  7. Monitoring and detection devices

Risk Levels and Clues

• Risk to responders increases as they move closer to the hazardous material.

  • It is much safer to identify a material from a distance based on a container shape than it is to physically sample the substance with a detection device.

  • $\text{Figure 24.70}$ The risk to responders increases as they move closer to the hazardous material.

• The order of the clues also represents, in general, an increasing level of risk to responders

• Using monitoring and detection equipment to identify hazmat is more likely to place responders in dangerous areas than using occupancy types or container shapes to provide information.

• Firefighters certified to NFPA 1001, Fire Fighter I should be able to identify hazardous materials based upon clues 1-6.

Preincident Plans, Occupancy Types, and Locations

• Hazardous materials may be found anywhere.

• Not all locations or occupancies are as obvious as the local chemical manufacturing plant.

• You may have little or no warning when hazmat is transported through your area by road, rail, or waterway.

• Preincident surveys and a structure's occupancy type may provide the first clue that hazmat is involved in an incident.

• The location and occupancy may also be an indicator that terrorism is involved.

• A new and emerging problem is clandestine laboratories and illegal or legal grow operations.

• These laboratories may be located in any occupancy or location, including vehicles, campgrounds, and hotel rooms.

• These labs may be haphazardly assembled and are often booby-trapped.

Preincident Plans

• Hazmat incidents can be quite volatile, so first responders may need to make decisions quickly and accurately.

• Conducting preincident surveys (also called preplans) and being familiar with local emergency response plans can simplify and reduce on-site decisions.

• With the groundwork laid, first responders can concentrate on the situation and operate more safely and efficiently.

• Preplanning reduces oversights, confusion, and effort duplication, and it results in a desirable outcome.

• Preincident surveys identify the following items:-

  • Exposures such as people, property, and environment

  • Hazmat types, quantities, dangers, and locations

  • Building features such as the location of fixed fire suppression systems

  • Site characteristics

  • Possible access/egress difficulties

  • Inherent limitations of response organizations when trying to control certain types of hazmat emergencies

  • Twenty-four hour telephone numbers of responsible parties and site experts

  • Site or occupancy response capability

• Planning is an ongoing process that includes reviewing surveys and updating them regularly.

• Preincident surveys are not always accurate, however, because inventories, businesses, and other factors may change without notice.

• Compliance with existing reporting rules and regulations cannot be guaranteed. Always expect to find the unexpected.

Occupancy Types

• Certain occupancies are likely to have hazardous materials, including the following:-

  • Fuel storage facilities

  • Gas/service stations and convenience stores

  • Paint supply stores

  • Plant nurseries, garden centers, and agricultural facilities

  • Pest control and lawn care companies

  • Medical facilities

  • Photo processing laboratories

  • Dry cleaners

  • Plastics and high-technology factories

  • Metal-plating businesses

  • Mercantile concerns such as hardware stores, groceries stores, certain department stores

  • Chemistry (and other) laboratories in educational facilities (including high schools)

  • Lumberyards

  • Feed/farm stores

  • Veterinary clinics

  • Print shops

  • Warehouses

  • Industrial and utility plants

  • Port shipping facilities (with changing cargo hazards) ($\text{Figure 24.71}$, p. 1094)

  • Treatment storage disposal (TSD) facilities

  • Abandoned facilities that may have contained or used hazardous materials

  • Big box retail stores

  • Shipping depots

  • Military installations

• Residential occupancies have hazardous chemicals, such as:-

  • Drain cleaners

  • Pesticides

  • Fertilizers

  • Paint products

  • Flammable liquids (gasoline)

  • Swimming pool chemicals

  • Propane tanks for gas grills

  • Other common household chemical products ($\text{Figure 24.72}$).

• Propane tanks often provide heating fuel, and farms may have dangerous products such as pesticides and anhydrous ammonia.

• Any building with a fume hood exhaust stack (or stacks) on the roof, such as a research and development company or medical office building, probably has a functioning laboratory inside ($\text{Figure 24.73}$).

Locations

• Hazmat transportation accidents may be more likely to occur in certain areas.

• Places where hazmat is transferred or handled, such as trucking warehouses, are also likely locations for hazmat accidents. These locations include:-

  • Ports

  • Docks or piers

  • Railroad sidings

  • Airplane hangars

  • Truck terminals

• Consult with local law enforcement officials to identify and determine potential problem spots or areas based on traffic studies.

• Each transportation mode has particular locations where accidents may occur more frequently:-

  • Roadways

  • Designated truck routes

  • Blind intersections

  • Poorly marked or poorly engineered interchanges

  • Areas frequently congested by traffic

  • Heavily traveled roads

  • Sharp turns

  • Steep grades

  • Highway interchanges and ramps

  • Bridges and tunnels

  • Railways

  • Depots, terminals, and switch or classification yards

  • Sections of poorly laid or poorly maintained tracks

  • Steep grades and severe curves

  • Shunts and sidings

  • Uncontrolled crossings

  • Loading and unloading facilities

  • Bridges, trestles, and tunnels ($\text{Figure 24.74}$)

  • Waterways

  • Difficult passages at bends or other threats to navigation

  • Bridges and other crossings

  • Piers and docks

  • Shallow areas

  • Locks

  • Loading/unloading stations

  • Airways

  • Fueling ramps

  • Repair and maintenance hangars

  • Freight terminals

  • Crop duster planes and supplies

  • Pipelines

  • Exposed crossings over waterways or roads

  • Pumping stations

  • Construction and demolition sites

  • Intermediate or final storage facilities

• First responders should also pay attention to the water level in rivers and tidal areas.

• Be aware of the following facts:-

  • Many accidents occur because flow volume and tidal conditions were not considered.

  • These flow and tidal variances affect clearance under bridges, many of which also have pipelines, water mains, gas lines, and the like attached to them.

  • Occupancies in low-lying areas that may be affected by flood conditions must have a contingency plan to isolate and protect hazardous materials ($\text{Figure 24.75}$).

  • Tidal and flow conditions are constantly changing.

  • Areas that were once considered safe may become compromised by change of tide direction, flow rate, and back eddies.

  • Once a hazardous material reaches an outside water source, it becomes a moving incident and is extremely difficult to contain, confine, and mitigate.

• First responders should be familiar with the types of hazmat shipments that come through their jurisdiction.-

  • For example, farming communities may be more likely to see tanks of anhydrous ammonia passing through, whereas a port serving an industrial complex with many refineries might see more petroleum products.

Container Types and Behavior

• Once you recognize that a location or occupancy may have hazardous materials, the presence of certain storage vessels, tanks, containers, packages, or vehicles can confirm their presence with certainty.

• These containers can also provide useful information about the materials inside, so it is important for you to recognize the shapes of the different containers and packaging in which hazardous materials are stored and transported ($\text{Figure 24.76}$).

• Depending on the container and packaging type, hazardous material behavior can vary.

Hazmat Incident Based on Container Type

• Some basic generalizations may be made about a hazmat incident based on the type(s) of container involved.

• For example, if the incident involves a pressure container, any product released is likely to be a gas or a liquid that rapidly evaporates and expands into a gas or vapor.

• Once released, the hazardous material will behave like a gas depending on its properties and the environmental conditions at the scene.

• Table 24.4, p. 1098, provides a basic overview of the four major types of containers and their relationship to aspects of the General Behavior Model. -

  • NOTE: Table 24.4 is not intended to be comprehensive.

  • CAUTION: Approach each hazmat incident as a unique situation, regardless of commonalities between incidents.

Pressure Measurements

• In addition to the general container shapes, first responders should be familiar with the basic concepts of pressure and their measurements:-

  • Pounds per square inch (psi), kilopascal (kPa), bar - Common measurements for pressure in the English or Customary System, the International System of Units (SI), and the metric (non-SI) unit, respectively (Table 24.5, p. 1099).

  • This manual uses psi (kPa) to describe pressure.

  • Atmospheric pressure - Force exerted by the weight of the atmosphere at the surface of the earth.

  • Atmospheric pressure is greatest at low altitudes; consequently, its pressure at sea level is used as a standard.

  • At sea level, the atmosphere exerts a pressure of $14.7 \text{ psi } (101 \text{ kPa})$.

  • A common method of measuring atmospheric pressure is to compare the weight of the atmosphere with the height of a column of mercury: the greater the atmospheric pressure, the taller the column of mercury ($\text{Figure 24.77}$, p. 1100).

  • Pressure at gauge - This describes a unit of pressure relative to the surrounding atmosphere.

  • The Customary System unit is pounds per square inch gauge (psig).

  • The International System of Units (SI) unit is kPaG; the metric (non-SI) unit is bar.

  • For example, at sea level, a reading of $30 \text{ psig } (207 \text{ kPaG}) {2.07 \text{ bar}}$ on a tire gauge represents an absolute pressure of $44.7 \text{ psi } (308 \text{ kPa}) {3.08 \text{ bar}}$ because the gauge was calibrated to zero in at-mospheric pressure of approximately $14.7 \text{ psi } (101 \text{ kPa}) {1.01 \text{ bar}}$.

Containers by Transport Mode and Capacity

• Skill Sheet 24-1 provides steps to analyze a hazardous materials incident to identify potential hazards.

• Hazmat containers are sometimes classified according to their transport mode (Table 24.6, p. 1100):-

  • Highway cargo trucks

  • Rail cars

  • Intermodal containers that transfer between modes

• Containers can also be classified by their capacity.-

  • Bulk packaging refers to a packaging, other than that on a vessel (ship) or barge, in which materials are loaded with no intermediate form of containment.

  • This packaging type includes a transport vehicle or freight container such as a cargo tank, railcar, or portable tank.

  • Intermediate bulk containers (IBCs) and intermodal (IM) containers are also examples.

  • To meet the criteria for bulk packaging, one of the following must be met:-

    • Maximum capacity is greater than $119 \text{ gallons } (475 \text{ L})$ as a receptacle for a liquid

    • Maximum net mass is greater than $882 \text{ pounds } (440 \text{ kg})$ or maximum capacity is greater than $119 \text{ gallons } (475 \text{ L})$ as a receptacle for a solid

    • Water capacity is $1,001 \text{ pounds } (500 \text{ kg})$ or greater as a receptacle for a gas

  • Nonbulk packaging is smaller than the minimum criteria established for bulk packaging ($\text{Figure 24.78}$, p. 1100).

  • Drums, boxes, carboys, and bags are examples.

  • Composite packages (packages with an outer packaging and an inner receptacle) and combination packages (multiple packages grouped together in a single outer container, such as bottles of acid packed inside a cardboard box) may also be classified as nonbulk packaging ($\text{Figure 24.79}$, p.1101).

• A drum is a nonbulk, flat-ended or convex-ended cylindrical packaging made of the following materials:-

  • Metal

  • Fiberboard

  • Plastic

  • Plywood

  • Other suitable materials

• Drum capacities range up to $119 \text{ gallons } (450 \text{ L})$, but $55-\text{gallon } (208 \text{ L})$ drums are the most common.

• Drums may contain a wide variety of hazardous and nonhazardous materials in both liquid and solid form.

• Typically, metal drums carry flammables and solvents, and plastic/poly drums carry corrosives.

Drum Heads

• Drums have the following two types of tops:-

  • Open heads — Removable tops

  • Tight (or closed) heads - Nonremovable tops with small openings plugged by bungs (stoppers)

Transportation Placards, Labels, and Markings

• The U.S., Canada, and Mexico use a placarding, labeling, and marking system to identify hazmat during transportation.

• All three countries use the same source for their systems: the United Nations Model Regulations, also known as, The Transport of Dangerous Goods (UN Recommendations).

• Therefore, with a few country-specific variations, the placards, labels, and markings used to identify hazardous materials during transport are very similar in all three countries.

• Generally speaking, transportation labels are designed for nonbulk packages, whereas transportation placards are designed for bulk packages.

• They look similar and convey similar information.

• However, there are certain unique labels for which there are no equivalent placards.

• Under the UN system, nine hazard classes are used to categorize hazardous materials:-

  • Class 1: Explosives

  • Class 2: Gases

  • Class 3: Flammable liquids

  • Class 4: Flammable solids, substances liable to spontaneous combustion, substances that emit flammable gases on contact with water

  • Class 5: Oxidizing substances and organic peroxides

  • Class 6: Toxic and infectious substances

  • Class 7: Radioactive materials

  • Class 8: Corrosive substances

  • Class 9: Miscellaneous dangerous substances and articles

  • NOTE: Because most North American first responders primarily deal with DOT or Transport Canada (TC) placards, labels, and markings, the unique UN placards are not detailed in the sections that follow.

  • Examples of the UN class placards and labels with brief explanations are found in Appendix C, UN Class Placards and Labels.

  • Placards, labels, markings, and colors associated with other systems (such as NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response, and military markings) are explained in the section, Other Markings and Colors.

Four-Digit Identification Numbers

• In addition to establishing hazard classes, the UN has assigned each individual hazardous material a unique four-digit number.

• This number is often displayed on placards, orange panels, and certain markings in association with materials being transported in cargo tanks, portable tanks, tank cars, or other containers and packages.

• The four-digit identification (ID) number must be displayed on bulk containers in one of the three ways illustrated by Figure 24.171.

• In North America, the numbers must be displayed on the following containers/packages:-

  • Rail tank cars

  • Cargo tank trucks

  • Portable tanks

  • Bulk packages

  • Table 1 materials, regardless of quantity (see DOT Chart 15)

  • Certain nonbulk packages (for example, poisonous gases in specified amounts)

• The Emergency Response Guidebook (ERG) provides a key to the four-digit identification (ID) numbers in the yellow-bordered section.

• Therefore, if the four-digit identification number is identified, first responders can use the ERG to determine appropriate initial response information based on the material involved.

• The four-digit identification number will also appear on shipping papers, and it should match the numbers displayed on tank or shipping container exteriors.

• Common reference materials such as the ERG do not list all four-digit UN identification numbers.-

  • For example, the ERG does not list any numbers below 1,000.

• In the U.S., the entire list is included in 49 CFR 172.101.-

  • NOTE: NA numbers (North America), also known as DOT numbers, are issued by the United States Department of Transportation and are identical to UN numbers, except that some substances without a UN number may have an NA number.

  • These additional NA numbers use the range NA8000 - NA9999.

Orange Panels

• Do not be confused by an orange panel with two sets of numbers on intermodal tanks and containers.

• The four-digit ID number is on the bottom.

• The top number is a hazard identification number (or code) required under European and some South American regulations (Figure 24.172).

• These numbers indicate the following hazards:-

  • 2 - Emission of a gas due to pressure or chemical reaction

  • 3 — Flammability of liquids (vapors) and gases or self-heating liquid

  • 4 - Flammability of solids or self-heating solid

  • 5 - Oxidizing (fire intensifying) effect

  • 6 - Toxicity or risk of infection

  • 7 - Radioactivity

  • 8 - Corrosivity

  • 9 - Miscellaneous Dangerous Substance

• Doubling a number (such as 33, 44, or 88) indicates an intensification of that particular hazard.

• When the hazard associated with a material is adequately indicated by a single number, it is followed by a zero (such as 30, 40, or 60).

• A hazard identification code prefixed by the letter X (such as X88) indicates that the material will react dangerously with water.

• When 9 appears as a second or third digit, this may present a risk of spontaneous violent reaction.

Placards

• Shippers provide diamond-shaped, color-coded signs (placards) on transportation containers to identify their contents.

• Each hazard class has a specific placard that identifies the material's hazard class.

• A material's hazard class is indicated either by its class (or division) number or name.

• $\text{Figure 24.173}$, p. 1154, provides the required dimensions of transportation placards and summarizes the information conveyed by them.

• Placards may be found on the following types of containers:-

  • Bulk packages

  • Rail tank cars

  • Cargo tank vehicles

  • Portable tanks

  • Unit load devices containing hazardous materials over $640 \text{ cubic feet } (18 \text{ m}^3)$

  • Certain nonbulk containers

• You may see containers with more than one placard, indicating that more than one hazard or product is present.

• $\text{Figure 24.174}$, p. 1155, provides the U.S. DOT's Chart 15, Hazardous Materials Placarding Guide.

• Unfortunately, improperly marked, unmarked, and otherwise illegal shipments are common.

• These shipments may include:-

  • incompatible products

  • products that contravene local, state/provincial, and federal laws

  • waste products shipped and disposed of without a permit.

Important Facts Related to Placards

• The following are important facts related to placards:-

  • A placard is not required for shipments of infectious substances, other regulated materials for domestic transport only (ORM-Ds), materials of trade (MOTs), limited quantities, small-quantity packages, radioactive materials (white label I or yellow label II; see Labels section), or combustible liquids in nonbulk packaging.

  • Some private agriculture and military vehicles may not have placards, even though they are carrying significant quantities of hazardous materials.

  • For example, farmers may carry fertilizer, pesticides, and fuel between fields of their farms or to and from their farms without any placarding.

  • The hazard class or division number corresponding to the primary or subsidiary hazard class of a material must be displayed in the lower corner of a placard ($\text{Figure 24.175}$, p. 1156).

  • The DANGEROUS placard is for mixed loads where the transport vehicle contains non-bulk packages with two or more categories of hazardous materials that require different placards ($\text{Figure 24.176}$).

  • Other than Class 7 or the DANGEROUS placard, text indicating a hazard (for example, the word FLAMMABLE) is not required.

  • Text may be omitted from the Oxygen placard only if the specific ID number is displayed.

  • Drivers may have varying degrees of information about the hazardous materials in their vehicles.

  • Containers may have placards even though they appear "empty" until they are certified as "clean."

Labels

• Labels provide similar information as vehicle placards.

• Labels are $3.9-\text{inch } (100 \text{ mm})$, square-on-point diamonds, which may or may not have written text that identifies the hazardous material within the packaging. $\text{Figure 24.177}$ shows the U.S. DOT's Chart 15, Hazardous Materials Labeling Guide.

• Class 7 Radioactive labels must always contain text. Most labels for the nine hazard classes and subdivisions are essentially the same as their placarding counterparts.

• Packages with more than one label have more than one hazard or product.

• These packages contain a primary label and a subsidiary label for materials that meet the definition of more than one hazard class.

• In $\text{Figure 24.178}$p. 1158, the toxic label is the primary label, while the flammable liquid label is the subsidiary.

• The "Cargo Aircraft Only" label is not associated with a particular hazard class.

• This label is used to indicate materials that cannot be transported on passenger aircraft.

Markings

• A marking is a descriptive name, an identification number, a weight, or a specification and includes instructions cautions, or UN marks (or combinations thereof) required on the outer packaging of hazardous materials.

• This section, however, shows only those markings found on DOT Chart 15 ($\text{Figure 24.179}$, p. 1158).

• Markings on intermodal containers, tank cars, and other packaging are discussed in later sections.

• One marking you should note is the "Hot" marking for elevated-temperature materials.

• Elevated temperature materials, such as molten sulfur and molten aluminum, can present a thermal hazard in the form of heat.

• Molten aluminum, for example, is generally shipped at temperatures above $1,300°\text{F } (705°\text{C})$.

• First responders must be extremely cautious around these materials to avoid being burned.

• Molten aluminum and other high-temperature materials can ignite flammable and combustible materials (including wood).

• Working around or near elevated-temperature materials can increase the effect of wearing personal protective equipment due to high ambient air temperatures.

• The U.S. Department of Transportation (DOT) defines an elevated-temperature material as one that when offered for transportation or transported in bulk packaging has one of the following properties:-

  • Liquid phase at a temperature at or above $212°\text{F } (100°\text{C})$

  • Liquid phase with a flash point at or above $100°\text{F } (38°\text{C})$ that is intentionally heated and offered for transportation or transported at or above its flash point

  • Solid phase at a temperature at or above $464°\text{F } (240°\text{C})$

Hazard Classes

• Transportation hazard classes are easier to understand once you have a better understanding of the basic physical and chemical properties explained in the previous sections.

• In general, a product's hazard class is assigned based on its most dangerous chemical and/or physical properties.

• Flammable gases combine the physical hazard of a gaseous state, which expands rapidly, spreads easily, and is difficult to confine, with flammability.

• This section describes:-

  • Class 1—Explosives

  • Class 2—Gases

  • Class 3—Flammable liquids (and combustible liquids in the U.S.)

  • Class 4—Flammable solids, spontaneously combustible, and dangerous when wet

  • Class 5—Oxidizers and organic peroxides

  • Class 6—Poisons, poison inhalation hazards, and infectious substances

  • Class 7—Radioactive

  • Class 8—Corrosives

  • Class 9—Miscellaneous hazardous materials

  • Canadian Placards

Class 1: Explosives

• Explosives are reactive.

• An explosive is any substance or article with a great deal of potential energy that may rapidly expand and release upon activation (undergo an explosion) ($\text{Figure 24.181}$).

• Explosives may release energy in the form of light, gas, and/or heat.

• Some explosives may not be specifically designed to explode.

• Explosive placards list both a division number and a compatibility group letter on them.

• First responders should pay particular attention to the division number, which assigns the level of explosion hazard to the product.

• Compatibility group letters categorize different types of explosive substances and articles for purposes of stowage and segregation ($\text{Figure 24.182}$, p. 1160).

Canadian Placards, Labels, and Markings

• Transport Canada (TC) and the Dangerous Goods Act govern transportation placards, labels, and markings in Canada.

• Like the U.S. HMR, the Dangerous Goods Act is based on the UN Recommendations and, therefore, is very similar.

• The nine hazard classes in both documents are identical. Table 24.17, provides Canadian placards, labels, and markings divided by class.

• There are some differences, however, between Canadian and U.S. placards, labels, and markings such as the following:-

  • Most Canadian transport placards do not have any signal words written on them.

  • Labels and markings may be in both English and French.

  • Canada requires a unique placard for anhydrous ammonia and Inhalation Hazards.

  • Radiation placard may have the four-digit UN number.

Mexican Placards, Labels, and Markings

• Like Canada and the U.S., Mexican transportation placards, labels, and markings are based on the UN Recommendations and have the same hazard classes and subdivisions.

• In fact, Canadian and Mexican placards and labels are virtually the same, although Mexico does not recognize the Inhalation placard.

• Because international regulations authorize the insertion of text (other than the class or division number) in the space below the symbol, as long as the text relates to the nature of the hazard or precautions to be taken in handling, placards and labels in Mexico may have text that is in Spanish ($\text{Figure 24.202}$, p. 1179).

• Likewise, information provided on markings is likely to be written in Spanish.

• English-speaking first responders in Mexico or along the U.S./Mexican border should familiarize themselves with the more common Spanish hazard warning terms such as peligro (danger).

Other Markings and Colors

• In addition to DOT placards, labels, and markings, a number of other markings, marking systems, labels, labeling systems, colors, color-codes, and signs may indicate the presence of hazardous materials at fixed facilities, on pipelines, on piping systems, and on other containers.

• These other markings may be as simple as the word chlorine stenciled on the outside of a fixed-facility tank or as complicated as a site-specific hazard communication system using a unique combination of labels, placards, emergency contact information, and color codes ($\text{Figure 24.203}$, p. 1179).

• Some containers may be marked with special information.-

  • For example, non-odorized means that the product will not have an intense smell by itself.

• Some fixed-facility containers may have identification numbers that correspond to site or emergency plans that provide details on the product, quantity, and other pertinent information.

• The sections that follow highlight the most common specialized systems in North America, including the following:-

  • NFPA 704 System

  • Globally Harmonized System

  • HMIS and other U.S. Hazard Communications labels and markings

  • Canadian Workplace Hazardous Materials Information System

  • Mexican Hazard Communication System

  • CAS numbers

  • Military markings

  • Pesticide labels

  • Other symbols and signs

  • ISO safety symbols

  • Color codes

NFPA 704 System

• The information in NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response, gives a widely recognized method for indicating the presence of hazardous materials at commercial, manufacturing, institutional, and other fixed-storage facilities.

• Use of this system is commonly required by local ordinances for all occupancies that contain hazardous materials.

• It is designed to alert emergency responders to health, flammability, instability, and related hazards (specifically, oxidizers and water-reactive materials) that may present as short-term, acute exposures resulting from a fire, spill, or similar emergency.

• Specifically, the NFPA 704 system uses a rating system of numbers from 0 to 4.-

  • The number 0 indicates a minimal hazard, whereas the number 4 indicates a severe hazard.

• The rating is assigned to three categories: health, flammability, and instability.

• The rating numbers are arranged on a diamond-shaped marker or sign.

• The health rating is located on the blue background, the flammability hazard rating is positioned on the red background, and the instability hazard rating appears on a yellow background ($\text{Figure 24.204}$, p. 1180).

• As an alternative, the backgrounds for each of these rating positions may be any contrasting color, and the numbers (0 to 4) may be represented by the appropriate color (blue, red, and yellow).

• Special hazards are located in the six o'clock position and have no specified background color; however, white is most commonly used.

• Only two special hazard symbols are presently authorized for use in this position by the NFPA: W, indicating unusual reactivity with water, and OX, indicating that the material is an oxidizer. However, you may see other symbols in the white quadrant on old diamonds, including the trefoil radiation symbol.

• If more than one special hazard is present, multiple symbols may be seen.

• NOTE: The NFPA 704 system may be used differently in countries outside of North America.-

  • For example, NFPA 704 symbols might be used on transportation containers.