Things to know about Labels, Placards, and Markings

1DURING EARLY-MORNING RUSH HOUR, YOU RESPOND to a report of a vehicle accident involving a tractor-trailer. On arrival, you discover the vehicle has overturned down an embankment. The driver has managed to escape from the vehicle but may have suffered a head injury, since he has no recollection of events just prior to the incident or what may be loaded on the trailer. Any attempt to retrieve the shipping papers from the truck cab is too dangerous at this time. Using binoculars, you notice a clear liquid is steadily leaking from the rear of the trailer. You do not see any placards on the trailer. Since the vehicle is not placarded, is it safe to conclude that the liquid is not a hazardous material? What would you do now?

During another incident, you respond to a report of a fire involving an 18-foot box truck. On arrival, the cab of the truck is fully involved and fire is quickly spreading to the cargo box. The truck displays the DANGEROUS placard. Just what does this placard indicate? What would you do now?

To effectively assess and manage the dangers associated with the release or potential release of a hazardous material, first responders must first know something about the material(s) involved. The best-case scenario involves knowing the name of the material, since product-specific information can then be requested from sources such as the manufacturer.

Keep in mind that many emergency incidents involving hazardous materials are related to transportation mishaps and include incidents such as vehicle accidents or mishandling of shipping containers. An understanding of the federal regulations that govern the transportation of hazardous materials is needed before first responders can identify the substances involved in these mishaps. Title 49 of the Code of Federal Regulations (CFR) (Transportation) provides directions for those involved in shipping and handling hazardous materials and guides first responders in identifying the materials and their potential hazards.

Specifically, the transportation regulations require the use of identification tools known as labels, placards, and markings, which often allow first responders to detect the presence of a hazardous material from a safe distance. The information provided is usually limited to a material's hazard class, not the name of the material. That is generally because many highway transportation incidents involve vehicles that might contain numerous types of hazardous materials packages, making it a logistical nightmare to display each product name on the outside of the vehicle. There are, however, situations when large containers, such as cargo tanks, which usually contain only one or two commodities, will display information that is more product-specific.

First responders must also remember that exceptions to the transportation regulations allow materials to be shipped without labels, placards, or markings. These exceptions are a fact of life in the transportation industry.

Not having the exact name of every hazardous shipment displayed on the exterior of every transport vehicle and the numerous exceptions to regulations are accommodations to the transportation industry, whose presence first responders must acknowledge. However, knowing the extent of the regulatory provisions and limitations and how to interpret the message from labels, placards, and markings allows first responders to be better prepared when making initial assessments during the early stages of an incident.


First responders often ask the following questions relative to the transportation of hazardous materials.

What is meant by the term hazardous materials as used in the transportation regulations?

Specifically, a hazardous material is defined in part by the regulations as “a substance or material that the Secretary of Transportation has determined is capable of posing an unreasonable risk to health, safety, and property when transported in commerce.”1 Many of these materials are assigned to one of nine hazard classes on the basis of definitional criteria that include characteristics such as flash point, inhalation or oral toxicity, or the ability of a liquid or solid to cause “full thickness destruction of human skin at the site of contact within a specified period of time.

First responders must understand that the regulations generally apply only to those materials that meet these specific “definitional criteria” and then only when these materials are “transported in commerce.” Many more materials and products not addressed by the transportation regulations can still pose potential hazards to first responders during a transportation mishap. In addition, materials considered hazardous for the purposes of transportation may not be identified with transportation labels, placards, or markings when used or stored at a fixed facility. Therefore, first responders must use caution when attempting to associate the absence of a label, placard, or marking with the absence of a hazard.

What are the nine hazard classes defined in the federal transportation regulations?

According to 49 CFR, 171.8, the term hazard class means “the category of hazard assigned to a hazardous material.” Hazard classes and their associated hazard class number are as follows:

1. Explosives,

2. Compressed gases,

3. Flammable liquids,

4. Flammable solids,

5. Oxidizers,

6. Poisonous materials,

7. Radioactive materials,

8. Corrosive materials, and

9. Miscellaneous hazardous materials.


Note that “a material may meet the defining criteria for more than one hazard class but is assigned to only one hazard class”3using a predetermined criteria known as the “Precedence of Hazard Table,” found in 49 CFR, 173.2(a). This assigned hazard class is also referred to as the primary hazard; any additional dangers are generally referred to as subsidiary hazards. This may sound like a bureaucratic word jumble, but remember that for the purposes of the transportation of hazardous materials, the regulations determine the defining criteria for primary and subsidiary hazards and that these definitions subsequently influence the amount of information made available to first responders. Only in limited circumstances will information on subsidiary hazards be displayed.

For example, consider that although gasoline is an obvious flammable liquid, it is also harmful if ingested. Yet, according to the Precedence of Hazard Table, the primary hazard of gasoline is its flammability instead of its health hazard; as such, first responders will not receive any warnings from labels or placards regarding the latter threat.

The same holds true for some corrosive materials that may pre-sent an inhalation hazard but are classified only as corrosives, which may lead first responders to erroneously conclude that the only threat posed by these materials is from direct skin contact. First responders must use caution when assessing the potential harm from a hazardous material classified by the transportation regulations. They must anticipate that subsidiary hazards may exist and take the necessary precautions until additional information regarding the material has been obtained.

Items designated as Class 9, or miscellaneous hazardous materials, present a unique challenge to first responders. These materials are those “which present a hazard during transportation but which do not meet the definition of any other hazard class.”4For example, these materials could include those with “noxious or other similar properties that could cause extreme annoyance or discomfort to a flight crew member so as to prevent the correct performance of assigned duties.”5 Remember, these same properties could affect first responders!

What is the difference between a label and a placard?

As a general rule, labels are applied to smaller individual packages, such as drums, cartons, crates, pails, and small compressed gas cylinders. Placards normally are affixed to the exterior of transport vehicles that include cargo-carrying vehicles such as automobiles, vans, tractors, trucks, and semi-trailers. Placards may also be used on certain large individual packages, such as large

portable tanks.Labels usually measure at least 3.9 inches6 on each side and can be printed on the exterior surface of a package or placed on a securely affixed tag. Labels may also be affixed by adhesive backings. Placards usually measure at least 10.8 inches7 on each side and are generally made of plastic or tag board; they are designed for placement in a metal frame or vinyl with an adhesive backing. There are also devices that contain hinged metal panels that allow for selecting the appropriate placard.


What information can I get from labels and placards?

Labels and placards function primarily as an information system designed to alert you to a material's assigned hazard class. Knowing a material's name will allow you to research specific information for that material; knowing at least the hazard class will still enable you to make better informed decisions during the early stages of a transportation mishap. The label and placard information system generally include the following components:

  • Background color(s),
  • Hazard class name (displayed in the center),
  • Hazard class number (single-digit number displayed in the lower corner), and
  • Symbol (displayed in the upper corner).

The background color, hazard class number, and symbol usually depend on the material's primary hazard class. As an example, labels and placards with a white background color usually identify materials in the poisonous primary hazard class, and a red background identifies materials in the flammable (liquid or gas) primary hazard class. Materials in the flammable (whether solid, liquid, or gas) primary hazard class are usually identified with a flame symbol. Refer to the individual label and placard charts for specific examples of this information system.

What is an identification number?

An identification number is a four-digit number generally assigned to each proper shipping name for a hazardous material. The same number may be used for several materials that have similar characteristics, but there are circumstances in which an identification number is used solely with one material, as is the case for number 1017, which represents ONLY chlorine. A material's identification number, referred to as a marking in the transportation regulations, is required in various circumstances that include display on some individual packages and on transport vehicles that contain large shipments of small packages, as well as vehicles intended for bulk shipments, such as cargo tanks. Specific information on marking requirements is provided later.

Note that the letters “UN” or “NA” may precede the identification numbers. According to the transportation regulations, “Those preceded by the letters 'UN' are associated with proper shipping names considered appropriate for international transportation and domestic transportation; those preceded by the letters 'NA' are associated with proper shipping names not recognized for international transportation, except to and from Canada.”8

The information system referred to earlier is particularly useful when a four-digit identification number replaces the name of the hazard class in the center of the placard (see box “Hazardous Materials Warning Labels”). Although the identification number can help determine the name of the product (or at least narrow the field to a few products with similar characteristics), the name of the hazard class will not be immediately available. However, first responders can still use the background color, the hazard class number, and the symbol to determine the hazard class.

For example, a red placard with a flame symbol may display either “2” or “3” as the hazard class number. In this situation, a red placard with flame symbol and a hazard class number 3 would represent a flammable liquid (see box “Hazardous Materials Warning Placards”), whereas a red placard with a flame symbol and a hazard class number 2 would represent a flammable gas. And although a placard for a gas that is poisonous by inhalation may also display a hazard class number 2, the placard for this material would use a white background color and a skull and crossbones symbol, differentiating it from a flammable gas placard.

Using the background color, hazard class number, and symbol can often help to determine a product's hazard class even though the hazard class name is not printed in the center of the placard. Remember that most labeling and placarding requirements are based on a material's primary hazard class and that there is still the potential for subsidiary hazards to personnel. Even though these subsidiary hazards may be displayed on some occasions, determining if subsidiary hazards are present usually requires additional research using information sources such as a material safety data sheet.

What are general requirements for the use of labels and placards?

The decision to use a specific label or placard depends on the requirements of the transportation regulations. This document provides general requirements, such as the types of containers to be marked and the type of label or             placard to be used. However, there are numerous exceptions, such as one that affects labeling requirements for packages containing small quantities and limited quantities of otherwise hazardous materials and those that allow shipping hazardous materials without placards based on the shipment's hazard class and gross weight.

There are also requirements that prohibit the use of labels and placards, and, although at first glance they might appear to be contrary to the best interest of first responders, these requirements usually offer safeguards. As an example, there are requirements that prohibit the use of labels or placards unless the label or placard actually “represents a hazard of the hazardous material being transported.”9

Another requirement prohibits the use of a four-digit identification number on a radioactive placard, meaning that if a four-digit number is displayed along with a placard during the transportation of a radioactive hazardous material, it must done in a manner that does not replace the hazard class name displayed on the placard. This is typically accomplished by displaying the four-digit identification number in an orange rectangular panel or a white square-on-point configuration. This requirement allows for both the hazard class name and the four-digit identification number to be displayed simultaneously, unlike situations stated earlier where the four-digit identification number may be used in lieu of the hazard class name.

In addition to exceptions and prohibited placarding, there is an allowance for permissive placarding, meaning that placards can be used even though an exception may exist. The intent of permissive placarding is admirable, but the unfortunate reality is that those responsible for transporting hazardous materials may be reluctant to placard transport vehicles unless it is absolutely necessary, since doing so may, among other things, garner unwanted attention from enforcement officials.

It is important to remember that the exceptions discussed earlier constitute a potential danger to first responders who erroneously equate the absence of a label or a placard on a package or transport vehicle with the absence of a threat from a hazardous material. Furthermore, never forget that labels and placards are used ONLY during the transporting of a hazardous material and therefore are NOT required by the transportation regulations for transport vehicles relegated for use as on-site storage containers (such as at construction sites). Neither are labels and placards generally required on storage tanks or buildings for use at fixed facilities.

When are placards displayed on transport vehicles such as vans and flatbeds?

Unless there is an exception, labels and placards must be displayed whenever a person offers a hazardous material for transportation or transports a hazardous material. As stated earlier, labels are affixed to packages and can be printed on the exterior surface of the package or can be displayed through means such as an adhesive label.

The requirements to display placards on a transport vehicle generally affect those transporting individual packages or materials in bulk form, such as cargo tanks. Placards are generally required on each side and each end of the transport vehicle. However, the required placarding of the front of a motor vehicle may be on the front of a truck-tractor instead of, or in addition to, the placarding on the front of the cargo body to which the truck tractor is attached. Beware that the aerodynamic design of some truck tractors may incorporate a cab configuration intended to direct air flow around the trailer and, as such, may block the front of the cargo body, thereby making it difficult to see a placard placed there.

Vans or flatbed trucks usually are used to transport individual packages. Once individual packages are loaded onto a transport vehicle of this type, the decision to display placards is based on what is sometimes referred to as the “1,000-pound rule.”

According to the transportation regulations, shipments of packages containing materials assigned to certain hazard classes are exempt from placarding requirements if the “aggregate gross weight of the hazardous materials is less than 1,001 pounds.”10These hazard classes are found in Table 2 of 49 CFR 172.504(c) and include categories such as flammable liquids, flammable solids, oxidizers, and corrosives. As an example, a transport vehicle containing packages with an aggregate gross weight of 999 pounds of a material whose primary hazard class is corrosive is exempt from displaying corrosive placards.

“Aggregate gross weight” includes the weight of a package AND the weight of its contents. This is an advantage to first responders, since the weight of a container counts toward the total weight required to placard a transport vehicle as opposed to the weight of only the material itself.

Hazard classes found in Table 1 include certain types of organic peroxides, materials that are poisonous inhalation hazards, and various types of radioactive materials. Placards for materials from Table 1 must be affixed to a transport vehicle whenever that vehicle contains any amount of these materials, regardless of weight, since the exemptions afforded Table 2 materials do not apply. Refer to the Placarding Tables on page 104for a complete list of Table 1 and Table 2 hazard classes.

Once hazardous materials are no longer being transported on vehicles such as vans and flatbeds, placards must be removed, since, as was stated previously, it is prohibited to display a placard for a hazard class that is not represented.

Why do some placards on vans and flatbed trucks display a four-digit identification number?

Although most placards used with individual shipments on vans and flatbeds display the name of the hazard class, in certain situations materials shipped in large packages or large quantities of small packages on these types of transport vehicles may be required to display the material's four-digit identification number. For example, shipments of intermediate bulk containers and large rigid or flexible packaging (other than a cylinder or portable tank) designed for mechanical handling (such as by a forklift) generally require that the product's identification number be displayed on the transport vehicle.

In another example, there are various circumstances under which transport vehicles containing large quantities (usually in excess of 8,820 pounds)11 of a single hazardous material in small packages must also be marked with the product's identification number. However, the specific requirements for this type of marking include several provisions and limitations that must be taken into consideration prior to use.

As was discussed earlier, display of an identification number is typically accomplished by having the four-digit identification number in the center of the hazard class placard. However, in some circumstances, the four-digit identification number may be displayed on an orange rectangular panel or by using a white square-on-point configuration.

 When is the DANGEROUS placard used?

An interesting exception to placarding requirements affects shipments of two or more categories of hazard classes found in Table 2 of the transportation regulations. For example, consider a shipment of a flammable material with a gross weight of 800 pounds that would be exempt from placarding requirements. If an additional shipment consisting of a corrosive material with a gross weight of 600 pounds were to be added to the transport vehicle, the aggregate gross weight of these materials would now be 1,400 pounds, which would exceed the exemption limit for placarding.

One option is to apply both corrosive and flammable placards. However, an exception in this situation allows the use of a DANGEROUS placard in lieu of the individual placards for each hazardous class onboard the transport vehicle. Use of this placard, therefore, indicates a mixed load of materials from Table 2.

Note that it is entirely possible for a local delivery truck containing various hazardous materials that allow the use of the DANGEROUS placard to leave a freight terminal in the morning only to return later the same day with a totally different load of hazardous materials while still using the same DANGEROUS placard.

 What are some placarding requirements for cargo tanks?

Bulk shipments that involve cargo tanks, such as those intended to transport liquids or compressed gases, are subject to placarding requirements similar to those for vehicles that transport individual packages. Differences involve the fact that there is no exemption for commodities based on weight (remember the 1,000-pound rule) and that placards usually cannot be removed from a cargo tank unless it is “sufficiently clean of residue and purged of vapors to remove any potential hazard.”12

In addition, cargo tanks are normally required to display the four-digit identification number along with the appropriate hazard class placard. Once again, the four-digit identification number can be displayed in the center of the hazard class placard, on an orange rectangular panel, or on a white square-on-point configuration.

There are some exceptions to displaying identification numbers on cargo tanks, including one that states that identification numbers are not required on the ends of a cargo tank having more than one compartment if hazardous materials having different identification numbers are being transported therein. However, in situations such as this, transportation regulations generally require that the identification numbers on the sides of the tank be displayed in the same sequence as the compartments containing the materials they identify.

Another exception involves situations where a cargo tank with multiple compartments contains different liquid petroleum distillate fuels (such as gasoline and gasohol). In this case, the identification number for the distillate having the lowest flash point (and thus the more dangerous commodity) may be displayed instead of the individual number for each material.

As stated previously, the required placarding on the front of a motor vehicle may be on the front of a truck tractor instead of or in addition to the placarding on the front of the cargo body to which the truck tractor is attached. Remember, though, that the aerodynamic design of some truck tractors may block the front of the cargo body, thereby making it difficult to see a placard.



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