Hazardous materials are those chemicals or substances that are classified as a physical hazard material or a health hazard material (see this blog for more information). There's often some confusion around what the appropriate occupancy classification is when hazardous materials are present. Unfortunately, there isn't a straight answer. It is going to depend on what code is applicable in your particular situation. This blog is going to take a closer look at the differences in occupancy classification when using NFPA Codes and the International Building Code (IBC). For some basic information regarding the differences in occupancy classification check out this blog. Before digging into the actual differences between the codes it's helpful to understand the concepts of maximum allowable quantity (MAQ) and control areas. Although NFPA Codes and the IBC both address these concepts in their own documents, the overall approach is similar. For a closer look at how to determine a MAQ using NFPA 1, Fire Code, be sure to look at this blog. NFPA Approach One of the major differences between the way the IBC and NFPA codes address occupancy classification for spaces using hazardous materials, is the actual creation of a unique occupancy classification within the IBC. NFPA codes do not create a separate occupancy classification specific to hazardous materials. Instead, regardless of whether they contain hazardous materials or not, all buildings are given an occupancy classification(s) based on how the space is being used and the expected characteristics of the occupants. Then, if the building contains hazardous materials additional provisions must be met. If the hazardous materials in a given control area exceed the MAQ, additional protections are required. These are called Protection Levels and they range from Protection Level 1 to Protection Level 5. It is important to note that although a building must comply with the additional protection levels, the occupancy classification itself does not change. This means when the MAQ is exceeded and NFPA documents apply, you are required to comply with both the requirements specific to that occupancy as well as the appropriate protection level requirements for that hazardous material. NFPA Approach- Protection Levels Features for Protection Level 1 through Protection Level 3 are intended primarily to provide protection from physical hazards. Protection Level 1 is the highest level of protection. This protection level is required when high hazard Level 1 contents exceed the MAQ. These materials are unstable and can pose a detonation hazard. Examples of high hazard level 1 contents include Class 4 oxidizers; detonable pyrophoric solids or liquids; Class 3 detonable and Class 4 unstable (reactive) solids, liquids, or gases; and detonable organic peroxides. This protection level requires that the materials be stored in a one story in height, detached building that is used for no other purpose. Protection Level 2 is designed to limit the spread of fire from materials that deflagrate or accelerate burning. Additionally, the protection features are designed to limit the potential for fire to spread from an outside source and affect the hazardous materials in the building. This protection level is required when high hazard Level 2 contents exceed the MAQ. These materials present a deflagration hazard or a hazard from accelerated burning. Examples of high hazard Level 2 contents include Combustible dusts that are stored, used, or generated in a manner that creates a severe fire or explosion hazard; Class I organic peroxides; flammable gases; nondetonable pyrophoric solids, liquids, or gases; and Class 3 water-reactive solids and liquids. Protection Level 3 is one of the most common protection levels encountered in the general inspection of storage and industrial operations that use hazardous materials. These types of operations and storage facilities normally operate with amounts of hazardous materials greater than the MAQ while conducting business. This protection level is required when high hazard Level 3 contents exceed the MAQ. These materials readily support combustion or present a physical hazard. Examples of high hazard level 3 contents include Class IIA, Class IIB, and Class III organic peroxides; Class 2 solid or liquid oxidizers; Class 2 unstable (reactive) materials; and oxidizing gases. Protection Level 4 is intended to mitigate the acute health hazards resulting from the storage, use, or handling of high hazard Level 4 materials. These contents include corrosives, highly toxic materials, and toxic materials. The objective is to protect evacuating occupants and arriving first responders from being injured by these hazardous materials. Protection Level 5 applies to semiconductor fabrication facilities. Buildings that require Protection Level 5 must comply with NFPA 318, Standard for the Protection of Semiconductor Fabrication Facilities. IBC Approach The IBC uses a High-Hazard Group H, occupancy classification for buildings that, among others, manufacture, process, generate, or store hazardous materials in excess of the MAQ in a control area. There are 5 sub-categories within the High Hazard Group H occupancy, H-1 through H-5 which closely resemble the protection levels in NFPA documents. IBC Approach- Occupancy Subclassifications H-1 is the subclassification for buildings that contain hazardous materials that pose a detonation hazard. H-2 is the subclassification for buildings that contain hazardous materials that pose a deflagration hazard or a hazard from accelerated burning. H-3 is the subclassification for buildings that contain hazardous materials that readily support combustion or that pose a physical hazard. H-4 is the subclassification for buildings that contain hazardous materials that are health hazards. H-5 is the subclassification for semiconductor fabrication facilities and comparable research and development areas. Although at first glance it seems like NFPA and the IBC handle things extremely different, the overall concepts are actually not all that different. The IBC creates an entirely separate occupancy classification while NFPA uses protection levels. In both cases, compliance with additional provisions is going to be required to minimize the risk associated with the presence of hazardous materials in those quantities.  

Which code or standard applies to hazardous materials? How much of a particular hazardous material can be stored or used? What floor of the building can that hazardous material be stored or used on? These are all questions some are faced with daily. There is an assumption that people, such as facility managers, building owners, and first responders, just inherently know when a material is a hazardous material. And, that once they know it is a hazardous material, they know how to deal with that material properly and safely. We have seen the potential impacts of materials that are improperly stored or used such as in the 2013 fire and explosion at West Fertilizer Company in Texas. How can we prevent incidents like this from happening? This blog will focus on determining the maximum allowable quantity (MAQ) for a hazardous material per NFPA 1, Fire Code and NFPA 400, Hazardous Materials Code. The eight-step process outlined here, is just one way to determine the MAQ. Step 1: Determine hazardous material classification The first step in identifying the Maximum Allowable Quantity (MAQ) is to determine the category of the hazardous material. NFPA 400 divides hazardous materials into 14 different categories. Using the definitions within the Code, the category or categories of the material must be determined. A hazardous material may fall into more than one category. It is also important to acknowledge that there are additional types of hazardous materials that fall outside the scope of what is intended to be covered by NFPA 400 and thus Chapter 60 of NFPA 1. This includes things like: Flammable and combustible liquids that have no other health hazard covered by NFPA 400 (instead see NFPA 30) LP-gas storage or utilization systems (instead see NFPA 58 or NFPA 59) Storage and use of aerosol products (instead see NFPA 30B) For additional information related to classifying a hazardous material, check out this blog. Step 2: Determine occupancy classification Next, we need to determine the occupancy classification of the area where the hazardous material is going to be stored or used. Different occupancies modify the MAQs so, once we determine the MAQ per the general MAQ table (Table 60.4.2.1.1.3 of the 2021 Edition of NFPA 1), we will need to consult the other appropriate paragraphs (60.4.2.1.2 through 60.4.2.1.5) to see if that quantity is modified in any way. An excerpt of the general MAQ table can be seen below in step 4. Step 3: Determine how the material will be used The next variable that needs to be determined is based on how the material is going to be used. There are two main ways the material could be used. It could be stored, or it could actually be used. The storage use is intended for those instances where a hazardous material is entering the building in a container, cylinder, or tank and will not be removed from the original container, cylinder, or tank. If the hazardous material is being used, you must then identify whether it is being used in a closed system or an open system. A closed use system designation means that, under normal conditions, the hazardous material will not be open to the atmosphere and will be kept within a container, a pipe, or equipment that does not allow vapors to escape into the air. Closed use and storage have very similar risks and are treated the same with respect to MAQ. An open use system designation means that the process involves pouring or dispensing into an open vessel, open mixing, transferring, or processing of a hazardous material that is exposed to the atmosphere. This type of activity is considered the most hazardous and, therefore, is most restricted with respect to an MAQ. Step 4: Determine base maximum allowable quantity The next step is to determine the MAQ. The term "maximum" can be misleading because there are certain conditions that would allow higher amounts of material to be used or stored. The term "MAQ" really means the maximum amount of a material that is permitted in a control area before requiring additional protection. So, it's not really a "maximum", rather a threshold before additional protection requirements would need to be applied. NFPA 1, the Fire Code, has a couple different MAQ tables which are copied from NFPA 400. The applicable table will depend on the occupancy you are in. Generally speaking, you would start with the general MAQ table (Table 60.4.2.1.1.3) and then see if/how the occupancy specific sections modify the table. In the case of a laboratory that is a business office, the code states you are to use the amounts from Table 60.4.2.1.1.3 without using the modifications found in 60.4.2.1.2. In order to best explain how the table and associated footnotes work, we will walk through an example. The space is used as a laboratory but is considered a business occupancy. There are two different hazardous materials. One is classified as an organic peroxide class I and will only be stored. The other will be used in an open system and is classified as water-reactive class 2. Organic Peroxide Class I Using the table, the MAQ for an organic peroxide class I that is to be stored as a solid is 16 lbs (7.26 kg). However, looking at the table there are two applicable footnotes. Applying these footnotes is explained in the next step. Water Reactive Class 2 Using the table, the MAQ for a water reactive class 2 material that is to be used in an open system is 10 lbs (4.54 kg). However, looking at the table there is one applicable footnote. Applying this footnote is explained in the next step Step 5: Apply footnotes Once the base MAQ is determined from the table, adjustments to the MAQ should be made based on the applicable footnotes. Returning to our example: Organic Peroxide Class I Per the table 16 solid lbs (7.26 kg) of a class I organic peroxide are permitted. However, footnote a allows 100% increase where the hazardous material is stored in an approved cabinet, gas cabinet, exhausted enclosure, gas rooms explosive magazines, or safety cans, as appropriate for the material stored. The second footnote, b, allows for a 100% increase if the building is equipped throughout with an automatic sprinkler system. These increases can be used in conjunction with each other as noted in the footnotes. This means the MAQ will depend on what additional features are provided. If the material is not stored in an approved cabinet or similar container and there is no sprinkler system, then the 16 lbs (7.26 kg) from the table stands as the MAQ. If the material is going to be stored in an approved cabinet or other similar container, but the building is not sprinklered then the MAQ is 32 lbs (14.54 kg). 16+(16×1)=32 lbs 7.26+(7.26*1)=14.52 kg This would also be the MAQ if the building was sprinklered but the material wasn't going to be stored in an approved cabinet or other similar container. If the material will be stored in an approved cabinet or other similar container and is in a building equipped with an automatic sprinkler system, then the MAQ is 64 lbs. The original MAQ is 16 lbs (14.52 kg). This is allowed to be increased by 100% because of the use of an approved cabinet: 16+(16×1)=32 lbs 7.26+(7.26*1)=14.52 kg Then that new MAQ, 32 lbs (14.52 kg) is permitted to be increased by 100% because the building is protected throughout with an automatic sprinkler system. This results in an MAQ of 64 lbs (29.04 kg): 32+(32×1)=64 lbs 14.52+(14.52*1)=29.04 kg Water Reactive Class 2 Per the table 10 solid lbs (4.54 kg) of a class 2 water reactive material is permitted. There is only one applicable footnote which allows a 100% increase if the building is equipped with an automatic sprinkler system. In this case if the building has a sprinkler system the MAQ would be 20 lbs (9.08 kg): 10+(10×1)=20 lbs 4.54+(4.54×1)=9.08 kg If the building does not have a sprinkler system, then the MAQ remains 10 lbs (4.54 kg). Step 6: Adjust Based on Control Area Location As I mentioned earlier, the term "MAQ" really means the maximum amount of a material that is permitted in a control area before requiring additional protection. A control area is a building or portion of a building or outdoor area within which hazardous materials are allowed to be stored, dispensed, used, or handled in quantities not exceeding the MAQ. It is possible to have multiple control areas per floor depending on where in the building the control areas are located. The table below can be found in NFPA 1 (and NFPA 400) and dictates how many control areas are permitted per floor depending on the location within the building. This table also identifies the required fire resistance rating for the fire barriers that separate the control area from other control areas and what percentage of the MAQ is permitted based on the location within the building. It is important to note that the fire barriers are required to include floors and walls as necessary to provide complete separation. You'll notice that the further, vertically, from grade, the control area is, the higher the required fire resistance rating is for the separation of control areas and a lower percent of the MAQ is permitted in each control area. This is because the vertical distance increases the time required for emergency responders to reach the incident and increases the difficulty in controlling and resolving it. Returning to our example, the floor ceiling assembly between the 1st and 2nd floor is a fire barrier with a 1-hour fire resistance rating. Therefore, these can be considered two separate control areas. MAQ Floor 1: The MAQ for floor 1 is permitted to be 100% of the MAQ per control area. Therefore, 64 lbs ) of class I organic peroxide is permitted and 20 lbs (9.08 kg) of class 2 water reactive material is permitted. Organic peroxide class I: 64×100%=64 lbs 29.04×100%=29.04 kg Water reactive class 2: 20×100%=20 lbs 9.08×100%=9.08 kg MAQ Floor 2: The MAQ for floor 2 is permitted to be 75% of the MAQ per control area. Therefore, 48 lbs (21.78 kg) of class I organic peroxide is permitted and 15 lbs (6.81 kg) of class 2 water reactive material is permitted. Organic peroxide class I: 64×75%=48 lbs 29.04×75%=21.78 kg Water reactive class 2: 20×75%=15 lbs 9.08×75%=6.81 kg Step 7: Determine if Design is Acceptable The last step is to determine if the proposed design and amounts is acceptable based on the MAQ identified and control area location. Returning to our example, our building requires the storage of 150 lbs (68.1 kg) of class I organic peroxide and the open system use of 12 lbs (5.45 kg) of a class 2 water reactive material in both locations. To determine if our design of one control area on floor 1 and one control area on floor 2 with no additional protection is acceptable, we must compare the amounts of hazardous materials present with the MAQs.   Floor 1: Remember, the MAQs for floor 1 were 64 lbs (29.04 kg) of class I organic peroxide and 20 lbs of class 2 water reactive material. The 12 lbs (5.45 kg) of class 2 water reactive material is acceptable. However, the 150 lbs (68.1 kg) of class I organic peroxide exceeds the MAQ of 64 lbs (29.04 kg). This means a change to our design is necessary. One option is to provide additional protection (see the next step for more information on this). The other option would be to provide additional control areas on the same floor, if permitted per Table 60.4.2.2.1. It is important to remember these additional control areas would need to be separated from each other by fire barriers. In the case of the first floor up to 4 control areas containing 64 lbs (29.04 kg) of the class I organic peroxide are permitted. Therefore, adding two additional control areas and properly separating them would permit the storage of up to 192 lbs (87.17 kg). If the additional control areas are added, then the Protection Level 2 requirements need not be applied.   Floor 2: Remember, the MAQ for floor 2 were 48 lbs of class I organic peroxide and 15 lbs of class 2 water reactive material. The 12 lbs (5.45 kg) of class 2 water reactive material is acceptable. However, the 150 lbs (68.1 kg) of class I organic peroxide exceeds the MAQ of 48 lbs (21.78 kg). Again, this would require a change to our design. Looking at Table 60.4.2.2.1 we see that only 3 control areas are permitted on floor 2. This means that only a total of 144 lbs (65.38 kg) would be permitted on floor 2. Either, we need to add the fire barriers to create the additional control areas and store 6 lbs (2.72 kg) less than what was originally planned, or we need to add additional protection (see the next step for more information on this). Step 8: Apply additional protections, if necessary If the amount of hazardous material cannot be accommodated based on the number of permitted control areas and the MAQ of those control areas, then additional protection is required. There are 5 different protection levels outlined in the code ranging from Protection Level 1 to Protection Level 5.   Protection Level 1 is the highest level of protection. The only way to provide a greater level of protection is to prohibit additional hazardous materials at the site or to move the hazardous materials to a detached building. This protection level is required when high hazard Level 1 contents exceed the MAQ. These materials are unstable and can pose a detonation hazard.   Protection Level 2 is designed to limit the spread of fire from materials that deflagrate or accelerate burning. Additionally, the protection features are designed to limit the potential for fire to spread from an outside source and affect the hazardous materials in the building.   Protection Level 3 is one of the most common protection levels encountered in the general inspection of storage and industrial operations that use hazardous materials. These types of operations and storage facilities normally operate with amounts of hazardous materials greater than the MAQ while conducting business. The protection features should be understood in detail, and the amounts of hazardous materials should be reviewed due to their frequent presence within most jurisdictions. Features for   Protection Level 1 through Protection Level 3 are intended primarily to provide protection from physical hazards.   Protection Level 4 is intended to mitigate the acute health hazards resulting from the storage, use, or handling of high hazard Level 4 materials. These contents include corrosives, highly toxic materials, and toxic materials. The objective is to protect evacuating occupants and arriving first responders from being injured by these hazardous materials.   Protection Level 5 applies to semiconductor fabrication facilities.   Returning to our example, the class I organic peroxide is considered a high hazard protection level 2. Therefore, if the MAQ is to be exceeded then the requirements for Protection Level 2 must be followed. The general requirements for this (and all) protection level(s) can be found in Chapter 6 of NFPA 400. In addition to chapter 6, the appropriate chapters from 11-21 need to be consulted as well as the building code. Examples of additional requirements include required separation of occupancies, shorter travel distance limits and common path of travel limits, and more restrictive requirements relating to the number and access of means of egress. For example, the travel distance limitation for a Protection Level 2 area is 100 ft and the common path of travel is 25 feet. These would generally be more restrictive than what the building code or life safety code would say for a business occupancy. In addition to chapter 6, chapter 14 would need to be reviewed as it has requirements for organic peroxide and the building code. Conclusion This 8-step process is just one way to approach determining the MAQ. It is important to remember that they type of hazardous material, whether the material is going to be stored or used, the occupancy classification, and the location of the control area all impact the MAQ. This means that any proposed change to the material, or the location of the material should be carefully evaluated to ensure quantities still fall below the MAQ, or the necessary additional protection requirements are met. If you are looking for more information on classifying a hazardous material or the applicability of NFPA 400 be sure to check out my other blogs. 

Responders are called to an ever-increasing number of diverse types of incidents these days, which makes it difficult to stay prepared and practiced for all the possibilities we may encounter. That especially applies to responding to hazardous materials incidents. So, if you are not on a hazardous materials response team how often do you review and refresh your knowledge on the classes of hazardous materials we encounter in the course of doing the job? Sure, it’s important to keep sharp on fire operations but those calls that we don’t respond to very often can really hurt us or worse. Recent events like the devastating explosion in Beirut, Lebanon give us pause to think about those firefighters who were just doing their jobs and, boom, tragedy happens. This incident makes me think about the impact that oxidizers can have on fire and what they can do when they mix with incompatible material such as organic compounds. Guidelines for safely handling incidents involving oxidizers A good definition of oxidizers can be found in NFPA 400, Hazardous Materials Code, 2022 edition. Oxidizers are: “Any solid or liquid material that readily yields oxygen or other oxidizing gas or that readily reacts to promote or initiate combustion of combustible materials and that can, under some circumstances, undergo a vigorous self-sustained decomposition due to contamination or heat exposure.” Furthermore, oxidizers are broken down into four classes from Class 1, “…does not moderately increase the burning rate…” to Class 4, “…can undergo an explosive reaction due to contamination or exposure to thermal or physical shock…” NFPA 400 provides a wealth of information and can be a helpful resource. Annex E covers Properties and Uses of Ammonium Nitrate and Fire-Fighting Procedures and is included for informational purposes only, but can be a helpful guide when developing department standard operating procedures for handling events that include oxidizers. An additionally helpful chapter is Annex I, Emergency Response Guideline. This chapter speaks to the emergency response training requirements for handling hazardous materials emergencies found in OSHA 29 CFR 1910.120, including the levels of awareness, operations, technician, specialist and incident commander also explained in NFPA 470 Hazardous Materials/Weapons of Mass Destruction Standard for Responders, 2022 edition. Sure, the larger cities have hazmat units to handle all that, but many of our more rural departments may rely on a regional response team who is several miles away or some teams may have to assemble at the station before they respond to your incident, which takes time. Some departments don’t even have that luxury, so what do we do? Oxidizer identification and pre-planning matter One of the first things that is necessary is identification. Identifying what oxidizers look like, how they are identified, and where they exist in your response area is an important step. You can do that by reviewing what the container markings look like and by getting out into your response area on pre-planning trips to learn about what and where they are used and stored. In the case of rail transport, what is traveling through your jurisdiction? I would recommend connecting with the rail transport organizations that have stock rolling through your jurisdiction. Pre-planning is a very important part of keeping your team situationally aware and prepared for an incident at a specific location. When arriving on-scene, the Emergency Responder Guide (ERG) can help Another very useful quick guide is the Emergency Response Guide (ERG). This guidebook created by the US Department of Transportation, Pipeline and Hazardous Materials Safety Administration, is a guide designed to provide important information to responders in the first minutes of an incident. The guide is set up with separately colored pages that provide important information about material identification, classification, attributable hazards, and response and evacuation guidelines. For example, information on general oxidizers can be found in Guide #140. In this yellow page portion of the document, you will find information on potential hazards such as fire or health, what considerations to make on protective clothing, evacuation measures to consider, emergency response actions in the case of spill or fire, and first aid measures to take if exposed. The information found on this guide page and others can be reviewed with your team in a quick drill format and be a useful refresher on dealing with oxidizers. Another example of what can happen when oxidizers are exposed to heat is an incident that occurred May 28, 2013 in Rosedale, Maryland when a three-axle roll-off straight truck entered a grade level train crossing and was struck by an oncoming freight train. Fifteen of the train cars derailed with three of the cars carrying hazardous materials. Two of the cars spilled their contents, including an oxidizer and an organic acid, resulting in fire. The heat from the fire caused the oxidizer to explode early into the fire. Fortunately, the responding units had not arrived, or the results might have been tragic. Additional information about this accident may be found in the investigation report, which can be accessed at the NTSB website under report number NTSB/HAR-14/02. Slow down and be cautious So especially when responding to bulk storage units or large capacity transportation rail cars, use the utmost caution until you can verify the identity of the contents contained within. Based on the reports of the first due units trained to identify railcars carrying chemicals such as oxidizers, they can alert other incoming units and help initiate the appropriate action plan. Remember when responding into a potential hazardous materials incident: slow down and take some time to look for signs that indicate what you may be dealing with before getting into a potentially career ending event. Take the time to refresh on the basic types of hazardous materials and what their characteristics are. Especially with oxidizers, remember that when exposed to other types of organic compound they can react explosively and when exposed to heat they can explode. It’s all part of situational awareness. Be aware and be safe.

As I discussed in a previous blog, organizations, and even different documents produced by the same organization, define hazardous material differently. NFPA 400, Hazardous Materials Code, defines hazardous material as: A chemical or substance that is classified as a physical hazard material or a health hazard material, whether the chemical or substance is in usable or waste condition. One quality that makes a chemical or substance a physical hazard material is if it is flammable. If that material is a liquid, how would you know if NFPA 400, NFPA 30, Flammable and Combustible Liquids Code, or both apply? The answer to this question and many like it can often be found in Chapter 1 of most NFPA documents. Chapter 1 is typically the administration chapter. I believe it is often overlooked but contains some extremely important information regarding the scope and application of a particular document. Let’s focus on the scope and applicability of NFPA 400. There are two different components that must be considered when determining if NFPA 400 is applicable to a particular situation: 1) what is the material; and 2) what is being done with that material. NFPA 400 covers the use, storage, and handling (including on-site transportation) of certain hazardous materials. Any other use, such as off-site transportation, of these materials would be outside the scope. NFPA 400 covers the following materials: Ammonium nitrate solids and liquids Corrosive solids and liquids Flammable solids Organic peroxide formulations Oxidizer—solids and liquids Pyrophoric solids and liquids Toxic and highly toxic solids and liquids Unstable (reactive) solids and liquids Water-reactive solids and liquids Compressed gases and cryogenic fluids as included within the context of NFPA 55 There are chemicals or substances that meet the hazardous materials definition in NFPA 400 that fall outside the scope of the document. One example is a flammable or combustible liquid. Ignitibility is one characteristic that results in a liquid being considered a physical hazard material; however, you will not see ignitible liquid (or flammable or combustible liquid) in the above list. This is because a flammable or combustible liquid, which has no other physical or health hazard properties covered by NFPA 400, is outside the scope of NFPA 400. Instead, NFPA 30 would provide the requirements. If, however, the flammable or combustible liquid has an additional health or physical hazard property covered by NFPA 400, then both NFPA 30 and NFPA 400 would be applicable. It is important to remember that multiple codes and standards may apply. So, when designing or determining how much of a material can be stored or used it is imperative that all relevant documents be consulted. For example, if quantities of hazardous materials exceed certain thresholds set by Occupational Safety and Health Administration (OSHA) or Environmental Protection Agency (EPA) then federal requirements under the Process Safety Management and Risk Management Program may apply in addition to NFPA 400. Chapter 1 of NFPA 400 not only identifies what is covered, it also includes a list of items that are not covered. Many of the situations that NFPA 400 does not apply to, are covered by other codes and standards, like the ignitible liquid example above. The complete list of what NFPA 400 does not apply to is: Storage or use of hazardous materials for individual use on the premises of one- and two-family dwellings Explosives or blasting agents, which are regulated by NFPA 495, and fireworks Refrigerants and refrigerant oil contained within closed-cycle refrigeration systems complying with the fire code and the mechanical code adopted by the jurisdiction High-hazard contents stored or used in farm building or similar occupancies and in remote locations for on-premises agricultural use Corrosive materials in stationary batteries utilized for facility emergency power or uninterrupted power supply, or similar purposes, in accordance with NFPA 1 Aerosols complying with NFPA 30B Corrosive materials displayed in original packaging in mercantile occupancies and intended for personal or household use or as building materials Ignitible (flammable or combustible) liquids having no other physical or health hazard properties covered by NFPA 400 Organic peroxide formulations that are capable of detonation as manufactured or when unpackaged or in authorized shipping containers under conditions of fire exposure, when stored, manufactured, or used in accordance with NFPA 495 Combustible metals, as defined in NFPA 484 LP-Gas complying with NFPA 58 or NFPA 59 Where approved, materials that have been satisfactorily demonstrated not to present a potential danger to public health, safety, or welfare based upon the quantity or condition of storage The off-site transportation of hazardous materials when in accordance with Department of Transportation (DOT) regulations Cellulose nitrate film complying with NFPA 40. As you can see, there are a number of documents that regulate hazardous materials. Therefore, before even digging into the actual requirements you need to: 1) make sure you are defining a hazardous material correctly; 2) confirm that the material you have, in the specific situation you have, is covered by that particular document. Remember, Chapter 1 of NFPA documents will help you through this process. Be on the lookout for my future blogs which will take a deeper dive into NFPA 400, covering topics like, maximum allowable quantities (MAQs), control areas, and more. If you missed the first blog in the series on how to define hazardous materials, you can find it here. 

Which code or standard applies to hazardous materials? How much of a particular hazardous material can be stored or used? What floor of the building can that hazardous material be stored or used on? These are all questions some are faced with daily. There is an assumption that people, such as facility managers, building owners, engineers, and first responders, just inherently know when a material is a hazardous material. And, that once they know it is a hazardous material, they know how to deal with that material properly and safely. We have seen the potential impacts of materials that are improperly stored or used such as in the 2013 fire and explosion at West Fertilizer Company in Texas. How can we prevent incidents like this from happening? The first step is knowing how to identify a hazardous material. Part of the challenge when it comes to determining and classifying hazardous materials is that there is not one consistent definition of “hazardous material” nor is there one consistent approach to the classification of hazardous materials. Therefore, when looking at Safety Data Sheets (SDS) or literature provided by the manufacturer, it is imperative to know and understand which hazardous material classification system is being used. NFPA 400, Hazardous Materials Code, has its own definition and classification method that consists of 14 different categories. The U.S. DOT uses a 9-category classification system. OSHA has its own definitions established in 29 CFR, which has been revised to align with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).  While there has been an effort to coordinate between the groups, differences do still exist. Information on SDS is often based on the GHS system and not the system in NFPA 400. Defining Hazardous Material The approach I like to take is to assume materials are hazardous, until I have proven that a particular material is not. As we will discuss there are a number of different definitions and triggers that could lead to a material being considered hazardous. Therefore, I would not want to rely on an initial assumption that a material is not hazardous. When determining if a material is to be considered hazardous, the first step is to identify for what purpose you are evaluating the material for. If you are transporting the material in the United States then the DOT’s definition is what you would need to use, whereas if you are storing or using the material, then you would need to use the definition found in the applicable building code or fire code. GHS does not define the term “hazardous material”, but the DOT defines a hazardous material as “means 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, and has designated as hazardous under section 5103 of Federal hazardous materials transportation law (49 U.S.C. 5103). The term includes hazardous substances, hazardous wastes, marine pollutants, elevated temperature materials, materials designated as hazardous in the Hazardous Materials Table (see 49 CFR 172.101), and materials that meet the defining criteria for hazard classes and divisions in part 173 of this subchapter.” NFPA 1, Fire Code, NFPA 101, Life Safety Code, and NFPA 5000, Building Construction and Safety Code, all use the definition from NFPA 400 for hazardous material. NFPA 400 defines a hazardous material as: A chemical or substance that is classified as a physical hazard material or a health hazard material, whether the chemical or substance is in usable or waste condition.  The definitions of physical hazard material and health hazard material are integral in understanding and properly applying this definition. A physical hazard material per NFPA 400 is a substance that is classified as any one of the following: Explosive Flammable cryogen Flammable gas Flammable solid Ignitible (flammable or combustible) liquid Organic peroxide Oxidizer Oxidizing cryogen Pyrophoric Unstable (reactive) Water-reactive material A health hazard material per NFPA 400 is a chemical or substance that is classified as any one of the following: Toxic Highly toxic Corrosive material Many of these terms are defined within NFPA 400 to further help in defining what a hazardous material is. It is also worth noting that other NFPA codes and standards may use a different definition for “hazardous material”. That is why it is essential to understand for what purpose (e.g., offsite transportation, storage, use, etc.) you need to determine whether something is a hazardous material or not and then consult the appropriate document to determine if it meets the definition. There is not one universally accepted definition. One example of a document that defines hazardous material differently is NFPA 30, Flammable and Combustible Liquids Code. NFPA 30 defines hazardous material or hazardous chemical as a “material presenting dangers beyond the fire problems relating to flash point and boiling point.” The annex material goes on to explain that the other dangers could include things like toxicity, reactivity, instability, or corrosivity. However, that is not intended to be an exhaustive list.  While this may seem to conflict with NFPA 400, when you consider the scope of NFPA 400 the definition from NFPA 30 actually aligns with how NFPA 400 is applied. Although a flammable and combustible liquid that has no other physical or health hazards would be considered a hazardous material per NFPA 400, it is excluded from the scope of the document. I’ll talk more about this in a future blog where we will look in detail at the scope and applicability of NFPA 400.  Classifying Hazardous Materials As I mentioned earlier, different organizations have different ways of classifying hazardous materials. The DOT uses a 9-system classification method while NFPA 400 uses a 14-system category method. Some of the DOT classifications are further broken into divisions, while some of the NFPA 400 categories are broken into subclassifications. The 9 classes used by the DOT are: Class 1: Explosives Class 2: Gases Class 3: Flammable Liquid and Combustible Liquid Class 4: Flammable Solid, Spontaneously Combustible, and Dangerous When Wet Class 5: Oxidizer and Organic Peroxide Class 6: Poison (Toxic) and Poison Inhalation Hazard Class 7: Radioactive Class 8: Corrosive Class 9: Miscellaneous The 14 categories of hazardous materials used in NFPA 400 are: Corrosive solids, liquids, or gases Flammable solids Flammable gases Flammable cryogenic fluids Inert cryogenic fluids Inert gases Organic peroxide formulations Oxidizer solids or liquids Oxidizing gases Oxidizing cryogenic fluids Pyrophoric solids, liquids, or gases Toxic or highly toxic solids, liquids, or gases Unstable (reactive) solids, liquids, or gases Water-reactive solids or liquids Compounding the challenge associated with determining and classifying hazardous materials, is the fact that between the two systems many of the categories use similar verbiage but may have different thresholds that trigger that particular classification.  One example is flammable liquid. DOT defines flammable liquid as “a liquid having a flash point of not more than 60 °C (140 °F), or any material in a liquid phase with a flash point at or above 37.8 °C (100 °F) that is intentionally heated and offered for transportation or transported at or above its flash point in a bulk packaging”. NFPA 400 states that a flammable liquid is an ignitible liquid that is classified as a Class I liquid. There are three subclassifications of a Class I liquid. The table below summarizes the specific thresholds for the subclassifications. Subclassification Flash point Boiling point Class IA Liquid Below 73 OF (22.8O C) Below 100 OF (37.8O C) Class IB Liquid Below 73 OF (22.8O C) At or above 100 OF (37.8OC) Class IC Liquid At or above 73O F (22.8O C) but below 100O F (37.8O C N/A These discrepancies mean that when determining the category of hazardous material you have, you need to know what system was used to provide a classification, such as the one found on a Safety Data Sheet, or you need the actual test data so the classification can be determined based on the definitions. In summary, although there is agreement that hazardous materials are physical or health hazard materials, there is not one standard definition or approach to determining if a material should be considered hazardous or not. NFPA 400 defines hazardous material as any chemical or substance that is a physical hazard material or a health hazard material. Hazardous materials are then categorized based on the physical or health hazard they present. There are 14 different categories in NFPA 400 and a material may fall into one or more of those categories. Be on the lookout for my future blogs which will take a deeper dive into NFPA 400, covering topics like applicability of NFPA 400, maximum allowable quantities (MAQs), and more.

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