3.1 Emergency Response Guidebook (ERG 2024)

3.1 Emergency Response Guidebook (ERG 2024)

Quick Answer: The current Pipeline and Hazardous Materials Safety Administration (PHMSA) book is the 2024 Emergency Response Guidebook (ERG). Use it in the initial phase of a transportation incident. Look up a four-digit identification number in the yellow index or a name in the blue index, open the numbered orange guide, and—if the entry is highlighted green and there is a spill—use the green Table of Initial Isolation and Protective Action Distances. Do not treat orange fire isolation as the same thing as green protective-action distances, and do not use the ERG as your only tool once you are doing technician-level offensive work.

National Fire Protection Association (NFPA) 470 job performance requirements 11.2.1 and 11.2.2 require technicians to collect and interpret hazard and response information. Occupational Safety and Health Administration (OSHA) 29 CFR 1910.120(q)(6)(iii)(B) requires classification, identification, and verification of known and unknown materials with field survey instruments. The ERG is the book you open first on a highway, rail, or intermodal release. It is not the book you hide behind when you later open a chlorine kit or start transfer. If you cannot explain when the green pages override the orange distances, the exam will fail you on a scenario that looks like a simple lookup.

What the 2024 edition is—and is not

PHMSA, with Transport Canada and Mexican authorities, issued ERG 2024 in April 2024. It remains the current printed and app edition in 2026. PHMSA states the guidebook is intended for use during the initial phase of a transportation incident involving hazardous materials/dangerous goods. That sentence is doing real work:

• Initial phase means the first decisions: isolate, deny entry, protect downwind people, call for the right team, and avoid making the release worse.
• Transportation incident means highway, rail, air, vessel, and pipeline-in-transit problems where placards, identification numbers, and shipping papers are the expected clues. A drum farm inside a closed facility is not what the orange pages were built to run as a complete incident action plan.
• It is not a substitute for a Safety Data Sheet (SDS), the NIOSH Pocket Guide to Chemical Hazards, facility pre-plans, or air monitoring. Once you leave the warm zone with instruments and chemical protective clothing, you have outgrown the ERG as a sole reference.

A free ERG 2024 mobile application is published for iOS and Android in English, French, and Spanish. The paper book still matters: batteries die, gloves destroy screens, and the exam still tests the color-section logic, not which app menu you tapped.

Color sections you must navigate under stress

White-page 2024 updates worth knowing because they change how you enter the book: obsolete marine-pollutant and old Division 5.2 placard artwork was removed; the rail-car chart added a cryogenic car; road-trailer notes were expanded; a table was added to help choose evacuation versus shelter-in-place; and a liquid-spill-control subsection (absorbents) plus lithium-battery/electric-vehicle fire guidance were added. BLEVE safety distances live in the white pages at the back. Do not confuse those BLEVE standoffs with green Table 3.

Orange-page 2024 first-aid change: general first-aid recommendations were moved to a General First Aid section before Guide 111. Orange guides keep only material-specific notes. If a test item still talks as if every orange page reprints the full first-aid block, the item is describing an older edition.

Polymerization hazard (P): in the yellow and blue indexes, a P after a guide number means the material may polymerize explosively when heated or involved in a fire. ERG 2024 added that P notation to UN 3302 (2-dimethylaminoethyl acrylate, stabilized). Treat P as a fire-and-heat warning, not as a green-page trigger by itself.

Lookup sequence that matches the book

Work the book the way the inside cover flowchart intends:

1. Placard only → white placard table → four-digit ID if shown → yellow index.
2. Four-digit ID on a placard, orange panel, or shipping paper → yellow index.
3. Name on a shipping paper, tank stencil, or interview → blue index.
4. Either index gives an orange guide number. Open that guide and apply public-safety and fire/spill actions for the initial phase.
5. If the yellow or blue entry is highlighted green and there is a spill or leak, go to the green pages. If it is a fire with no spill, stay with the orange isolation/evacuation distances for fire. That split is the trap.
6. Green Table 1 is built as small spill versus large spill and day versus night. A small spill is generally a release from a small package or a small leak from a large package; the ERG treats 55 U.S. gallons (208 liters) or less as the small-spill threshold used with Table 1. Night protective-action distances are typically farther because a more stable atmosphere mixes the plume less.
7. Table 2 lists water-reactive materials and the toxic gases they can generate in water. It does not replace Table 1 distances.
8. Table 3 is not a BLEVE table. It gives isolation and protective-action distances for large spills of six common TIH gases, using container type and wind speed. Table 1 will send you there when it applies (anhydrous ammonia and chlorine are the high-volume examples).

Unknown material: if you cannot find a name or ID, Guide 111 is the mixed-load / unidentified orange guide. That is a holding action, not an identity.

Orange isolation versus green protective action

Orange guides give public-safety isolation (and fire-related evacuation distances) for that guide family. The white how-to pages still teach the familiar starting isolation of about 75 feet for solids, 150 feet for liquids, and 330 feet for gases except explosives, then the specific orange guide may raise those numbers. Green Table 1 adds a second, often much larger, downwind protective-action distance for TIH and certain water-reactive spills, plus a larger all-directions initial isolation than the generic orange starting numbers.

Exam trap: a cargo tank of a green-highlighted TIH gas is leaking. A candidate reads the orange guide, isolates to the orange fire or public-safety distance, and never opens the green pages because "we already have isolation." That choice under-protects downwind neighborhoods. The reverse trap is using green Table 1 distances for a pool-fire only event with no product leak, which can over-evacuate for the wrong reason and starve the fireground of a workable perimeter. Highlight plus spill is the green-page trigger.

2024 chemical and biological warfare agent change

Starting with the 2024 edition, chemical warfare agents were removed from the yellow and blue indexes. Those agents, and the biological-warfare material that used to be scattered through the book, now sit in the Criminal or Terrorist Use of Chemical, Biological and Radiological Agents material in the white pages. Chemical warfare agents are listed by type and symptoms, not by name. That subsection includes biological and chemical agent tables plus initial isolation and protective-action distances for those agents. If a question still expects you to look up a warfare agent as if it were UN 2810 in the yellow index "the same way as a commercial TIH," the question is using a pre-2024 mental model.

Limitations that keep technicians alive

The ERG assigns families, not unique chemicals. Many products share one orange guide. The book will not give you immediately dangerous to life or health (IDLH) values, permissible exposure limits, compatibility charts for your specific chemical protective clothing, or a monitoring strategy. It will not tell you whether the tank's lading is what the placard claims. It is the wrong tool to run plugging, patching, chlorine kits, or product transfer. Those jobs need SDS-level chemistry, instruments, and the later PPE and product-control chapters.

Exam scenario: highway TIH versus "we already opened orange"

A northbound cargo tank overturns. The orange panel reads 1017. Yellow index: chlorine, orange Guide 124, green highlight. There is a visible vapor cloud at the manway—this is a spill/leak, not a fire. Correct sequence: orange Guide 124 for fire/spill public-safety actions and green Table 1 (small versus large, day versus night). If Table 1 points a large chlorine spill to Table 3, use container type and wind, not the orange starting isolation as your downwind protective-action distance. Then verify with shipping papers, the driver, CHEMTREC or the shipper 24-hour number, and monitoring—because ERG identity is still a lead, not a closed investigation.