# Introduction to the Numerical Material Index

**Citation:** ERG 2024, Introduction to the Numerical Material Index  
**Type / status:** guidance / guidance  
**Agency:** U.S. DOT / Transport Canada / SICT  
**Effective:** Not stated  
**Published:** 2024-04-04

Official ERG2024 introduction to the numerical material index guidance, pages 30-30.

## Document text

INTRODUCTION TO YELLOW SECTION
For entries highlighted in green follow these steps:
•
•
IF THERE IS NO FIRE:
- Go directly to Table 1 (green section)
-
- Look up the ID number and name of material
-
- Identify initial isolation and protective action distances
-
- Also consult the appropriate Orange Guide
-
IF A FIRE IS INVOLVED:
- Use the appropriate Orange Guide for EVACUATION distances
-
- Also protect in downwind direction according to Table 1 for residual
-
material release
Note 1: If the name in Table 1 is shown with (when spilled in water), these materials
produce large amounts of Toxic Inhalation Hazard (TIH) (PIH in the US) gases
when spilled in water. Some water-reactive materials are also TIH materials
themselves (e.g., UN1746 (Bromine trifluoride), UN1836 (Thionyl chloride)). In
these instances, two entries are provided in Table 1 for land-based and water-
based spills. If a water-reactive material only has one entry in Table 1 for (when
spilled in water) and the product is NOT spilled in water, Table 1 and Table 2
do not apply. You will find safe distances in the appropriate Orange Guide.
Note 2: Explosives are not individually listed by their ID number because in an emergency
situation, the response will be based only on the division of the explosive, not on
the individual explosive.
For divisions 1.1, 1.2, 1.3 and 1.5, refer to GUIDE 112.
For divisions 1.4 and 1.6, refer to GUIDE 114.
Note 3: Chemical and biological warfare agents are now found in the “Criminal or Terrorist
Use of Chemical, Biological and Radiological Agents” section.
Page 28

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2024-04/ERG2024-Eng-Web-a.pdf#page=30>
- Source ID: `phmsa-erg-2024`
- SHA-256: `bd9d20de5449b7c3f9ebe1cec0ba6ea6efb17d0642575f9909af667beac56927`
- Retrieved: 2026-08-13T11:31:32.574Z
- Exported: 2026-08-23T22:14:56.427Z
- Document slug: `phmsa-erg-2024-yellow-index-introduction`

### Source metadata

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  "caveat": "Emergency-response guidance for the initial phase of a transportation incident. It is not controlling regulation, a compliance determination, a chemical-specific worker safety document, or a substitute for required shipping-paper emergency-response information.",
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