Extremely Hazardous Substances (EHS): List, Reporting, and Penalties

Extremely hazardous substances are the roughly 360 chemicals the Environmental Protection Agency has flagged as posing the greatest risk to nearby communities during an accidental release, based mainly on how toxic they are to breathe and how easily they spread through the air.¹ If your facility stores one of these chemicals above its threshold, federal law under the Emergency Planning and Community Right-to-Know Act of 1986 requires you to notify state and local emergency planners, file an annual inventory, and report any release immediately.²

What Puts a Chemical on the List

The EPA’s primary screening factor is acute inhalation toxicity: how likely a substance is to kill or seriously injure someone who breathes it during a short exposure. The agency measures this using the median lethal concentration, or LC50, the airborne concentration expected to kill half of test animals during a fixed exposure period.³

Physical properties matter just as much. A chemical that becomes airborne easily can affect a much wider area than one that stays put. The combination of high toxicity at low concentrations and rapid dispersion is what separates an EHS from an ordinary hazardous chemical. The EPA can add or revise entries as new peer-reviewed research emerges.

Where to Find the Official List

The current list is published under EPCRA Section 302 and codified at 40 CFR Part 355, Appendix A (alphabetical) and Appendix B (by CAS registry number).⁴ Entries range from common industrial chemicals like chlorine and ammonia to specialized laboratory reagents. Each row shows a Chemical Abstracts Service number, a reportable quantity in pounds, and a threshold planning quantity. The Electronic Code of Federal Regulations always carries the current version.

One point of confusion worth clearing up: the EHS list is not the same as the CERCLA hazardous substances list maintained under the Superfund law. The two overlap on more than a third of EHS chemicals, but a substance can appear on one without being on the other, so facility managers should check both.¹ EHS designation adds emergency planning duties at the state and local level that CERCLA on its own does not require.

Threshold Planning Quantities: What Actually Counts

Every EHS is paired with a threshold planning quantity (TPQ) in pounds. Store the substance at or above that amount at any one time, and the facility is subject to EPCRA emergency planning.⁴ More dangerous chemicals get lower TPQs. Phosgene sits at 10 pounds; sulfuric acid at 1,000.

Solids Get Two Possible TPQs

Solid EHS chemicals have two possible thresholds: a lower value and a default of 10,000 pounds. The lower TPQ applies only when the solid is a fine powder with particles smaller than 100 microns, is dissolved in solution, is molten, or has a National Fire Protection Association reactivity rating of 2, 3, or 4. Otherwise, the 10,000-pound default governs.⁵ A stable chunky solid poses less airborne risk than the same chemical ground into powder.

EHS in Mixtures

When an EHS is part of a mixture, the amount on hand is the weight-percent concentration multiplied by the total weight of the mixture in pounds. If the EHS concentration is 1 percent or less, it doesn’t count toward the TPQ at all.⁶ A large tank of dilute cleaning solution with only trace EHS content may not trigger planning even if the total weight is significant.

Section 302: The One-Time Emergency Planning Notification

A facility that first acquires an EHS at or above its TPQ has 60 days to notify both the State Emergency Response Commission (SERC) and the Local Emergency Planning Committee (LEPC).⁷ The same 60-day clock applies if the EPA revises the list and you already have the newly listed substance above its TPQ.

The notification must include the facility’s name and physical address, the identity of every EHS present above its TPQ, the maximum quantity held at any one time, and the name and contact information for a designated emergency coordinator. That coordinator has to be reachable around the clock to give first responders technical guidance during an incident.⁸ State and local planners use this information to build evacuation routes, sheltering plans, and hospital surge protocols tailored to the chemicals in the area.

Annual Tier II Inventory Reporting

Section 302 is a one-time filing. Sections 311 and 312 add ongoing annual duties. Any facility required to keep a Safety Data Sheet (SDS) under federal workplace-safety rules must submit that SDS, or a list of covered chemicals, to three recipients: the SERC, the LEPC, and the local fire department. The initial SDS submission is due within three months of the chemical first exceeding the reporting threshold.⁹

The reporting thresholds are:

Extremely hazardous substances: 500 pounds or the TPQ, whichever is lower.
All other hazardous chemicals: 10,000 pounds.¹⁰
Gasoline at retail stations stored entirely underground: 75,000 gallons.
Diesel fuel at retail stations stored entirely underground: 100,000 gallons.¹¹

Once above the threshold, facilities file a Tier II hazardous chemical inventory form every year by March 1 covering the prior calendar year.¹² Most states require electronic filing through the EPA’s Tier2 Submit software or a state-managed portal, and specifics vary by state.¹³ Local fire departments can also inspect the site and request specific storage locations for any chemicals reported on Tier II forms.⁹

There is no federal recordkeeping requirement for Tier II submissions, but individual states may impose retention rules, so check with your SERC.¹⁴

Exemptions Are Narrower Than They Sound

Federal regulations do carve out some categories from EPCRA reporting:

Substances used for personal, family, or household purposes, or present in the same form and concentration as a consumer product.¹⁵
Substances used in a research laboratory, hospital, or other medical facility under the direct supervision of a technically qualified individual.¹⁵

Read these carve-outs tightly. A hospital pharmacy qualifies; a chemical warehouse that supplies hospitals generally does not. Retail gas stations are not blanket-exempt from Tier II reporting either. They just get the higher underground-storage thresholds above when their tanks meet federal tank regulations.¹¹

Section 304: Reporting a Release

When an EHS release occurs and the amount released meets or exceeds its reportable quantity, the facility must immediately contact the SERC and the LEPC for every area likely to be affected.¹⁶ If the substance is also a CERCLA hazardous substance, the facility must simultaneously call the National Response Center at 1-800-424-8802, which is staffed 24 hours a day.¹⁷

The initial notification must include:

Chemical name and whether it is an EHS
Estimated quantity released into the environment
Time and duration of the release
Release medium: air, water, land, or some combination
Known or anticipated health risks and any needed medical guidance for exposed individuals
Recommended precautions such as evacuation or sheltering in place
Contact person name and phone number¹⁶

A written follow-up is required as soon as practicable. It updates the initial information and adds containment actions taken, known or anticipated acute and chronic health risks, and medical advice for people exposed.¹⁸ Later information triggers additional follow-ups. The written record becomes part of the public file on the incident.

Penalties for Non-Compliance

EPCRA violations carry civil and criminal consequences, and the numbers are higher than many facility managers expect. Congress’s statutory base penalties have been adjusted for inflation, so current maximums significantly exceed the 1986 figures.¹⁹

Civil Penalties (2025 Maximums)

Emergency planning violations (Sections 302/303): up to $71,545 per day the violation continues.²⁰
Emergency release notification violations (Section 304): up to $71,545 per day, rising to $214,637 per day for a second or subsequent violation.²⁰
Tier II reporting violations (Section 312): up to $71,545 per violation.
Safety Data Sheet violations (Section 311): up to $28,619 per violation.²⁰

Because each day of non-compliance counts as a separate violation for most of these categories, a facility that ignores a planning or release-notification duty for even a few weeks can face six-figure exposure quickly.

Criminal Penalties

Individuals who knowingly and willfully fail to provide required emergency release notification under Section 304 face up to two years in prison and fines on conviction. A second conviction raises the maximum to five years.²¹ Criminal charges are reserved for deliberate failures rather than honest mistakes, though federal prosecutors are comfortable arguing the difference.

1
U.S. Environmental Protection Agency. EPCRA Extremely Hazardous Substances and Relationship to CERCLA Hazardous Substances
2
Office of the Law Revision Counsel. 42 USC Chapter 116 – Emergency Planning and Community Right-To-Know
3
United States Environmental Protection Agency. OPPTS 870.1300 – Acute Inhalation Toxicity
4
eCFR. 40 CFR Appendix A to Part 355 – The List of Extremely Hazardous Substances and Their Threshold Planning Quantities
5
U.S. Environmental Protection Agency. Threshold Planning Quantity for Extremely Hazardous Substances in Solid Form
6
eCFR. 40 CFR 355.13 – How Do I Calculate the Quantity of an Extremely Hazardous Substance Present in Mixtures?
7
Office of the Law Revision Counsel. 42 USC 11002 – Establishment of State Commissions, Planning Districts, and Local Committees
8
U.S. Environmental Protection Agency. Chapter 2 – EPCRA Section 302 Emergency Planning Notification
9
U.S. Environmental Protection Agency. EPCRA Sections 311 and 312 – Hazardous Chemical Inventory Reporting
10
eCFR. 40 CFR Part 370 – Hazardous Chemical Reporting: Community Right-to-Know
11
U.S. Environmental Protection Agency. Retail Gas Stations Are Not Exempt from Tier II Reporting
12
U.S. Environmental Protection Agency. State Tier II Reporting Requirements and Procedures
13
U.S. Environmental Protection Agency. Tier2 Submit Software
14
U.S. Environmental Protection Agency. Federal Recordkeeping Requirements Under EPCRA Sections 311 and 312
15
eCFR. 40 CFR 370.13 – What Substances Are Exempt From These Reporting Requirements?
16
U.S. Environmental Protection Agency. EPCRA Emergency Release Notifications
17
U.S. Environmental Protection Agency. What Information Is Needed When Reporting an Oil Spill or Hazardous Substance Release?
18
Office of the Law Revision Counsel. 42 USC 11004 – Emergency Notification
19
Office of the Law Revision Counsel. 42 USC 11045 – Enforcement
20
eCFR. 40 CFR Part 19 – Adjustment of Civil Monetary Penalties for Inflation
21
U.S. Environmental Protection Agency. Criminal Provisions of the Emergency Preparedness and Community Right-To-Know Act (EPCRA)