Short answer: EPCRA §302 and Tier II measure the most a facility has on hand at any one time. TRI measures how much is manufactured, processed, or otherwise used over a calendar year. The CAA §112(r) Risk Management Program and OSHA PSM measure the quantity in a single process. CERCLA and EPCRA §304 reportable quantities measure the amount released in 24 hours. The same chemical can have a different threshold in each: chlorine is 100 lb for §302 and Tier II, 1,500 lb for PSM, 2,500 lb for RMP, and a 10-lb reportable quantity.
The comparison table
| Program | What is measured | Threshold basis | Scope | Deadline or trigger |
|---|---|---|---|---|
| EPCRA §302 (40 CFR 355) | Total EHS present at any one time, pure plus mixtures | At or above the EHS’s TPQ (Part 355, App. A/B); solids have two TPQs | Facility | Notify SERC and LEPC and name a facility emergency coordinator within 60 days of first becoming subject |
| EPCRA §311/312, Tier II (40 CFR 370) | Maximum amount present at any one time during the calendar year | At or above 10,000 lb; EHS at 500 lb or the TPQ, whichever is lower; retail gasoline 75,000 gal and diesel 100,000 gal in compliant USTs | Facility | §311: SDS or list within 3 months of first reaching threshold. §312: Tier II by March 1 each year |
| EPCRA §313, TRI (40 CFR 372) | Amount manufactured (including imported), processed, or otherwise used during the calendar year | In excess of 25,000 lb manufactured or processed, or 10,000 lb otherwise used; lower thresholds for chemicals in 372.28 | Covered facility (10 or more full-time employees and a covered industry code, or designated by EPA) | Form R or Form A by July 1 for the prior calendar year |
| CAA §112(r), RMP (40 CFR 68) | Quantity of a regulated substance in a process | More than the threshold quantity in 68.130: 500 to 20,000 lb for listed toxics; 10,000 lb for listed flammables | Process, at a stationary source | Comply and submit the RMP by the date the substance is first present above threshold in a process; update at least every 5 years |
| OSHA PSM (29 CFR 1910.119) | Quantity in a process; for flammables, on site in one location | At or above the Appendix A threshold for listed toxics and reactives; 10,000 lb or more of a Category 1 flammable gas or a flammable liquid with flash point below 100 °F, with exceptions | Process | PSM program elements apply to the covered process; no filing with OSHA is required by the standard |
| CERCLA §103 (40 CFR 302) and EPCRA §304 | Amount released in any 24-hour period | Equal to or exceeding the RQ in Table 302.4, or the EHS RQ in Part 355, App. A | The release, from a facility or vessel | Immediately notify the National Response Center (CERCLA) and the LEPC and SERC (EPCRA §304), with written follow-up under §304 |
One chemical, six numbers: chlorine (CAS 7782-50-5)
EPCRA §302 TPQ: 100 lb on site at any one time (40 CFR Part 355, App. A).
Tier II threshold: 100 lb, the lower of 500 lb and the TPQ (40 CFR 370.10).
EPCRA §304 EHS RQ and CERCLA RQ: 10 lb released in 24 hours (Part 355, App. A; 40 CFR 302.4).
OSHA PSM: 1,500 lb in a process (29 CFR 1910.119, App. A).
RMP: 2,500 lb in a process (40 CFR 68.130, Table 1).
TRI: chlorine is a listed toxic chemical (40 CFR 372.65), so the 25,000-lb and 10,000-lb annual activity thresholds apply at a covered facility.
EPCRA §302: threshold planning quantity
A facility is subject when any Extremely Hazardous Substance is present in an amount equal to or greater than its TPQ, or when the SERC or Governor designates it (40 CFR 355.10). The amount is the facility-wide total at any one time, adding the EHS in every mixture and skipping only concentrations at or below 1% (355.13–355.14). It is a one-time notice. Details, including the solid-form rules, are in EPCRA 302 EHS and TPQs.
EPCRA §311/312: Tier II
Tier II applies when OSHA requires an SDS for a hazardous chemical and it is present at or above threshold at any one time (40 CFR 370.10). This is the broadest program by chemical coverage, because it reaches every OSHA hazardous chemical rather than a fixed list. The annual report is due March 1; the §311 notice is due within three months of a first crossing. See Tier II reporting and EPCRA 311 notification.
EPCRA §313: Toxics Release Inventory
TRI is the only program in this table that measures annual activity rather than inventory or a release. A covered facility reports a listed toxic chemical that it manufactured or processed in excess of 25,000 pounds, or otherwise used in excess of 10,000 pounds, during the calendar year (40 CFR 372.25). The chemicals in 40 CFR 372.28 have lower thresholds. A facility is covered if it has 10 or more full-time employees, is in a listed industry code, and exceeds a threshold, or if EPA has designated it (372.22). A small tank can drive a TRI report if it is refilled often, and a large stock that is rarely drawn down may never reach one. Mixtures below 1% (0.1% for carcinogens) can be excluded (372.38(a)), and when only the upper bound concentration is known, the facility must assume the upper bound (372.30(b)(3)(ii)). Reports are due July 1 for the prior year (372.30(d)).
CAA §112(r): Risk Management Program
RMP applies to a stationary source that has more than a threshold quantity of a regulated substance in a process (40 CFR 68.10(a)). The comparison is per process, not per facility, but “process” is defined broadly: any group of interconnected vessels, or separate vessels located such that a regulated substance could be involved in a potential release, is a single process (40 CFR 68.3). Mixtures follow 68.115: a regulated toxic below 1% by weight is not counted, and at 1% or more it can be excluded where the owner documents a partial pressure under 10 mm Hg (with listed exceptions). For a regulated flammable at 1% or more, the whole mixture counts unless it does not have an NFPA flammability rating of 4. Gasoline in distribution or related storage for use as fuel is excluded from flammable threshold determination. The first RMP is due no later than the date a regulated substance is first present above its threshold in a process (68.150(b)), and updates are due at least every five years (68.190(b)(1)).
OSHA Process Safety Management
PSM applies to a process involving a chemical at or above its threshold quantity in Appendix A, or a process involving a Category 1 flammable gas or a flammable liquid with a flash point below 100 °F (37.8 °C) on site in one location in a quantity of 10,000 pounds or more (29 CFR 1910.119(a)(1)). The flammable criterion excludes hydrocarbon fuels used solely for workplace consumption as fuel, and flammable liquids stored in atmospheric tanks or transferred while kept below their normal boiling point without chilling or refrigeration. Retail facilities, oil or gas well drilling or servicing, and normally unoccupied remote facilities are outside the standard. PSM and RMP lists overlap but differ in substances and numbers, as chlorine (1,500 vs 2,500 lb) shows. A new chemical in a covered process falls under PSM’s management of change procedures (1910.119(l)).
CERCLA and EPCRA §304: reportable quantities
Reportable quantities are about releases, not storage. The person in charge must immediately notify the National Response Center when a hazardous substance is released in a quantity equal to or exceeding its RQ in any 24-hour period (40 CFR 302.6(a)). For a mixture, if the quantities of all hazardous constituents are known, notification is required when an RQ of any constituent is released; if any is unknown, it is required when the total mixture released reaches the lowest constituent RQ (302.6(b)). EPCRA §304 adds immediate notice to the LEPC and SERC for releases of an EHS or CERCLA hazardous substance at or above its RQ, and a written follow-up as soon as practicable, with exemptions in 355.31, including releases that result in exposure only within the facility boundary (40 CFR 355.33–355.43).
Why the differences matter in practice
Each program needs a different number from the same inventory. A Tier II total is a facility-wide snapshot of the worst day. A TRI threshold needs a year of receipts and usage. RMP and PSM need the inventory broken down by process and by connected vessels. A release decision needs the chemical’s RQ in hand before anything spills. Keeping one record by CAS number, with location, process, and transaction history, lets each of these be computed from the same data. The purchase screening checklist walks through all six for a single new chemical.
Common questions
What is the difference between a TPQ and an RQ?
A threshold planning quantity (TPQ) is an amount on site that triggers EPCRA section 302 emergency planning. A reportable quantity (RQ) is an amount released within 24 hours that triggers release notification under CERCLA and EPCRA section 304. Many EHSs have both, and they are usually different numbers.
Is the TRI threshold based on inventory?
No. TRI thresholds are based on the amount of a listed chemical manufactured (including imported), processed, or otherwise used at a covered facility during the calendar year: 25,000 pounds for manufacturing or processing and 10,000 pounds for otherwise use (40 CFR 372.25), with lower thresholds for the chemicals in 40 CFR 372.28.
Are RMP and PSM thresholds the same?
No. They are separate lists with different substances and quantities. Chlorine, for example, is 2,500 pounds under RMP (40 CFR 68.130) and 1,500 pounds under PSM (29 CFR 1910.119 Appendix A). Both apply per process, not per facility.
Does Tier II apply per facility or per process?
Per facility. Tier II totals each hazardous chemical across all buildings and storage areas on contiguous sites owned or operated by the same person, at the highest point during the year (40 CFR 370.3 and 370.10).
Which thresholds use the 24-hour release amount?
CERCLA reportable quantities (40 CFR 302.6) and EPCRA section 304 emergency release notification, which uses the RQs for EHSs and CERCLA hazardous substances (40 CFR 355.33).
Where Chemsana fits
Chemsana checks each chemical against EPCRA 302, CAA 112(r) (40 CFR 68.130), OSHA PSM, CERCLA RQ, TRI, and RCRA lists and the site’s permits, and returns an Allowed, Flag, or Block decision with the citation and the math. Release screening compares a spill against CERCLA and EHS RQs. See intake decisions.
Sources
- 40 CFR Part 355, Emergency Planning and Notification, eCFR, accessed October 2026.
- 40 CFR Part 370, Hazardous Chemical Reporting, eCFR, accessed October 2026.
- 40 CFR Part 372, Toxic Chemical Release Reporting, eCFR, accessed October 2026.
- 40 CFR Part 68, Chemical Accident Prevention Provisions (§§68.3, 68.10, 68.115, 68.130, 68.150, 68.190), eCFR, accessed October 2026.
- 29 CFR 1910.119, Process safety management of highly hazardous chemicals, eCFR, accessed October 2026.
- 40 CFR Part 302, Designation, Reportable Quantities, and Notification (§§302.4, 302.6), eCFR, accessed October 2026.
This guide summarizes federal requirements for general information. States can set lower thresholds or extra requirements, and it is not legal advice. Confirm obligations with your SERC, LEPC, or a qualified EHS professional.