Threshold Planning Quantity (TPQ)

EPCRA created a list of extremely hazardous substances, and each has its own TPQ. The numbers vary a great deal from one chemical to another because they reflect how dangerous a release could be. A very toxic gas will have a far lower threshold than a less acutely hazardous liquid.

When a facility has a listed substance at or above its TPQ at any one time, it must notify the state emergency response commission and the local emergency planning committee. It also has to name a facility emergency coordinator who can work with the local planners, and it must provide information they request for the community emergency plan.

The TPQ is a planning trigger. It is different from a reportable quantity, which applies to a release and sets when a spill must be reported. A facility may be subject to both, depending on what it handles and how much.

TPQ also affects other reporting. Extremely hazardous substances have lower thresholds for the Tier II inventory report, so it is easy for small facilities to be caught if they hold a very toxic chemical. Mixtures can be tricky, because the quantity of the listed substance within the mixture is what counts.

Check the current list in 40 CFR Part 355 and the supplier's SDS to see whether a product contains a listed substance.