RQ Calculator



Any U.S. entity who handles hazardous substances is subject to federal spill or release reporting requirements according to the following laws:

  • Any time a Hazardous Substance as defined under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or "Superfund") is released to the environment, and that release exceeds its Reportable Quantity (RQ) within a 24-hour period, the release must be reported to the National Response Center (NRC) in Washington, DC.
  • Any time an Extremely Hazardous Substance as defined under the Emergency Planning and Community Right-To-Know Act (EPCRA) is released beyond the boundaries of a facility in an amount that exceeds the chemical's RQ, the owner or operator of the facility must immediately notify both the Community Emergency Coordinator for the Local Emergency Planning Committee (LEPC) and the State Emergency Response Commission (SERC).

Determining if a substance has exceeded its RQ is complicated. A number of factors, such as the regulatory identity of the substance(s) released, the amount of material released, and the time period of the release may or may not be readily known at the time of the release.

To streamline this process, the Office of Sustainable Environmental Stewardship (EHSS-21) has developed the RQ Calculator [note: this version has been recreated from the former (December 2013) RQ Calculator assistance tool]. The program simplifies the calculation of whether a release exceeds a chemical's RQ. The program will calculate the amount of the regulated substance released, compare the resulting value to the chemical's RQ, and advise the user as to whether or not a notification must be made.


CERCLA, as amended, creates a framework for federal involvement in response to and cleanup of hazardous substance releases. Under CERCLA, the Environmental Protection Agency (EPA) has broad statutory authority to undertake or require responsible parties to undertake actions addressing releases of hazardous substances or pollutants and contaminants. Recognizing that EPA can only exercise that authority if it receives notice of such releases, Congress enacted Section 103(a) of CERCLA, which requires the person in charge of a facility or vessel to notify the NRC as soon as the person in charge has knowledge that the release of a hazardous substance is at or above the RQ for the substance.

Section 103(a) requirements are triggered only when there is a "release," which is defined in Section 101 (22) of CERCLA as any "spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment. "Thus, when a hazardous substance is spilled, leaked, or discharged, the incident must be reported to the NRC if the amount that enters the environment within a 24-hour period equals or exceeds its RQ. "Environment" is defined in Section 101(8) of CERCLA as "the navigable waters, the waters of the contiguous zone, and the ocean waters...of the United States..." and "any other surface water, ground water, drinking water supply, land surface or subsurface strata, or ambient air..."

CERCLA Section 101(14) defines "hazardous substance" to include:

  • Any substance designated pursuant to Section 311(b)(2)(A) of the Federal Water Pollution Control Act (also known as the Clean Water Act or CWA);
  • Any element, compound, mixture, solution, or substance designated pursuant to Section 102 of CERCLA;
  • Any hazardous waste having the characteristics identified under or listed pursuant to Section 3001 of the Solid Waste Disposal Act (also known as the Resource Conservation and Recovery Act or RCRA);
  • Any toxic pollutant listed under CWA Section 307(a);
  • Any hazardous air pollutant listed under Section 112 of the Clean Air Act (CAA); and
  • Any imminently hazardous chemical substance or mixture with respect to which the Administrator has taken action pursuant to Section 7 of the Toxic Substances Control Act.

The list of CERCLA hazardous substances is codified in Table 302.4, "List of Hazardous Substances and Reportable Quantities," in 40 CFR 302.4. Currently there are nearly 800 specifically designated CERCLA hazardous substances. Also about 1,500 radionuclides are CERCLA hazardous substances because radionuclides are listed under Section 112 of the Clean Air Act.


Section 304 of EPCRA requires owners and operators of facilities where hazardous chemicals are produced, used, or stored to report releases of CERCLA hazardous substances or extremely hazardous substances (EHSs) to state and local authorities (i.e., SERCs and LEPCs).

EHSs are listed in Appendices A and B of 40 CFR 355. These appendices contain 360 EHSs; 138 of the EHSs are CERCLA hazardous substances. Reportable releases of an RQ or more of a substance that is both an EHS and a CERCLA hazardous substance must be reported to the NRC, SERC and LEPC; similar releases of an EHS that is not a CERCLA hazardous substance must be reported only to state and local officials.

Version History

The backbone of the RQ Calculator consists of several databases of chemical substances, chemical substance synonyms, and radionuclides that have been assembled from a number of sources.

  • Version 4.1
    January 2021. The RQ Calculator design was updated to fix compatibility issues for 508 Compliance.
  • Version 4.0
    August 2019. In 2016, the previous version of the RQ Calculator was taken offline due cybersecurity issues with the server where this tool was maintained. Due to the level of interest (as reflected by the considerable number of inquiries received), an effort was undertaken to redevelop and update the program. All of the previous features were ported to the new version, and modernization of the website design and functionality were completed.
  • Version 3.1
    December 2013. The color scheme was changed on the desktop version of RQ Calculator from green to blue in accordance with DOE policy on DOE support websites not hosted on energy.gov.
  • Version 3.0
    April 2012. The RQ Calculator mobile version was completely rewritten using jQuery Mobile for tablets and handheld devices and Skeleton to provide a pleasing format when displayed on large screen devices. Options and materials in the desktop version 2.0 which had been removed for the mobile version 2.0 were restored in mobile version 3.0. A number of formatting errors resulting from server-side software upgrades since version 2.0 was released were addressed. The database was checked against current RQs lists. One chemical was added, and several RQs were revised.
  • Version 2.0
    September 2007. The RQ Calculator was completely rewritten to include a "mobile" version to run on Internet-capable mobile devices such as Blackberries, PDAs, etc. Additionally the code was completely rewritten to improve ease of use and data input.
  • Version 1.2
    April 2004. The RQ Calculator was updated with changes from the regulations (40 CFR 302.4 and 355.5). A total of 11 new chemicals have been added.
  • Version 1.1
    April 2004. Minor style changes were made to improve cross-browser compatibility. Minor programming changes were made to improve response time.
  • Version 1.0
    October 1998. Initial release of the program.