Search Frequent Questions

Displaying 1 - 15 of 121 results

• How do the different parts of particulate matter (PM) fit together?

  The various parts of PM in the NEI are related as follows. PM10-FIL > PM25-FIL because PM10-FIL includes PM25-FIL PM25-PRI = PM25-FIL + PM-CON This equation only applies at the process level. Because some sources only can report PM2.5 (due to test method differences), this equation does not apply to…

  • Last published: April 17, 2024

• How does PM2.5 relate to PM species such as EC, OC, SO4, NO3, PMFINE, and DIESEL-PM25?

  Primary PM2.5 estimates are speciated into the five PM species in the NEI: elemental (black) carbon (EC), organic carbon (OC), nitrate (NO3), sulfate (SO4), and the remainder of PM25-PRI (PMFINE). Diesel engine PM25-PRI and PM10 emissions are also labeled as DIESEL-PM25 and DIESEL-PM10 for mobile source diesel engines. For all…

  • Last published: April 17, 2024

• Does the distance to endpoint start at the process or stationary source boundary?

  When selecting the worst-case release scenario for Program 2 and 3 processes as required by 40 CFR §68.25, a stationary source owner or operator must analyze the release scenario that results in the greatest distance to an endpoint. Does the "greatest distance to an endpoint" refer to the greatest total…

  • Last published: May 22, 2024

• Using meteorological station data for off-site consequence analyses

  For the purpose of the offsite consequence analyses required under 40 CFR Part 68, Subpart B, there are several instances in which data gathered at a local meteorological station may be used to establish the modeling parameters of wind speed, atmospheric stability, temperature, and humidity for the stationary source. How…

  • Last published: May 22, 2024

• Underground storage tank off-site impacts to groundwater, drinking water, or soil

  For the worst-case and alternative release scenarios of an underground storage tank, should I consider any impact on groundwater, drinking water, or soil? No. As part of the worst-case and alternative release scenarios, you need to define the offsite impacts to the environment (40 CFR §68.33) by listing the environmental…

  • Last published: May 22, 2024

• Administrative controls considered when determining worst-case release quantity

  For the purpose of analyzing the worst-case release scenario required as part of the hazard assessment at 40 CFR Part 68, Subpart B, the worst-case release quantity is identified as the greatest amount held in a single vessel or pipe, taking into account administrative controls that limit the maximum quantity…

  • Last published: May 22, 2024

• Are Mechanical Controls Considered Administrative Controls?

  For the purpose of analyzing the worst-case release scenario required as part of the hazard assessment at 40 CFR Part 68, Subpart B, the worst-case release quantity is identified as the greatest amount held in a single vessel or pipe, taking into account administrative controls that limit the maximum quantity…

  • Last published: May 22, 2024

• Worst-case release from smaller process with larger distance to endpoint

  The owner or operator of a stationary source covered by the risk management program regulations must conduct a worst-case release scenario analysis as part of the required hazard assessment (40 CFR §68.25). The worst-case release is defined as the release of the largest quantity of a regulated substance from a…

  • Last published: May 22, 2024

• Can I use any previous three year meteorological data for worst case scenario?

  I am trying to complete my worst case release scenario for the Risk Management Plan under §68.25. I understand that I am required to use a wind speed of 1.5 m/s and F atmospheric stability class as specified in §68.22(b), unless I can prove that at no time over the…

  • Last published: May 29, 2024

• Where can I download hourly emissions data from continuous monitoring?

  Hourly emissions data files are available from the Clean Air Markets Division of EPA, collected as part of 40 CFR Part 75. The download location has changed in February, 2023. The new location is https://campd.epa.gov/data/bulk-data-files . Once on this new site, use the menu (at the left) and the Keyword…

  • Last published: January 7, 2025

• What does it mean when EPA finds contamination that “exceeds screening levels?”
  

  Screening levels are not the same as cleanup or action levels. An exceedance of a screening level indicates the need for additional evaluation, potentially including a site-specific risk assessment.

  • Last published: February 11, 2025

• What state or federal agencies are responsible for evaluating records from the PADOH cancer registry? Are all types of cancers considered in this evaluation [including rare and/or environmentally associated cancers]?

  A few important items to note regarding the Pennsylvania Cancer Registry:  PADOH’s Pennsylvania Cancer Registry is a statewide data system responsible for collecting information on all new cases of cancer diagnosed or treated in Pennsylvania. It is part of the National Program of Cancer Registries administered by the Centers for…

  • Last published: February 11, 2025

• If EPA finds any contamination associated with the Norwood Landfill site that “exceeds” what is considered safe, will EPA clean up that contamination - even if the Agency cannot find any “pathways” for that contamination to reach humans or sensitive environments?

  If the sampling data shows an exceedance of a screening level, EPA will consult with the site Toxicologist and the Agency for Toxic Substances and Disease Registry (ATSDR) to conduct a human health risk screening assessment to determine any potential threat to human health. EPA will also consult with the…

  • Last published: February 18, 2025

• Criteria for selecting alternative release scenarios

  As part of the hazard assessment, owners and operators of Program 2 and Program 3 covered processes must identify and analyze alternative release scenarios (40 CFR §68.28). What criteria should be used when selecting an alternative release scenario? The owner or operator of a stationary source subject to the risk…

  • Last published: February 20, 2025

• What is a site assessment and what is the difference between a site assessment and a site investigation?

  The first step of the site assessment process is known as a preliminary assessment (PA). This assessment gathers historical and other readily available information on site conditions and surroundings to evaluate whether the site poses a potential threat to human health and the environment and/or whether further investigation is needed…

  • Last published: February 25, 2025