Combustion Portal

Hospital/Medical/Infectious Waste Incinerators (HMIWI)

This section applies to incinerator units whose primary purpose is the combustion of hospital and/or medical/infectious waste.

Air Emissions Regulations

  • 40 CFR Part 60 Subpart Ec - New Source Performance Standards (NSPS) for Hospital Medical Infectious Waste Incineration Units Which Construction is Commenced After June 20, 1996
  • 40 CFR Part 60 Subpart Ce - Emission Guidelines (EG) and Compliance Times for Existing Hospital Medical Infectious Waste Incineration Units
  • 40 CFR Part 62 Subpart HHH - Federal Plan Requirements for Hospital Medical Infectious Waste Incineration Units Which Construction is Commenced After June 20, 1996

The U.S. Environmental Protection Agency (EPA), under section 129 of the Clean Air Act (CAA), is required to regulate emissions from certain categories non-hazardous solid waste incinerators. Section 129 requires EPA to set numerical emissions limitations of nine pollutants from Hospital Medical Infectious Waste Incineration (HMIWI) units. The nine pollutants are:

  • cadmium (Cd)
  • carbon monoxide (CO)
  • total mass basis dioxins/furans (TMB PCDD/PCDF) and toxic equivalency basis dioxin/furans (TEQ PCDD/PCDF)
  • hydrogen chloride (HCl)
  • lead (Pb)
  • mercury (Hg)
  • nitrogen oxides (NOx)
  • particulate matter (PM)
  • sulfur dioxide (SO2)

All standards established pursuant to CAA Section 129(a)(2) must reflect maximum achievable control technology (MACT). The MACT "floor," or minimum level of stringency set forth differing levels of minimum stringency that EPA’s standards must achieve, depending on whether they regulate new or existing sources.

The CAA allows EPA to subcategorize a source category based on differences in class, type, or size. The HMIWI regulation is subcategorized by unit size:

  • Very Small (rural: 50 miles from nearest Standard Metropolitan Statistical Area & burn less than 2,000 pounds per week)
  • Small (≤ 200 lb/hr)
  • Medium (>200 to 500 lb/hr)
  • Large (>500 lb/hr)

A HMIWI is defined as any device used to burn hospital waste or medical/infectious waste. Hospital waste means discards generated at a hospital, and medical/infectious waste means any waste generated in the diagnosis, treatment, or immunization of human beings or animals, in research pertaining thereto, or in the production or testing of biological (e.g. vaccines, cultures, blood or blood products, human pathological waste, sharps).

The enforcement authority is different for the NSPS and EG. The NSPS are directly enforceable federal regulations, and under CAA section 129 (f)(1), become effective 6 months after promulgation. The EG are not themselves directly enforceable. Rather, the EG are implemented and enforced through either an EPA-approved state plan or a promulgated federal plan. States are required to submit a plan to implement and enforce the EG to EPA for approval not later than 1 year after EPA promulgates the EG (CAA section 129 (b)(2)). The state plan must be "at least as protective as" the EG and must ensure compliance with all applicable requirements not later than 3 years after the state plan is approved by EPA, but not later than 5 years after the relevant EG are promulgated. If a state does not develop an approvable implementation plan, EPA will promulgate a federal plan that will apply to existing HMIWI units located in that state.

For additional information, fact sheets, and supporting documents on the HMIWI standards and guidelines please visit:

Solid Waste

The burning of waste in incinerators creates residual ash (fly ash and bottom ash), which can contain any of the elements that were originally present in the waste. Incinerators reduce the need for landfill capacity because disposal of ash requires less land area than does unprocessed waste. However, because ash and other residues from incinerators may contain toxic materials, the combustion residuals wastes must be tested regularly to assure that the wastes are safely contained to prevent toxic substances from migrating into groundwater supplies. Under RCRA and state regulations, incinerator ash must be sampled and analyzed regularly to determine whether it is hazardous or not. Hazardous ash must be managed and disposed of as hazardous waste. Non-hazardous ash may be disposed of in a municipal solid waste landfill, an ash monofill or recycled.

More resources for solid waste:

Water Resources Protection

Incinerators generate wastewater associated with processes such as cooling tower blowdown, flue gas treatment, and washdowns. Discharges of wastewater are regulated under the Clean Water Act (CWA). Facilities which discharge indirectly through a publically owned treatment works (POTW) are regulated under the Pretreatment Program, which insures that facilities pretreat wastewater to remove pollutants which would affect the pollutant removal ability of the POTW. Facilities that discharge process or non-process wastewater directly streams, rivers, etc. are regulated under the National Permit Discharge Elimination System (NPDES) and must obtain coverage under a General Permit or an Individual Permit.

In addition to compliance with rules covering wastewater generated by incinerators, applicable facilities must be concerned with stormwater runoff.

Each of these topics is summarized below with links to related web pages and documents.

Indirect Discharge. Facilities with HMIWI incinerators that discharge wastewater into a sewer system that leads to a municipal treatment plant, also known as Publicly Owned Treatment Works (POTW) are indirect dischargers. The POTW typically is owned by the local municipality or a regional board or sewer authority.

In response to potential problems caused by industrial wastewater being discharged into POTW's, federal pretreatment regulations were developed. These regulations apply to all municipal, industrial and commercial facilities. Local POTW's with approved pretreatment programs have responsibility for enforcing pretreatment requirements. Otherwise, the rules are enforced by the state or EPA regional authority.

All indirect dischargers must meet national General Pretreatment Regulations (40 CFR 403). Additionally, certain types of facilities must also meet applicable categorical pretreatment standards. When a pollutant, discharged by an indirect discharging industry is not specifically limited by pretreatment standards, it is up to the state or local regulatory agency to develop local limits or to determine other appropriate means to control its discharge.

More information on indirect discharges to POTW's:

Direct Discharge. Facilities with HMIWI incinerators that discharge process wastewater or cooling water to surface waters are direct dischargers. Direct dischargers must obtain a permit under EPA's National Pollutant Discharge Elimination System (NPDES) program. A NPDES permit sets limits on the amount of specific pollutants that can be discharged to surface waters.

Some states offer general permits for non-contact process water (e.g., cooling water). The purpose of the general permit is to provide a streamlined NPDES permitting process for certain classes or categories of industrial point source discharges. Coverage under a NPDES general permit is unique in that a facility operates and discharges under the requirements of the applicable general permit rule rather than the requirements of an individual permit. Check with your state environmental agency to determine if a general permit is applicable to your facility.

More information on direct discharge NPDES permits:


Leachate from waste unloading and storage operations caused by exposure to precipitation may contain organic matter, metals, and hazardous chemicals. Stormwater regulations promulgated under the Clean Water Act help prevent these materials from polluting nearby streams and other water courses. Operations such as HMIWI incinerators must develop a stormwater pollution prevention plan (SWPPP), obtain coverage under a NPDES stormwater permit, and implement methods of controlling stormwater pollution, including best management practices. For more information about the Stormwater Program, visit the Stormwater Basic Information page.

Throughout most of the nation, U.S. EPA has delegated the stormwater program to the states to administer as they see fit, so long as minimum federal requirements are met. For more information on state stormwater rules see the Industrial Stormwater Resource Locator. The locator will help you find state-specific information on permitting, technical resources and points of contact.

More information on Stormwater:

Spill Prevention, Control and Counter Measures

EPA promulgated the Spill Prevention, Control and Counter Measures (SPCC) rule to reduce the risk of damaging our waterways from oil spills. These rules are applicable to a very wide rage of facilities and operations, including fuel oil storage tanks for incinerators. The rule requires specific facilities to prepare, amend, and implement SPCC Plans. The SPCC rule is part of the Oil Pollution Prevention regulation, which also includes the Facility Response Plan (FRP) rule.

An SPCC Plan is required for facilities which due to their location, could reasonably be expected to discharge oil to surface water or adjoining shorelines and have:

  • Total aboveground storage capacity of 1,320 gallons or more of oil (however, only containers or oil-containing equipment with a capacity equal to or greater than 55 gallons count toward the threshold); or

  • A total oil underground storage capacity of 42,000 gallons or more (however, underground storage tanks subject to regulation under RCRA [40 CFR 280 or 281] are not included); or

  • Been required by the EPA to prepare and implement an SPCC Plan.

The SPCC regulations require the facility owner/operator to prepare and implement an SPCC plan for their facility. This plan must be well thought out and prepared in accordance with good engineering practices. It must document the location of storage vessels, types of containment, dangers associated with a major release of material from the tanks, types of emergency equipment available at each site, and procedures for notifying the appropriate regulatory and emergency agencies.

To assist facility owners and operators with SPCC compliance, EPA has published a useful document: Spill Prevention, Control, and Countermeasure (SPCC) Regulation.

More resources on SPCC:

Applicable rules: 40 CFR 112.

Pollution Prevention

The following Pollution Prevention (P2) suggestions apply both to facilities with on-site incinerators and to those that send their infectious wastes off-site for incineration.

  • Segregate wastes at the source to minimize the volume of actual regulated medical waste (RMW). Further, isolate RMW that must be incinerated; depending on state regulations, at least a small portion of biohazardous waste, including sharps, may have to be incinerated. This will likely include pathological wastes and wastes contaminated with small amounts of chemotherapy substances.

  • Minimize the quantity of PVC plastics, products, and packaging (which comprise a portion of plastic wastes in healthcare) that are going to incineration.  These materials can create dioxins when incinerated.  Recycle plastics to the maximum extent possible.

  • Do not incinerate mercury wastes, including spill cleanup material.

  • Manage CFC-containing wastes separately from incineration wastes.

  • Implement alternative technologies for infectious wastes, including autoclaving, hydropulping, pyrolysis, microwave, chemical treatment, and irradiation.

More resources on Pollution Prevention:

Healthcare Environmental Resource Center (HERC). This site provides pollution prevention and regulatory information to the healthcare sector. In particular, see the Incinerators section.

The Sustainable Hospitals Project The Sustainable Hospitals Project provides health care personnel with tools, training and technical support to improve the environmental practices of hospitals and healthcare facilities.

Compliance and Enforcement Information

Applicability Determination Index (ADI).   The ADI is maintained by EPA's Office of Enforcement and Compliance Assurance (OECA) and provides a data base of memoranda dealing with applicability issues. The database is searchable by Subpart. Hint: use keyword search "HMIWI".

NCMS   Compliance Assistance Centers EPA