Glossary of terms: National Pollutant Release Inventory

This glossary presents information on terms and expressions used by the National Pollutant Release Inventory.


Abrasive blasting:
The process of cleaning or texturing materials such as metals and ceramics with an abrasive material.
Acidic drainage:
A naturally-occurring process caused when rock materials containing sulphur are exposed to both oxygen and water, and when insufficient acid-neutralizing minerals are present. The produced acid can leach metals from surrounding rocks, causing drainage that has elevated levels of metals and dissolved salts. Rainfall and snowmelt flush the metal-laden acidic solutions from the waste sites into the downstream environment. If acidic drainage is left uncollected and untreated, the drainage could contaminate groundwater and local water courses, damaging the health of plants, wildlife, and fish.
Surrounding, or on all sides.
Metal products containing two or more elements as a solid solution, intermetallic compounds and mixtures of metallic phases.
Alternate threshold substances ( ATH):
Reporting for the majority of substances currently listed on the NPRI is triggered when the substance is manufactured, processed or otherwise used in quantities equal to or greater than 10 tonnes. However, there is a growing list of NPRI substances that have an alternate threshold ( ATH); and many of the substances that are being or will be added to the NPRI in future may require an ATH.
Area sources:
Small collective sources that are inventoried as a group, such as any small residential, governmental, institutional, commercial or industrial fuel combustion operations; on-site solid waste disposal facilities; and motor vehicles, aircraft, vessels or other transportation facilities; as well as other miscellaneous sources, which are too numerous to inventory as point sources.
A manufactured item that does not release a substance, listed in Schedule 1 of the Canada Gazette notice, when it undergoes processing or other use.


Base metal:
Copper, lead, nickel or zinc. It does not include aluminum or any other metals.
Biogenic emissions:
Biogenic emissions refer to emissions of volatile organic compounds from vegetation and emissions of nitrogen oxides from soil.
Biomedical or hospital waste:
Waste generated by human or animal health care facilities, medical or veterinary research and testing establishments, health care teaching establishments, clinical testing or research laboratories and facilities involved in the production or testing of vaccines. Biomedical or hospital waste includes human anatomical waste, animal waste, microbiology laboratory waste, human blood and body fluid waste and waste sharps that have not been disinfected or decontaminated. It does not include waste from animal husbandry or waste that is controlled in accordance with the Health of Animals Act (Canada).
An external combustion unit that turns water into steam for heating or power, or a tank for heating­ or storing water.
A substance, listed in Schedule 1 of the Canada Gazette notice, which is incidentally manufactured, processed or otherwise used at the facility at any concentration, and released on-site to the environment or disposed of.


Canada-wide standards ( CWS):
Intergovernmental agreements developed under the Canadian Council of Ministers of the Environment ( CCME) Canada-wide Environmental Standards Sub-Agreement, which operates under the broader CCM ECanada-wide Accord on Environmental Harmonization.
Carbon monoxide:
A colourless, odourless, poisonous gas formed during the incomplete combustion of fossil fuels or the incomplete oxidation of carbon to carbon dioxide.
CASRegistry Number (CAS No.):
The Chemical Abstracts Service Registry Number. (This is a standard identifier for all chemical substances.)
Commercial grade natural gas:
Consists of a high percentage of methane (generally above 85%) and varying amounts of ethane, propane, butane and inert gases.
Contiguous facility:
All buildings, equipment, structures and stationary items that are located on a single site, or on contiguous sites or adjacent sites that are owned or operated by the same person and that function as a single integrated site that includes wastewater collection systems that release treated or untreated wastewater into surface waters.
Criteria air contaminants ( CACs):
Emissions of criteria air contaminants contribute to smog, poor air quality and acid rain. CACs include Total Particulate Matter (TPM), Particulate Matter with a diameter less than 10 microns (PM10), Particulate Matter with a diameter less than 2.5 microns (PM2.5), Carbon Monoxide (CO), Nitrogen Oxides (NOx), Sulphur Oxides (SO x), Volatile Organic Compounds (VOC) and Ammonia (NH 3).
Cumulative nameplate capacity:
Total nameplate capacities of all stationary external combustion equipment at the facility.


The final disposal to landfill, land application or underground injection, either on the facility site or at a location off the facility site; transfer to a location off the facility site for storage or treatment prior to final disposal; or movement into an area where tailings or waste rock are discarded or stored, and further managed to reduce or prevent releases to air, water or land, either on the facility site or at a location off the facility site. The disposal of a substance is different from a direct release to air, water or land.


For the purposes of reporting criteria air contaminants (CACs) to the NPRI, any discharge of a CAC to air.
Emission factor ( EF):
The average emission/release rate of a given pollutant for a given source, relative to units of production or activity. EFs are usually expressed as a weight of contaminant divided by a unit weight, volume, distance or duration of associated activity that emits the pollutant (e.g., kg of SO 2 emitted per tonne of coal burned). EFs are usually obtained from data of varying degrees of accuracy and may be presented for either uncontrolled sources or facilities having air pollution control devices in place. The Canada Gazettenotice categorizes EFs as:
  1. "published emission factors", namely, those that have been published by the Government of Canada or another government or an industry association for application to an emission source that falls under the jurisdiction of the Government of Canada or another government or to emission sources of a specific industry sector; or
  2. "site-specific emission factors", namely, those that have been developed by an individual facility using their own specific emission-testing data and source-activity information.
An individual employed at the facility, including the owner of the facility who performs work on-site; and individuals, such as a contractor, who, at the facility, perform work that is related to the operations of the facility, for the period of time that the individual is performing that work.
The Environmental Protection Agency in the United States. It is the U.S. federal equivalent of Environment Canada.
External-combustion equipment:
Any equipment with a combustion process that occurs at atmospheric pressure and with excess air.


A contiguous facility, a portable facility, a pipeline installation, or an offshore installation.
The use of yeast, bacteria, enzymes, etc., to break down complex organic compounds, as in alcohol production and baking processes.
A container in which fermentation takes place.
Fossil fuel:
Fuel that is in a solid or liquid state at standard temperature and pressure, such as coal, petroleum or any solid or liquid fuel derived from such.
Fugitive emissions:
Air pollution derived from human activities that do not emanate from a particular point, such as an exhaust pipe or stack. Roadway dust and volatile organic compounds (VOCs) from refinery valves are examples of fugitive emissions.
Fugitive release:
The total of all releases to air that are not released through confined process streams. These releases include:
  • fugitive equipment leaks from valves, pump seals, flanges, compressors, sampling connections, open-ended lines, etc.,  
  • evaporative losses from surface impoundments and spills,
  • releases from building ventilation systems, and   
  • any other fugitive or non-point air emissions from land treatment, mine tailings, storage piles, etc.
Full-time employee equivalent:
The unit obtained by dividing by 2 000 hours, the sum of:
  1. the total hours worked by individuals employed at the facility, and the total hours of paid vacation and of sick leave taken by persons employed at the facility;
  2. the hours worked on site at the facility by the owner of the facility, if not employed by the facility; and
  3. the hours worked on site at the facility by a person, such as a contractor, who, at the facility, performs work related to the operations of the facility.


An internal combustion unit that produces gas or steam, or that changes mechanical energy into electrical energy.
A geographical zone for reporting and displaying emissions information. Grid sizes vary depending on their use. For example 100 km has been used for displaying emissions maps of Canada, but for ambient air quality modeling, grid sizes of 4 km or even 1 km may be used.


Hazardous waste:
Waste substances whose nature and quantity makes them potentially dangerous to human health and/or the environment, and that require special handling techniques.
Heavy metals:
A group of metals that have a relatively high atomic mass and are of particular concern for human health and the environment. Some examples are Lead (Pb), Cadmium (Cd), and Mercury (Hg).
Heavy-duty vehicle:
A motor vehicle that is rated at more than 3 856 kg (8 500 lbs.) Gross Vehicle Weight Rating ( GVWR) [includes eight weight categories each of Heavy-Duty Gasoline Trucks and Heavy-Duty Diesel Vehicles].


Industrial space heater:
An external combustion unit used to heat a single confined area.
Internal combustion equipment:
Equipment with a combustion process that occurs in a confined space and above atmospheric pressure.
Refers specifically to the term “isokinetic source sampling,” which means sampling in a manner where the linear velocity of the gas entering the sampling nozzle is equal to that of the undisturbed gas stream at the sampling point.


Key air pollutants:

Through the National Pollutant Release Inventory, Environment Canada tracks pollutant releases, disposals and transfers for recycling of over 300 pollutants from industrial and other facilities. For 17 of these pollutants, Environment Canada also compiles air emission estimates for non-industrial sources such as motor vehicles, residential heating and agriculture. Combined, this information provides a complete picture for air emission sources of these key air pollutants.

The key air pollutants are the main pollutants that contribute to smog, acid rain and poor air quality, or are of particular concern to human health and the environment due to their persistence, bioaccumulation and toxicity. Information for these pollutants is also required to fulfill international reporting obligations.

These pollutants are included in three main groups:

Criteria Air Contaminants (CACs): Emissions of criteria air contaminants contribute to smog, poor air quality and acid rain. CACs include Total Particulate Matter (TPM), Particulate Matter less than or equal to 10 Microns (PM10), Particulate Matter less than or equal to 2.5 Microns (PM2.5), Sulphur Oxides (SOx), Nitrogen Oxides (NOx), Volatile Organic Compounds (VOCs), Carbon Monoxide (CO) and Ammonia (NH3).

Heavy Metals: A group of metals that have a relatively high atomic mass and are of particular concern for human health and the environment. Data on air emissions in Canada from all sources is available for the following heavy metals: Lead (Pb), Cadmium (Cd) and Mercury (Hg).

Persistent Organic Pollutants (POPs): Organic compounds that are resistant to environmental degradation and have been associated with adverse effects on human health and the environment. Data on air emissions in Canada from all sources is available for the following POPs: Dioxins and Furans (DF), Benzo[a]pyrene, Benzo[b]fluoranthene, Benzo[k]fluoranthene, Indeno[1,2,3-cd]pyrene, and Hexachlorobenzene (HCB).


Level of quantification:
The lowest concentration of a substance that can be accurately measured using sensitive but routine sampling and analytical methods.
Light-duty vehicle:
A vehicle that is rated at 3 856 kg (8 500 lbs.) Gross Vehicle Weight Rating or less, that has a curb weight of 2 722 kg (6 000 lbs.) or less and a basic vehicle frontal area of 4.2 m 2(45 square feet) or less and that is:
  • designed primarily for the transportation of property or that is a derivative of a vehicle that is so designated;
  • designed primarily for the transportation of persons and has a designated seating capacity of more than 12 persons; or
  • available with special features that enables it to be operated and used off-road.
    (Includes Light-Duty Gasoline Trucks and Light-Duty Diesel Trucks).
Liquefied petroleum gas (LPG or LP-gas):
Consists of propane, propylene, butane and butylenes; however, the most common LPG is propane. There are two grades of LPG available as heating fuels. Grade 1 fuel is intended for use in internal combustion engines operating under moderate to high engine severity while Grade 2 fuel is adequate for most industrial uses, especially where low ambient temperatures exist and uniform fuel volatility is important. Propane is also used as an alternative to gasoline and as a standby fuel for facilities with interruptible natural gas service contracts.
Any domestic or domesticated animal including bovine (cattle, buffalo and bison), ovine (sheep), porcine (pigs), caprine (goats), equine (horses, donkeys and mules), poultry (chicken, turkey, ducks, geese and quails) and bees raised for food or used in the production of food (products of hunting or fishing of wild animals are not considered part of this definition).


To produce, prepare or compound a substance listed in Schedule 1 of the Canada Gazette notice and includes the coincidental production of a substance, listed in Schedule 1, as a by-product as a result of the manufacturing, processing or other use of any other substances.
Marine transportation:
This sub-sector covers commercial marine vessels, but not land-based port support equipment, loading/unloading equipment or recreational marine vessels (captured under off-road applications).
Includes exploitation of oil sands, but does not include peat mining or any other mines that are closed.
Mobile source:
A segment of the area source classification representing transportation sources such as wheeled vehicles, ships, aircraft and railroad locomotives.


Nameplate capacity:
The total designed energy input capacity of the external stationary combustion equipment.
Natural sources:
Emission sources such as biogenic emissions from vegetation, biological and geological sources, wildfires, and other sources not made by man.
Non-hazardous solid waste:
Waste, regardless of origin, that might normally be disposed of in a non-secure manner, such as at a sanitary landfill site, if not incinerated.
Number (or Type) 1 or 2 fuel oils:
Distillate oils suitable for use in liquid fuel-burning equipment without preheating. Type 1 fuel oil is primarily intended for use in sleeve type, wick-fed and most vaporizing pot-type burners. Type 2 fuel oil is a heavier distillate than Type 1, and is intended for use in medium-capacity, commercial-industrial burners, where ease of handling and availability justify its use. Neither Type 1 nor 2 fuel oils include heavy fuel oils or residual oils.


Off-road engines:
Emissions from this sector result from the use of fuel in a diverse collection of vehicles and equipment such as recreational vehicles (e.g. all-terrain vehicles and off-road motorcycles), logging equipment (e.g. chain saws), agricultural equipment (e.g. tractors), construction equipment (e.g. graders and back hoes), industrial equipment (e.g. fork lifts and sweepers), residential and commercial lawn and garden equipment (e.g. leaf and snow blowers); and recreational marine vessels (e.g. power boats and personal water craft).
Offshore installation:
An offshore drilling unit, production platform or ship, or subsea installation that is related to the exploitation of oil or natural gas and that is attached or anchored to the continental shelf of Canada or within Canada's exclusive economic zone.
Open sources:
Sources that emit air contaminants over large geographical areas, primarily in a stationary but non-point source manner, and are diffuse in nature. In general, these emissions are dispersed over too great an area to allow control by conventional equipment that requires enclosures or ducting to be effective. Examples include dust from farms, construction, and paved and unpaved roads.
Other use:
In respect of a substance listed in Schedule 1 of the Canada Gazette notice, any use, disposal or release of that substance which is not included under the definitions of "manufacture" or "process".
Oxides of nitrogen (expressed as NO 2) :
Includes nitric oxide (NO) (CAS No. 10102-43-9) and nitrogen dioxide (NO 2) (CAS No. 1012-44-0). Nitrogen and oxygen in air at high temperatures can combine to form nitrogen oxides (NO x). Therefore, fuel combustion at high temperatures and industrial processes produce NO x. In addition, the nitrogen content found in fuels also increases the amount of NO x produced.


Parent company:
The highest level company or group of companies that own or directly control the reporting facility.
Particulate matter:
Microscopic solid and liquid particles, of various origins, that remain suspended in the air for any length of time. Only filterable PM is reportable to NPRI. The NPRI breaks down particulate matter into the following categories:
Total particulate matter ( TPM):
Any particulate matter with a diameter less than 100 microns.
Particulate matter less than or equal to 2.5 microns ( PM 2.5):
Any particulate matter with a diameter less than or equal to 2.5 microns
Particulate matter less than or equal to 10 microns ( PM 10):
Any particulate matter with a diameter less than or equal to 10 microns
Paved road:
Any road that has semi-permanent surface placed on it such as asphalt or concrete.
Persistent organic pollutants (POPs):
Organic compounds that are resistant to environmental degradation and have been associated with adverse effects on human health and the environment, such as dioxins and furans (DFs), polycyclic aromatic hydrocarbons (PAHs) and hexachlorobenzene (HCB).
Pipeline installation:
A collection of equipment situated at a single site, used in the operation of a natural gas transmission or distribution pipeline.
An excavation that is open to the air and that is operated for the purpose of extracting sand, clay, marl, earth, shale, gravel, stone or other rock but not coal, a coal-bearing substance, oil sands, or oil sands-bearing substance or an ammonite shell and includes any associated infrastructure, but does not include a quarry.
Point sources:
Any stationary source that usually releases emissions through stacks or other emissions sources, for which individual source records are maintained in the inventory and for which annual emissions exceed a specified cut-off level. These stationary sources include NPRI facilities or other operations with a specific geographical location that may be inventoried through provincial programs or other means (e.g. Federal / Provincial / Industrial Association collaborative projects) and included as part of the point sources category in the comprehensive emissions inventories.
Pollution prevention:
The use of processes, practices, materials, products, substances or energy that avoid or minimize the creation of pollutants and waste, and reduce the overall risk to the environment or human health.
Portable facility:
Portable polychlorinated biphenyl ( PCB) destruction equipment, portable asphalt plants and portable concrete batching plants.
The concentration in units of parts per million.
The preparation of a substance listed in Schedule 1 of the Canada Gazette notice, after its manufacture, for commercial distribution and includes preparation of a substance in the same physical state or chemical form as that received by the facility, or preparation which produces a change in physical state or chemical form.


An excavation that is open to the air and that is operated for the purpose of working, recovering and extracting stone, limestone, sandstone, dolostone, marble, granite, construction materials and any mineral other than coal, a coal-bearing substance, oil sands, or oil sands-bearing substance or an ammonite shell and includes any associated infrastructure but does not include a pit.


Any activity that prevents a material or a component of the material from becoming a material destined for disposal.
The emission or discharge of a substance from the facility site to air, surface waters, or land and includes a spill or leak.


Secondary aluminum:
Aluminum-bearing scrap or aluminum-bearing materials.
Secondary lead:
Lead-bearing scrap or lead-bearing materials, other than lead-bearing concentrates derived from a mining operation.
A grouping of similar industries, or other entities that are involved with common activities, such as petroleum refining or aluminium production. In many instances, a Standard Industrial Classification ( SIC) code and/or a North American Industrial Classification ( NAICS) code are used to describe an industry or activity for purposes of facilitating the collection, assimilation and reporting of data relating to the establishment.
Sewage sludge:
Sludge from a facility treating wastewater from a sanitary sewer system. The drying of sludge to reduce water content is part of the incineration stage.
To cause something to become a coherent mass by heating without melting or the growth of contact area between two or more initially distinct particles at temperatures below the melting point, but above one-half of the melting point (in Kelvin).
A semi-liquid mass removed from a liquid flow of wastes.
The melting of raw or scrap materials (containing metals) to produce metal for further processing into metal products (e.g., castings, ingots, sheets).
A "source" is an Area Source, a Mobile Source, a Natural Source, an Open Source, or a Point Source
Stationary combustion equipment:
Combustion equipment that needs to be stationary in order to function or operate properly or is not capable of self-propulsion.
Stationary, external combustion equipment:
Stationary equipment with a combustion process that occurs at atmospheric pressure and with excess air. This may include thermal electric generating plants, industrial boilers and commercial and domestic combustion units. Commercial grade natural gas, liquefied petroleum gas and Number 1 and 2 fuel oils are among the fuels used.
Sulphur dioxide (SO 2):
Formed during oxidation reactions involving sulphur and oxygen. SO 2 emissions are generated primarily from the smelting of ore and fuel combustion.


Terminal operations:
  1. The use of storage tanks and associated equipment at a site used to store or transfer crude oil, artificial crude or intermediates of fuel products into or out of a pipeline; or
  2. Operating activities of a primary distribution installation normally equipped with floating roof tanks that receives gasoline by pipeline, railcar, marine vessel or directly from a refinery.
Toxicity equivalent ( TEQ):
A mass or concentration that is a sum of the masses or concentrations of individual congeners of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans multiplied by weighting factors set out in the Guide for Reporting to the National Pollutant Release Inventory. There are two schemes currently in use: the World Health Organization (WHO) Toxicity Equivalency (WHO-TEQ) and the North Atlantic Treaty Organization/Committee on the Challenges of Modern Society (NATO/CCMS) Working Group on Dioxins and Related Compounds as International Toxicity Equivalency Factors ( I-TEF). The main differences between these two schemes are the factors for octochloro-dibenzodioxin and octochlorodibenzofuran and the inclusion of co-plannar PCBs in the WHO-TEQ. The NPRI uses the I-TEF scheme.
Toxic substances:
Section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999) defines a substance as toxic "if it is entering or may enter the environment in a quantity or concentration or under conditions that:
  1. have or may have an immediate or long-term harmful effect on the environment or its biological diversity;
  2. constitute or may constitute a danger to the environment on which life depends;
  3. or constitute or may constitute a danger in Canada to human life or health."
An NPRI-listed substance may be transferred to a location off the facility site for treatment prior to final disposal or for recycling and energy recovery.
Subjecting a substance to physical, chemical, biological or thermal processes at a location off the facility site prior to final disposal.
An internal combustion unit that is driven by the pressure of steam, water, air, etc., against the curved vanes of a wheel or set of wheels attached to a drive shaft.


Unpaved roads:
Includes roads such as gravel surfaced roads, roads with thin membrane bituminous surface treatment and roads with bituminous cold mix surfaces.


Virtual elimination:
The "virtual elimination" of a toxic substance released into the environment as a result of human activity is defined in subsection 65(1) of the Canadian Environmental Protection Act, 1999 (CEPA 1999), as “the ultimate reduction in the quantity or concentration of the substance in the release below the level of quantification.” Substances that are determined to be CEPA-toxic, persistent, bioaccumulative and primarily the result of human activity are slated for virtual elimination.
Volatile organic compounds ( VOCs):
Volatile organic compounds that participate in atmospheric photochemical reactions, excluding compounds such as methane, ethane, acetone, methylene chloride, methyl chloroform and several chlorinated organics, as defined in the List of Toxic Substances in Schedule 1 of the Canadian Environmental Protection Act, 1999 (CEPA 1999).


Waste incinerator:
A device, mechanism or structure constructed primarily to thermally treat (e.g., combust or pyrolyze) a waste for the purpose of reducing its volume or destroying hazardous chemicals or pathogens present in the waste.
Wastewater collection system:
A system of sewers and/or ditches that convey sanitary or combined sewage for a community. A collection system includes adjacent service areas or adjoining sewage sheds that function as a single integrated system for a community.
Wastewater treatment system:
A plant or process location that accepts collection system flows of a community for the purposes of removing substances from the wastewater.
Wood preservation:
The use of a preservative for the preservation of wood by means of heat or pressure treatment, or both, and includes the manufacture, blending or reformulation of wood preservatives for that purpose.

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