General Considerations
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Some pollutants of concern are not reported to the NPRI. For example, the
Government of Canada regulates pesticides and tracks emissions of greenhouse
gases in Canada through programs other than the NPRI.
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Some of the pollution in Canada originates in other countries. This is known as
transboundary pollution, and it is a key source of smog-forming pollutants and
other air pollution in certain areas of Canada.
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Not all pollutants are equally hazardous.
o Identification of risks to human health and the environment from pollution
is complex and cannot be determined from NPRI data alone. Environment
Canada and Health Canada continue to assess the health and
environmental risks of chemical substances.
o A pollutant's potential to cause harm to human health and the environment
depends on a variety of factors, including its toxicity; whether it is
released to air, land or water; if and to what extent it is broken down in the
environment; and the resulting amount, nature and level of exposure for
people and other organisms.
 NPRI reporting requirements have evolved over time to provide more comprehensive
information on pollution in Canada. Substances have been added, thresholds (limits) at
which substances must be reported have been reduced, and exemptions for several
industry sectors have been eliminated. These changes need to be taken into account when
conducting trend analysis based on NPRI data.
 There are a variety of reasons why facilities may report different amounts of pollutants
that they release, dispose of or recycle from year to year. These reasons range from new
reporting requirements (as highlighted above), to changing production levels, facility
expansions and process modifications. Reported data may also be updated from time to
time as new or more up-to-date information is received and reviewed.
 Adding values reported by facilities may result in errors. For example, this may occur
when a facility generates pollutants and transfers them to another site to manage disposal,
which then transfers them to a third facility for disposal. In this case, "double-counting"
of the off-site disposal may occur between the originating facility and the second one.
 Total reduced sulphur consists of 6 substances. Three of these substances (hydrogen
sulphide [H2S], carbon disulphide [CS2] and carbonyl sulfide [COS]) are also listed
individually in the NPRI substance list. When conducting analysis of NPRI data, caution
should be taken to avoid "double counting" of total reduced sulphur and these
individually-listed substances.
 Facilities may use different methods to determine how much of a particular substance
they release, dispose of or recycle. These methods may vary depending on the substance
or the facility and may also change from year to year. Estimation and direct measurement
are examples of these methods.
 Emission summaries and trends for a given year may be different from those
previously published by Environment Canada, other governmental agencies and
international organizations.
 A portion of emissions from the Marine Transportation sector is attributed to
movement (“innocent passage”) of domestic and international commercial vehicles
through provincial waters. These emissions have been proportionally allocated to the
provinces nearest to the release of the emissions in the different waterways.
 Mercury emissions from products are included in the 2007 and 2008 estimates,
however, they are not yet included in the estimates from previous years. Updates to
historical trends are currently being compiled and will be published in the near future.
Highlights
Overall, air emissions of criteria air contaminants, certain heavy metals and persistent
organic pollutants declined between 1990 and 2008, with the exception of emissions from
open and natural sources. For natural and open sources there have been slight year-toyear increases since 1990 for some pollutants, such as particulate matter emissions from
construction and agriculture due to growth in these activities, and from road dust due to
growth in vehicle kilometres travelled.
Emissions from Mobile, Industrial, Commercial and Residential Sources (1990–
2008)
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Sulphur oxide (SOx) emissions declined by 46%, with reductions from fossil
fuel-fired electricity generating utilities and base metal smelters.
Nitrogen oxide (NOx) emissions decreased by 15%, with emission decreases
from on-road vehicles partially offset by increases from oil and gas extraction.
Volatile organic compound (VOCs) emissions decreased by 25%, due to
reductions from mobile sources and small reductions from many industries.
Emissions of Particulate Matter less than or equal to 2.5 Microns (PM2.5)
decreased by 31%. Large reductions occurred from fossil fuel-fired electricity
generating utilities, wood products and pulp and paper industries, and from
mobile sources.
Air emissions of ammonia decreased by 14% factoring in reductions from
industrial sources and increases from mobile sources.
Lead and cadmium emissions declined by 79% and 75% respectively due
primarily reductions from the nonferrous (base metal) smelting and refining
sector. Lead emissions from aviation fuel use also decreased.
Dioxins and furan emissions decreased by 89%, primarily due to large
reductions from incineration activities, the iron and steel sector and the pulp and
paper sector.
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Emissions of polycyclic aromatic hydrocarbons (PAHs)* declined by 58%.
Reductions from mobile sources as well as the aluminum and iron and steel
sectors were partially offset by increases from residential wood combustion.*
Hexachlorobenzene emissions decreased due to reductions from municipal
incineration and fossil fuel-fired electricity generating utilities.
Emissions from Natural and Open Sources (1990–2008)
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Emissions from open and natural sources such as road dust, construction,
agricultural activities and forest fires increased between 1990 and 2008. In
Canada, natural and open sources are the largest sources of emissions of
particulate matter, volatile organic compounds and ammonia.