Tips on Using the NPRI Data

There are a number of other factors to consider in interpreting NPRI data

• The NPRI is a major starting point for identifying and monitoring sources of pollution, disposal and recycling activity by thousands of facilities in Canada. However, there are other sources and types of pollution that are not part of the NPRI. Click here for more information on this topic.
• Several hundred substances are listed on the NPRI. While some of these are parts of groups of substances with similar chemical properties and potential risks for the environment as well as the health of humans and nature, others are very different. This should be considered when comparing individual or groups of pollutants.
• Identification of risks to human health and the environment from pollution is complex and cannot be determined from NPRI data alone. Risk determination depends on many factors, such as the physical and chemical properties of the pollutant, its ability to cause harm to human health or the environment, the medium to which it is released (e.g., air, water or land), how, when and where it is broken down and the amount to which people or other organisms are actually exposed.
• Changes in amounts released, disposed of or recycled could be due to a number of factors, including changes to reporting requirements, the number of facilities reporting on the substance in a given year and the types of pollution prevention and control technologies used. Comparing facilities should also take into account whether or not the facilities are in the same sector and if they have similar regulatory requirements or production levels.
• Sometimes adding values reported by facilities can 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.
• 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.