The Canadian National Pollutant Release Inventory (NPRI) is a federal program that strives to collect data on the release, disposal, and transfer of harmful pollutants across the country. Developed as part of the government’s Green Plan Initiative and mandated by the Canadian Environmental Protection Act of 1999, the program obligates owners and operators of facilities making use of these substances to report the quantities they emit or otherwise discharge into the environment every year. The collected information is ultimately made available to the public to enable individuals to track pollutants in their backyards and to empower provincial and municipal governments to monitor environmental performance and implement corrective policies.

    Unfortunately, knowing what, how, and whether your facility is required to report can be a tough nut to crack. The Government of Canada’s website is certainly thorough, but the exact piece of information people are looking for is often hidden within or scattered among the countless webpages on the site.

    For that reason, ERA compiled and reviewed all available materials, including the 155-page 2022-2024 Guide for Reporting to the NPRI, to prepare an overview of everything you, as a potential reporter, must know as far as NPRI reporting requirements go. Read it in tandem with our NPRI eBook (which you can download for free below) for all the answers you are looking for.

    We have structured this page to reflect the order in which you should ask yourself questions when determining whether your facility must submit an NPRI report or not, but you are welcome to jump to a particular topic using the Table of Contents.



    The Three Main NPRI Emissions Reporting Criteria

    There are three criteria that define a facility's NPRI status.

    1. Employee count

    2. Facility purpose

    3. Substances present

    Employee count should be simple enough to work out. If the total number of annual labour hours adds up to 20,000 or more, you meet the requirement. This value often translates to 10 full-time employees, but even facilities that operate with fewer people year-round exceed that threshold when they account for the hours worked by the owner(s), students, part-time and term employees, and contractors. In some cases, including paid overtime, vacation hours, and sick leave in the calculation is enough to tip the scales!

    That said, there are certain activities that may require reporting irrespective of the total number of labour hours worked at the facility where they took place. We have listed them out in full as an Appendix at the bottom of the page.

    In short, if there are 10 or more full-time employees at your facility, or if there aren’t but your facility is engaged in an employee-threshold-exempt activity, it is most likely subject to NPRI reporting.


    Who Has to Report to NPRI Canada — ECCC Facility Categorization

    In 2021, 7,191 industrial facilities submitted NPRI reports -- read the highlights for more information. These facilities were divided into three main categories: industrial (mines, sawmills, oil and gas extraction facilities, etc.), treatment (waste incinerators and large municipal sewage treatment plants), and service (stationary establishments like airports and power plants). 5,472 (76%) of those facilities fell under the manufacturing and oil and gas extraction industry sectors, making facilities in the first category the clear target of NPRI compliance monitoring.

    However, even if your facility is the most polluting of industrial emitters, it must still match one of the following Environment and Climate Change Canada (ECCC) facility categories before it can be considered a probable reporter.

    1. Contiguous: A facility that functions as a single integrated site, operated by the same person or company. It encompasses all buildings, equipment, structures, stationary items, and wastewater collection systems on site.
      1. In general, owners/operators of contiguous facilities report substances in one or more of all five parts (see “NPRI Chemical Substances” section below).

    2. Portable: A facility that is capable of being entirely relocated for operation. As far as NPRI data collection is concerned, these usually consist of polychlorinated biphenyl (PCB) destruction equipment, asphalt plants, and concrete batching plants.
      1. In general, owners/operators of portable facilities submit reports for substances in one or more of parts 2 to 5.

    3. Pipeline Installation: A facility at a single site as composed of equipment used in the operation of a natural gas transmission or distribution pipeline, including pipeline compressors and storage stations along pipelines.
      1. In general, owners/operators of pipeline installation facilities are only subject to the reporting criteria for CACs (Part 4) and speciated VOCs (Part 5).

    4. Offshore: Drilling units, production platforms, ships, or subsea installations for the exploitation of oil or natural gas. These must be anchored to the continental shelf of Canada, or within Canada’s economic zone, to be required to report.
      1. In general, owners/operators of offshore installations report substances in one or more of all five parts.


    Once you have established that your facility fits one of the four descriptions above (as it likely does) and exceeds the labour hours (employee count) threshold, the next order of business is studying the exemption criteria for both facilities and activities.


    NPRI Reporting Exemptions: Facilities

    If one (or more) of the three activities listed here is the ONLY activity taking place at your facility, your facility is exempt from NPRI reporting

    • Exploration for oil and gas OR the drilling of oil or gas wells
    • Discharge of wastewater (treated or untreated) from a wastewater collection system, as long as the average daily discharge is equal to 10,000 m3 or less
    • Production of 500,000 tonnes or less at pits or quarries, excluding open-pit mines (which are always subject to NPRI annual reporting)


    NPRI Reporting Exemptions: Activities

    If the sole source or use of a substance in PARTS 1 TO 3 is from one of the activities listed here, your facility is exempt from reporting PARTS 1 TO 3

    • The education or training of students
    • Research, testing, or development
    • Maintenance and repair of vehicles (see our eBook for more details)
    • Distribution, storage, or retail sale of fuels, except as part of terminal operations
    • Wholesale or retail sale of articles/products that contain a substance in parts 1 to 3, or the retail sale of the substance itself
    • The growth, harvest, or management of renewable natural resources
    • Dentistry


    Annual Re-evaluation

    Keeping up with changes in NPRI reporting requirements will not grant you an exemption per se, but it could mean the difference between meeting the reporting criteria and having the simplest reporting season possible.

    Take the number of facilities that reported in 2020, for example. 8,411 facilities reported to the NPRI; as shown above, that number dropped to 7,191 in 2021. Suddenly, there were 1,067 facilities that did not meet the reporting criteria (and a couple hundred that disappeared, likely due to shutting down operations). While it is entirely possible that these facilities suffered from COVID-induced downturn, the decline can in part be explained by changes to the substance list. Certain facilities fluctuate between being above and below NPRI reporting thresholds, and as the thresholds themselves change and substances are constantly added or removed from the NPRI list, these (usually smaller) facilities may find they are not obligated to submit a report for a given year.

    That is why, as a reporter, you should study the annual changes to NPRI toxic substances and re-evaluate report quantities after significant alterations to your facility’s operations, such as changes in production levels, plant expansions, implementation of pollution prevention measures, accidental releases, etc.

    Facilities that no longer meet NPRI reporting criteria but did file a report in the previous year will only be required to submit a “Does Not Meet Criteria” report.


    What to Include in Environmental Reporting — NPRI Chemical Substances

    The foundation of the Canadian pollutant inventory is the 320+ substances that form part of its official list, all of which may pose a risk to the environment or to human health. Only facilities that release, dispose of, or transfer off-site one (or more) of these substances at or above its reporting threshold are the focus of NPRI reporting, provided they also satisfy the employee count and facility category criteria above.

    For those in need of clarification, the three processes of concern have specific definitions:

    • Releases: direct discharges, whether routine or accidental, of pollutants into the environment (air, water, land) within the physical boundaries of the facility

    • Disposals: Any form of management of a substance to limit its release, including landfilling, land application, or underground injection, either on the facility site or at a location off it

    • Transfers: Transport of a substance off the facility site to a location where it is treated (physically, chemically, biologically, thermally, or in a municipal wastewater treatment plant) prior to final disposal or for recycling and energy recovery

    If you meet all three NPRI reporting requirements, you must report the total quantities of NPRI substances that underwent any of these processes, even if the quantity is zero.

    Your safest bet would be to search the most recent NPRI substance list for the chemicals in your facility, identify the pollutant category (parts 1 to 5) they belong to, and follow the guidelines (outlined below) for each chemical one by one. Alternatively, you could enlist the help of a reliable software that automatically identifies the substances in your facility reportable to the NPRI, calculates whether any of them exceeds its individual threshold, and implements Environment Canada updates entirely free of charge.


    What Does MPO Mean in NPRI Reporting?

    Before delving into substances on parts 1A or 1B, we should define an acronym that features prominently in reporting determinations for this category: Manufacture, Process, or Otherwise Use (MPO). When reporting for these parts, you will more often than not have to calculate the quantity of the substance that was MPO.

    The manufacture of a substance refers to its production, preparation, or compounding, including the incidental production of a substance as a by-product from the MPO of other substances. Consider, for example, the production of hydrochloric acid during the manufacture of chlorofluorocarbons (CFCs).

    Processing a substance entails preparing it, after its manufacture, for distribution in commerce, with or without changes in physical state or chemical form. One example of processing would be the use of chlorine to manufacture hypochloric acid, which is not itself an NPRI substance.

    Otherwise Use encompasses any form of use, disposal, or release of a substance that is not accounted for by either of the previous definitions, including uses as chemical processing or manufacturing aids.

    REMEMBER: the quantity of a substance that is MPO is NOT reported to the NPRI. It merely serves to indicate whether you must calculate said substance’s releases, disposals, and transfers for reporting to the NPRI, which is done whenever the MPO threshold is met.


    NPRI Pollutant Categories: Parts 1A and 1B


    Over half of the substances and groups of substances in the entire list—181 as of June 2023, to be precise—belong to this subset of part 1. Most have been on it since the very beginning of the NPRI, as they are widely known to be damaging to health and ecosystems (think carcinogens, like benzene, or compounds that release GHGs into the atmosphere, such as the production of nitric acid).

    Almost all of these obey a simple rule of thumb: report a part 1A substance if it was MPO in a quantity of 10 tonnes or more AND at a concentration (by weight) of 1% or more. No concentration threshold applies to incidentally MPO substances and by-products, or to substances contained in tailings disposed of during the calendar year.

    Reporters also have the option to report releases smaller than one tonne as “releases to unspecified media”, which count as on-site releases.

    Lastly, don’t forget to review the table of reporting qualifiers (2022-2024 Guide, page 50) for substances that deviate from the norm, such as those that are only reported in certain forms or as aggregates.


    Given their potential for significant adverse effects at relatively low levels, the 23 substances in this subpart have lower reporting thresholds than those in part 1A, hence their name.

    The reportable amount varies considerably by substance. The best way of ascertaining whether your facility must file a report for these (without the reliance on software) is to go through the whole list and study your records in search of substances that were present at a total quantity at or above their distinct mass thresholds AND MPO at or above their distinct concentration thresholds. Once again, no concentration threshold applies to incidentally MPO substances and by-products; substances contained in tailings or in waste rock that is not inert are also concentration independent.

    Mass and Concentration Thresholds for All Part 1B Substances

    Source: 2022-2024 Guide for Reporting to the NPRI (page 54)
    Substance/Substance Group Mass Threshold (kg) Concentration Threshold (by weight)
    Acrylonitrile 1,000 0.1%
    Arsenic (and its compounds) 50 0.1%
    Azo disperse dyes 10 0.1%
    1,4-Benzenediamine, N,N’-mixed phenyl and tolyl derivatives 50 1%
    Bisphenol A 100 1%
    Cadmium (and its compounds) 5 0.1%
    Chlorhexidine (and its salts) 100 1%
    Chlorinated alkanes, medium-chain, CnHxCl(2n+2–x), 14 ≤ n ≤ 17 1,000 1%
    Chlorinated alkanes, long-chain, CnHxCl(2n+2–x), 18 ≤ n ≤ 20 1,000 1%
    Cobalt (and its compounds) 50 0.1%
    Hexavalent chromium (and its compounds) 50 0.1%
    Hydrazine (and its salts) 1,000 1%
    Isoprene 100 1%
    Lead (and its compounds) 50 0.1%
    Mercury (and its compounds) 5 N/A
    Nonylphenol and its ethoxylates 1,000 1%
    2-Propanone, reaction products with diphenylamine 50 1%
    Selenium (and its compounds) 100 0.000005%
    Tetraethyl lead 50 0.1%
    Thallium (and its compounds) 100 1%
    Toluene-2,4-diisocyanate 100 0.1%
    Toluene-2,6-diisocyanate 100 0.1%
    Toluenediisocyanate (mixed isomers) 100 0.1%


    NPRI Pollutant Categories: Part 2

    A total of 31 polycyclic aromatic hydrocarbons (PAHs) make up the part 2 substances of the NPRI list. They are used as commercial chemicals, incidentally manufactured as a result of industrial processes and during combustion, or contained in tailings.

    With the exception of facilities that preserve wood using creosote, which report regardless of quantities and hours worked by employees, reporting takes place whenever 50 kgs or more of all (aggregated) PAHs are released, disposed of, or transferred off-site either as a result of incidental manufacture and/or as a result of the generation of tailings.

    If an individual PAH is reported, the threshold goes down to 5 kg.


    NPRI Pollutant Categories: Part 3

    Reporting for the 7 polychlorinated dibenzo-p-dioxins (dioxins), 10 polychlorinated dibenzofurans (furans), and hexachlorobenzene substance that compose part 3 is entirely dependent on the activities that take place at the facility where these substances are present (as opposed to their quantity or concentration).

    There is no shorthand for determining whether you are required to report or not. You should read each item in the infographic below and calculate the quantities of dioxins, furans, and hexachlorobenzene that result from the activities listed, then compare them (the quantities) to the level of quantification (LoQ) for each substance and material state – refer to our eBook for a table showing all the estimated LoQs.

    Quantities greater than or equal to LoQ must be reported; quantities lower than the LoQ are optional. All quantities that were estimated (via remote quantification, mass balance, emission factors, etc.; see “Methods of Estimate” section below) must be reported, no comparison to the LoQs needed.



    NPRI Pollutant Categories: Part 4

    Criteria Air Contaminants (CACs) are a group of pollutants that can cause or contribute to smog, acid rain, and other air quality issues. There are seven total: carbon monoxide, nitrogen oxides (expressed on an NO2-equivalent basis), PM2.5, PM10 (which includes PM2.5), total particulate matter (which includes PM2.5 and PM10), sulphur dioxide (SO2), and volatile organic compounds (total).

    Reporting for CACs is based on the total quantity released into the air, rather than the quantity MPO. There are, however, a handful of conditions your facility and its activities have to meet to classify as Case 1 and 2 facilities subject to reporting.

    You facility must submit a report for a part 4 substance if it meets one of the following criteria AND if the substance is released to air at a total quantity greater than or equal to its threshold.


    There are, unfortunately, a handful of conditions and caveats too numerous and lengthy to spell out here that govern CAC emission calculations, exemptions from reporting according to the type of fuel and nameplate capacity at your facility, and the height of the stacks qualifying for stack-specific releases. For all these criteria and NPRI reporting guidance for Part 4, refer to our eBook.

    [Note that Cases 3 and 4 are reserved to facilities in the oil and gas extraction sector that do not meet the employee threshold. These have their own guide to reporting, separate from the guidelines described here].


    NPRI Pollutant Categories: Part 5

    Part 5 is reserved to speciated Volatile Organic Compounds (VOCs), 62 of which are included in the NPRI list. They are similar to Part 4 substances in that reporting is based on releases to air; indeed, speciated VOCs are contained in the “VOCs (total)” group of pollutants for part 4, but they obey much stricter thresholds.

    Starting this year, RY 2022, facilities are subject to reporting for part 5 if they emit a speciated Volatile Organic Compound (VOC) above 1 tonne. The 10-tonne total VOCs threshold (for part 4) no longer applies to reporting speciated VOCs. Only the 0.25 tonnes emissions threshold for speciated VOCs released from an individual stack applies, in addition to the stack release thresholds (see our eBook).

    Don’t forget that part 5 substances are reported as BOTH the total for each individual stack that exceeds the threshold (0.25 tonnes) AND the total of all other releases, not from individual stacks, that exceed the threshold (1 tonne).

    When calculating releases of speciated VOCs, you will also need to take certain qualifiers into account. For example, hexane should be reported as the total of all isomers, found by aggregating individual isomers, except n-hexane (110-54-3). A complete list of Qualifiers for part 5 speciated VOCs is available on our eBook.

    It is common to be overwhelmed by the frequent changes to annual NPRI reporting guidelines, such as the new reporting threshold for speciated VOCs. The ECCC publishes a list every year, but even the most well-versed reporters need at least a few hours every quarter to go through the website and dissect what the changes mean for their chemical inventories. Ideally, you should have some sort of system that flags these updates and the affected chemicals—some companies use spreadsheets, others use Environmental Management Software that implements these modifications into their reporting engine (entirely free of charge!).


    NPRI Reporting Exemptions: Substance Exclusions

    Not all pollutants are created equal. The quantities of some substances should not be included when calculating whether said substance exceeds the reporting threshold; they should also be excluded when reporting releases, disposals, and transfers.

    The following should not be considered during threshold calculations

    • Substances in materials used as structural parts of the facility building (not process equipment)
    • Substances used for janitorial purposes or maintenance (note that this does not include the cleaning of processing equipment, such as spray booths)
    • Articles (pre-manufactured items) that do not emit NPRI substances during use (for example, a sealed glass bulb containing mercury)
    • Substances in materials for personal use by employees
    • Substances already in the water or air taken into the facility during operations (such as for cooling)
    • Substances MPO during the exploration for oil or gas or in the drilling of oil or gas wells, from initial exploration to production
    • Vehicle emissions (excluding unpaved road dust)


    For information on substance exclusions for tailings and waste rock, refer to page 13 of our eBook.


    How to Report to NPRI Canada — Methods of Estimate and Emissions Tracking

    Working out substance quantities for the pollutants at your facility can be an upsetting rigmarole, further complicated by the fact that ALL releases, disposals, or transfers (not just those that are measured or monitored) must be included in threshold calculations. That means you must go through the “trouble” of calculating or estimating the quantities of any substance that meets or exceeds its reporting threshold, even if you are not actively measuring or monitoring it.

    Thankfully, if you are left with no choice but to estimate the quantity of a substance manufactured, processed, or otherwise used at your facility, or the quantity released, disposed, or transferred, you may use any one of nine methods of estimate:

    • Continuous Emission Monitoring Systems (CEMS) that record emissions over an extended and uninterrupted period

    • Predictive Emission Monitoring (PEM) that correlates substance emission rates with process parameters, usually considered a hybrid of continuous monitoring, emission factors, and stack tests

    • Source Testing in the form of concentration calculations derived from samples of the emission or effluent taken from the source, then multiplied by the volumetric flow rate

    • Remote Quantification, i.e. measurements of the concentration of air pollutants based on their interaction with electromagnetic radiation

    • Mass Balance Calculations of releases from a facility, process, or piece of equipment resulting from the differences in input, output, accumulation, and depletion of a substance

    • Site-specific Emission Factors, developed by facilities using emission testing data and source-activity information

    • Published Emission Factors, taken from government entities, industry associations, manufacturers, or sales centres

    • Speciation Profiles used to disaggregate substance quantities into detailed species (such as PM fractions from total PM)

    • Engineering Estimates derived from engineering principles, chemical and physical processes and laws, and design features of the source 

    According to the ECCC, CEMS are the most accurate method of estimate (when properly calibrated), and engineering estimates based solely on judgement are the least accurate. Should you have the opportunity to report actual measurements or quantities of monitored releases, whether they were required by federal/provincial/municipal legislation or not, you are better off doing so.

    The NPRI’s sector-specific tools for calculating emission estimations is a great starting point.


    When Are the NPRI Reporting Deadlines?

    Generally, facilities that manufacture, process, or otherwise use one or more NPRI chemical substances submit a report to the inventory by June 1st of every year. When that date falls on a weekend, the deadline is pushed to the next business day, as is the case in 2024 (deadline: Monday, June 3rd) and 2025 (deadline: Monday, June 2nd).

    Owners and operators obligated to report must do so using the ECCC’s Single Window Information Manager. It’s best to follow along to the government’s step-by-step instructions and video tutorials when you do.


    Common Errors in NPRI Reporting Forms that You Should Avoid

    Once you have compiled your data and/or produced reliable estimates for the releases, disposals, and transfers of all NPRI toxic substances at your facility, you will finally be able to complete and submit NPRI forms for the year. It is at this stage that reporters make small, mostly innocent mistakes that can prove costly for them.

    For instance, several reporters see the inventory solely as an equation, brimming with unambiguous formulas, emission factors, and numerical operations that add up to a single annual value (for a given substance). They ignore that numbers only tell half the story; as a matter of fact, a common error NPRI evaluators come across is a lack of context, in that reporters forget (or overlook) the comment boxes beside certain fields. If you would like to attach any form of clarification to a value, don’t hesitate to find a use for these boxes!

    Similarly, careless reporters neglect to bring their forms up to speed with their operations. They often fail to update the quantities that pop up in prepopulated forms, which pull from the previous year’s submission. They also fail to review changes in the quantity reported, going as far as to indicate that “No significant change or no change” was observed when, in fact, the quantity increased or decreased by over 10%.

    VOCs and their many variations tend to confuse reporters as well. They frequently and mistakenly think that part 4 VOCs are somehow different than those in parts 1, 2, or 5, disregarding the mathematical truth that individually reported VOCs (in parts 1 and 2) cannot add up to an amount greater than the total VOCs (part 4). Or they forget to report speciated VOCs released to air over one tonne as individual part 5 VOCs AND as part of the total calculation for part 4. An effortless addition (using the diagram below as a guide) should be enough to assure you that you will not make the same mistake.


    Diagram taken from the Government of Canada’s “Using and Interpreting Data from the National Pollutant Release Inventory” webpage.

    Here are a few more of the most common issues NPRI evaluators encounter during quality control

    • Failing to identify a public and/or technical contact
    • Failing to report releases, disposals, and transfers for a part 1 substance that meets the MPO threshold but is eventually not released (i.e. the quantity release is zero)
    • Reporting NPRI substances contained in final products that have been shipped to customers or end users
    • Forgetting to include mitigation activities in calculations for substances controlled or mitigated in any way
    • Double or triple counting substances that are subsets of others—refer to the NPRI’s “Using and Interpreting Data” webpage and navigate to the “Avoid double or triple counting” subsection under Using our Data


    NPRI Reporting Guidance: Tips and Best Practices

    If the previous section was meant to familiarize you with the blunders you were most likely to accidentally make in the process of filing your report, this next section is supposed to empower you to file said report in the optimal way, although there may be no repercussions to acting otherwise.

    Case in point: you have no obligation to study the preliminary, unreviewed data the NPRI publishes between June and December of each year, but if you do so, you may spot an error in your facility’s pollution report ahead of the inventory’s publication. Since you are able (read: encouraged) to contact the NPRI to update one of your facility’s reports, be it the one you recently submitted or one from previous years, studying these data could mean dodging a fine! We recommend giving them a thorough examination in search of omitted substances or sources, typos in reporting units, incorrect reference data or assumptions for calculations, etc.

    The lesson, in short, is to never give up on NPRI reporting. Even if you completely miss the deadline, you can and should rectify the situation by submitting a faithful report as soon as possible.

    The other two tips we have for you are a bit more practical.

    The first concerns zero values. There are three cases for which you can report zeros for quantities: if the measured or estimated value of a substance is equal to zero; if the MPO reporting criteria were met but the substance was never released, disposed of, or transferred; and if the substance in question is an acid and was neutralized (pH of 6.0 or above) before exiting the facility. Before finalizing your report, go through each and every instance of a zero value and validate that it corresponds to one of the three cases.

    Lastly, and arguably the best piece of advice we can give you, always keep accurate records of your emissions, transfers, estimate methodologies, emission and conversion factors, equipment calibration parameters, production assumptions, and internal calculations that support estimates (and more… the list is not exhaustive!). Doing so is the only way to guarantee you’ll be well prepared for an audit, should one rear its head. Of course, having a centralized software platform built on total accuracy and rigorous gathering of measured, actual facility data is one way to take the hassle out of daily recordkeeping.


    Appendix: Activities Not Subject to the Employee Threshold

    Owners and operators of facilities where one or more of these activities take place must report to the NPRI regardless of the employee count or the number of hours worked by facility personnel throughout the year:

    • Hazardous waste incineration

    • Sewage sludge burning

    • Non-hazardous waste incineration where 26 tonnes or more of waste are incinerated (including the use of small combustion units, tepee burners, and beehive burners)

    • Biomedical or hospital incineration where 26 tonnes or more of waste are incinerated

    • Wood preservation, including heat and/or pressure treatment

    • Fuel terminal operations, excluding bulk plants or service stations

    • Discharge of an average equal to or greater than 10,000 m3/day of treated or untreated wastewater from a wastewater collection system into surface waters

    • Operations at pits or quarries where production is greater than or equal to 500,000 tonnes


    Additionally, facilities subject to Chromium Electroplating, Chromium Anodizing, and Reverse Etching Regulations are required to report hexavalent chromium (and its compounds), regardless of the number of employees and the 50 kg NPRI threshold.



    DISCLAIMER: All the material in this article is accurate as of June 2023. ERA accepts no liability for the content of this article or for the consequences of any actions taken on the basis of the information presented. To ensure the accuracy of the information, please contact Environment & Climate Change Canada and read their Guide for Reporting to the NPRI.

    Andres Cabrera Rucks
    Post by Andres Cabrera Rucks
    June 19, 2023
    Andres is a Science Content Writer at ERA Environmental Management Solutions.