Step 1: Domestic waste generated

Overview of the process to calculate the plastic net input and domestic waste generated within a country.

Plasteax scheme highlighting the step that calculates the domestic waste generated.

The main outcome of the first step is the calculation of the domestic waste generated for the selected country in a given year. Domestic waste refers to the waste generated by the country’s population and it does not account for trade of waste (import and export of waste).

At the outset, an extensive list of industry sectors is considered, including agriculture, automotive (tires and other components), construction, electrical and electronics, household goods, industrial packaging, industrial products, packaging, textile, and others. For each sector, we calculate the net input, which represents the amount of plastic remaining within the country after accounting for trade. This is determined by summing domestic production and imports of plastic, then subtracting exports — covering both raw materials and finished products — while carefully avoiding double-counting. The net input essentially reflects the country’s plastic consumption for the year.

Next, we estimate the share of this net input that becomes waste. Not all plastics consumed in a given year become waste in the same year; some sectors produce items with lifespans exceeding a year. The Plasteax model accounts for these variations when estimating waste generated from the net input.

While this outlines the general process, for packaging, the approach is more straightforward: all packaging consumed in a given year is assumed to become waste within the same year.

For other sectors, the model considers the lifespan of products (based on 'Geyer et al., Production, use, and fate of all plastics ever made, 2017’) and estimates the amount of waste by examining the net input for the sector in previous years. The latter is reverse engineered considering the country's GDP history.

To achieve the desired level of granularity for packaging (by polymer and packaging category) while splitting by sector, mappings are applied when available data lacks sufficient detail. For example, production data may be provided by polymer but lack information on sector or category. In such cases, a polymer-to-sector matrix is used to allocate plastic input across different sectors. Subsequently, a packaging-specific polymer-to-category matrix is applied to break down the plastic packaging input into specific categories.

Similarly, trade data may sometimes include the required granularity (by polymer, sector, and category), but in other cases, it might only be available by polymer. When this happens, polymer-to-sector and polymer-to-category mappings are used.

In instances where data is only available at the sector level, without details on polymer or product category, a sector-to-polymer mapping is used to distribute the input across the different plastic polymers.

By the end of this step, the model provides detailed information on waste generated by polymer and sector for all plastic polymers and sectors. For packaging, this step specifically yields waste generation data by polymer and category.

The subsequent steps focus on waste management within the packaging sector.