On the inside of our aseptic cartons, a layer of aluminium eight times thinner than a human hair provides vital protection from oxygen and light, keeping perishable food safe without refrigeration for months. We are continually innovating to make this layer as thin as possible, while investigating alternative barrier materials.
Although the aluminium layer used in our aseptic packaging is minute, it is also responsible for about a third of the climate impact of our base materials. We set tough CO2 emissions targets for our aluminium foil suppliers and are continually innovating to reduce how much we use, while investigating alternative barrier materials.
Aluminium is included in aseptic cartons because it prevents oxidation and light damage. However, its production can be associated with environmental and social issues, ranging from land use and hazardous by-products; to working conditions, health and safety. Furthermore, because aluminium is traded in an open market, it can be difficult to trace back to the original source. Addressing these challenges is complex and requires continuous research and innovation, as well as working with multiple stakeholders.
As a founding member of the Aluminium Stewardship Initiative (ASI), we aim to address sustainability topics related to aluminium at an industry level. Along with Rio Tinto Aluminium, BMW, Nespresso, WWF and the International Union for the Conservation of Nature, we are working to establish a global standard that raises the bar for aluminium production, environmentally and socially. We are also certified to the ASI's Production Standard, which defines 59 environmental, social and governance principles and criteria.
In 2019, we helped ensure that a further six of our ten aluminium suppliers also became certified. Along with the two suppliers already certified, this means that 90% of all our aluminium volumes were covered by this standard by year-end. The final two suppliers are due to be certified in 2020.
Furthermore, in 2019, we helped ensure that four of these suppliers were also certified for ASI Chain of Custody (CoC), which enables a link between verified ASI Performance Standard practices at successive steps of the supply chain. This means that this CoC certification covered 75% of our volume by year-end. We expect ASI CoC certification to extend across all our aluminium suppliers by the end of 2020.
We are working towards developing an aseptic package that uses an alternative to aluminium for its barrier layer. In 2019, we delivered our first ever filling machine for aluminium-free aseptic packages and the solution is now being field-tested. Our goal is to begin a market trial of an aseptic package made fully from renewable sources by 2022.
The Aluminium Stewardship Initiative (ASI) has announced Tetra Pak as the sixth company, and third end user of aluminium to become ASI Certified, less than a year after the certification programme was launched.