Carbon Black Residue and Rubber Playground Flooring. Is it Safe?

Recycled rubber playgrounds are a common choice for local councils and schools looking for sustainable flooring solutions. However, there can be unintended impacts on the safety and longevity of your surface with low-quality recycled rubber, including what is known in the industry as ‘Carbon Residue’ or ‘Carbon Black’.

In some older playgrounds, you may notice once vibrant bonded rubber mulch colours fading to black and leaving dark marks on clothing and skin during play. PlaySmart’s surfacing experts are here to explain why this happens and what you can do about it with our Virgin EPDM rubber solution.

Core principles of modern playground design

Recycled, non-virgin rubber shred is not UV stable and therefore can degrade over time, leaving behind Carbon Black residue. The recycled rubber from tyre rubber is not protected from stabilisers that prevent this breakdown of pigments that release the chemical fillers and treatment substances that include carbon black.

In order to produce industrial rubber at a lower cost, tyres often contain fillers like carbon black that reinforce the rubber and enhance other properties such as tensile strength. Due to its molecular structure being similar to graphite, when released from recycled rubber granules, carbon black molecules can easily stain clothing, skin and other materials when they come into contact with it

Other particulates and chemicals like zinc used in the manufacturing of tyres are present in recycled rubber crumb surfaces. The treatments and colouring of only the outside of recycled rubber chippings and granules mean that when worn down over time, these internal pigments and chemicals are exposed, causing colours to fade and staining to occur.

Are there Health Risks from Carbon Residue on Playgrounds?

Parent groups often express concern over the impacts of carbon residue. Recycled rubber crumb flooring has come under fire for containing toxic or harmful chemicals not removed during the processing of true-virgin rubber.

The Environmental Protection Agency and various other studies find that exposure to these chemicals as part of the material environment is limited and less hazardous to health than many allege, but can still be present. For more technical information on the different chemical risks of a range of untreated vulcanised rubber materials, before you make your surfacing decision, we recommend this recent study by Teresa Moreno and colleagues from the Institute for Environmental Assessment and Water Studies.

However, considering these risks and parents’ perceptions of these risks is important when designing play spaces for young children. We do not recommend recycled rubber mulch granules where regular contact with the surface is likely and young children and toddlers may even ingest the materials. Families may not visit your play area if they have concerns over the materials used, so using other materials may be worth it to provide a safe and fun play space for everyone.

Even if risks of harm to health are low, keeping kids away from contact with staining substances keeps your play area fun and parents happy!

How PlaySmart’s EPDM can help reduce Carbon Residue

If you choose that removing your recycled rubber surface is right for your play area, you don’t need to abandon rubber flooring materials altogether. Rubber is a great natural material with natural shock absorbent properties that has many applications in creating rubber mulch safety surfacing with vibrant colours and fun patterns kids love.

Before EPDM Rubber Mulch Installation, black rubber surfacing
After EPDM Rubber Mulch Installation, vibrant green rubber surfacing

Virgin rubber EPDM crumb used in PlaySmart’s MulchSmart rubber playground solution is UV stable, treated with high-quality Peroxide vulcanized rubbers and non-toxic binders. The whole of each rubber granule is treated and coloured, not just the outside like recycled rubber is. This means that unlike with other rubber surfaces, with wear and stretching of the crumb from play, the exposed material will not show untreated, black rubber that can release Carbon black.

Find out more about the technical aspects of EPDM as a resistant surface material with higher tensile strength than other rubber solutions with our EPDM information brochure.

Discover more alternatives and solutions for your playground flooring with PlaySmart

If you are looking for a sustainable flooring option with zero risk of carbon black, our Corkeen surfacing with 90% natural Cork with non-toxic binders and treatments is a sustainable solution for any site. For more details on the manufacturing process and sourcing, visit our full guide to Corkeen play flooring.

PlaySmart’s experts can help you renovate and redesign your outdoor space with the right materials for you. Get in touch today with the handy contact form at the top of the page, or call us at 01564 742811.

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