Osaka Prefecture has worked on stopping marine plastic litter and promoting plastic resource circulation. This follows the “Osaka Blue Ocean Vision”, shared at the 2019 G20 Osaka Summit, which aims for zero additional pollution from marine plastic litter by 2050. In fiscal 2020, Pirika, Inc. (“Pirika”) was commissioned by Osaka Prefecture to survey microplastics in Osaka Bay. The survey found artificial turf among the microplastics floating in the bay.

After this result, in fiscal 2021 Osaka Prefecture began a survey (commissioned to Pirika) at sports facilities in the prefecture. It looked at how artificial turf leaks and at technology for recycling the recovered turf.

In fiscal 2022, Pirika continued the work under a commission from Osaka Prefecture. At several artificial turf sports grounds in the prefecture, working with facility managers and turf makers, we aimed to measure how much turf leaks and how well prevention works, and to make concrete countermeasures. We surveyed turf wear, measured the amount captured by leakage prevention equipment, and drew up leakage prevention guidelines.

1. Measuring wear on older artificial turf sports grounds

After installation, the tips of artificial turf pile (the “blades”) wear down or break off with use. The infill placed between the blades can also leave the ground. Pile pieces and infill are mostly made of synthetic resin, so if they leak out they can cause microplastic pollution in nature. To learn how much leaks from facilities with artificial turf, the fiscal 2022 survey measured actual turf wear at several sports facilities in the prefecture.

We surveyed two types of facilities: long-pile turf (soccer fields, baseball fields, etc.) and sand-filled turf (tennis). We measured pile length from root to tip at many points with a measuring tool. From the data, we drew a distribution map of wear and estimated the wear for the whole facility. At one facility, we vacuumed up the rubber-chip infill and measured how much had moved (decreased) since installation.

The results showed that, compared with the amount installed, long-pile turf wears by about 1% a year and sand-filled turf by about 2 to 3% a year. Wear was proportional to the number of years and how often the ground was used. At a ground more than 8 years old, the survey suggested that about 50% of the rubber chips may have moved away (disappeared).

2. How can turf leakage be prevented? Testing the countermeasures

To stop pile pieces and infill from leaving a site, it is important to capture them before they leak. We attached a non-woven fabric barrier (developed and provided by Sumitomo Rubber Industries, Ltd.) to the fence around the site, and measured the amount of flying pile pieces and infill it captured. We also installed filters in drains (developed and provided by Sumitomo Rubber Industries, Ltd. and Sekisui Jushi Corporation), and measured the amount of pile pieces and infill carried by rainwater, to test how well the filters work.

In this test, both methods captured a certain amount of pile pieces and infill. However, there is a gap between the amount of wear (what is produced) and the amount actually captured (the effect of the measures). We need to keep testing hypotheses, understand leakage routes and amounts more accurately, and consider effective measures.

3. Making concrete measures for sports facilities in the prefecture

Based on these results, we worked with Osaka Prefecture to make leakage prevention at artificial turf facilities in the prefecture more concrete. Together we created the Guidelines for Preventing Microplastic Leakage at Artificial Turf Facilities in Osaka Prefecture, Ver. 1.0 (Japanese). They were published on the Osaka Prefecture website in March 2023.

The guidelines are written for facility staff. Starting from the basic approach to preventing turf leakage, they explain in plain language what to do at each phase: considering installing turf, construction, operation and renovation. The Japan Sports Facilities Association and artificial turf makers (Sumitomo Rubber Industries, Ltd., Sekisui Jushi Corporation and Mizuno Corporation) also gave advice and support.

Going forward, Pirika will also support leakage prevention so that facility staff in the prefecture can use the guidelines to raise awareness.

4. Closing

Microplastic leakage from artificial turf is now widely known through Pirika’s and related surveys. But how well facilities and regions understand the leakage and put concrete measures in place still varies. Osaka Prefecture is one of the local governments that started early, and we believe what it has learned will help many other governments and organizations.

Challenges remain, such as understanding the facts accurately, effective leakage measures and easy-to-run systems. Pirika will keep working actively on this issue to help realize the Osaka Blue Ocean Vision, which aims for zero additional marine plastic pollution by 2050.

For details on the Osaka Plastic Countermeasures Promotion Platform, see here (Japanese).

For details on Pirika’s consulting service, see here.