We have all most likely seen artificial grass playing fields in our towns and cities. They are becoming increasingly popular as a durable, year-round alternative to traditional grass sports fields. Each artificial grass surface consists of a mat of synthetic fibres held in place by a layer of sand. An additional layer of rubber granules is added to improve the suitability of the surface for sports.
Ninety percent of the granules added to artificial playing fields are composed of SBR rubber from recycled tyres .These granules have been found to contain chemicals which are toxic and potentially even carcinogenic.
A study conducted in Norway in 2006 looked at the potential dangers of using SBR rubber granules as a filler on artificial grass and concluded that the granulate “contains a considerable number of components which are associated with adverse effects on health.” In Michigan, USA, a 2008 study found harmful chemicals, including arsenic, chromium and lead, were present in practically every sample of artificial grass surface they tested. The Dutch journal, Chemosphere, concluded in 2013 that “uses of recycled rubber tires, especially those targeting play areas and other facilities for children, should be a matter of regulatory concern.”
Anecdotal evidence regarding football goalkeepers from the USA and the UK points to a potential link between high levels of exposure to these rubber granules and Hodgkin’s Lymphoma.
The adverse impact of using rubber granules is, however, not limited to its potential harm to human health.
A year in the life of an artificial grass playing field.
Throughout the course of a regular year, the layer of rubber granules needs to be ‘topped up’.
Where do the rubber granules disappear to?
Some of the granules cling to players’ hair, clothes and shoes and are carried away at the end of the game. Some get washed away when it rains. Yet more become mixed up with snow and are carried away when the snow is removed from the playing field.
In Denmark, it is estimated that 3-5 tonnes of granulate is added to each artificial grass football field per year, half of which will end up in the environment. The rates are similar in other European countries.
|Country||Rubber in-fill granulate from artificial football pitches discharged into the environment per year|
|The Netherlands||500 tonnes|
The figures above are conservative as they do not take into account secondary microplastics which are created from the wear and tear of the synthetic fibres making up the ‘grass’ part of the artificial turf. It is estimated that 5-10% of the synthetic grass fibres are degraded in this way annually – further polluting the environment.
From playing field to the ocean
There are various ways for microplastics from artificial playing fields to end up in the ocean:
- Particles are released to paved areas surrounding the field (e.g. transported via shoes and clothing or deposited with cleared snow) and are subsequently released to the sewerage system via grates.
- Release of infill particles to the indoor environment, as the particles get stuck in sportsbags, shoes and clothing where they can be released to sewerage system via discharges from washing machines.
- Release to drainage via drainage water (directly through run-off or blown by the wind). Drainage water may then be released to the sewerage system or end up in nearby streams due to heavy rainfall.
In Sweden, the amount of microplastics entering the sea and waterways is estimated at 70 kg (or 293 million particles) per year for each artificial playing field. This figure might be higher in countries which have less stringent wastewater treatment practices.
What can be done?
The City of Gothenburg, a KIMO member municipality, has changed the way they maintain their artificial turf playing fields. They provide a number of ‘Best Practice’ examples for other local authorities or any sporting bodies that maintain artificial grass playing fields. The Norwegian Environment Agency has likewise commissioned a report investigating potential ways of reducing microplastic pollution from artificial grass playing fields. The guidelines below are informed by both of the above mentioned sources:
Steps to reduce microplastic pollution from artificial grass playing fields:
- Promote natural football pitches and playing fields through selective funding
- Promote indoor pitches
- Improve the design of playing fields to minimise the amount of granulate which escapes the playing field area
- Improve storage facilities for new and used rubber granulate so that the risks of accidental dispersion through runoff or wind are minimised
- Use sweeping machines which are able to collect and sort the rubber granulate for re-use. This cuts down on cost by reducing the amount of new granulate added to the fields each year. Machines can be shared across clubs further cutting down on costs.
- Store snow which has been collected from the playing fields on a plastic nonwoven cover. This allows the collected granules to be reused the following season.
- Used granulate should be treated as hazardous waste. Ensure that arrangements are in place to safely remove and dispose of used granulate (preferably before a new playing field is built). Consider negotiating a ‘take-back’ scheme with the manufacturers of the granulate.
- Do not use SBR granules. Consider alternatives such as EPDM granulate. In Sweden municipalities are trialling the use of granules made from cork and coconut fibre. For certain areas such as playgrounds, sand alone (without any added granulate) may suffice. Gothenburg city administration is investigating the potential of hybrid grass in which the artificial grass gives structure and reinforcement to the ordinary grass – however, care must be taken that the grass is never cut too short which could result in the artificial fibres being shredded.
- Do not allow runoff water from artificial playing fields to enter storm drains untreated. This is especially important if the storm drains empty directly into local waterways. If possible, drainage systems which incorporate retention basins for the first flush of water should form part of the design. The retained water can be redirected into the sewerage system where at least a portion of the microplastic particles will be filtered out before discharge into the environment.
- Encourage investment in better filtration systems at your local sewerage treatment plant. For example, last step treatments of effluent such as membrane bioreactors and sand filters with hydrous ferric oxide can greatly increase the retention of particles including microplastics. It is estimated that improving the retention of particles to 99% would reduce microplastic discharge by 430 tonnes a year in Norway alone.
Artificial grass is here to stay but by better managing its use, we can reduce its impact on the environment.