How microplastics get into the environment

Globally, 350 million metric tons of plastic are produced annually. This corresponds to an average of 50 kilograms of plastic per person per year. About half of this is released into the environment through various processes, i.e. around 20 to 30 kilograms per person per year. The main sources of microplastics – around 1 kilogram per person per year – are:

  • Road traffic, especially the abrasion of car tyres, brakes and road markings
  • Sources from industry, e.g. sandblasting with microplastics as a sand substitute
  • Plastic particles from cosmetics
  • Washing of synthetic textiles
  • Building paints, e.g. for building façades
  • Artificial turf
  • Improper waste disposal, throwing away of plastic packaging, bottles, cigarette butts etc.

Viewed worldwide, primary microplastics hardly contribute to the pollution of the environment with plastics. More than 99.95 percent of the microplastics in the environment are secondary microplastics, i.e. tiny plastic particles that are only created by the decay or decomposition of larger plastic parts.

On behalf of the Swiss Federal Office for the Environment (FOEN), Empa has used calculations to estimate how much plastic is released into the environment in Switzerland. The seven most frequently used plastic materials were recorded: Polyethylene (LD-PE and HD-PE), polypropylene, polystyrene and expanded polystyrene, PVC and PET. It is estimated that around 5100 metric tons of plastic are released annually: 4500 metric tons of macroplastics and 615 metric tons of microplastics. Of this, about 600 metric tons of microplastics are released into the soil and almost 15 metric tons into the waters. (Source: "More than 5000 metric tons of Plastic released into the Environment each year", Empa, 2019)

In the EU, only around 7 percent of the microplastics flow into wastewater treatment plants via domestic and industrial wastewater. There, between 80 and 99 percent of the microplastics is removed and disposed of via sewage sludge. The treated wastewater still contains 1 to 5 micrograms of microplastics per litre.

In the Canton of Zurich, the Office for Waste, Water, Energy and Air (AWEL) investigated 28 wastewater treatment plants (WWTP). They released about 18 billion microplastic particles or 330 g into the environment every day. Extrapolated to all 64 WWTPs in Zurich, this results in a quantity of 31 billion particles or 600 g being released into Zurich’s waters every day. No microplastics could be detected in groundwater and drinking water. (Source: Scientific article “Microplastics in Wastewater and Waters”, Aqua&Gas No 7/8, 2016)