3 June 2022
Insulation foam, better known as PUR (polyurethane) is commonly used in construction. It is sprayed on or is made on the spot and applied using hoses. It hardens when it comes into contact with the air. PUR is not recyclable and any leftovers are lightweight and so blow or wash away easily.
How much PUR enters the environment is hard to say. It is a hidden pollution and little is done to prevent it.
When used, PUR expands and sticks to surfaces such as concrete, wood, and glass. It is exceptionally useful as insulation material and has a long life. Sprayed PUR is frequently used to seal doors and windows and insulate floors, roofs, and cavity walls. PUR is a thermosetting plastic. This means that once hardened, it will not melt anymore and cannot be remoulded. PUR can thus not be recycled. The material consists of hazardous chemicals that are linked to various conditions including occupational asthma (in Dutch).
Large quantities of PUR are released during construction work, renovation and demolition. PUR pieces are lightweight and float on water. Chunks of PUR are easily dispersed by wind and water. Despite this, PUR is a relatively invisible and unknown source of the plastic soup.
A LOT OF INSULATION FOAM FOUND ON THE WADDEN SEA ISLANDS
There are reports of PUR being found in litter. In 2019, a lot of insulation foam from the building industry was found on the uninhabited Wadden Sea island of Griend. The researchers (in Dutch) assume that it came from the industrial area in Harlingen, passed through the sea locks to the Wadden Sea, and then washed up there. These reports are incidental.
More than 80 percent of all the rubbish found along river banks is plastic. The top three are pieces of unidentifiable plastic, hard or soft plastic, and polystyrene foam. PUR is not listed separately in the records. Clean Rivers volunteers register it in the ‘other plastic’ category.
FOURTH TYPE OF PLASTIC AS A NATURAL PHENOMENON
That PUR is less visible as litter is undoubtedly partly because the pieces often look like pebbles on river banks. They have lost their sharp edges and have become darker. A comparable better-known phenomenon is pyroplastics. These are ‘pebbles’ shaped from melted plastic in the sea. They are found in several places including on pebble beaches in the southwest of England. Other ‘natural phenomena’ are plastic crust (crusts of plastic on rocks on the coast) and plastiglomerate (lumps of melted plastic with stone, coral and shells).
As the pieces of PUR are light in weight because of their air cells, they are carried away in the current. However, the material is brittle and crumbles into ever smaller pieces. Once crumbled into microplastics, the PUR particles do not float anymore but sink to the seabed. In a report (in Dutch), the Netherlands National Institute for Public Health and the Environment assumes that microplastic PUR ends up in sediment.
RESEARCH IS NEEDED
There is little policy to prevent PUR from entering the environment. This is partly because we do not know exactly how seriously PUR pollutes the living environment. Plastic Soup Foundation believes that more research on PUR pollution is needed and argues for measures to avoid PUR ending up in the environment.
Photos: Harmen Spek. PUR pebbles in Haatlandhaven harbour in Kampen.
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