Polyester is a synthetic petroleum-based fiber and is therefore made from a carbon-intensive non-renewable resource. The environmental impacts of polyester are relatively high. Cheap polyester is probably the biggest offender when it comes to the negative environmental cost of fashion.
It is not only the production phase of polyester that is a high pollution source, but also when the clothes reach a washing machine. Every time you run your washing machine, thousands of microfibers are flushed down the drain. These are microscopic pieces of plastic, that could reach beaches and oceans where they can remain for decades.
But one of the most positive aspects of polyester is that it is often recyclable, and it is also possible to manufacture polyester from recycled plastics. If we are using polyester, we try to use as much recyclable as possible. If you want to maintain a sustainable wardrobe, it is best to avoid purchasing.