The Problem With Polyester

rolls of orange patterned polyester fabric

Polyester is probably the most common and cheapest clothing fabric on earth. It's also highly versitile and popular for athletic gear because of the the heat and wicking capabilities. But we here at CoolYourSweats don't use polyester-based fabrics for our sleepwear. In fact we don't even choose fabric blends that contain as little as 4% polyester, nylon, Elastane or Lycra. In this blog post, our blogger, Brendan Shaw, describes what polyester is and how it affects us and our planet. 

Take it away, Brendan! 


What is Polyester? What is it Used for?

Polyester is a type of synthetic fiber that is petroleum-based ­– made of plastic. By means of an extrusion process, thin threads of plastic are released from a machine, and after a few more steps, you have plastic fabric.

Polyester’s use goes beyond just clothing – it is also used for home furnishings such as upholstery and pillows, film, mouse pads, etc.

As Merit Clothing describes it, polyester is basically “plastic spaghetti”. It is not biodegradable or compostable, and it can sit in a landfill site for well past our great grandchildren's lifetimes.

In contrast, natural fibers, such as wool, linen, hemp and cotton, are biodegradable along with some semi-synthetic fibers, such as viscose rayon, or lyocell (Tencel) which are made from plants. 


What are the Benefits of Polyester?

How Polyester Became Popular in the First Place

The reasons why polyester became the most commonly used synthetic fiber make sense. Beyond being cheap and versatile, polyester is generally wrinkle and stretch free. Being that it’s made of plastic, the material is anti-bacterial and has low water absorption, making it unlikely for mildew to grow. It's also very easy to access and can be woven in specific ways to accelerate moisture wicking and coatings can be added for different purposes, such as absorbing or reflecting heat. So, from a technical perspective, polyester is a great fabric.


What are Polyester’s Drawbacks?

Human Health Concerns with Polyester

By 2022, the various reasons why plastics are bad for the environment are fairly evident – toxic chemicals seeping into and contaminating groundwater, CO2 releasing into the atmosphere, the high possibility that most plastics will outlive humanity itself. But it is only recently that we're discovering that plastic is actually harmful for our own health

In March of 2022  for the first time microplastics were found in human blood  for the first time

In a sample size of twenty-two donors, microplastics were found in seventeen of the patient’s blood. In half the samples PET plastic was found – the type most commonly used in drinking bottles. In a third of the samples; polystyrene – food packaging plastic. In a quarter – polyethylene, plastic carrier bags.

Recently, another study was published showing microplastics found in lungs of people. In a study of thirteen patients undergoing surgery, plastics were found inside the lungs of eleven.

This is caused by the fact that over time polyester sheds tiny plastic fibers known as microplastics. These mircoplastics are shed into our environment, particulary our interior environment as well as into our water system and drinking water. It's almost impossible to escape them. Microplastics are found in dust particles and therefore are in the air we breathe.

Considering how our human health and the health of the environment are inextricably linked, it’s surprising that more attention isn’t given to the clothes we put on our back and how the fabric they’re made from might affect our own health, let alone, the environment’s.

Perhaps we’ve all just spent too much time in doors to be worried about what the environment might be doing to us. But even if you had an auto-immune disease that kept you in doors your entire life, like the fictional character Ana Stelline (‘Blade Runner 2049’) who lives in a bubble, chances are high you’re still intaking microplastics into your body. 

Truthfully, the health effects of polyester and microplastics on our bodies is a subject that has only recently entered scientific inquiry. Lab studies have shown evidence that plastic can cause damage to human cells. At this stage, it’s better to err on the side of caution and reduce your exposure to plastic.


Environmental Concerns with Polyester

The primary concern with polyester is that it is produced from fossil fuels, which are the largest contributor to CO2 emissions, non-renewable, and are of highly problematic for the environment.

The PET plastic used in polyester also decomposes at a glacial pace – as in up to two hundred years, or more. Worse than CO2, when plastic is exposed to the elements (in the ocean, for instance), it releases methane, which is a greenhouse gas that has a warming power that is 20 to 85 times more potent than carbon dioxide (the broad range of potency is dependent on how you do the math).

When polyester is washed, small microfibers are released into our water supply. These microfibers end up in our rivers and oceans, and then, eventually, back into our bodies.

The same goes for the dyes and chemicals used to give our clothing colour. Rivers (like the one pictured below) could be a different colour every month, depending on what’s in fashion.

polluted river


The majority of polyester production occurs in China, India and Bangladesh. As you can gather from the image above (one of many like it), these countries’ governments tend not to enforce their environmental laws.

When considering landfills, mounds of plastic bottles might come to mind, but landfills often also have mounds of clothing. This wouldn’t be such an issue if the clothes naturally decomposed, but with polyester, the end of life, as mentioned earlier, may not occur for hundreds of years.

A study done in 2005 by the Stockholm Environmental Institute compared the environmental footprint of three fabrics, cotton, hemp and polyester, to see if there was a clear winner.

Polyester has a significantly lower environmental impact than cotton in terms of the land and water required to produce it. This might lead you to think that polyester isn't so bad after all. However, polyester does require the most energy in its production compared to hemp and cotton.


Energy requirements of hemp, cotton and polyester

(graph: courtesy of the SEI, Ecological Footprint of Hemp, Cotton and Polyester, 2005, p. 13)

And, comparing CO2 emissions for crop growth and fiber production, polyester manufacturing is the highest as well.

Energy requirements of hemp, cotton and polyester

 (graph: courtesy of the SEI, Ecological and Water Footprint of Hemp, Cotton and Polyester, 2005, p. 14)


Of the three materials, the one with the lowest environmental impact is hemp. CoolYourSweats makes its nightgowns with a blend of hemp and organic cotton in part for the ecological benefits of hemp.


Polyester was created as a cheap alternative to natural fibers. But, while we've known for many years that manufacturing it is harmful to the environment, we're only recently finding out that it's harmful to humans and wildlife while it's in use. 

It's almost impossible to escape polyester, but perhaps with more awareness of the dangers of it, we can start choosing better and safer fabrics for the clothes we put on our backs.


*In full disclosure, at this time our products contain less than 1% polyester – due to the thread used in the seams. We are unable to switch to organic cotton thread until we are able to produce larger volumes.


Brendan Shaw is a Montreal-based freelance writer and CoolYourSweats team member.

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