Microfibers are, as the name implies, synthetic fibers that are far smaller in diameter than “typical fibers.” As an example, they are 100 times finer than a human hair, one-third of the diameter of cotton, one-fourth the diameter of wool, and one-half the diameter of silk.
The measurement that is used for measuring such fibers is “denier.” Silk has a denier of 1.25, and for a synthetic fiber to be deemed a “microfiber,” it has to be less than 0.9 denier. Most microfibers used for upholstery are .4 to .5 denier.
Microfiber is a textile made from ultrafine synthetic yarns, usually polyester and nylon. Polyester is derived from crude oil. It is also the terminal product in a chain of very reactive and toxic precursors. Most are carcinogens; all are poisonous. And even if none of these chemicals remain entrapped in the final polyester structure (which they most likely do), the manufacturing process requires workers and our environment to be exposed to some or all of the chemicals. There is no doubt that the manufacture of polyester is an environmental and public health burden that we would be better off without.
What does all of that mean in terms of our health? Just by looking at one type of cancer, we can see how our lives are being changed by plastic use:
- The connection between plastic and breast cancer was first discovered in 1987 by
research scientists Dr. Ana Soto and Dr. Carlos Sonnenschein at Tufts Medical School. In the midst of their experiments on cancer cell growth, endocrine-disrupting chemicals leached from plastic test tubes into the researcher’s laboratory experiment, causing a rampant proliferation of breast cancer cells. Their findings were published in Environmental Health Perspectives (1991). 
- Spanish researchers, Fatima and Nicolas Olea, tested metal food cans that were lined with plastic. The cans were also found to be leaching hormone disrupting chemicals in 50% of the cans tested. The levels of contamination were twenty-seven times more than the amount a Stanford team reported was enough to make breast cancer cells proliferate. Reportedly, 85% of the food cans in the United States are lined with plastic. The Oleas reported their findings in Environmental Health Perspectives(1995). 
And nylon is not such a great thing to use with polyester. It too is derived from crude oil. The New York Times reported in 1991 that nitrous oxide is increasing in the earth’s atmosphere at a rate of about 0.2 percent a year. In the journal Science, two chemists reported that nitrous oxide is generated and emitted during the manufacture of nylon.  The nitrous oxide is a greenhouse gas that is 310 times more potent than carbon dioxide, and because of it’s long life (120 years) it can reach the upper atmosphere and deplete the layer of stratospheric ozone, which is an important filter of UV radiation. In fact, during the 1990s, nitrous oxide emissions from a single nylon plant in the UK were thought to have a global warming impact equivalent to more than 3% of the UK’s entire CO2 emissions. It’s also a very energy-hungry process, which contributes to environmental degradation and global warming. Very large quantities of water are used to cool the fibers, leading to environmental contamination and pollution.
And it’s a plastic, which contributes to our body burden.
- Chemicals added to plastics are absorbed by human bodies. Some of these compounds have been found to alter hormones or have other potential human health effects.
- Plastic doesn’t biodegrade – it sticks around in the ecosystem long after natural fibers have returned to the soil.
- Plastic debris, laced with chemicals and often ingested by marine animals, can injure or poison wildlife.
- Floating plastic waste, which can survive for thousands of years in water, serves as mini transportation devices for invasive species, disrupting habitats.
- Plastic buried deep in landfills can leach heavy metals, including antimony, that spreads into groundwater. If plastics are burned for energy, the chemicals are released into the air.
- Around 4 percent of world oil production is used as a feedstock to make plastics, and a similar amount is consumed as energy in the process.
But let’s say that you did use a microfiber. What then? According to CLEANFAX, a website for cleaning and restoration professionals, “considering the strength and durability of the two dominant fibers used in microfibers (polyester and nylon) one might consider microfibers to be an “idiot proof” fabric. This, unfortunately, is not the case.” The information below was taken from the CLEANFAX website:
A polyester microfiber may adsorb more than seven times its weight in water. This makes microfiber a great cleaning cloth, but a “spill magnet” when used for upholstery fabrics.
Microfibers will hold great volumes of dried sugary materials from spills, and may require heavy preconditioning and hot water extraction to completely remove such materials.
Polyester is also very oil loving; thus hair and body oils will take thorough preconditioning to break these oily films down so that they can be emulsified and flushed from the fabric.
Microfibers will flatten out and become permanently distorted in heavy usage areas, and care must be taken to open available vacuum relief valves when using a truckmount to clean microfiber upholstery; otherwise, permanent wand marks could be caused by excessive vacuum, especially if the cleaning tool has sharp, angular edges and lips.
Microfibers are also heat-sensitive, and ultra-high temperatures could potentially create nap distortion, depending on the type of cleaning tool and spray nozzle being used. To be on the safe side, keep cleaning temperatures at the machine below 200 degrees Fahrenheit.
Due to the need to restore as much of the product’s soft hand as possible, microfiber fabrics should be rinsed with acidic rinse agents or clear water, rather than with extraction detergents.
Likewise, solvent-based protectors are preferable to water-based products, as water-based protectors also likely stiffen the hand of this otherwise soft fabric.
Don’t let the relatively “easy care” advantages of microfibers lull you into carelessness.
From a different website, microfibers tend to create a lot of static, making it hard to move around on furniture. They are also a magnet for pet hair and clothing fibers.
Formaldehyde is found in microfibers, and emits the volatile organic compound as a gas at room temperature.
And finally, 85% of the human-made material found on the shorelines of the world are microfibers. Researchers at the University of California at Santa Barbara found that, on average, synthetic fleece jackets release 1.7 grams of microfibers each wash. It also found that older jackets shed almost twice as many fibers as new jackets. “These microfibers then travel to your local wastewater treatment plant, where up to 40% of them enter rivers, lakes and oceans,” according to findings published on the researchers’ website.
 Fletcher, Kate, Sustainable Fashion and Textiles, Earthscan, 2008, Page 13