Your morning hair routine might be quietly harming your health.
That familiar ritual of reaching for a straightener or curling iron could expose you to toxic particles at levels comparable to a busy highway.
Scientists are now raising alarms over what’s really in the air when you style your hair.
Researchers at Purdue University in the United States investigated what happens when people use heat styling tools in their bathrooms.
Using equipment usually reserved for measuring car exhaust, they found that a simple 10-minute styling session could release toxic chemicals equivalent to dense traffic fumes.
During typical hair styling routines, cyclic volatile methyl siloxanes dominated emissions, with decamethylcyclopentasiloxane (D5) contributing the most.
'We found the results to be extremely alarming. We did not expect to see such significant emissions from off-the-shelf hair care products during typical routines that many people perform each and every day.'
The main villain is decamethylcyclopentasiloxane, or D5 siloxane, a common ingredient in sprays, gels, and creams valued for giving hair products their smooth texture and heat-resistant properties.
The European Chemicals Agency classifies D5 as 'very persistent' and 'very bioaccumulative', meaning it can build up in living organisms and the environment.
Animal studies link D5 to adverse effects on the respiratory tract, liver and nervous system, although its long-term impact on humans remains unclear.
The European Union banned D5 in hair styling aerosols in 2015 and later restricted its use in wash-off cosmetic products to prevent accumulation in the water supply.
Raising a hair straightener from room temperature to 210°C can increase toxic emissions by 50-310 per cent.
Most straighteners operate above 150°C, with many exceeding 200°C, producing nanoparticles small enough to be inhaled and absorbed into the bloodstream.
This issue forms part of a broader pattern of concern over hair products.
A 2022 study by the National Institutes of Health found that women who used chemical hair straighteners had a higher risk of uterine cancer, while earlier studies linked these products to increased breast and ovarian cancer risk.
Nearly 8,000 lawsuits have been filed in multidistrict litigation against manufacturers for failing to warn users about these risks.
The urban air quality connection
Research shows that morning hair styling routines in cities create a collective pollution problem.
As thousands of people style their hair simultaneously during morning routines, these chemicals get ventilated outside, only to be drawn back into buildings through air conditioning systems.
This means even if you don't use these products yourself, you may still be exposed in urban environments.
Ventilation is critical—turning on a bathroom exhaust fan can cut D5 inhalation by over 90 per cent.
Using lower heat settings can also significantly reduce emissions.
Limiting product frequency and choosing heat-free alternatives like rollers or braiding are other effective strategies.
As one researcher noted, 'If you must use hair care products, limit their use and ensure the space is well ventilated. Even without heating appliances, better ventilation can reduce exposure to volatile chemicals.'
Simple steps to reduce your exposure
- Always use bathroom exhaust fans when styling with heat
- Choose lower temperature settings when possible
- Look for products that don't list D5 siloxane in the first few ingredients
- Consider heat-free styling alternatives like rollers or braiding
- Style hair in well-ventilated areas, not confined bathrooms
Some brands now formulate products without D5 siloxane, so checking ingredient lists can help minimise risk.
Simple changes—better ventilation, lower temperatures, less frequent use—can meaningfully reduce long-term exposure to harmful chemicals.
Dr Jung reflected on the findings personally, saying, 'The best solution is to simply not use these products. I used to use similar products myself to straighten my hair, but after we analysed the data, it became immediately clear that the best thing I could do to protect my own health was to stop using them.'
Australia’s Therapeutic Goods Administration may be observing these developments as regulators elsewhere act on emerging evidence.
Being informed and taking precautions in everyday routines can help protect long-term health.
What This Means For You
Hair styling with heat can release toxic chemicals at levels comparable to dense traffic fumes.
One of the main culprits, D5 siloxane, is common in many hair products and is persistent, bioaccumulative, and potentially harmful.
Higher temperatures and poor ventilation can dramatically increase your exposure, making everyday styling routines riskier than many realise.
The good news is that practical steps—like improving ventilation, using lower heat settings, limiting styling frequency, and choosing D5-free products—can significantly reduce these risks.
For Australians over 60, taking these precautions can help protect long-term health while still allowing you to enjoy your morning styling rituals safely.
Scientists warning straightening HAIR — The article warns that using heat styling tools can expose users to toxic chemicals comparable to traffic fumes.
https://www.dailymail.co.uk/science...tml?ns_mchannel=rss&ns_campaign=1490&ito=1490
Siloxane Emissions and Exposures during the Use of Hair Care Products in Buildings | Environmental Science & Technology — Study finds cyclic volatile methyl siloxanes dominate emissions during hair styling, with D5 contributing the most.
https://pubs.acs.org/doi/10.1021/acs.est.3c05156
Siloxane Emissions and Exposures during the Use of Hair Care Products in Buildings — PMC — Confirms that D5 is the main contributor to toxic emissions during typical hair styling routines.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10702429/
Chemicals in Home Hair Care Products Raise Concerns About Inhalation, Air Quality — Researchers report that people could inhale 1–17 milligrams of harmful chemicals in a single styling session.
https://www.drugwatch.com/news/2023...-raise-concerns-about-inhalation-air-quality/
Hair styling products may release billions of harmful nanoparticles into your lungs — D5 siloxane is a common ingredient in sprays, gels, and creams, valued for texture and heat resistance.
https://knowridge.com/2025/08/hair-...ons-of-harmful-nanoparticles-into-your-lungs/
Hair styling products may release billions of harmful nanoparticles into your lungs — D5 is classified as very persistent and very bioaccumulative, building up in living organisms and the environment.
https://knowridge.com/2025/08/hair-...ons-of-harmful-nanoparticles-into-your-lungs/
Chemicals in Home Hair Care Products Raise Concerns About Inhalation, Air Quality — Animal studies link D5 to respiratory, liver, and nervous system effects, though long-term human impacts remain unclear.
https://www.drugwatch.com/news/2023...-raise-concerns-about-inhalation-air-quality/
Cyclopentasiloxane in Cosmetics: Safety and More — EU restricted D5 use in wash-off cosmetics in 2018 to prevent environmental accumulation.
https://www.healthline.com/health/cyclopentasiloxane
Siloxane Emissions and Exposures during the Use of Hair Care Products in Buildings — PMC — Heating hair straighteners to 210°C increases toxic emissions by 50–310 per cent.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10702429/
Chemicals in Home Hair Care Products Raise Concerns About Inhalation, Air Quality — Heat applied to D5 can further release toxins by up to 310 per cent.
https://www.drugwatch.com/news/2023...-raise-concerns-about-inhalation-air-quality/
Chemicals in Home Hair Care Products Raise Concerns About Inhalation, Air Quality — NIH study found chemical hair straighteners linked to higher risks of uterine, breast, and ovarian cancers.
https://www.drugwatch.com/news/2023...-raise-concerns-about-inhalation-air-quality/
Chemicals in Home Hair Care Products Raise Concerns About Inhalation, Air Quality — Nearly 8,000 lawsuits filed against manufacturers for failing to warn users about cancer risks.
https://www.drugwatch.com/news/2023...-raise-concerns-about-inhalation-air-quality/
Chemicals in hair care products cause surprising amount of health issues — Turning on bathroom exhaust fans can reduce D5 inhalation exposures by over 90 per cent.
https://www.earth.com/news/chemicals-in-hair-care-products-cause-surprising-amount-of-health-issues/
Hair styling releases billions of toxic nanoparticles that then enter your body — Limiting product use and ensuring proper ventilation reduces exposure.
https://www.earth.com/news/hair-styling-releases-billions-of-harmful-nanoparticles-indoors/
Chemicals in hair care products cause surprising amount of health issues — Lead researcher Dr Jung stopped using these products personally to protect health.
https://www.earth.com/news/chemicals-in-hair-care-products-cause-surprising-amount-of-health-issues/
What changes, if any, are you considering to your hair care routine after reading this?
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