A routine involving hair sprays and hot tools may carry hidden health risks, according to new research from Purdue University. Engineers have shown that chemicals in common styling products, when combined with the high temperatures of straighteners or curling irons, can generate billions of nanoparticles that lodge deep in the lungs.
The study, conducted by assistant professor Nusrat Jung and her doctoral student Jianghui Liu at Purdue’s Lyles School of Civil and Construction Engineering, found that a 10–20 minute styling session could expose a person to more than 10 billion nanoparticles. These particles, smaller than 100 nanometers, can penetrate the pulmonary region, raising concerns about respiratory stress, inflammation, and even cognitive impacts. Their findings appear in Environmental Science & Technology.
Jung explained that no earlier work had measured real-time nanoparticle emissions from heat-based grooming in residential environments. The team reported that particle levels during tests were far higher than anticipated. Liu emphasized that heat was the main driver, with appliance temperatures above 300°F causing ingredients such as cyclic siloxanes to vaporize and quickly form new airborne particles.
A chemical of particular concern was decamethylcyclopentasiloxane, or D5 siloxane, frequently listed among the first ingredients in styling sprays, gels, and creams. Although widely used for its smooth finish and heat resistance, the European Chemicals Agency has flagged it as highly persistent and bioaccumulative. Animal studies suggest it may affect the liver, lungs, and nervous system. The compound is already restricted in certain cosmetic products in the European Union.
The Purdue experiments were carried out in a specially designed test house, where participants replicated real-life grooming routines. Advanced instruments measured both volatile chemicals and nanoparticle bursts in real time. Results showed that particle concentrations often reached levels comparable to urban traffic exposure.
The researchers advised limiting the use of heated products when possible and improving ventilation with exhaust fans if avoidance is not feasible. They stressed the need for further research using advanced sizing tools to examine the smallest particles and to determine the chemical composition of these emissions.
This work highlights indoor hair styling as an underestimated source of nanoparticle pollution and a potential health risk worth closer attention
