Many people fix their hair in the morning before heading to work or school, but they may not be aware of the potential dangers. A recent study has found that using hair care products and hair dryers can produce up to 10 billion nanoparticles, equivalent to the air pollution faced when standing on a busy road.
This research, led by Assistant Professor Nusrat Jung from the School of Civil and Environmental Engineering at Purdue University in the United States, shows that a 10 to 20-minute high-temperature hair care process can expose individuals to as many as 10 billion nanoparticles.
These particles, with a maximum size of only 500 nanometers (about 200 times smaller than the width of a human hair), are small enough to penetrate the lungs, directly depositing in the lungs and leading to severe health risks such as respiratory stress, lung inflammation, and decreased cognitive function.
Jung said, “This is truly worrisome. The amount of nanoparticles inhaled from common store-bought hair care products far exceeds our expectations.”
She added, “By detailing the emission characteristics of indoor nanoparticles during these personal care processes, our study has laid the foundation for future research on their impact on indoor air chemistry and inhalation toxicity. Prior to this study, little was known about the potential health risks associated with daily hair care habits.”
Researchers point out that these hair care products are so harmful because they combine with styling tools such as curling irons, straightening irons, and hair rollers, generating significant amounts of heat. When this heat exceeds 300 degrees Fahrenheit (149 degrees Celsius), these chemicals not only rapidly release into the air but also form a large number of new nanoparticles.
In this study, seven volunteers underwent a total of 21 hair care sessions involving five different products and styling tools. The researchers then measured the level of nanoparticle pollution in each scenario.
The results showed that a hair care process lasting 10 to 20 minutes could release over 100,000 nanoparticles per cubic centimeter. Modeling suggests that such concentrations could result in over 10 billion nanoparticles being inhaled, with many reaching the deepest parts of the lungs.
Researchers say that heat is the primary driving factor for nanoparticles – cyclosiloxanes and other low-volatile components evaporate, nucleate, and grow into new nanoparticles, with most being smaller than 100 nanometers.
As for how to avoid the risk of inhaling nanoparticles and volatile chemical mixtures in the air, researchers recommend avoiding the use of such products, especially when used with heat-generating styling tools. If that’s not possible, they suggest using a bathroom exhaust fan for improved ventilation to reduce exposure.
Jianhui Liu, a doctoral student under Jung’s guidance, advises, “If you must use hair care products, limit the usage time and ensure good indoor ventilation.” Even without using heating tools, better ventilation can reduce people’s exposure to volatile chemicals like cyclosiloxanes.
Jung stated that for a more comprehensive understanding of the complete formation and development process of nanoparticles, future research should integrate instruments capable of detecting nanoparticle migration rates at the nanoscale. The chemical composition of these particles should also be assessed.
The study was published on August 4 in the journal “Environmental Science & Technology.”