Indoor Nanoparticle Emissions and Exposures During Heat-Based Hair Styling Activities
JIANGHUI LIU, Jinglin Jiang, Satya Patra, Xiaosu Ding, Chunxu Huang, Jordan Cross, Brian Magnuson, Nusrat Jung, Purdue University
Abstract Number: 305
Working Group: Chemicals of Emerging Concern in Indoor and Outdoor Aerosol: Sources, Vectors, Reactivity, and Impacts
Abstract
Heat-based hair styling activities, such as straightening, curling, and waving, can emit volatile and semi-volatile chemicals when used with hair care products like creams, lotions, and serums. These emissions can nucleate and condense to form airborne nanoparticles, which may adversely impact human health and indoor air quality. This study investigates airborne nanoparticle formation (6 to 500 nm) as a previously underrecognized source of indoor air pollution during typical hair styling routines. Realistic hair styling activities were conducted in the Purdue zero Energy Design Guidance for Engineers (zEDGE) Test House, with real-time nanoparticle measurements obtained using a high-resolution electrical low-pressure impactor (HR-ELPI+). Our results showed that hair styling at temperatures above 300°F produced nanoparticle concentrations ranging from 10,000 to over 100,000 particles/cm3, with sub-100 nm particles comprising more than 93% of emissions at temperatures exceeding 360°F. Different heating appliances were found to influence particle size distributions. The primary mechanism for nanoparticle formation was heat-driven vaporization of cyclic siloxanes and other low-volatility constituents in hair care products, followed by nucleation. Oxidation of these compounds and fragrance additives contributed as a secondary pathway. Respiratory tract deposition modeling indicated that more than 10 billion nanoparticles could deposit in the respiratory system during a single hair styling session, with the highest dose occurring in the pulmonary region – even under well-ventilated indoor conditions. These findings highlight heat-based hair styling as a significant indoor source of airborne nanoparticles and draw attention to previously underestimated inhalation exposure risks. This work advances the understanding of the physical and chemical processes underlying emissions from personal care product use and emphasizes the need for mitigation strategies to reduce exposure in residential environments.