UC Berkeley

Personal care products (PCP) might be a source of ultrafine particle exposure for users owing to the reaction of ozone with terpene ingredients. The near-person emissions associated with PCP may contribute to exposures that would not be properly accounted for with indoor microenvironmental measurements. To better understand this issue, screening experiments were conducted with 91 PCP to detect the occurrence of ultrafine particle production from exposure to common indoor levels of ozone (23 ± 2 ppb). Twelve products generated measurable particle emissions; quantification experiments were performed for these to determine total particle production and peak particle production rate. A high-resolution, small volume reaction chamber was used with a heated sample plate to simulate conditions found in the human thermal plume. Ten of the quantified PCP exhibited total emissions of less than 10⁹ particles, suggesting that they may not be significant sources of total ultrafine particle exposure. Two samples, a tea tree oil-based scalp treatment and a white lavender body lotion, exhibited relatively elevated peak particle emission rates, 6.2 × 10⁷ min^-1 and 2.0 × 10⁷ min^-1, respectively. The use of such products in the presence of significant ozone levels might materially influence personal exposure to ultrafine particles.