Ultrafine Particle Production from the Ozonolysis of Personal Care Products

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.