In:
Environmental Science: Atmospheres, Royal Society of Chemistry (RSC), Vol. 2, No. 3 ( 2022), p. 539-546
Abstract:
Non-exhaust emissions have surpassed exhaust emissions in their contribution to traffic particulate matter (PM). One major type is brake wear and, although its physical and toxicological properties have been studied, its atmospheric reactivity is unknown. In a first step toward addressing this knowledge gap, we explored the reactivity of ground brake pads (ceramic, semi-metallic, organic) and common brake pad components (phenolic resin, graphite, Fe 2 O 3 , Fe 3 O 4 , Fe and Cu powders) with ozone, an important urban pollutant. The steady-state surface area-normalized ozone uptake coefficients ( γ BET,SS ) for the brake pads were (1–3) × 10 −6 under dark conditions and increased to (2–5) × 10 −6 upon illumination. Interestingly, whereas γ BET,SS values were similar for all sample types, γ BET values at shorter ozone exposure times were larger and exhibited greater sample-to-sample variability ( γ BET,30min = (0.7–9) × 10 −5 ). As all brake pad components tested were reactive toward ozone, we conclude that multiple mechanisms likely underlie the observed sample reactivity. Our γ BET values suggest that ozone loss to “real-world” brake material may be larger than to organic PM during high-traffic periods. As this loss pathway is still small compared to ozone dry deposition, we suggest that future studies of brake wear–ozone interactions focus on their potential to change brake wear properties ( e.g. , hygroscopicity, toxicity) relevant in an air quality context.
Type of Medium:
Online Resource
ISSN:
2634-3606
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
3057711-1
