Analysis of Tire Tread Rubber Particles and Rubber Additives in Airborne Particulates at a Roadside

Rubber particles emitted by abrasion of automobile tire tread have caused environmental pollution, and may be hazardous to our health. In this study, airborne particulate samples were collected on the glass fiber filter using high-volume air sampler at the roadside of the 2-nd Shinmei highway in Kobe. Rubber particles in the roadside atmosphere were analyzed by pyrolysis gas chromatography. The concentration of rubber particles was estimated from the total amount of styrene and isoprene, because these two compounds are pyrolysates of styrene butadiene rubber and natural rubber which are main materials for tires. These concentrations were 0.5-10.5 μg/m3, which corresponded to 0.4-6.3% of total airborne particulates. These concentrations were higher than those in other reports, because the sampling point was the roadside of the highway in this experiment. Furthermore quantitative and qualitative analyses of rubber additives (Zn-DMDTC and IPPD) in airborne particulates were carried out by HPLC, GC and MS. Zn-DMDTC, after converted into Co-DMDTC, in airborne particulates was analyzed by HPLC. The concentrations of Zn-DMDTC were 0-5.1 pg/m3. The detected amount of Zn-DMDTC did not show mutagenic activity. However, in the case of long term exposure to these tire tread particles, we must take a hazardous effect by Zn-DMDTC into consideration. On the other hand, IPPD was confirmed in none of samples by GC and MS.