Atmospheric oxidation of the anti-degradation compounds 6PPD and DPPD that are present in tire wear particulates produce approximately 90 compounds that are found in near-road environmental air samples. This mixture caused inflammation and death of human macrophages, and was more toxic than 6PPD-quinone.
Summary: https://phys.org/news/2026-05-atmospheric-compounds-pose-human-health.html
Original paper: https://www.sciencedirect.com/science/article/pii/S0160412026002655

New study shows atmospheric compounds formed from tire wear may pose human health risk
Tire rubber contains antioxidant chemicals, most notably 6PPD and DPPD, that are released into the air as tiny particles during normal driving. A single compound formed from 6PPD, known as 6PPD-quinone was previously shown to be implicated in the death of coho salmon in urban waterways, but the broader atmospheric chemistry and potential human health impacts of these compounds have remained largely unexplored until now.






