Widespread N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine Quinone in Size-Fractioned Atmospheric Particles and Dust of Different Indoor Environments

Transformed from the antioxidant N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6-PPD), the emerging toxicant 6-PPD quinone (6-PPDQ) has received extensive attention because of its potential toxic effects. However, evidence on the size distribution patterns of atmospheric particles and environmental occurrence remains limited. We determined 6-PPDQ pollution levels in eight size-segregated particles (0.43–10 μm) from four waste recycling plants and dust samples from six typical indoor compartments in South China. 6-PPDQ tended to accumulate in the coarse particles (9–10 μm) with the highest concentrations (7.78–23.2 pg m–3). Model simulations revealed that the deposition efficiency (flux) of particle-bound 6-PPDQ were 89%–91% (10.8–39.1 pg h–1), 3.2%–3.8% (0.45–1.64 pg h–1), and 6.0%–6.9% (0.80–2.85 pg h–1) in workers' head airways, tracheobronchial, and pulmonary alveoli areas of respiratory tracts, respectively. The dust matrix was not the main carrier of 6-PPDQ, because of its lower concentrations in multiple indoor environments than those of suspended air particles. In-vehicle and rubber-related places seemed to be the areas most polluted by this ozone-initiated quinone. Our study further enriches the knowledge on the ubiquitous distributions of environmental 6-PPDQ. Additional toxicity experiments should be conducted using 6-PPDQ, based on the high exposure risk for humans the upper respiratory tract via inhalation.