Nanocluster aerosol formation via ozone chemistry on worn clothing: Influence of environmental parameters

Nanocluster aerosols (NCA, particles <3 nm) are associated with climate feedbacks and potentially with human health. Recent studies have revealed the formation of NCA through ozone reaction with human surfaces, primarily skin lipids, in indoor environments. However, the formation of NCA via ozone chemistry on worn clothing, acting as a reservoir for human skin lipids, remains unexplored, along with the influence of various environmental factors that may play a role in NCA formation and subsequent growth. To bridge this knowledge gap, our study experimentally investigated NCA generation from ozone-worn clothing chemistry in a climate-controlled chamber. We examined the dependence on ozone levels (30 vs. 80 ppb), ammonia (NH3, 300 vs. <150 ppb), relative humidity (RH, 40 vs. 65%), and background air condition (filtered vs. unfiltered air). We found that the ozonolysis of worn clothing contributes to NCA formation at a rate ranging from 1010 to 1011 NCA per hour. Elevated ozone levels caused a threefold increase in NCA generation, whereas reduced NH3 levels were associated with a small decrease in larger-sized NCA formation. Elevated RH caused a decrease in total NCA, especially for 1.27–1.55 nm. The influence of background air condition was inconsistent, probably owing to dynamic NCA behavior influenced by two opposing forces: enhanced generation by synergic reactions of ozone, background chemicals, and the worn clothing, and increased loss by coagulation and condensation. This study highlights the nuanced factors driving NCA generation from ozone-clothing chemistry.