New particle formation contribution to aerosol mass: regimes and implications for future urban environments

New particle formation (NPF) is a major source of global aerosol number concentration yet its contribution to aerosol mass remains unclear. Here we propose a regime framework for NPF mass contributions using aerosol dynamic simulations constrained by atmospheric measurements. We show that new particles can contribute more than 10 µg m −3 to particle mass under conditions characterized by high initial new particle concentrations, high condensable vapor production rates, and low background condensation sink (CS bg ). Among these influencing factors, the initial CS bg governs NPF mass contribution under the simulation conditions: NPF contributes significantly to aerosol surface area and mass at an initial CS bg of ∼ 0.001 s −1 (regime I), while its contribution becomes negligible when CS bg exceeds 0.01 s −1 (regime III). Results show that NPF events in urban Beijing occur mostly in a transition regime (initial CS bg 0.001–0.01 s −1 , regime II), in which the NPF mass contribution is also modulated by the mass accommodation coefficient of background particles, while events at a Finnish forest site fall in regimes I and II. Our simulations suggest that NPF mass contribution in urban environments with a declining CS bg will shift toward regimes I and II. This indicates that control of anthropogenic NPF precursors may represent an effective strategy for present and future particulate matter pollution in urban environments, which warrants further investigation.