Fine Particle pH and Sensitivity to NH and HNO over South Korea During KORUS-AQ.

Using a new approach that constrains thermodynamic modeling of aerosol composition with measured gas-to-particle partitioning of inorganic nitrate, we estimate the acidity levels for aerosol sampled in the South Korean planetary boundary layer during the NASA/NIER KORUS-AQ field campaign. The pH (mean ± 1σ = 2.43±0.

Dependence of aerosol-borne influenza A virus infectivity on relative humidity and aerosol composition.

We describe a novel biosafety aerosol chamber equipped with state-of-the-art instrumentation for bubble-bursting aerosol generation, size distribution measurement, and condensation-growth collection to minimize sampling artifacts when measuring virus infectivity in aerosol particles. Using this facility, we investigated the effect of relative humidity (RH) in very clean air without trace gases (except ∼400 ppm CO) on the preservation of influenza A virus (IAV) infectivity in saline aerosol particles. We characterized infectivity in terms of 99%-inactivation time, , a metric we consider most relevant to airborne virus transmission.

Seasonal Changes in the Oxidative Potential of Urban Air Pollutants: The Influence of Emission Sources and Proton- and Ligand-Mediated Dissolution of Transition Metals.

The inhalation of fine particulate matter (PM) is a major contributor to adverse health effects from air pollution worldwide. An important toxicity pathway is thought to follow oxidative stress from the formation of exogenous reactive oxygen species (ROS) in the body, a proxy of which is oxidative potential (OP). As redox-active transition metals and organic species are important drivers of OP in urban environments, we investigate how seasonal changes in emission sources, aerosol chemical composition, acidity, and metal dissolution influence OP dynamics.

Predicted Concentrations and Optical Properties of Brown Carbon from Biomass Burning over Europe.

Black carbon (BC) and brown carbon (BrC) are light-absorbing carbonaceous aerosol components that can contribute to radiative forcing and thus affect the climate. In this study, we focus on the modification of aerosol optical properties associated with BrC emissions from biomass burning. BrC is simulated with the introduction of three new species in the three-dimensional chemical transport model PMCAMx-SR, two primary-absorbing (inert and reactive BrC) species, and one "photobleached" BrC species.