Decreases in Epoxide-Driven Secondary Organic Aerosol Production under Highly Acidic Conditions: The Importance of Acid-Base Equilibria.

Isoprene has the highest atmospheric emissions of any nonmethane hydrocarbon, and isoprene epoxydiols (IEPOX) are well-established oxidation products and the primary contributors forming isoprene-derived secondary organic aerosol (SOA). Highly acidic particles (pH 0-3) widespread across the lower troposphere enable acid-driven multiphase chemistry of IEPOX, such as epoxide ring-opening reactions forming methyltetrol sulfates through nucleophilic attack of sulfate (SO). Herein, we systematically demonstrate an unexpected decrease in SOA formation from IEPOX on highly acidic particles (pH < 1).

Numerical Simulations of Synthetic Ester Hydrolysis in the Indoor Environment.

The hydrolysis of synthetic esters (SEs), including phthalates and adipates, in damp indoor environments can lead to the release of volatile organic compounds implicated in poor air quality and acute health impacts, known as "sick building syndrome" (SBS). We have adapted the multiphase atmospheric chemistry box model, GAMMA, to simulate SE hydrolysis occurring in surface films in the indoor environment, along with multilayer boundary layer mass transfer and ventilation, in order to investigate this phenomenon on a process level. We then applied the model to analyze three scenarios in which hydrolysis has been hypothesized to have a significant impact on indoor air quality.