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Fresh produce-associated outbreaks of foodborne illnesses continue to occur every year in the U.S., suggesting limitations of current practices and the need for effective intervention technologies. Advanced oxidation process involves production of hydrogen radicals, which are the strongest oxidant. The objective of the present study was to evaluate the effectiveness of advanced oxidation process by combining gaseous ozone and aerosolized hydrogen peroxide. Grape tomatoes were inoculated with a 2-strain cocktail of Salmonella typhimurium on both stem scar and smooth surface. Gaseous ozone (800 and 1600 ppm) and aerosolized hydrogen peroxide (2.5, 5 and 10%) were separately or simultaneously introduced into a treatment chamber where the inoculated tomatoes were placed. During the 30 min treatments, hydrogen peroxide was aerosolized using an atomizer operated in two modes: continuously or 15 s on/50 s off. After the treatments, surviving Salmonella on the smooth surface and stem scar were enumerated. Results showed that ozone alone reduced Salmonella populations by <0.6 log CFU/fruit on both the smooth surface and the stem scar area, and aerosolized hydrogen peroxide alone reduced the populations by up to 2.1 log CFU/fruit on the smooth surface and 0.8 log CFU/fruit on stem scar area. However, the combination treatments reduced the populations by up to 5.2 log CFU/fruit on smooth surface and 4.2 log CFU/fruit on the stem scar. Overall, our results demonstrate that gaseous ozone and aerosolized hydrogen peroxide have synergistic effects on the reduction of Salmonella populations on tomatoes. • Gaseous ozone at up to 1600 ppm had little effect on populations of Salmonella. • Aerosolized hydrogen peroxide reduced Salmonella populations up to 2.1 logs. • AOP reduced the population by up to 5.2 logs on surface and 4.2 logs on stem scar. • Synergistic effects were observed between ozone and hydrogen peroxide via AOP. [ABSTRACT FROM AUTHOR]

Organic aerosol (OA) is chemically dynamic, continuously evolving by oxidative chemistry, for instance, via hydroxyl radical (OH) reactions. Studies have explored this evolution (so-called OA aging) in the atmosphere, but none have investigated it indoors. Aging organic molecules in both particle and gas-phases undergo changes in oxygen content and volatility, which may ultimately either enhance or reduce the condensed-phase OA concentration (C OA ). This work models OH-induced aging using the two-dimensional volatility basis set (2D-VBS) within an indoor model and explores its significance on C OA relative to prior modeling methodologies which neglect aging transformations. Lagrangian, time-averaged, and transient indoor simulations were conducted. The time-averaged simulations included a Monte Carlo procedure and sensitivity analysis, using input distributions typical of U.S. residences. Results demonstrate that indoors, aging generally leads to C OA augmentation. The extent to which this is significant is conditional upon several factors, most notably temperature, OH exposure, and OA mass loading. Time-averaged C OA was affected minimally in typical residences (<5% increase). However, some plausible cases may cause stronger C OA enhancements, such as in a sunlit room where photolysis facilitates significant OH production (~20% increase), or during a transient OH-producing cleaning event (~35% peak increase)., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)