Increasing Contributions of Temperature-Dependent Oxygenated Organic Aerosol to Summertime Particulate Matter in New York City.

As part of the summer 2022 NYC-METS (New York City metropolitan Measurements of Emissions and TransformationS) campaign and the ASCENT (Atmospheric Science and Chemistry mEasurement NeTwork) observational network, speciated particulate matter was measured in real time in Manhattan and Queens, NY, with additional gas-phase measurements. Largely due to observed reductions in inorganic sulfate aerosol components over the 21st century, summertime aerosol composition in NYC has become predominantly organic (80-83%). Organic aerosol source apportionment via positive matrix factorization showed that this is dominated by secondary production as oxygenated organic aerosol (OOA) source factors comprised 73-76% of OA.

Simultaneous time-resolved inorganic haloamine measurements enable analysis of disinfectant degradation kinetics and by-product formation.

We demonstrate the application of proton transfer time-of-flight mass spectrometry (PTR-TOF-MS) in monitoring the kinetics of disinfectant decay in water with a sensitivity one to three orders of magnitude greater than other analytical methods. Chemical disinfection inactivates pathogens during water treatment and prevents regrowth as water is conveyed in distribution system pipes, but it also causes formation of toxic disinfection by-products. Analytical limits have hindered kinetic models, which aid in ensuring water quality and protecting public health by predicting disinfection by-products formation.

Bleach Emissions Interact Substantially with Surgical and KN95 Mask Surfaces.

Mask wearing and bleach disinfectants became commonplace during the COVID-19 pandemic. Bleach generates toxic species including hypochlorous acid (HOCl), chlorine (Cl), and chloramines. Their reaction with organic species can generate additional toxic compounds.