Impact of the COVID-19 Pandemic on Air Quality in Atlanta, GA

Abstract:

The COVID-19 pandemic has forced states and cities to significantly reduce activities, imposing lockdowns, shelter-at-home orders, telework or other measures that reduce the number of people commuting in and out of the city. Previous studies in the southeastern U. S. (including Atlanta) have shown that the amount of organic aerosol (OA) is largely mediated by anthropogenic emissions including NO_X and SO­₂. For this reason, we expect reductions in anthropogenic activities will impact the air quality in the city. To evaluate this, we deployed a suite of instrumentation at Georgia Institute of Technology campus starting the last week of April and measurements are still on going. The sampling site has been used in multiple previous field campaigns for characterize urban Atlanta air quality, as recently as last summer. It is 840 m away from Interstate 75/85 and 30−40m above ground. The deployed instrumentation includes NO, NO₂, and O₃ measurements as well as submicron non-refractory aerosol components measured using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a Scanning Mobility Particle Sizer (SMPS). Volatile Organic Compounds (VOCs) were measured using a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS). In addition, oxidized VOCs and speciated aerosol components were measured using a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer fitted with a Filter Inlet for Gases and Aerosols (FIGAERO HR-ToF-CIMS) and using iodide as the reagent ion. The results show reduced concentrations of NO and NO₂ and apparent reductions in particulate matter. We also compare the observed aerosol components to those observed during a similar period last year at the same site. Particularly, we will investigate if and how the reduced anthropogenic emissions affects the oxidation of biogenic VOCs and the corresponding SOA formation and properties.