Implications of a New Normal Urban Air Quality

Abstract

The COVID-19 pandemic related lockdown measures have led to dramatic reductions in air pollution across the globe [1]–[5]. Observations of trace gases and aerosols from ground and satellite have shown a reduction in concentrations from pre-lockdown to the lockdown phase because of reduced emissions from the transportation and industrial sectors. Most studies have used Google or Apple cell phone data to assess reduced mobility [5]. Our study used the derived on-road emissions data for 2019 and 2020 for five different locations in the US (four urban and one rural region) to quantify NOx (NO+NO2) emissions reductions from cars and trucks during the lockdown to study the impact on air quality (NO2, PM2.5, and aerosol optical depth as indicators of air quality). Those findings are reported in [6]. The consistency between bottom-up emissions estimates and satellite observed NO2 concentrations for these five locations will give us confidence in using the satellite NO2 data elsewhere in the globe in analyzing co-emitted pollutants such as aerosols.