Monitoring the Impact of COVID-19 Lockdown and Correlates on Nigeria's
Air Quality Using TROPOMI Data
Abstract
Abstract It has been debated globally that the COVID-19 lockdown had
significantly diminished the emission levels of anthropogenic greenhouse
gases (GHGs). However, different countries possess different footprints
of GHGs emission. In regions with inconsistent air quality observation,
spaceborne sensors can provide synoptic assessment of air quality with
time-based environmental decision making. In this study, we utilised
satellite data to quantify the temporal dynamics of carbon monoxide (CO)
and nitrogen dioxide (NO2) between the pre-lockdown
(January–March 2020), lockdown (April–July 2020) and post-lockdown
(August–September 2020) periods in Nigeria. Periodic TROPOspheric
Monitoring Instrument (TROPOMI) datasets were acquired from the Google
Earth Engine Sentinel-5 Explorer and the Copernicus Open Access Hub. The
Population-Weighted Mean Concentration (PWEC) of CO and
NO2 was computed using raster-based population data and
place-based air quality estimates. The associated economic correlates
were computed using data mined from TROPOMI and available health records
of Nigeria. Satellite data analysis showed that aggregate CO reduced by
35.1% (25.32⋅105 tons) and 9.06%
(6.54⋅105 tons) and NO2 plummeted by
32.81% (22,500 tons) and 11.63% (5,360 tons) during the lockdown and
post-lockdown periods across the 36 States of the country. While
mobility rate dwindled substantially, mortality rate savings from the
exposure to damaging effects of the GHGs were roughly $ 14 million (CO)
and $10 million (NO2). The fluxes in CO and
NO2 suggest that anthropogenic interference in air
quality accounting can aid the understanding of the convoluted
human–nature relationships for sustainable environmental management.