The impact of measures taken against COVID-19 on air quality: Istanbul case study

Abstract:

Coronavirus disease 2019 (COVID-19) caused many problems in many countries around the world. Turkey announced the first recorded case of COVID-19 on March 2020. The total number of patients in Turkey is about 230.000 people. Istanbul, as one of the most populated cities in the world and the center of the Turkish economy, has the highest number of patients in the country. This study used remote sensing technology and satellite data for understanding the impacts of precautions taken (i.e., quarantine measures) for COVID-19 on air quality of Istanbul in 2020. In total, 300 daily Level-3 satellite data of NASA’s Ozone Monitoring Instrument (OMI) with spatial resolution of 0.25 deg Lat/Lon grids were used in this study to quantify the total column amount NO₂ in two study periods of 01.01.2019 – 31.05.2019 and 01.01.2020 – 31.05.2020. The mean value of grids covering Istanbul was calculated as the total column amount NO₂ for Istanbul. According to the results of this study, the minimum daily value of NO₂ (about 2.36e+15 molec cm^-2) in 2020 was observed during quarantine times, when traffic levels were significantly reduced. The total column amount NO₂ increased after quarantine time especially on Mondays of each week (about 6.34e+15 molec cm^-2). In the second step, monthly mean NO₂ values were calculated using daily ones and the results of same months were compared in 2019 and 2020. The results indicated that monthly mean total column amount NO₂ decreased about 1.07e+15 molec cm^-2 from 2019 to 2020. This paper compares findings using the satellite data to daily traffic changes as well as air quality monitoring measurements.