Spatio-temporal Analysis Mapping of Air Quality Monitoring in Cairo Using Sentinel-5 Satellite Data and Google Earth Engine

Abstract

Air pollutants including nitrogen dioxide (NO2), carbon monoxide (CO), and sulphur dioxide (SO2) cause serious damage to human health and the environment. This research aims to assess built-up seasonal variations of air pollution maps over Cairo city in Egypt using remote sensing data. Land Surface Temperature (LST) data was obtained from the MODIS Terra Satellite data, specifically the MOD11A1 V6 product, from January to December 2022. The Sentinel-5 project utilizes the tropospheric monitoring instrument (TROPOMI) sensor to capture images across different spectral bands, enabling precise monitoring of air pollution levels. The concentration data of NO2, CO, and SO2 were extracted from Sentinel-5P using Google Earth Engine (GEE), which was utilized extensively in this study. The study found that the eastern region had the highest levels of NO2 and CO emissions, attributed to transportation and heating in densely populated areas. The northern region had the highest SO2 emissions due to industrial activities. Higher pollution levels were observed during colder months, which can be attributed to the temperature version phenomenon. However, summer pollutants pose greater health risks to humans. The statistical analysis showed a positive correlation between average pollutant concentrations (NO2, CO, SO2) and mean LST in 2022, with R-squared values indicating moderate associations (0.3757 for NO2, 0.2865 for CO, and 0.1774 for SO2). Additionally, the exponential smoothing (ETS) algorithm was employed to forecast a time series, and the results were evaluated by comparing the original and predicted values, calculating the root-mean-square (RMS) error to validate the approach. The findings demonstrate that the ETS is highly effective and precise. Our study provides a spatio-temporal analysis of air quality monitoring in Cairo using Sentinel-5 satellite data and highlights the spatial and temporal patterns of NO2 concentrations and LST in the region. The findings of the study indicate that Cairo City's air quality is significantly compromised because of urban expansion, the rise in vehicular activity, and the rapid growth of industries. Consequently, the deteriorating air quality directly contributes to the city's climate change issues.