Relationship between Nighttime Light (Ntl) and air quality (NO2& SO2) In a developing area in Peninsular Malaysia / Nurul Shuhadah Salehudin

Artificial light emissions, also known as night-time light (NTL), can be used to monitor human activity from space. Malaysia was also no exception to the spread of the COVID-19 pandemic in 2020, leading the government to implement the Movement Control Order (MCO), which had a significant impact on various sectors. Among the most affected sectors are the economy, companies, and services, including tourism, creative industries, manufacturing, healthcare, and more. This might have indirectly led to a decline in artificial light emissions at night. Even if COVID-19 had negative consequences for the country's economy and health, the air quality actually improved during the Malaysian Government Movement Control Order (MCO). The Movement Control Order (MCO), Conditional Movement Control Order (CMCO), Recovery Movement Control Order (RMCO), Total Lockdown, and National Recovery Plan (NRP) phases are among those that make up the MCO. Therefore, it is interesting to see how the emission of artificial light at night and the improvement of air quality are related. This study aims to investigate the relationship between NO2 and SO2 levels in the air and NTL emissions caused by human activities in a developing area of Peninsular Malaysia from 2019 until 2021. Using the Google Earth Engine platform, this study measured NTL radiation values using VIIRS-DNB images and column density values (NO2 and SO2) using Sentinel-5P images. Spatial-temporal maps were generated for NTL, NO2, and SO2 for the years 2019, 2020, and 2021, respectively. The analysis of the correlation between NTL and NO2 resulted -0.136 till 0.705, while the relationship between NTL and SO2 resulted in -0.075 till 0.2. These findings indicate that NTL can be used as an indicator to assess changes in air quality associated with human activities.