Planetary Health Check: A Regional Evaluation of Aerosol Loading and Air Quality in Asia

This study on the planetary boundary: Atmospheric aerosol loading focuses on methods to develop high-resolution, chemically differentiable data, along with practical strategies to retain the boundary within limits. Planetary boundaries are a framework of nine interdependent processes that are altered by human activities. The boundaries define safe limits for these processes beyond which irreversible damage occurs to the Earth's ecosystem.

Atmospheric aerosol loading refers to the amount of aerosols readily available in the atmosphere. Aerosol Optical Depth is a measure of aerosols in the atmosphere through the amount of sunlight blocked from reaching the Earth's surface. High AOD accounts for low visibility, increased air pollution, and alters cloud formation, therefore disrupting monsoon patterns.

This planetary boundary quantifies the inter-hemispheric difference in atmospheric aerosol loading and defines a safe operating space to be less than 0.1. A significant decrease in this boundary value was observed in 2025 (0.063) compared to 2023 (0.076). However, regional exceedances have been observed throughout the year in Asia and Africa, with the regional boundary set at 0.25 (high risk), taking into consideration heavy monsoon areas. A decrease in atmospheric aerosols helps reduce air pollution and immediate health risks; however, the possibility of global warming increases due to the decrease in cooling aerosols and their impact on lowering the temperature.

The 2025 planetary health check takes into account the dual effect of aerosols (cooling & warming). The effective radiative forcing of aerosols affects the Earth's energy balance through scattering or absorbing sunlight. Aerosol-cloud interactions have a significant impact on the global net cooling or warming. Local variations and exceedances are primarily observed due to differences in aerosol type and emissions. Time series AOD data were obtained from the Copernicus Atmosphere Monitoring Service (CAMS) to analyse further and relate to surface-level pollution trends in the Indian Region. Further research needs well-consolidated data from observations and modelling to better understand local and global effects and consequences.

KEYWORDS: Atmospheric Aerosol Loading, Aerosol Optical Depth, Air Pollution.