Characteristics, Sources, and Regional Origins of Aerosols

Atmospheric particulate matter (PM), a major component of aerosols, is increasingly recognized as a significant factor in the climate system of planet Earth due to its ability to influence the planet’s radiative balance. In recent years, aerosols have been linked to declining air quality, negatively affecting both human health and the climate. Understanding the sources and behavior of aerosols, both primary and secondary, as well as their spatial and temporal distribution, it is essential for evaluating their impact on air quality and climate. This chapter examines the features of PM in two significant regions of India—the Gangetic Plains and the Himalayan region. The Gangetic Plains, among the most densely populated and agriculturally productive regions globally, are a significant source of particulate pollution. This is largely due to rapid industrial growth, urban expansion, and activities such as burning fossil fuels (coal, diesel, gasoline, etc.), biomass burning (including crop residue, wood, and dung cakes), and agricultural practices involving livestock waste. The IHR, traditionally known for its cleaner air, has seen a rise in air pollution in recent years, much of which originates from the Indo-Gangetic Plain (IGP) and surrounding regions. In recent years, various heavy elements such as Cr, Mn, As, Ni, Pb, Cd, and Al, etc., have emerged as significant threats to human health, posing both carcinogenic and non-carcinogenic risks. These elements, present in the atmosphere, often originate from multiple pollution sources (soil and crustal dust, road dust, vehicle emissions, waste incineration and biomass burning, combustion of fossil fuels, secondary inorganic aerosols, and industrial discharges, etc.,) that interact in complex ways. To better understand and address these issues, the advanced receptor models like principal component analysis with absolute principal component scores (PCA-APCS) and positive matrix factorization (PMF) have been employed in various studies. This chapter also explores local, regional, and transboundary influences on aerosol composition and evaluates the broader implications on human health, air quality, and climate. Additionally, it identifies research gaps and suggests future directions for improving aerosol characterization and developing strategies to mitigate their harmful effects.