Micropollutants, which include a variety of organic chemicals, heavy metals, and microplastics, are persistent and widespread contaminants that originate from multiple sources, such as industrial processes, agricultural runoff, pharmaceuticals, and everyday household products. Their extensive presence in air, water, and soil presents significant threats to ecosystems and human health. This chapter provides a thorough analysis of how micropollutants are assessed and their fate in the environment. Micropollutants can be classified into three primary categories—organic chemicals, inorganic elements, and microplastics. Each of these categories has unique origins, environmental impacts, and routes through which they enter various environmental compartments. The discussion includes the pathways through which these pollutants affect air, water, and soil, focusing on their behavior, distribution, and the factors that influence their persistence, including bioaccumulation, biomagnification, degradation processes, and potential for long-distance movement. The various assessment methods, such as analytical techniques for detection, toxicity evaluations using laboratory and field studies, and predictive modeling for environmental impact and risk analysis. The challenges and limitations associated with detecting micropollutants, including issues related to sensitivity, incomplete data, and uncertainties in modeling their effects. It emphasizes the need for ongoing innovation, robust regulation, and international cooperation to effectively address the multifaceted issues posed by micropollutants and protect environmental and public health.