What term refers to the contamination of the atmosphere by harmful substances?

The term that best encapsulates the contamination of the atmosphere by harmful substances is air pollution. This term specifically refers to the introduction of pollutants into the air that can have detrimental effects on human health, wildlife, and the overall environment. Air pollution can originate from various sources, including industrial emissions, vehicle exhaust, and even natural events like wildfires.

While air quality degradation refers to a decline in the overall quality of the air, it is more a consequence of air pollution rather than a direct term describing the act of contamination itself. Atmospheric contamination is a more general term that can apply to various contexts and is less commonly used in the study of geography. Gas emissions, while related to the release of gases that may contribute to air pollution, do not comprehensively cover the broader range of pollutants, including particulates and chemical compounds, that define air pollution. Therefore, air pollution is the most accurate and widely recognized term used in discussions about harmful substances in the atmosphere.