Ground-level ozone, also known as tropospheric ozone, is a significant air contaminant which poses serious threats to agricultural productivity and ecosystem health. This chapter examines the detrimental effects of ozone on crop yields, emphasizing its role in reducing photosynthesis rates, biomass accumulation, and fruit quality. The concentration of ground-level ozone has more than doubled since pre-industrial times, with its impacts varying based on concentration levels, specific crop species, and exposure duration. The document highlights the increasing emissions of ozone precursors in Asia, contrasting with the reductions observed in Europe and North America. Additionally, it discusses the interaction of ozone with other pollutants, such as hydrogen sulfide (H2S), and the complex signaling mechanisms in plants that mediate their responses to these stressors. Understanding these dynamics is crucial for developing strategies to breed ozone-tolerant crops and mitigate the opposing effects of air pollution on agriculture.