Ground-level ozone is one of the most injurious pollutants for plant life. It can reduce yields of sensitive species such as varieties of soybeans, spinach and lettuce and stress various plants and trees. Some estimates put annual U.S. agricultural crop losses at $3 billion in reduced crop yields due to ozone damage.

Air pollutant impacts on Iowa plants, crops, forests, land and water is largely unstudied. Ozone also affects vegetation and ecosystems, leading to reductions in agricultural and commercial forest yields, reduced growth and survivability of tree seedlings, and increased plant susceptibility to disease, pests, and other environmental stresses such as harsh weather. In long-lived species, these effects may become evident only after several years or even decades, thus having the potential for long-term effects on forest ecosystems.

Recent research indicates ozone inhibits the ability of plants to open the microscopic pores on their leaves to breathe. Ozone also negatively impacts plants by interfering with the photosynthesis process by reducing the amount of carbon dioxide the plants can process and release as oxygen.