Tropospheric ozone is a type of ozone found in the Earth's lower atmosphere, specifically in the troposphere, which extends from the surface up to about 10 kilometers (6 miles) high. Unlike stratospheric ozone, which protects us from harmful ultraviolet (UV) radiation, tropospheric ozone is considered a harmful air pollutant. It forms when volatile organic compounds (VOCs) and nitrogen oxides (NOx) react in the presence of sunlight. This ground-level ozone can cause respiratory problems, aggravate asthma, and reduce lung function. It also negatively impacts vegetation and ecosystems, leading to decreased agricultural productivity. Efforts to reduce tropospheric ozone levels often focus on controlling emissions from vehicles and industrial sources.