Read the given paragraph and answer the following questions.

Air pollution leads to an increase in harmful gases rather than depleting a specific gas, but it is indirectly linked to ozone layer depletion. The ozone layer, located in the Earth's stratosphere, is degraded by chlorofluorocarbons (CFCs), halons, and other ozone-depleting substances (ODS) found in products like refrigerants and aerosol sprays. These substances cause the breakdown of ozone (O3) molecules, thinning the layer that shields Earth from harmful ultraviolet radiation. This decline in ozone concentration poses risks to human health, ecosystems, and climate. Additionally, smog, a secondary air pollutant made of smoke and fog, reduces visibility. Lichens, sensitive to air pollution, serve as environmental indicators, particularly for sulfur dioxide. Incomplete combustion of organic material produces carbon monoxide and soot, highlighting the importance of proper oxygen supply for combustion.