CBSE Class 10 Answered

Ozone has two distinct concentrations, that which resides near the surface of the atmosphere is referred to as tropospheric ozone and that which resides in the upper atmosphere is referred to as stratospheric ozone.

The stratospheric ozone is considered extremely beneficial and essential for life. The ozone present in this region has the very special property of absorbing the highly energetic ultraviolet (UV) rays coming from the sun. This partial absorption of UV light protects life from several complications. The stratospheric ozone is a thus, a blessing to the life on Earth because of its ability to absorb and therefore, block much of the UV light from reaching the earth’s surface.

In the lower atmosphere, particularly near the surface, the tropospheric ozone is not so beneficial. Ozone often causes respiratory problems and damage to the lungs when inhaled. Human beings primarily cause the ozone levels to rise above thresholds. Urban centers with heavy traffic and industry tend to have much higher levels than rural areas due to gaseous emissions from motor vehicles and factories in these locations. These emission sources do not release ozone into the atmosphere directly, but ozone is produced as a major byproduct when their gaseous effluents such as nitrogen oxides and hydrocarbons undergo photochemical reactions. Expanded utilisation of public transportation and continued improvement in the technology of hybrid or fuel-cell vehicles appears to be an appropriate way to reduce the problems associated with tropospheric ozone.