Ground level ozone:

Ground level ozone is the ozone present at the lower level of earth atmosphere. It is not emitted directly into the environment but produced by complex chemical reaction, when nitrogen oxides (NO_x), carbon monoxide (CO) and volatile organic compounds (VOC'S) react in presence of sunlight. NOx and VOC's are called ozone precursors and produced from cars, trucks, electric power plants, paint's fumes and industrial process. Ground level ozone is the primary constituents of smog (smoke + fog). Ground level ozone, though less in concentration than ozone in the stratosphere is more of a problem because of its adverse health effects. The major health effects are:

(i)  Irritation of the respiratory system causing coughing, throat irritation and uncomfortable sensation in the chest.

(ii)Increases susceptibility to respiratory infections.

(iii) Aggravates asthama.

(iv) Inflammation and damage to lining of lungs.