Explanation

At cellular level, $SO_{2}$pollution destroys all membrane systems. In intense exposure to $SO_{2}$, these is bleaching of leaf pigments due to conversion of chl. $–a$ to phaeophytin$- a$. Thus, $SO_{2}$exposure has an impact on plant productivity. $SO_{2}\$pollution is the main cause of acid rain, which is threatening the shining of Taj Mahal. Mosses and lichens are very sensitive (indicator) to $SO_{2}$ pollution.