(i) Due to better medical care there is a fall in death rate both for infants and the old. As long as birth rate exceeds death rate population grows rapidly.
(ii) Haemoglobin has very strong affinity for carbon monoxide, forming a stable compound carboxyhaemoglobin. This cuts down the capacity of blood for transporting oxygen, sometimes resulting in death.
(iii) Excessive fertilizers make the soil hypertonic as compared to root hair cells. Exosmosis takes place and root hair cells become flaccid due to which they droop.
(iv) Acid rain is dangerous for vegetation, decays building materials, paints and corrodes building and monuments and statues. It acidifies lakes and streams which affect aquatic life.
(v) Provides oxygen for respiration. Provides food and maintains food chain.
