Following factors are responsible for air pollution.

(i) Industrial Emissions : Various dangerous and poisonous gases emitted by different industries cause air pollution. These gase causes smog and acide rain. 

(ii) Vehicles : The combustion of fuel inside the vehicle  releases many pollutants like carbon monoxide, carbon dioxide, nitrogen oxides and smoke.

(iii) Natural Pollutant : Forest fire, volcanic eruption, dust storms etc., also cause air pollution.

(iv) Other activities of Man : Besides above described causes many other human activities like using cow dung, coal, wood as fuels etc. pollute the air. Burning of crackers on Diwali and other celebrations releases many harmful gases in the atmosphere.

Water pollution is caused by many factors  :

(i) Industrial discharges : Various harmful and poisonous chemicals and substances are discharged by industries directly into water bodies. 

(ii) Domestic discharges : Sewage from homes are collected and disposed off in rivers nearby. This untreated sewage is one of the prominent causes of water pollution.

(iii) Religious Rituals : Various religious rituals like dispersion of dead bodies or remains of dead bodies in rivers is causes water pollution .

(iv) Other Human Activities : Human activities like washing of clothes on garbage in water bodies aalso pollutes the water bodies.

The characteristics of potable water are :

(i) It should be colourless and odourless.

(ii) It should be free from any suspended impurities.

(iii) It should be free from any harmful germs.

(iv) It should be free from large quantity of salts.

(v) It should be free from any harmful salt such as nitrates, cyanides, urea etc.

B.

Air pollution

B.

Respiratory diseases