Acid rain and smog are said to be the consequences of air pollution. How are they

caused? What are the ill effects of breathing polluted air on human health?


Acid rain is the term used to define :

i. wet deposition and 

ii. dry deposition 

of sulfuric acid and nitric acid. When these depositions have a higher amount of acids than is found in the atmosphere naturally is called acid rain. They occur when rain water combines with SO and NO in the atmosphere and oxygen to form sulfuric acid and nitric acid respectively.


N2 (g) + O2 (g) → NO (g)

NO (g) + 1/2 O2  (g) → NO2  (g)

3NO2  (g) + H2 O → 2HNO3 (aq) + NO (g)


SO2 (g) + 1/2 O (g) → SO3  (g)

SO3  (g) + H2 O → H2 SO4  (aq)

These depositions occur due to :

i. natural events like volcano eruptions and 

ii. man made causes like burning of fossil fuels in large amounts.


Smog is referred when smoke and fog occur simultaneously. The two important components in smog are sulphur di-oxide and particulate matter.

Smog is produced by a set of complex photochemical reactions involving volatile organic compounds (VOCs), nitrogen oxides and sunlight, which form ground-level ozone.

 Smog is a problem in a number of cities and continues to harm human health. Ground-level ozone, sulfur dioxide, nitrogen dioxide carbon monoxide are especially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma. It can inflame breathing passages, decreasing the lungs' working capacity, and causing shortness of breath, pain when inhaling deeply, wheezing, and coughing. It can cause eye and nose irritation and it dries out the protective membranes of the nose and throat and interferes with the body's ability to fight infection, increasing susceptibility to illness.

  • -2

the fossil fuel contain a small amount of nitrogen and sulphur .when the fossil fuel are burnt the the nitrogen and sulphur also get burnt and release their own oxides which are harmful . these oxides remain suspended in air and when the rain falls it get mixed with these oxide and give acid rain. some times it so happen that the unburnt small particles of the carbon are suspended in air . when they get ,mixed with fog they are called smog (smoke+fog=smog).these are very harmful as they reduce visibility , and pose a threat to human life by causing many diseases like asthama ,heart disease, high blood pressure etc .

if you like the answer plz give a thumbz up ... bye and take care !!!

  • 12
What are you looking for?