With rapid industrial revolution, there has been lot of changes takes place in the composition of the atmosphere mainly due to the combustion of fossil fuels used for the generation of energy and transportations. Air pollution regarded as the presence of chemical, biological and pollutants in the atmosphere around the living spaces. Today, it is considered as major environmental health problem that affecting the developed as well as developing countries. The effects of air pollution on human health are very critical as there are various sources. The ambient air quality in the cities and the indoor air quality in the urban and rural areas are the biggest issues. When air pollutants are inhaled the lungs and respiratory system of the person gets severely affected. Another way of entering air pollutants in throughout the body is that by blood and pumped. These pollutants are spread through the form of soil, plants and water as well. Large scale industrialization and vehicle emission are considered to be the biggest primary culprits of air pollution.

Air pollution leads to several life threatening diseases. People are not much aware about the effects of air pollution. Consistent exposure to pollutants contributes to development of various diseases. The gasses mentioned below are mostly outdoor air pollutants but some of them can take place indoor depending on the source and the circumstances.

1) Biological pollutants:-
These pollutants are usually causes asthma, fever and other allergic diseases.

2) Volatile organic compounds:-
Volatile compound usually causes irritation to the eye, nose and throat. In serious cases headache, nausea and loss of coordination may also cause. In the longer period of time, some of them are suspected to lead to damage to the liver and other parts of body.

3) Tobacco smoke:-
Tobacco smoke is said to be major cause of all health disorders. It yields a wide range of harmful chemicals. It is the primary culprit of cancer and it affects not only to the smoker but also the passive smoker. It ranges from burning sensations in the eyes, nose and throat irritation up to the severe diseases such as cancer, bronchitis, asthma and decreased in lung function.

4) Ozone:-
Studies indicate that ground level ozone not only affect people with impaired respiratory system but healthy adults and children as well. Exposure to this gas for 6-7 hours even at comparatively low concentration considerably dilutes lung function and stimulates respiratory inflammation to normal and healthy people during periods of moderate exercise. It may include the symptoms such as chest pain, nausea, pulmonary congestion and coughing. One study has found that continuous exposure to high level of ozone for long period of time can produce permanent structural damage in the lungs. Apart from this it makes your eyes itch and burn. It lower you resistance power to cold and pneumonia and results in increasing the respiratory diseases such as asthma.

5) Formaldehyde:-
Consistent exposure to this gas may result in damaging or irritation to the eyes, nose and may cause allergies in some people.

6) Nitrogen dioxide:-
These gases usually form when fuel is burned at high temperatures and primarily come from motor vehicle exhaust and stationary sources such as electric utilities and industrial boilers. Exposure to this gas lowers resistance to respiratory infection such as influenza and causes the lung diseases as well. The effects of short term exposure to this gas are still not observe or unclear. But consistent or frequent exposure may contribute to chronic respiratory illness in children.

7) Lead:-
Lead is the rich source of smelters and battery plants. It is considerably found in the vicinity of nonferrous smelters and other stationery sources of lead emissions. Exposure to lead mostly takes place through inhalation of air and ingestion of lead in food, paint, water, soil or dust.

Exposure to this gas results in damaging the nervous system, kidney, liver, digestive problem and other organs. In some cases contributes to life threatening cancer as well. Prolonged exposure to lead may contribute to cause anemia, kidney diseases, reproductive disorders and neurological impairments such as mental retardation, behavioral disorders, seizures and so on. Even low exposure to lead is linked with changes in fundamental enzymatic, energy transfer and other processes in the body. Even little exposure to lead is especially harmful and hazardous to small children and fetuses as well, as their central nervous system gets damaged. In recent study found that lead may be a factor in high blood pressure and consequent heart diseases in the middle aged white males. Apart from these, lead is also associated with developing the risk of osteoporosis disease in postmenopausal women.

8) Radon:-
This gas usually accumulated inside the house and originates from the rocks and soil under the house. Exposure to radon is associated with the risk of developing lung cancer.

9) Carbon monoxide:-
It enters into the blood stream and lowers the oxygen delivery to the body’s organs and tissues. Exposure to carbon monoxide is hazardous for those who are suffering from cardiac diseases. Prolonged exposure affect to healthy individual as well. Exposure to eminent CO level is linked with visual impairment and result in reducing work capacity, reduces manual dexterity, poor learning ability and difficulty in performing complex tasks.

10) Particulate matter:-
It is mostly consist of dust, mist, smoke and fumes. Exposure to particulate matter is associated with developing the risk of cancer, damages lung tissue, and premature death, affect breathing and respiratory diseases. The elder people, children and people who are suffering from chronic lung diseases are get affected instantly due to exposure to this gas.

11) Sulfur dioxide:-
These gases occur when fuel containing sulfur is burned during meal smelting and other industrial processes. The effects of this gas contribute to shortness of breath, cardiac diseases, respiratory illness, lung disorders, alterations in pulmonary defenses and so on.