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Automobiles are the major sources of air pollution in Delhi. Measures that were taken to reduce vehicular air pollution are as follows.

1. Use of CNG (Compressed Natural Gas) for its public transport system.

2. Phasing out of old vehicles.

3. Use of unleaded petrol.

4. Use of low sulphur petrol and diesel.

5. Use of catalytic converter in vehicles.

6. Application of Euro II norms for vehicles.

Because of above mentioned steps taken up by the Government, the air quality of Delhi  improved with a substantial fall in carbon monoxide, oxides of sulphur and nitrogen level between 1997-2005.

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(a) Greenhouse gases trap heat in the atmosphere, which makes the Earth warmer. Carno dioxide, methane are generally called greenhouse gases. These gases absorb long wave (infrared) radiation radiated from the earth. Theses gases radiate heat energy a major part of which again comes to Earth’s surface, thus heating it up. They prevent heat from escaping to outer space, so are functionally comparable to glass panels of a greenhouse and are called greenhouse gases  

(b) Catalytic converter is a device that uses a catalyst to convert the harmful compounds in car exhaust into harmless compounds. They are fitted into the automobiles and have expensive metals namely platinum-palladium and rhodium as the catalysts. As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively. 

(c) Ultraviolet-B radiations. These are high energetic UV-radiations which are mostly blocked by the ozone layer. UV-B damages DNA  and causes mutations in it. UV-B radiation is very harmful for eyes. It leads to aging of skin and causes skin cancers. When cornea absorbs UV-B, it leads to the inflammation of cornea and may cause diseases like snow blindness cataract. Exposure may even permanently damage cornea.

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Wastes generated at home include waste paper, plastic bags, paper napkin, toiletries, kitchen wastes (such as peelings of vegetables and fruits, tea leaves), domestic sewage, glass, etc.
Wastes generated at schools include waste paper, plastics, vegetable and fruit peels, food wrappings, sewage etc.
Wastes generated at trips or picnics include plastic, paper, vegetable and fruit peels, disposable cups, plates, spoons etc.
Yes, these wastes can be easily reduced by the judicious use of the above materials. Wastage of paper can be minimized by writing on both sides of the paper and sending it for recycle. Plastic and glass waste can also be re-used. Substituting plastics bags with biodegradable jute bags can reduce wastes generated. Domestic sewage can be reduced by optimizing the use of water while bathing, cooking, and other household activities.
The reduction of non- biodegradable wastes such as plastic, metal, broken glass, etc, prove to be difficult as they are not decomposed by the micro-organisms in the soil. Thus, they persist in the environment for long and cause harm to it. 

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A. Catalytic converter	(i) Carbon monoxide and nitrogen oxides
B. Electrostatic precipitator	(ii) Particulate matter
C. Earmuffs	(iii) High noise level
D. Earmuffs	(iv) Solid wastes

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(a) Radioactive wastes are the wastes that contain radioactive material. it is generated when nuclear energy is used  for generating electricity or other purposes. radioactive wastes are extremely dangerous as they radiation given off from them causes mutations at a very high rate. Safe disposal of radioactive wastes is another major problem. 

(b) Defunct ships and e-wastes. Defunct ships are a kind of solid waste requiring proper disposal. Such ships are broken down in developing countries for scrap metal. They often contain toxic substances such as asbestos, polychlorinated biphenyls, tributyltin, lead and mercury.

E-waste are irreparable computers and electronic goods . Most of them are shipped to developing countries for metals like copper, nickel, silicon, gold, that are recovered by recycling. E-wastes are buried and incinerated.

(c) Municipal Solid Wastes. Municipal solid wastes are wastes generated  from homes, offices, stores, schools, etc. and they are collected and disposed by the municipality. The municipal solid wastes generally comprise paper, food wastes, glass, metals, rubber, leather, textile, etc. Burning reduces the volume of the wastes, although it is generally not complete and open dumps often serve as the breeding ground for rats and flies.