Read the passage given below and answer the questions that follow:Air pollution is an issue which concerns us all alike. One can willingly choose or reject a food, a drink or a life comfort, but unfortunately, there is little choice for the air we breathe. All, what is there in the air is inhaled by one and all living in those surroundings. Air pollutant is defined as a substance which is present in an amount exceeding the normal concentrations. It could either be gaseous or a particulate substance. The important and harmful polluting gases are carbon monoxide, carbon dioxide, ozone and oxides of sulphur and nitrogen.The common particulate pollutants are the dust of various inorganic or organic origins. Although we often talk of the air pollution caused by industrial and vehicular exhausts, indoor pollution may prove to be as or a more important cause of health problems. Recognition of air pollution is relatively recent. It is not uncommon to experience a feeling of ‘suffocation’ in a closed environment.It is often ascribed to the lack of oxygen. Fortunately, however, the composition of air is remarkably constant all over the world. There are about 79 per cent nitrogen and 21 per cent oxygen in the air – the other gases forming a very small fraction. It is true that carbon dioxide exhaled out of lungs may accumulate in a closed and overcrowded place.But such an increase is usually small and temporary unless the room is really air-tight. Exposure to poisonous gases such as carbon monoxide may occur in a closed room, heated by burning coal inside. This may also prove to be fatal. What is more common in a poorly ventilated home is a vague constellation of symptoms described as the sick – building syndrome. It is characterized by a general feeling of uneasiness, headache, dizziness and irritation of mucous membranes. It may also be accompanied by nausea, itching, aches, pains and depression.Sick building syndrome is getting more common in big cities with small houses, which are generally overfurnished. Some of the important pollutants whose indoor concentrations exceed those of the outdoors include gases such as carbon monoxide, carbon dioxide, oxides of nitrogen and organic substances like spores, formaldehyde, hydrocarbon aerosols and allergens.The sources are attributed to a variety of construction materials, insulations, furnishings, adhesives, cosmetics, house dust, fungi and other indoor products.Smoking of tobacco in the closed environment is an important source of indoor pollution. It may not be high quantitatively, but significantly hazardous for health. It is because of the fact that there are over 3000 chemical constituents in tobacco smoke, which have been identified. These are harmful to human health.Obviously, the spectrum of pollution is very wide and our options are limited. Indoor pollution may be handled relatively easily by an individual. Moreover, good work must start from one’s own house.1. What is a major source of indoor pollution?2. What is an issue of deep concern?3. What are the most harmful polluting gases?4. What are the symptoms of sick building syndrome?5. What are the sources of indoor pollution?6. What is the composition of air?Find out a word from the passage which means the following:7. Not clear8. Feeling of worry9. Lasting for a short time