Respiration is the fundamental biological process that keeps the metabolic machineries of living organisms, eventually their lives, functioning. Every living system requires oxygen, and to terrestrial systems the amount required is relatively voluminous. Human beings intake oxygen directly from air which usually comprises 20.946% oxygen. This oxygen keeps our metabolic machineries steady and purposeful. Apart from oxygen, air usually contains about 78% nitrogen and trace amounts of argon, carbon dioxide, neon, helium and methane. With the advent of civilization and all-around mechanization, scientific development has however turned around as a boomerang, as the developments in agricultural, industrial and transportation arenas have perturbed the natural balance and disarrayed the composition of air in the global scale. But nevertheless, the intensity of air perturbation in Dhaka is catastrophic, as the air pollution in Dhaka has recently surpassed most, if not all, of the cities' in the world: Dhaka is now regarded as one of the most polluted cities in the world! My recent exposure to the air in Dhaka has catapulted immense concerns in me about the coming-day lives in Dhaka. The indiscriminate development in conjunction with poor civic practices and improper municipal management has polluted the air in Dhaka alarmingly. The intensity of air pollution in Dhaka has reached to such a level that, to my perception, it has eventually depauperated the city as a place to reside.

Air pollutants in Dhaka
The commonly found air pollutants fall into two major categories, the gaseous compounds and the particulate materials. The gaseous compounds include predominantly various oxides of sulfur and nitrogen, carbon monoxides, ozone and ammonia. The particulate materials include mainly dusts, fly ash, smoke, fumes, shoots, aerosol, heavy metals, etc. Dr. Khalequzzaman of Bangladesh Atomic Energy Commission in a meeting in 1998 reported that the air in Tejgaon area of Dhaka contained 64-143 µg of sulfur dioxide per cubic meter of air. He also reported that the composition of nitrogen oxides in the air of Farmgate area of Dhaka was 25-32 µg/m3 of air. Environmentalist J. Core, a World Bank consultant in Dhaka, in the same meeting reported that the concentration of suspended particulate materials in the air of Dhaka was found to be 665-2456 µg/m3, which is alarmingly higher than the recommended standard level of 200 µg/m3 of air. Lead is a heavy metal, which is toxic and affects mammalian brains. According to the WHO report 2001, the lead concentration found in the blood of children in Dhaka was up to four times higher the acceptable level of 10 g/dl. This high level of lead concentration in blood is correlated with that in the air.

Sources of air pollutants
In the context of Bangladesh, vehicle exhausts are regarded as one of the major culprits of air pollution. The total number of motor vehicles trafficking in Dhaka city is not as high as it is in the other mega cities in the world. But nevertheless, mechanically defective vehicles coupled with trafficking of a large number of two-stroke engine vehicles that run on partial burning of impure gasoline and emit CO, CO2, SO2 and other components including the lead cause the major damage to the air. On top of these, industrial exhausts, irresponsible civic practices and improper municipal services are also serving the cause of air pollution.

Why is the air pollution a concern?
Air pollution is imposing a significant setback to our economy, as it is associated with health hazards and curtailed economic growth of the country. According to the World Bank report 2001, the air pollution claims about 15000 lives each year in Bangladesh. Apart from these death tolls, air pollution is linked with over nine million cases of sickness in the country. Air pollution can cause various diseases including dizziness, continuous headache, reduced nervous system functioning, heart diseases, kidney and lung damages, etc. Some of the pollutants, particularly the lead impairs the brain and reduces the processing efficiency of brain, which is really an alarming issue. These health problems reduce the working efficiency of the victims and eventually increase their chance of being burdens to others. In terms of the lucrative currency, the air pollution reduces an estimated growth of as low as 200 to as high as 800 million U.S. dollars a year (World Bank, 2001). The amount of this projected revenue loss is a significant loss relative to the total productivity of the country.

Measures taken to mitigate the problem
To reduce the air pollution in Bangladesh, the World Bank, the United Nations Development Program and the Bangladesh Government have designed and initiated some plausible measures. A project was initiated in 2000 in which the World Bank has funded a loan of about 4.7 million U.S. dollars toward teaching and practicing proper air quality management. The Energy Sector Management Assistance Program, the World Bank, an NGO and a local motor vehicle company are funding an auto-clinic program to train the auto-rickshaw drivers, mechanics, and owners to help them operate and maintain the
vehicles in ways that reduce the emission of pollutants (Chen Jian, 2001). The Energy Minister Dr. K. Mosharraf Hossain in a meeting in 2001 informed that the government is planning to convert all petrol engine vehicles into CNG (Compressed Natural Gas)-engine vehicles within next two years. He also informed that the government is going to impose a ban on imports of non-CNG vehicles in the country in the near future. Technical development project on reduction of lead in petroleum is also underway in the country. In addition to these, several other projects funded by ADB, World Bank, UNDP and other
organizations are also underway to integrate effective means of reducing the emission of air pollutants in urban areas. The Government has also appreciably decided to withdraw the old vehicles from the city, enforced ban on using polythenes and marched for clean city program. Furthermore, initiatives have been planned in ways that the two-stroke engine auto-rickshaws are going to be withdrawn from the city in a succession. However, the way these vehicles are planned to withdraw from Dhaka doesn't sound perfect, as the agreement between government and people associated with these vehicles will allow these vehicles to run in other towns of the country. This is a sarcastic move, as the agreement will in fact produce nothing to add up to the benefits. It will rather help spread the problems in other towns as well. Lack of integrity and aptitude toward civic welfare has depauperated us so viciously that nothing is designed and materialized for the future. Interests surrounding the sickness of apparent political and bureaucratic gains are nailing our futures down the floors: frustratingly most of the motions designed to save the environment are going into vein. Corruption and irresponsibility appear to be mightier than the Government! It's really difficult to be optimistic of any good moves in the country!! I wonder if any good wills that are prospective of bearing fruits for civilians can be realized in the country.

Conclusions
The ambient air quality in Dhaka is going down day by day. The increasing air pollution is impeding the development of the country. The conflict between the air pollution and the public health is good enough to give a serious thrust of resolving the problem. The plausible reasons of air pollutions are mostly known and the major causal culprits of the pollution are identified. A set of feasible and cost effective technical measures is already available to combat the pollution and bring it down to a shape. Government should strengthen moves for pollution regulation initiatives and their enforcements. Finding alternate measures that will reduce the fuel demand and its use, improving traffic conditions in the city, controlling two-stroke engine vehicles in the city are also very important. Creation of social awareness is always important and the mass media are required to be incorporated in this regard. Development of new industrial enterprises in the city should also be stopped. Beside these long term projects including tree plantation are to be undertaken and realized, so that the situation does not worsen further.