Air has lost its natural freshness since long. Both natural courses of action and human activities can affect quality of air in the hemisphere. The deteriorating air quality has become dangerous for the lives on earth. It takes lives of millions every year while putting more into suffering. This alarming situation has arrested attention of Government, donors, non-government organizations and members of civil society of the country. These agencies could have identified the causes of air pollution, its impact on public health and ways to come out of it. Availability of fresh air largely depends on the success of government efforts of phasing out air polluters like two-stroke engines and shifting the industries from the city.
Fresh air in nature contains 78.02% nitrogen, 20.71% oxygen, 0.80% argon, 0.41% vapor, 0.03% carbon dioxide (CO2), other gases 0.02% and dust 0.01%. Any imbalance of these gases beyond the limit of tolerance can cause harm to the environment. Industrial revolu-tion of the western world in the 17th century could be the first massive thrust to disorder the natural components of air on earth. Natural courses of action added with use and misuse of natural resources by the earthen creature cause environmental degradation. Vulcanization, earthquake, fire in forest, desertification etc are the natural causes of air pollution. Again nuclear explosion, radiation, emission of poisonous smoke from mills, factories and vehicles, removal and disposal of municipal wastes, indiscriminate cutting of trees, enormous use of petroleum, coal, lignite, and natural gas, use of excessive aerosol and other spray, spray of pesticide for killing mosquitoes and insecticide are the causes of air pollution. Such natural and human actions help increase or decrease the orderly components of air. In the long process the concentration and amount of air become unacceptable for the living creature on earth. This state of air is called air pollution. Main components of air pollution caused both ways are CO2, carbon monoxide (CO), hydrogen sulfide, hydrogen chloride (HC), hydrocarbons, nitrogen oxides, sulfur oxides (SO2), ozone, wind bound particulate, photo chemical oxidant, asbestos, beryllium, lead, venial chloride, benzene, arsenic etc.
Of the gases CO2 plays vital role in the hemisphere. It keeps covering the outer
hemisphere of the earth. It works as good as a roof of green house and keeps downward portion of hemisphere warmer. Any increase of CO2 in the air helps increase the tempera-ture of earth. Sources of CO2 in the natural courses are many. The living creatures including human beings on earth exhale CO2 during breathing time. One person exhales two pounds of CO2 daily. Natural action and desperate use of mineral energy by human beings add CO2 in the hemisphere beyond the level of acceptability. Continuous emission of smoke from motor vehicles, industries and various furnaces also maximizes CO2, CO, H2S, HCI, hydrocarbons, oxides of nitrogen and SO2 in the air. On the other hand plants and trees consume huge amount of CO2 in the process of photosynthesis. Some minerals on the surface of earth also extract this gas. Furthermore some sea animals take CO2 that makes the outer shell of them harder. These natural processes could have maintained equilibrium of content of CO2 in the hemisphere. Unfortunately it does not happen for the reason that the amount of CO2 being poured into air is much more than the amount is consumed through different process.
Fine particulate matters are the most serious threat to public health in the city. Particulate matters (PM) are the smallest parts of solid and liquid substances that can keep floating on the air. Annual deposit of lead particulates alone in the world is more than 2000 million tons. Of them the PM generated from vehicles have a radius of 5 microns. The effects of PM depend on particle size, with the finer particles (PM10 and PM2.5) causing the most damage. The transport related fraction of PM10 is estimated at Dhaka to be around 27% of the yearly average rising to as much as 41% during dry months. Vehicles use gasoline with mixture of tetraethyl lead, ethylene dibromide and ethylene dichloride are responsible to generate this kind of harmful gases in the air. Sources of fine PM that keep the air polluting are two-stroke engines, heavy-duty diesel engines, combustion of solid fuels (biomass) in small sources such as houses and small industries, and use of low quality lube oil. Two stroke engines; particularly baby taxi, tempo and motorcycle produce some 35% of PM10 and 48% of HC in the city. They contain carbon particles leaded substances and cranks oil. Exhaust fumes from the engines of automobiles contain a number of polluting substances including CO and a variety of complex hydrocarbon, nitrogen oxide, and other compounds. Incomplete combustion of fuel and non-combustion of the lube oil mixed with fuel are responsible for producing CO and smoke in the air. Again there is a serious lack of technical education and knowledge among the drivers. They do not know as to how to properly fuel and maintain the vehicles. Inappropriate handling of vehicles also causes maximum emission of polluted gases. Uncontrolled emission from motor vehicles has been identified as one of the major causes of air pollution. World Bank conducted a study in Dhaka on the amount of smoke emission from different motorized vehicles a couple of years ago. The finding of the study reveals that emission of smoke from baby taxi, bus, truck and others are 35%, 27%, 21%, and 17% respectively. Again emission of oil particles from baby taxi, cars and others are 47%, 36% and 17% respectively. In order to control vehicular emission mandatory emission standards have been introduced in may countries including Bangladesh. Emission levels of pollutants from in-use vehicles depend on vehicles characteristics, fuel characteristics, level of maintenance and operating conditions. Burning of mixed gasoline in the vehicles that discharges lead bromide, lead chloride and metallic particles of lead also affect freshness of air.
Air pollution causes headache, burning of eyes, pains in throat, bronchitis, breathing problems, heart disease, anemia, mental problems, kidney disease and even cancer. Acid rain in the developed countries is another aspect of environmental degradation. Acid rain oc-curs due to excessive sulfur and nitrogen emission from vehicles and industries. Acid deposition can make aluminum, cadmium, lead, and mercury more soluble. The metal then can leach from soil and lake sediments into aquifers, streams, and reservoirs. It can then contaminate water supplies and edible fish. Acid water can also dissolve toxic metals from the conduits and pipes of municipal and home water systems, poisoning drinking supply. Lead is very poisonous substance for human beings. Lead particles contaminate soil and water in the process of pouring from vehicles. Lead particles deteriorate the decaying parts, if any of human body. There are some lead particles that help grow cancer in human body.
The city dwellers are the victims of all poisonous gases. World Health Organization and United Nation Environment Program estimates that two-thirds of more than 1.8 billion people of the cities are living at risk of SO2 and other vapor-bound particles. Developed countries alone emit 100 million tons of poisonous gas a day from their vehicles. By the year 2025 more or less 4 billion people would live in the cities of the world with 66 million in the cities of Bangladesh. Most of the 100 million people living in the city are exposed to the contaminated air. The school children, day labourers, non-motor vehicles pullers, traffic police on duty, baby taxi drivers, drivers of other motor vehicles and passersby are the worst victims of this environment degradation. Different studies show that the air in Dhaka contains many harmful elements that are detrimental for human health. It has thus become most vulnerable place for human beings to live in. Some measurements taken in Dhaka show that the emission of CO has exceeded WHO guidelines by a factor of ten. A study of WHO shows that a blood lead level above 10mcg/dl (microgram per deciliter) constitutes lead poisoning. The mean of lead levels in children in Dhaka was found at 15mcg/dl. Such a level can cause potential neurological damage and diminished IQ in children. In the stock of human casualties the yearly death toll due to air pollution is about 15000 in four major cities of Bangladesh putting another 6.5 millions to sufferings. Air pollution alone kills about 3 million people that constitute 6% of total deaths on the globe.
Government, academicians, environmental experts and conscious citizens ponder to make out ways and means for combating the deteriorating situation of air pollution. They have been able to identify most of the reasons of air pollution. Apparently there is no lack in political will to get rid of air pollution of the capital city and eventually of other cities. There is no political opposition to the government program in controlling air pollution. Various citizen groups that work hard for a clean environment of the city also extend their full supports to the government efforts. Bangladesh Petroleum Corporation (BPC) has imposed ban on production, blending, import and marketing of straight mineral oil. It has also started marketing lead free petrol and octane as well as diesel of minimum sulfur content (0.50%wt.max). BPC in a press notification urged upon the consumers to use pure and upgraded lube oil for the sake of preventing environment from pollution. Government is contemplating to phase out two-stroke engines within months time. It is also working to ban plying of vehicles in the city that has exceeded 15 years’ lifetime. Government has already introduced fueling of Compost Natural Gas in the vehicles as a substitute of petroleum oil. It has again accorded approval for installing catalytic converter and diesel particulate filter in the vehicles of both private and public sectors. Implementation of these devices in the vehicular system can help reduce emission of black smokes and other harmful gases to a large extent. Among others there is a specific project on air quality management supported by foreign aid and being implemented by the Ministry of Environment and Forests. Government agencies are holding conferences, seminars, workshops and addressing the press to win people participation and create public awareness for the cause of conservation of environment that includes a call for mitigation of air pollution. From the citizen groups Bangladesh Paribesh Andolon (Bangladesh Environment Movement) is carrying out various programs that also help government to take corrective measures towards controlling air pollution. These are all praiseworthy steps that the government and social organizations are considering for controlling air pollution. The actions under these programs are yet to give any good shape. Result of the efforts will largely depend on the enforcement of law, implementation of directives and monitoring of ongoing action plan on air pollution issues by the authorities and civil society. The important legal instruments for fighting against all kinds of environmental pollution are Bangladesh Environment Conservancy Act, 1995, Bangladesh Environment Conservation Rules, 1997 and Environment Court Act, 2000. These legal instruments could yet to come for enforcement due to a set of irrelevancies and contradictions in themselves. Government has already realized the fact that these legal instruments cannot address the problems of environment pollution unless they are amended. The government is going to take up the matter of amendment of the Acts and Rules very soon. The matter left for reducing air pollution is perhaps to undertake massive awareness campaign among the stakeholders, users, owners, drivers, mechanics, traders and other persons, who are related to the vehicular system. Training the drivers and helpers may help improve maintenance of vehicles for subsequent improvement of engines that shall give fewer pollutants in the air. Most importantly the implementation of government directives and enforcement of legal instruments are at the lowest level in Bangladesh. Strict measure of the government in this area of concern may improve the situation to a great extent.
The writer is member of Bangladesh Poribesh Andolon (BAPA
Source: The Daily Independent, Dhaka, March 18, 2002