Published: 01:20 AM, 13 August 2022
Harmful effects of air pollution
Air pollution is caused by the mixing of harmful substances in the air. It causes damage to health, environment and resources. As a result, the ozone layer in the atmosphere becomes thinner. This affects the climate and causes global climate change. Industries, vehicles, population growth and urbanization are some of the major causes of air pollution. Air pollution is caused by many factors, many of which are beyond human control. Dust storms and forest fires in desert regions cause chemical and particulate pollution in the air.
The harmful effects of pollution can be easily detected as the amount of harmful substances released into the air is higher in any air polluted area than in other places. The main sources of air pollution are vehicular smoke, smoke from power and heat generators, factories and solid waste burning. Another cause of air pollution is the increasing depletion of the ozone layer in the atmosphere above the continent of Antarctica. Air pollution also has negative effects on humans, flora, fauna and aquatic ecosystems through the occurrence of acid rain.
Recently, air pollution has gained prominence among environmental issues in Asia, as elsewhere in the world. The problem is evident in Bangladesh's capital Dhaka and other centers of commercial activity. The health impact of air pollution in urban areas of Chittagong, Khulna, Bogra and Rajshahi regions is less than that of Dhaka. In the urban areas of different countries of the world, houses are often built on rocks and soils whose foundations emit radioactive gases.
Long-term inhalation of this gas can cause lung cancer. Air pollution has not yet been identified as a major problem in rural areas of Bangladesh. Because the number of motorized vehicles is less in all these areas, the number of industrial factories is also less. However, considerable air pollution is occurring in urban and rural areas from brick kilns and cooking furnaces. Wood, coal and different types of biomass are used as fuel in rural areas. As a result, the main air pollutants in rural areas are particulate matter and volatile organic compounds.
Air pollution in Bangladesh mainly comes from two sources – smoke from industrial plants and smoke from vehicles. Brick kilns, fertilizer factories, sugar mills, paper mills, jute mills, textile factories, spinning mills, tanneries, garment factories, bread and biscuit factories, chemical and pharmaceutical industries, cement factories, metal workshops, saw mills etc. are major sources of air pollution. These sources of air pollution produce large amounts of smoke, vapors, gases and dust particles which create fog and hazy environment.
Some types of industrial factories in Bangladesh such as tanneries are constantly emitting hydrogen sulphide, ammonia, chlorine and other odorless chemicals which are poisonous and causing annoyance and suffering to the local people. These pollutants are causing headaches and other health problems. Due to the high rate of urbanization, the number of vehicles in the city is increasing, resulting in a high rate of air pollution.
The Department of Environment and other environmental agencies have identified mini-trucks and motorcycles as major air polluting vehicles. Overloaded with passengers and goods, old buses and trucks with weak engines are emitting black smoke and toxic gases. In fact, many vehicles plying on the roads of Dhaka are defective and emit more than tolerable levels of smoke every day. Diesel powered vehicles emit black smoke containing carbon particles.
In Bangladesh, modern equipment is currently being used to detect air pollutants. Air pollution monitoring centers have been established in Dhaka, Chittagong, Khulna and Bogra. Dhaka has vehicle emission testing centers at Tejgaon, Farmgate, Manik Mia Avenue, Gulshan, Lalmatia and Agargaon. BUET has been regularly testing air quality.
Air quality levels are different for residential areas, industrial areas, commercial areas and sensitive areas. The most polluted areas of Dhaka city are Hatkhola, Manik Mia Avenue, Tejgaon, Farmgate, Motijheel, Lalmatia and Mohakhali. According to the survey, the concentration of pollutant particles in the atmosphere has increased to 3,000 micrograms per cubic meter, while the acceptable level is 400 micrograms per cubic meter.
Children suffer the most from air pollution. The presence of excess lead in the air impairs the mental development of children. Every year about 50 tons of lead is released in the air of Dhaka city. Lead content in the air reaches its maximum during the dry season i.e. November to January. Cases of lead contamination have been detected in children's bodies at the Child Development Center of Dhaka Children's Hospital. The children tested had about 80 micrograms/dL to 180 micrograms/dL of lead in their blood, which is 7 to 16 times the acceptable level.
Bangladesh Atomic Energy Commission and Bangladesh Council of Science and Industrial Research in collaboration with the Department of Environment measured the concentration of lead in Dhaka's air. Dhaka Children's Hospital, in a joint venture with the Bangladesh Atomic Energy Commission, tested the blood lead levels of children in Dhaka city. Bangladesh Road Transport Authority has set up a center in Mirpur to measure vehicle emissions. Bangladesh Atomic Energy Commission has mentioned in a report that the lead that the city dwellers are inhaling on the streets is more than 10 times the level declared safe by the Department of Environment.
According to guidelines from the US Centers for Disease Control and Prevention, blood lead levels up to 10 micrograms/dL are safe. A significant increase in average blood lead levels is observed in residents living in urban slums compared to middle-income urban areas or rural areas. In addition to attacking the central nervous system, increasing lead pollution damages kidney function and causes high blood pressure. Excess lead in children's blood can damage their brains and kidneys. Children are three times more likely to be affected by lead pollution than adults.
Dust and mine gases cause problems in coal mines. Fortunately, since the amount of gas in Barapukuria coal mine of Dinajpur district is very negligible, the possibility of methane gas emission and other disasters related to methane gas in the coal extraction process from the mine is also very low. Barapukuria Coal mine also produces large amount of coal dust due to mechanical extraction of coal, but it can be controlled if proper measures are taken.
Similarly, Madhyapara hard rock quarry in Dinajpur district also produces large amount of dust. Also, frequent traffic and the process of loading and unloading of goods are likely to generate a lot of dust. Air in the surrounding area can be polluted by gases produced by the combustion of coal, fuel and lubricants on the surface and in mine cavities. Dust generated during the cutting, smelting, crushing and transportation of coal and hard rock from the mine poses a threat to the workers working in the mine and the residents of the surrounding areas.
Md Arafat Rahman is a Columnist & Asst. Officer, Career & Professional Development Services Department, Southeast University
