Dhaka's air reaches hazardous level

Published : 22 Jan 2019, 11:50

Sahos Desk

Presence of heavy metal particles in Dhaka's air has exceeded the level even many polluted cities have experienced, seriously affecting public health, especially the children, in recent times.

Metals such as lead, cadmium, zinc, chromium, nickel, arsenic, manganese, and copper that can cause fatal diseases like cancer were found in alarming proportion in the Dhaka city's air, according to two studies carried out in December 2018 and January 2019.

Dust in Dhaka city contained 200 times higher than generally acceptable level of cadmium, supposed to be present in the soil, revealed the study reports published in Science of the Total Environment and Environmental Science and Population Research this month.

Lead and nickel were found to have been more than double in Dhaka's air. The researchers further detected arsenic in an alarming proportion in the city air.

These particulate matters, researchers say, are so fine that they can easily come in contact with skin and enter human body through foods and drinks.

"The amount of very fine particles has increased greatly in Dhaka city and it is higher than what many countries have seen," said Abdus Salam, a key researcher and professor of chemistry department at Dhaka University.

The particles found in Dhaka's air are not normal dust, and can float in the air if there is no rain, he pointed out, adding that they affect human health.

The DU chemistry department, in association with Bangladesh Atomic Energy Commission (BAEC) and University of Iowa, USA, conducted the two studies.

Air pollution, a new threat

Professor Salam, who has been working on air pollution for two decades, and Md Shafiur Rahman, chief scientific officer at the BAEC, led the study on health issues caused by heavy metal in the dust of Dhaka roads.

They collected samples from 88 roads of 22 areas in the city in January 2017. This included 300 grammes of dust from the roads, footpaths, and from the soil around the ditches in the areas that were chosen on a random selection basis. The samples were later analysed at the BAEC laboratory.

There was heavy metal in almost all the 88 areas, said the study. Among these, the highest level of metal including cadmium, led, nickel, arsenic, copper, chromium, was found in GPO area.

Emissions from the vehicles often stranded in traffic congesion as well as from various factories in the city were blamed for the air pollution.

The studey said the level of cadmium in GPO, Bangabhaban and Rampura TV station areas was around 200 times higher than normal one. Though the presence of lead was slightly lower in these areas, arsenic and nickel were high.

There is a good number of vehicles that operate in different routes in the city use nickel and cadmium batteries, the study confirmed. The researchers added, many factories producing hybrid metal and plates along with enamel, plastic and glass also use cadmium for pigments.

The researchers also confirmed high level of chromium presence in the dust around the BFDC rail crossing area in Karwan Bazar, Banglamotor and GPO areas.

Metal found in these areas are three times heavier than normal level. Tanneries and dying factories sprung across Dhaka and its outskirts are the source of this high chromium, said the study reports.

Level of zinc is the highest in area from Farmgate to Manik Miah Avenue, from Asad Gate to Kalyanpur and from Mahakhali to Tejgaon Industrial Area. Zinc was high across all the areas covered by the research.

Air pollution

Professor Abdus Salam and Mohammad Sohel, chemistry professor of Iowa University in the US, conducted a joint research on the level of particulate matters and gas substances indoor. Five residential areas of Dhaka were selected.

The research team detected presence of lead, zinc and nickel in the particulate matters in the air indoor. Smokes of vehicles, factories that operate relentlessly and construction works were found to be responsible.

The paint on the wall is also said to be another source of lead for indoor pollution.

Air samples were collected between August to October in 2017 from the houses of 25 residents at five households. The areas included Mirpur, Khilkhet, Rampura, Dolairpar, and Tongi. The buildings were built between one and 24 years. The buildings were one to six storied.

The density of the particulate matters including PM1, PM2, PM2.5 and PM10 was higher than the ratio declared as safe by the World Health Organisation.

The study says harmful particles enter human body reducing the strength of the lungs.

More than 40 per cent (42 per cent to be specific) of the contaminated outside air also enter the houses, affecting the residents. Detergents and the polluted air from kitchen and toilet contribute to deteriorating the condition.

The highest level of particles was found in Khilkhet houses, were followed by Dolairpar and Rampura houses.

The minimum particulate matters were found in Mirpur. But, during the study, it rained there regularly helping the particulate matters to dissolve.

Three other areas had no rain then and the researcehrs concluded that the condition of Mirpur was not properly reflected in the study.

The level of heavy metal in the air rose when two-stroke auto-rickshaws ran across the city and these transports were eventually banned, said Rakibul Islam, the general secretary of Bangladesh Doctors for Health and Environment, a physicians' organisation working on health risks caused by environmental pollution in the country.

This, he regretted, is a matter of grave concern that such heavy particulate matters have returned to the city air.

The number of children affected by these has increased by 50 per cent over the past five years, said Rakibul Islam, adding that particulate matters in the air causes cancer, asthma, nerve problem and other problems.

No one to control heavy pollution

The government's Department of Environment (DoE), responsible for addressing pollution, is currently running a World Bank-financed project in two phases for 12 years to control air pollution. Some regular tasks are also being carried out, but the air quality is consistently getting worse.

The DoE authorities say they have sent letters to the companies involved in construction of building , roads, metro railway and flyover for controlling dust.

It sat for talks with the representatives from government and private companies that are implementing such projects, but to no avail.

The two city corporations are responsible to sprinkle waters on roads in the city every morning to control the dust. However, that is not being done as widely alleged.

Rajdhani Unnayan Kartripakkha (RAJUK) or the capital development authority, is responsible to inquire whether or not the builders are taking necessary measures to control the dust. The RAJUK is allegedly not doing the job properly.

When asked, DoE director general Sultan Ahmed said, "What we can do is calling on government organisations to take steps to control dusts. But if the responsible agencies do not take any steps, what else can we do?”

Bangladesh is one of the most vulnerable countries in pollution, said a World Bank report titled “Enhancing Opportunities for Clean and Resilient Growth in Urban Bangladesh: Country Environmental Analysis 2018”. About 80,000 people died in urban areas in 2015.

Gloab average rate of death caused by pollution is 16 per cent, whereas it is 28 per cent in Bangladesh.

According to the WB report, brick fields are responsible for 58 per cent of the air pollution. And 26 per cent air pollution occurs due to dust on roads and automobile pollution.

However, according to the environment department, the three said sectors contributed to only 15 per cent of the pollution five years ago.

City planner Nazrul Islam said, "It is sad that minimum environment safety requirements are not followed while building infrastructures and setting up industries in the capital.”

“The intensity of pollution proves the government agencies are not doing their job properly,” he continued, “If the pollution control is not seen as an urgency, a big environmental disaster is awaiting us.”

Children at risks

The metal particles floating in the air are affecting the children.

A group of researchers found children are suffering for shortness in breath and other forms of sickness due to the air pollution.

The DU chemistry department last year measured the level of air pollution in 10 educational institutions of the capital. It found four times higher level of harmful particles than the World Health Organisation's standard by measuring PM-1, PM 2.5 and PM-10 and intense organic compound material on the school premises and around the classrooms.

Supervised by professor Abdus Salam, the research team surveyed as many as 250 students from 9 to 10 years of age from educational institutions in Mugda, Kakrail, Fuller Road, Jatrabari, Ahmadbagh, Motijheel, Gulshan, Nilkhet and Khilkhet.

The study showed that 16.8 per cent of children were suffering from cough, 6 per cent asthma and 5.6 per cent migraine or headaches. Many children were found to have shortness of breath.

Educational institutions located beside the roads are more likely to have harmful particles in the air, the study said.

There were harmful gases found in the air at the institutions that are located in the densely populated and traffic-prone areas.

Source: Prothom Alo

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