Dust posing serious health hazards in urban areas

Millions of people are exposed to dust in the country for at least five months in a year from November to March when rainfall is very little.

Director of International Training Network (ITN) and Professor of Bangladesh University of Engineering and Technology (BUET) Dr Mujibur Rahman told BSS that dust hazard can be controlled if its sources are identified.

Dust carries physical, chemical and biological particles like carbon, sulpher-di-oxide, nitrous oxide and viruses harmful to health, he said, adding that people suffering from chronic asthma, children and aged people are most vulnerable to dust.

Prof Rahman, an environmentalist, said dust also causes nose and throat irritation and bronchitis while toxic particles like lead, cadmium and dioxins causes cancer and reproductive problems.

He said open-air construction practices, open trucks carrying dusty construction materials like cement, sand and soil, crushing of bricks and stones in open space, road digging and dumping of soil on the streets, faulty system of solid waste collection, absence of effective road sweeping and vehicular, industrial and brick field emissions are the main sources of dust in urban areas.

Although there is no detailed studies on urban dust situation in the country, it is assumed that at least 20 to 30 percent of dust is produced from construction activities, he added.

About 270 micrograms of suspended particulate matters, up from the normal level of 150 microgram, have been found in Dhaka's one cubic meter air in January 2003, according to a study.

Sediments in rivers from upstream, river erosion, siltation, deforestation, hill cutting, coastal salt fields and heavy rainfalls produce a huge amount of dust in the rural environment, it added.

With the economic development in Bangladesh, migration from rural to urban areas have been increasing, the study said, adding that at least 24 percent of people are now living in urban areas and they are exposed to dust hazard.

Spraying water on the street is a traditional practice of dust control, Prof Rahman said. To improve dust control system in urban areas, construction sites should be surrounded by CI sheets or other protective fences, he added.

"Construction materials should be covered properly by thick polythene or jute sheets while brick and stone crushing should be done outside the city in covered sheds treating it as an industrial activity."

He said sand, cement and soil should be carried by covered vans and soil extracted from road digging should be dressed within the stipulated time.

In most cases, waste and dust are thrown into drains or carried by an open van after sweeping the roads, he said, adding that as a result, these particulate re-enter the environment.

In developed countries, vacuum cleaners are used to clean roads and streets which do not allow dust particles to re-enter the environment, Prof Rahman said and called for improving road cleaning system in the cities.

He said installation of waste treatment plants in the industrial areas and emission-control device in vehicular transports can help check air pollution.