Five types of gas layers have been created in Dhaka’s air. These gases have been produced from garbage dumps, brick kilns, vehicles and the fumes emitting from industries. These gases are increasing the temperature of Dhaka’s air and the ground. Added to the heat wave, these harmful gases are making Dhaka weather intolerable. These observations were made in two recent surveys conducted by a group of scientists.
Long-running surveys carried out by the group of scientists from Dhaka University and Georgia University in the US reveal that there are five types of gases accumulating in Dhaka’s air, leading to all sorts of diseases and problems for the city residents as well as heating up the air further. The five gases are carbon monoxide, nitric oxide, nitrogen dioxide, volatile organic compounds and ozone. These gases can remain in the city air for 10 to 400 years.
We have seen traces of five types of harmful gases in Dhaka air. If the sources of these gases could be reduced, then the city’s air pollution and extreme heat could be controlled and brought down to a tolerable levelProfessor Abdus Salam, Department of Chemistry, Dhaka University
The study appearing in the international Journal of Atmospheric Chemistry, mentions the existence of five types of gas in Dhaka’s air. The research report on ‘Quantification and source apportionment of atmospheric trace gases over Dhaka’ was published on 16 April this year.
A member of the research team and professor of the chemistry department at Dhaka University, Abdus Salam, told Prothom Alo, “We have tried to understand the extent of danger caused by the gases, alongside Dhaka air pollution and high summer temperatures. We have seen traces of five types of harmful gases in Dhaka air. If the sources of these gases could be reduced, then the city’s air pollution and extreme heat could be controlled and brought down to a tolerable level.”
Gases increase heat
The temperature of the capital city yesterday, Sunday, was 2 degrees less than the day before. Meteorologists say that basically on Sunday, winds increased all over the country compared to Saturday. Humidity fell too. Temperatures fall somewhat in such weather. For example, in the districts adjacent to Dhaka, Sherpur and Madaripur, temperatures fell by 2 to 3 degrees Celsius to 35˚ and 37˚ Celsius. But Dhaka’s temperature was 38.2˚ Celsius. The highest temperature recorded in the country was 42.2˚ Celsius at Chuadanga.
The UN IPCC (Intergovernmental Panel on Climate Change) report says that if the presence of particulate matter in the air exceeds the acceptable standards, temperatures rise by an additional 2˚ Celsius. And if the presence of ozone, carbon monoxide, nitric oxide, nitrogen dioxide gases increase, temperatures increase by 5 to 7 degrees Celsius. Scientists say that temperatures increase more in cities and areas with more gas emissions. In other words, in areas where temperatures rise due to the climate, temperatures rise even further due to these gases.
Dhaka North City Corporation mayor Atiqul Islam told Prothom Alo, “We have planted trees to reduce Dhaka city’s temperatures, but these will take time to grow. In order to deal with the immediate situation, it has been decided to provide 20,000 of Dhaka’s rickshaw-pullers with umbrellas and bottles of water. Other poor people of different professions will also be provided such assistance in phases.”
More gas in 10 garbage dumps of Dhaka
Another study reported that the presence of such gas and particulate matter was higher at Dhaka’s garbage dumps. The study was conducted from Dhaka University’s department of chemistry. The study carried out a survey of 10 garbage dumps of Dhaka North City Corporation and Dhaka South City Corporation as the garbage disposal points in Ramna Park.
Surveys were conducted at the Dhaka City Corporation’s central waste depot landfills in Matuail and Aminbazar. And surveys were also conducted at the temporary garbage dumps in Gulistan, Dhalpur, Banasree, Hazaribagh, Bangabazar, Rayer Bazar, Dhanmondi and Uttara. Surveys were carried out in a comparatively more systematic manner in the garbage disposal spots of Ramna Park.
The survey indicated that the presence of gas was at dangerous levels in all the locations other than Ramna Park. The presence of particulate matter there was PM2.5 and PM10 and the presence of those gases were at harmful levels.
The results of the research were published in November last year in the science journal Springer Nature. This study on ‘Emission of particulate and gaseous air pollutants from municipal solid waste in Dhaka City’ deliberated in the presence of harmful gases in the air.
The study found the highest presence of gas in the Matuail ad Aminbazar landfills, which was around six times higher than the World Health Organisation’s acceptable standards. In comparison to the other solid waste landfills, the presence of gas in those two locations was more than double. Alongside increasing air temperature, these gases also increase the presence of toxic elements in the air.
The study conducted by Dhaka University and Georgia University indicates that the gases which are rapidly increasing in Dhaka’s air are carbon monoxide, nitric oxide, nitrogen dioxide and volatile organic compound gases. Alarming levels of ozone were also detected. The research team also observed a dangerous level of methane in Dhaka air.
Volatile organic compounds and ozone gas were found at highest levels during summer and the rainy season. The presence of methane gas was also higher in these two seasons. These gases are basically produced from vehicles, brick kilns and dumped solid waste.
Speaking to Prothom Alo, the Department of Environment’s air quality management director Ziaul Haque said, “We are taking action against illegal brick kilns and vehicles that have crossed the expiry date in order to control Dhaka’s air quality. But harmful gases have increased in Dhaka due to pollution.”