Looking for a defence against heat waves

The current heat waves now sweeping all across the country are not like those of the month of April and May. In the middle of April temperature soared as high as the year's record so far at 43 degree Celsius in Ishwardi, Pabna and for days it hovered between 38 and 41 degree Celsius in several areas of the country. Yet the heat waves of the previous two months did not prove as punishing as the current one. Usually, temperature above 40 degree Celsius is considered dangerous. This time several places have recorded temperature well over 40 degree Celsius but Dhaka city is yet to experience its record temperature of 40.4 degree Celsius it did in 58 years on April 15 last.
Now this heat wave is different from that of April because of excessive humidity. Human body sweats to help keep it cool but it works if the sweat evaporates. Evaporation is a cooling process. Now if humidity in air is high, it slows down the process of evaporation. The more the moisture content in air is, the greater the feeling of heat. It means that the level of felt temperature is greater than the one recorded by mercury. The entire country is now smarting under this oppressive weather condition. Scientists refer to a condition of wet-bulb temperature. Perhaps this is what it is like.
On Monday, a school girl from Daudkandi, Comilla fell sick in her class and succumbed to what a physician attending her suspects a heat stroke. No wonder, government primary schools had to be closed in order to avoid children's exposure to the merciless sun and heat. A lack of coordination between the Directorate of Secondary and Higher Education (DSHE) under the Ministry of Education and the Ministry of Primary and Mass Education, however, botched up the issue of simultaneous closure of all primary schools with the result of the primary section of secondary schools missing Monday's holiday. It is because the DSHE announced closure of the primary section a day later. By this time on Wednesday, 26 students of three high schools in Daudkandi fell sick during their half-yearly examinations and 23 of them had to be admitted to a hospital.
If students in classrooms fall sick and even die, what about the elderly day-labourers who have to toil under the searing sun in this capital and other urban centres where temperatures are a few degrees higher and air pollution is beyond tolerable limit? Schools can be closed to avoid students' exposure to sun and heat but farmers and such labourers have no reprieve from the hostile weather. With no savings, they have to look for daily employment. In the capital mostly denuded of its trees, rickshaw-pullers, van-pullers pushcart workers are the worst sufferers.
Sure enough, the living conditions in this city have deteriorated sharply over the years. One of the most vital factors is the denudation of the city's green spaces. Over the past three decades, the city has lost as high as 56 per cent of its green cover. Although climate change is an issue that is not confined to this country's border, still there are some local solutions to adverse environmental conditions. None other than the inhabitants of this mega city and its satellite cities on its periphery are responsible for pollution of the rivers around the city. Similarly, the major portion of Dhaka's air pollution is a creation of Dhaka dwellers.
It is really sad that even today, trees are felled in the name of beautification of road and common people have to demonstrate against tree felling. Although Dhaka North's mayor Atiqul Islam has planned a tree plantation programme under which 0.20 million saplings will be planted in two years, the rapacious felling of hundreds of trees on the median strip of the Mohakhali-Gulshan road is contradictory to his professed tree plantation policy in search of bringing the city's temperature down. This is again in the name of expansion of road islands. Quite intriguing!
Indeed, there is no alternative to raising the tree cover to at least 20-25 per cent of the total urban area. This can arrest carbon dioxide belched out from vehicles and at the same time act as a natural shed against the scorching sun in summer. That Dhaka city's temperature at some hotspots is 3.0-5.0 degree Celsius higher than other areas within the city and at times 10 degree Celsius higher than in the countryside is proof enough that human activities are responsible for such variations in temperatures.
Brick kilns around the city are a major polluter. The policymakers are yet to come out with a decision of doing away with bricks fired either by wood or coal. Since there is a viable and even better alternative in the form of concrete blocks, those could be promoted with policy support. Then comes the issue of rampant use of polythene and plastic, tons of which are discarded every day. If the use of these two harmful substances could be reduced to a reasonable level, the noxious impact of pollution and heat would not be as telling as it is now on human health, economy, livelihoods, agriculture and environment.

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