Climate change – variation games of humidity, temperature and rainfall is likely to have wide ranging and severe health consequences. It is imperative to tell apart ‘climate and health’ relationships.Climate inconsistency occurs on many time scales. Weather events transpire in daily time scale and are allied with several health impacts.
Some health impacts are from direct-acting effects (heat wave related deaths, weather deaths); others are from disturbances of complex ecological processes (changes in patterns of infectious disease, freshwater supplies and food production). Unsurprisingly, urban poor are most awful sufferers of climate alteration.
Urban area is a composite of different subsystems of physical structures and human activities all having links with one another. Intended and unintended human activities taking place within the urban area have profound impacts both within and exterior of it. The degradation in the quality of the urban environment is the consequence of economic activities, which may affect the environment, sanitation security and public health either directly or indirectly.
Intensification in the urban population of Bangladesh is more or less centred on the three metropolitan areas of Dhaka, Chittagong and Khulna through rural to urban migration which is currently 55% of total migration. Everyday – due mainly to rural-push migration – thousands of people are migrating to the cities from their rural habitats and a huge number of them are heading towards cities either being destitute by landlessness, improvisation, employment contraction among the poor and the marginalised, stricken by floods, cyclones, river erosion, droughts or poverty. Population density of Dhaka stands at an astounding 49,182 per sq. km and Chittagong 16,613 sq. km. UN report, 2016 has mentioned the urban Population Status in Bangladesh: it was 23.8% in 2000; 30.4 % in 2010 and 2016 it is now 34.9%. Day by day it is escalating.
It can be 38% of the total population by the year of 2020. Economically affected, socially excluded and environmentally displaced people will join urban area as beggars, hotel workers, porters, day labourers, maid servants, rickshaw pullers, petty traders etc. It has been estimated that urban population in Bangladesh will rise to between 91 and 102 million by 2050 which will be 44% of total population.
In general, the urban poor live at slums, squatter and low income settlements. As city life is very expensive to fulfil the basic needs, these poor people are bound to search for a dwelling place at the city slums and those who cannot even afford to live in a slum dwelling are living on streets or pavements, in parks, bus or railway stations or other public infrastructures. They are experiencing with kutcha, jhupri, non-sanitary latrine, unhygienic garbage disposal and impure water supply. No sanitation is safe when covered by flood waters, as faecal matter mixes with flood water and spread to where the flood water goes. Dhaka − which has piped sewage network, 2% only of faecal load is treated.
Human faeces management and dumping is a major challenge in our urban area. The concern is financing required for proper management and disposal of human wastes. The step up of health of urban poor is not possible without sanitary disposal of human excreta. There are some problems of groundwater development in Bangladesh − arsenic in groundwater, excessive dissolved iron, salinity intrusion in coastal areas, water table is lowering due to over-exploitation of groundwater for irrigation and intensive cropping.
A survey over around 6,000 households (UNICEF Report, 2015) implies that in urban poor areas, pit latrine with slab without lid and water-seal constitute the majority of all latrines - 53%. Pit latrine with slab and water-seal is only 13%. Pit latrine with slab without water-seal is 5.9%. Pit latrine with slab and flap without water-seal is 8.1%. Latrine without slab or open pit latrine is 7.3%. Latrine connected with open drain with flush or pouring water is 5 %. Flush latrine connected to septic tank is 3.1%. Use of hanging latrines is 3.1%. Pit latrine with ventilation system 1.4%. The conditions of urban poor are so miserable.
In reality, human health depends on an adequate supply of potable water. By reducing fresh water supplies, climate change affects sanitation and lowers the efficiency of local sewer systems, leading to amplifying concentrations of pathogens in unprocessed water supplies. In addition, climate alteration reduces water availability for drinking and washing. The unforeseen increase in extreme rainfall events, which is associated with the outbreaks of diarrhoeal disease, may overwhelm the public water supply system.
The ecology and transmission dynamics of vector borne disease are complex. Climate change impact models suggest that the leading changes in the potential for disease transmission will occur at the fringes in terms of both latitude and longitude of the malaria risk areas.
Vector borne diseases are transmitted by insects − mosquitoes and ticks that are sensitive to temperature, humidity and rainfall. High temperature manipulates the reproduction and survival of the infective agents within the vector, thereby further influencing disease diffusion in areas where the vector is present.
Numerous diseases that are transmitted by mosquitoes (chikungunya, dengue, and yellow fever), sand flies (leishmaniasis) and ticks (Lyme disease, tick-borne encephalitis) may also be amplified by climate alteration. The poor who are environmentally or agriculturally displaced, live in urban areas have no capacity, education, financial aptitude to fight against climate induced health insecurity.
Against this backdrop, some effective steps can be taken: measures to resolve environmental hazards; provision of safe water and planning for preservation; improvement of health care services; practical and functioning urban poverty alleviation programmes; improvement in the public utilities services and their equitable distribution; improving the condition of urban squatter settlements. For sustainable health of the urban poor, application of education on primary health care, environment, sanitation, climatic insurgencies among them can play key role.
To appraise the prospective impacts of climate change on health, it is indispensable to reflect on both the sensitivity and vulnerability of population dynamics for explicit health outcomes. Apart from that, to reduce vulnerability is to develop waste management systems and supply potable water to poor communities of urban areas.
Shishir Reza, Dhaka