Risk Wise

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Climate change and disaster related

risks to human health in South Asia

C. Sharma, M.K. Tiwari, S.C. Garg and Vikram Kumar, National Physical Laboratory, New Delhi, India

uman health is of great concern for any country as it has

a strong bearing on national productivity and social well

being. Developing countries are especially vulnerable to

ill health due to the fact that their sizeable populations live

under poverty and are deprived of quality health care facilities,

which exacerbates the various impacts on human health.

Natural disasters like floods, cyclones and droughts are known to

affect human health as they create conducive conditions for the prolif-

eration of several diseases such as cholera, malaria, dengue and heat

stress. Bouma et al.

have reported that the number of persons affected

by natural disasters worldwide is strongly associated with the El Niño

Southern Oscillation (ENSO), with higher rates during the first El

Niño year and that following, compared to the pre-Niño year. These

associations are strongest for the South Asian region where more than

50 per cent of all disaster victims live. Climate change is likely to

further enhance human health risks, by either creating favourable

conditions in newer geographical areas for disease occurrences, or by

further facilitating the conditions for disease proliferation.

The South Asian region, which is home to about 22 per cent of

world population, is especially vulnerable due to the poor and

inequitable availability of resources to a very large segment of its

population. Countries in the region are struggling to develop national

economies that can provide social well being to all residents, and

available human resources are the key to this endeavour. Therefore,

the risk to human health in the region has serious implications for

the chances of achieving developmental goals. The generation of

public awareness about the adverse impacts of climate change and

disasters on human health is the key to empowering the population

to cope with this vulnerability.

Modelled climate change scenarios for the region show exacerba-

tion in various meteorological parameters such as temperature and

precipitation. For example, the high resolution climate change

scenario based on the HadRM2 regional climate model

for India

under increasing atmospheric carbon dioxide concentrations, shows

that mean surface temperatures are likely to increase everywhere in

the region during the 21st century, with more pronounced warming

on land areas and maximum increase over north India. Significantly,

the warming is expected to increase in winter and the post-monsoon

season compared to the summer season. These projected changes will

have a major influence on disease prevalence and need appropriate

adjustments in health care policies to minimize human health risks.

There are a large number of diseases which are influenced by

natural disaster and climate change parameters. Some of these

include diseases such as cholera, malaria, heat stress and pulmonary

diseases, which are discussed below.

Cholera

Cholera is a major enteric disease which is sensitive to

climate change and variability. Rodo et al.

have reported

the increased role of interannual climate variability on the

temporal dynamics of cholera in Bangladesh. They also

reported that warming over land in the Indian subconti-

nent might have noticeable effects on the temperature of

water bodies that serve as an environmental habitat and a

vehicle of bacterium transmission. Enhanced warming can

also affect transmission, due to changing human behav-

iour increasing the likelihood of coming into contact with

contaminated water sources. The combined effects of more

extreme ENSO and climate change might also affect the

sanitation conditions that are critical to cholera transmis-

sion. The endemicity of cholera in regions such as the

estuaries of the Ganges and Bramaputra in Bangladesh has

also been attributed to the presence of a marine reservoir

of cholera pathogens, which persists for long periods with

marine organisms in the mucilaginous sheath of blue-

green algae and copepods.

In view of severe productivity

losses due to cholera related human health risks, policies

need to be implemented to ensure safe drinking water and

sanitation, besides gearing up health care facilities in the

region. Several low cost technologies such as ceramic

filters are available to provide safe drinking water.

Heat stress

Climate change is likely to increase the heat stress risk to

human health due to high temperatures and humidity,

A stakeholders’ meeting organized jointly by the National Physical

Laboratory, New Delhi and Jadavpur University Kolkata

Image: C. Sharma