The truth about when it pours cats and dogs

NEW DELHI, MARCH 25: Weather is not just about hot and cold, maximum and minimum temperatures. Did you know that the measles virus prefer...

NEW DELHI, MARCH 25: Weather is not just about hot and cold, maximum and minimum temperatures. Did you know that the measles virus prefers to spread in summer and the diphtheria bacteria is active between August and September? Or that global warming may cause a spread of vector-borne diseases like malaria and yellow fever in the future? Or that thunderstorms could trigger asthma attacks?

Meteorologists the world over are now talking about measles, meningitis, summer and winter in the same breath. And on the occasion of World Meteorological Day (March 23) this year, they have decided to highlight the link between `Weather, Climate and Health’. At meetings across the world, meteorologists are saying that heat, cold and humidity are now affecting human health more than ever before.

A recent study on `The Influence of Weather on Some Infectious Diseases’, jointly conducted by the National Institute of Communicable Diseases and the Meteorological Office in Delhi, states: “Meteorological elements such astemperature and humidity have a good influence on the spread of infectious diseases like meningitis and measles”.

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Extreme weather conditions in the recent past, like the El Nino, have caused immense human suffering. The outbreak of epidemics, incidents of acid rain, the fast-disappearing ozone layer and global warming are likely to cause even more diseases, fear meteorologists, who have recorded the link between changing climate and human health.

This link is not new. Hippocrates wrote about regional differences in climate and its relationship with health a long time ago. But phenomena like El Nino have given it a new dimension. Evidence now suggests that human influence on the global climate is significant and impending changes have brought back the focus on health consequences of climate.

The study on weather and infectious diseases in Delhi states: “Cases of measles are maximum in the hot season. This indicates that the measles virus spreads faster in dry and hot weather. Meningitis cases come upin March, April and then in August and September in Delhi. Chicken pox on the other hand makes an appearance in December and peaks in May”.

Although humans have a great capacity to adapt to varied climates and environments, they are still vulnerable when there are extreme changes in climate. Scientists have found that many more people die of heart attacks during heat waves than in cooler periods. Depletion of the ozone layer means that people are exposed to more ultraviolet rays and subsequently greater risk of skin cancer and cataract. Weather affects the level of air pollution in a city and rainfall increases the local population of malaria mosquitoes. Recent studies also indicate that El Nino is linked to epidemics like malaria and rift valley fever.

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According to doctors, in a “typical year”, relatively few people die of heat-strokes. A World Meteorological Organisation (WMO) report states: “It is now becoming clear that hot weather can increase the likelihood of dying from other causes… Deathrates can rise by over 50 per cent during unusually hot episodes.”

Earlier, the influence of climate was primarily linked to conditions suitable for virus or bacteria to breed. In the future, a warmer world is expected to result in severe flooding in some places and severe droughts in others. Each situation will bring with it more diseases.