Feel hotter than usual in Delhi? Blame the rising heat index, say experts
Heat index combines temperature and relative humidity to determine how hot you actually feel. It is a measure of the stress on humans. This rising heat index is already taking a heavy toll on the health of Delhiites both directly and indirectly, doctors have warned.
Every time 15-year-old Shamita Jaiswal returns home after school, even during the monsoon, she seems to be drained out.
The family physician of the Jaiswals have told Shamita’s anxious mother that it was the rising heat index in Delhi, which is taking the toll on the girl.
Heat index combines temperature and relative humidity to determine how hot you actually feel. It is a measure of the stress on humans.
“This heat index is rising in Delhi, along with other cities. The heat index in Delhi is rising by 0.60 degrees a decade during summer months. During the monsoon months, it is increasing by 0.55 degrees per decade,” said AK Jaswal, a former scientist with the Indian Meteorological Department, Pune.
A recent study by four scientists from the IMD and Indian Institute of Tropical Meteorology, published earlier this year, revealed that the average heat index in India was also increasing. In summer, it is going up by 0.56 degrees Celsius and during monsoon it is increasing by 0.32 degrees Celsius every decade.
The study revealed that most of the mega cities in north India, including Delhi, are in the ‘hot’ category of the heat index during summer and in ‘very hot’ category in monsoon.
“It is because of heat index that Delhiites are complaining of exhaustion and heat stress, even though the mercury is staying in the normal range,” said a senior official of the National Weather Forecasting Centre in New Delhi.
This rising heat index is already taking a heavy toll on the health of Delhiites both directly and indirectly, doctors have warned.
“Over the past decade, the number of patients suffering from diseases triggered by rising heat, humidity and pollution have apparently shot up. Patients suffering from vector-borne diseases, viral diseases and other heat-and-humidity-related ailments such as heat strokes, heat exhaustion and cramps are occuring in more numbers,” said Rommel Tikko, senior consultant, department of internal medicine, Max Super Speciality Hospital, Saket.
The risk of heat-related illness becomes greater as the weather gets hotter and more humid. The human body normally cools itself by perspiration, or sweating, wherein the sweat evaporates and carries heat away from the body. However, when the relative humidity is high, the evaporation rate of sweat is reduced. This means heat is removed from the body at a lower rate.
“Viral diseases, respiratory diseases, skin diseases, allergies and a range of diseases triggered by parasites that thrive in hot and humid weather conditions are rising. These diseases have shot up by almost 20% over the past one decade at least,” said SP Byotra, head of medicine department, Sir Ganga Ram Hospital.
Delhi’s senior citizens and old timers also claimed that stress level because of weather conditions seems to be going up over the years.
“Heat is synonymous to Delhi and central India. But the character of this heat seems to be changing. Earlier, we never used to feel drained out. But now, it is gradually becoming hot and humid, which is taking a toll on us,” said Prakash Sharma, who owns a spice stall in Old Delhi.
“Even though the level of tolerance varies from person to person, usually heat index less than 35 degrees is considered comfortable. But when it goes beyond 50, it usually becomes stressful and we get exhausted very quickly,” said Amit G Dhorde from Pune University.
