Heat wave advisory :: 30th May 2019

Medical Directorate, Government of Manipur *

Summer Time Sun Set progression :: May 2009

World Meteorological Organization defines a heat wave as five or more consecutive days during which the daily maximum temperature exceeds the average maximum temperature by 5°C. If the maximum temperature of any place continues to be more than 45°C consecutively for two days, it is called a heat wave condition.

A. Criteria for Heat wave as per Indian Meteorological Department is as follows:

o Heat Wave need not be considered till maximum temperature of a station reaches at least 40°C for Plains and at-least 30°C for Hilly regions.
o When normal maximum temperature of a station is less than or equal to 40°C Heat Wave Departure from normal is 5°C to 6°C and Severe Heat Wave Departure from normal is 7°C or more.
o When normal maximum temperature of a station is more than 40°C Heat Wave Departure from normal is 4°C to 5°C and Severe Heat Wave Departure from normal is 6°C or more.
o When actual maximum temperature remains 45 °C or more irrespective of normal maximum temperature heat waves should be declared.

B. Health Impact of Heat Wave:

Major medical disorders resulting from Heat Wave are Heat Syncope, Heat Cramps, Heat Exhaustion and Heat Stroke.

* Heat rash: Also known as sunburn phenomenon with pinkish skin resulting in burning of skin and pain sensation.
* Heat syncope: Giddiness, vertigo headache and sudden onset drowsiness/unconsciousness.
* Heat Cramps: Edema (swelling) and Syncope (Fainting) generally accompanied by fever below 39°C i.e. 102°F
* Heat Exhaustion: Heat exhaustion is the most common heat related illness which can develop over days of exposure as in elderly living in hot and poorly ventilated spaces, or acutely as in athletes.

* Heat Stroke: Heat stroke is a form of hyperthermia, an abnormally elevated body temperature of 40°C i.e. 104°F with accompanying physical and neurological symptoms. Heat stroke is a true medical emergency that can be fatal if not properly and promptly treated.

It is observed that during during the Heat Wave number of cases of Gastroenteritis, Food poisoning are also increased due to spoilage of food and reduction in shelf life of food. It is also noted that cases of anxiety, palpitation, nervousness, behavior change linked to Heat stress are increased Common heat health impacts include dehydration, cramps, exhaustion and heatstroke.

C. Classification of Heat Index (HI) and health impacts:

As a consequence of climate change, the increase in the frequency and intensity of extreme weather events predicted for future is arousing a growing concern, in the scientific and public health communities. Heat Index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature.

Evaporation is a cooling process and has important considerations for the human body's comfort. When the body gets too hot, it begins to perspire or sweat to cool itself off. If the perspiration is not able to evaporate, the body cannot regulate its temperature. When the atmospheric moisture content (i.e. relative humidity) is high, the rate of perspiration from the body decreases and the human body feels warmer in humid conditions.

D. Table: Classification of Heat Index (HI) and health impacts

Heat Index
(1) 27°C - 32°C
(2) 32°C - 41aC
(3) 41 °C - 54°C
(4) >54°C

Category
(l) Warm
(2) Hot
(3) Very Hot
(4) Extremely Hot

Health Effects

(1) Caution- Fatigue possible with prolonged exposure and/or physical activity. Continuing activity results in Heat Cramps.
(2) Extreme Caution- Heat Cramps and Heat exhaustion possible with prolonged exposure and/ or physical activity.
(3) Danger - Heat Cramps and Heat exhaustion are likely Heat Stroke possible with prolonged exposure and/ or physical activity.
(4) Extreme Danger - Heat Stroke highly likely with continued exposure.

E. Vulnerable Pupulation:

Vulnerability to extreme heat depends upon the degree of exposure to the event, the individual's sensitivity and their capacity to adapt to the situation to protect health.

Most vulnerable groups are:
o Elderly People (often with associated heart diseases, lung diseases, kidney diseases, or who are taking medications that make them vulnerable to heat strokes)
o Persons with pre-existing health problems (particularly heart, kidney, and lung or liver diseases)
o Poor & economically weak population deprived of proper house, clothes, food, etc.
o Roadside Workers
o Infants
o Children under 5 year
o Pregnant women
o Mentally ill person
o Construction Workers
o The pavement dwellers
o Stone Quarry Workers
o Ceramic Workers

Many other factors or behaviour of people make them more vulnerable to Heat related diseases. Some vulnerable community members displayed unintentionally harmful behaviors during heat events. Due to such behavior, young healthy people may also be affected by heat wave.
o Many people wait until they are thirsty to hydrate, which might put them at greater risk for heat-related morbidity or mortality.
o Using a fan with windows closed, leading to increased heat indoors and, potentially, associated heat-related health outcomes. o It is not usual practice to use the fan to exhaust all the hot air outside and pull the cool breeze inside the house.
o Air conditioners appeared to be financially costly as well as utility bills as an obstacle to staying cool in the summer.
o Some people dislike the sounds from the air conditioner, or associated physiological reactions as they experience when using air conditioners, including aggravated respiratory problems or arthritis
F. Adaptation Steps:
o Drinking water supply arrangements at prominent public places.
o Oral rehydration salts and intravenous fluids are made available at public places like railway stations and bus stations o Emergency medical camps are set up across various heat wave prone states.
o Citizens are issued advisories such as not to leave their homes at noon unless absolutely necessary.
o Further, rescheduling of timing in educational institutions, working hours, especially of those doing physical labour, veterinary measures, bus timings, etc. can be modified.
o Promote the use of reflective paint or "Chuna" (Lime) o Cool roof over the buildings to keep temperatures lower o Promote the Rooftop garden or green roof.
o Placing gunny bags soaked with water on roofs can help to keep indoor temperatures cooler.
o Green netting (shade cloth) helps to keep lower temperatures of the area below it.
o Use of modular roofing system, a water- proof roof, made of paper waste and coconut husk.

G. Heat Wave Safety measures

o As far as possible, avoid going out in the hot sun, especially between 12.00 P.M. and 3.00 P.M.
o Listen to Weather Radio for critical updates.
o Stay indoors as much as possible and limit exposure to the sun.
o Postpone outdoor games and activities.
o Eat well-balanced, light, and regular meals.
o Drink plenty of water; even if you do not feel thirsty. Avoid drinks with caffeine. Limit intake of alcoholic beverages.
o Dress in loose-fitting, lightweight, and light-colored clothes that cover as much skin as possible. Avoid dark colors because they absorb the sun's rays. Protect face and head by wearing a wide-brimmed hat.
o Avoid strenuous work during the warmest part of the day. Use a buddy system when working in extreme heat, and take frequent breaks. o Avoid extreme temperature changes.
o Keep your home cool, use curtains, shutters or sunshade, etc. Open windows at night.
o Maintain adequate ventilation.
o Never leave children and pets alone in parked vehicles.
o Keep animals in the shade and give them sufficient water to drink.
o In case of illness and fainting, consult a doctor/ seek immediate medical help.

H. What to do in Heat Stroke

o Get the person indoors or into a cool/shady area, make him lie down with feet slightly elevated.
o Rub the body with wet cloth or spray cold water to the skin.
o Give the person ORS to drink, lemon water, salt-sugar solution or juice to re-hydrate the body.
o Do not give anything to eat or drink, if he is not fully conscious.
o Take the person to the nearest health center if symptoms does not improve in one hour.