Heat Stroke:
A heat-wave constitutes an extended period of hot weather relative to the
expected conditions of the area at a particular time of year. A heat-wave can
also refer to a prolonged period of a hot weather, which may be accompanied by
high humidity. The World Meteorological Organization (WMO) defines heat-wave as
"when the daily maximum temperature of more than five consecutive days exceeds
the average maximum temperature by 5 °C, from the normal temperature of an area.
In Pakistan, the heat waves are common in premonsoon months (May & June) in the
plains of the country.
The definition in terms of number of days and ambient temperature varies from
region to region. Heat-waves have several significant characteristics. These
include (i) the number of heat wave days and the annual number of summer heat
wave events; (ii) the length of the longest heat wave in a season; (iii) the
average excess temperature expected during a heat wave and the hottest day of a
heat wave; and (iv) the occurrence of the first heat-wave event in a season
(Steffen et al., 2014). These characteristics are important to understand for
identification and deeper exploration of the nature of heat-waves AS mercury
levels are soaring in Pakistan, being out in the sweltering heat can result in a
heat stroke which can be extremely harmful and even fatal.
During summer season, Karachi has displayed very high occasional day
temperatures. The historic data of maximum temperatures for the months of May
and June for this mega urban center shows 47.8 °C on 9th May 1938 and 47 °C on
18th June 1979.
The maximum temperature record along with humidity and wind (speed & direction)
data for the month of June for the normal period (1981-2010) and for the period
20132015 have been used to study heat wave conditions of 2015 heat-wave in this
sub-region. According to PMD records, this severe heat wave event persisted for
consecutive 5-days from 19-23 June. The daily temperature anomalies were more
than 5°C for consecutive five days. The departure of maximum temperature from
the normal ranged between 5.3 to 11ºC during severe heat wave as is evident. The
highest maximum temperature in Karachi was 44.8 °C on 20th June 2015 with a
departure of 11.1ºC from normal, which was the highest temperature for the month
of June after year 2000 (45.5 °C). The heat wave was unprecedented in terms of
persistence. There were incidences in Karachi when the temperature departures
were +5°C or more but it lasted only for 1-2 days.
The summer afternoons in Karachi during the month of June (15-16) displayed a
typical normal moisture quantity and transport into the area from the Arabian
Sea (figure 4). The atmospheric conditions went anomalous after a ridge
(extension of high pressure area) was extended over Baluchistan and adjoining
parts of the country including Karachi. The formation of this ridge led to a
weakened incoming sea breeze transport process from the Arabian Sea and
consequently reduced the humidity levels below normal over Karachi on the
afternoon of 17th June, 2015. The ridge further accentuated on 18th June and
penetrated more into south and eastward parts of the country.
Symptoms of heat stroke can include a high body temperature, headache,
dizziness, lack of sweating despite the heat, muscle weakness or cramps, nausea,
vomiting, rapid heartbeat, rapid breathing, confusion, disorientation and
unconsciousness.
Here are a few tips that will keep you safe from the scorching heat:
The most important measures to prevent heat strokes are to avoid becoming
dehydrated and to avoid strenuous activities in hot and humid weather. Drink
plenty of fluids even when not thirsty. Staying hydrated will help your body
sweat and maintain a normal body temperature.
Avoid tea and coffee as they dehydrate the body. Always carry water while
travelling.
Take cool showers or baths, especially before sleeping. This helps cool the body
temperature. Wear lightweight and light colored clothes. Keep windows and
curtains closed during the day, but open windows at night when the temperature
has dropped.
Turn off non-essential lights and electrical equipment, as they generate heat.
Seek medical help if symptoms such as breathlessness, chest pain, confusion,
weakness, dizziness or cramps persist and don’t go away.
Infants, the elderly, athletes and outdoor workers are more vulnerable to a heat
stroke. Leaving infants or children in a car can lead to heat stroke. Babies and
young children don’t have the ability to hydrate themselves. Never leave a child
in a closed, parked vehicle, not even for a minute. Make sure babies and
children drink plenty of fluids. During the hottest hours of the day, keep your
children indoors.