Lt Col Nazmul Huda Khan :
Bangladesh is facing temperature hike for months together even at the rainy season that has dire consequences on human health and well-being. Exposure to higher temperatures causes public health emergencies and cascading socioeconomic impacts such as loss of work capacity, labour productivity and mobility and exacerbates poverty. Continuous exposure to excessive heat causes serious health conditions such as heat rash, excessive sweating, heat cramps, exhaustion, heatstroke and even death. The International Labour Organization (ILO) predicts that by 2030, 2.2% of working hours worldwide or 80 million full-time jobs, will be lost as a result of higher temperatures. Multiple studies estimate that from 2000 to 2016, the number of people exposed to heat waves increased to 125 million worldwide. Recent studies found that it may affect more than 1.2 billion people annually by 2100.
South Asia is considered to be a hotspot for heat wave related incidences. The Indian Meteorological Department states that from 1979-2017 the extreme combination of both heat and humidity has doubled in many parts of India, Bangladesh, Pakistan, and Sri Lanka. Besides, it is also projected that by 2100 the average temperature will rise to 3-6C. This rising temperature will result in extensive heat wave which can potentially affect 800 million people in the region.
The Bangladesh Meteorological Department defines temperatures of 36 to 38 degrees Celsius as a mild heat wave, 38 to 40 as a moderate heat wave and temperatures above 40 degrees Celsius as an intense heat wave. In this year, Khulna, Rajshahi and Dhaka divisions and their surrounding areas were experiencing mild to moderate heat waves. Rajshahi has twice recorded temperatures of 41.2 degrees Celsius – the highest in the country so far this year. Eleven different locations across the country recorded temperatures between 36 to 40 degrees Celsius in the 30 days of April. Bangladesh is losing 7 billion working hours annually due to extreme heat exposure caused by global warming, a new study reveals. If the global temperature increases by 1 degree Celsius, the country could lose approximately 21 billion working hours, a US study has explored. It has estimated that if the temperature rises by 2 or 4 degrees Celsius it can result in a loss of 31 or 57 billion work hours annually in the country. Heat waves are associated with livestock and poultry disease and with crop damage also. In Bangladesh, mortality rates increase by about 20% during heat waves.
Heat related illnesses for human health include heat edema, heat rash, heat cramps, heat syncope and heat exhaustion etc. Heat edema presents as a transient swelling of the hands, feet and ankles. No particular treatment is required, wearing support stockings and elevating the affected legs will help minimize the edema. Heat rash, also known as prickly heat, accompanied by acute inflammation and blocked sweat ducts. In such cases, it is advised to wear loose- fitting clothing in the heat. Application of chlorhexidine lotion is beneficial to remove any desquamated skin. The associated itching may be treated with topical or systemic antihistamines. Heat cramps are painful, involuntary spasms of the large muscle groups used in strenuous exercise. Rehydration with salt-containing fluids provides rapid relief. Patients with mild cramps can be given oral salt solutions, while those with severe cramps require IV isotonic fluids. Heat syncope is related to heat exposure that produces hypotension. Management of heat syncope consists of cooling and rehydration of the patient using oral rehydration therapy or isotonic IV fluids. Heat exhaustion is marked by excessive dehydration and electrolyte depletion. Symptoms may include diarrhea, headache, nausea and vomiting, dizziness, tachycardia, malaise and myalgia. Definitive therapy includes removing patients from the heat and replenishing their fluids. The World Health Organization (WHO) identifies diarrheal diseases, respiratory infections and malaria in the top ten causes of environment related deaths. Rising temperature influences the emergence and re-emergence of many infectious diseases e.g. dengue fever, diarrheal disease, enteric fever, respiratory tract infections and meningitis etc. In addition, emerging and reemerging diseases such as chikungunya and Zika, have also been linked to climate change influences.
Staying healthy during heat waves is easier if we take the time to protect ourselves by drinking enough water and limiting our unnecessary exposure to the heat. We should remain hydrated by drinking plenty of fluids even if we do not feel thirsty. Eating small meals and eat more often; wearing loose-fitting, lightweight, light-colored clothing; slowing down, staying indoors and avoiding strenuous exercise during the hottest part of the day; taking frequent breaks if outdoor work is unavoidable and wearing sunscreen with a high SPF are few individual measures to mitigate adverse impact of heat waves amongst others. We should remain aware of family and friends who may need extra care who are at risk of heat-related Illness like dehydration, prolonged exertion, chronic illnesses, uncontrolled diabetes, uncontrolled hypertension, older age, increased body mass and younger age etc.
People should be informed of weather conditions via television, radio, newspapers and other print media. Long-term measures should focus on disaster prevention: starting from improving the climate adaptability of urban and architectural design, such as the reduction of urban heat generation and the weakening of urban heat island effect through building the urban green infrastructure and increase the quantity and quality of green space.
The concerned department should implement the high-temperature monitoring and warning system. Necessary action plans and respective national and municipal policies should be formulated and executed to address the heat stress impacts on human well-being and livelihood in Bangladesh following WHO public health guidance for the general public and medical professionals on coping with extreme heat.
Additionally, the introduction of the Heat Adaptation Plan (HAP) at the city and administrative level, capacity building of the institutions, mass awareness and knowledge campaigns can enhance the overall understanding as well as facilitate necessary measures to tackle the impacts of heat waves in Bangladesh.
(Lt Col Nazmul Huda Khan, MBBS, MPH, MPhil is a Public Health Specialist and Assistant Director, Kurmitola General Hospital).
