Until recently, billions of people across Asia and the Pacific lived through and adjusted to high seasonal temperatures, but extreme heat is increasingly putting lives at risk. Warmer temperatures now arrive earlier, bringing longer, more intense, and frequent heat waves that put everyone at risk, particularly women, the elderly, children, those who work outdoors, informal workers, and low-income individuals who often lack access to cooling measures. 

Extreme heat claims more lives than any other climate-related disaster in the United States and Australia.  Globally, between 2000 and 2019, there were an estimated 489,000 heat-related deaths annually, almost half of which occurred in Asia and the Pacific.

Yet, the impact of extreme heat is not limited to fatalities. Heat is known as the silent killer— because it deeply affects health in ways that precede the loss of life. People may experience severe physical, mental, and emotional consequences due to heat events— symptoms that  are less visible and poorly understood. 

For instance, during heat waves, the heart must work harder and faster to pump blood to the skin, facilitating heat dissipation through sweat evaporation. This intense exertion can lead to severe cardiovascular issues, including heart attacks, which can affect individuals of any age. Heat waves also bring other serious health complications such as heat exhaustion, heat syncope (fainting due to heat), heat cramps, and heat rashes. Heat exhaustion, characterized by heavy sweating, weakness, cold, pale, and clammy skin, can escalate to heatstroke if not promptly addressed.

Heatstroke occurs when the body's temperature regulation system is overwhelmed, rapidly increasing core body temperature. Symptoms like confusion, seizures, and loss of consciousness require urgent medical attention. The risk of heatstroke climbs dramatically with prolonged exposure to high temperatures, especially for those without access to adequate cooling. Notably, there is a gender gap in access to cooling, with an estimated 60% more women lacking access compared to men.

 Studies show that heat exposure leads to elevated risk of morbidity and mortality for women, people 65 years and older, those living in tropical climates, and lower-middle income countries. Without early action to address these risks, the number of heat-related cardiovascular fatalities could more than triple by 2050.

The combination of extreme temperatures and air pollution also poses significant health risks, with research indicating a 21% increase in mortality from these factors together. Studies have shown that in South Asia, air pollution alone can reduce a person’s life expectancy by more than five years. In 2023, soaring temperatures in Viet Nam and Thailand, reaching 44.2°C and 43.5°C respectively, occurred alongside weeks of intense smog, multiplying the risk of adverse health effects.

This combined effect is particularly harmful to women's health. Air pollution has been linked to elevated incidences of miscarriages, pregnancy complications, stillbirths, and ovarian cancer. Additionally, each 1ºC rise in maternal heat exposure is tied to an increased risk of stillbirth, preterm labor, preeclampsia, and neural tube defects. Extreme heat also disrupts hormonal balances, further complicating the reproductive health challenges that women face at different stages of life.

In many countries in the Asia and Pacific region, the majority of agricultural workers are women. Over the long term, outdoor heat exposure among agricultural workers has been linked to kidney injury and the development of chronic kidney disease. Workplace heat stress interventions such as regulated rest periods, fixed hours of work, and rest-shade-rehydrate interventions (RSH) have significantly reduced heat risks and increased worker productivity. 

Prioritizing women's health and well-being is crucial as key to building a resilient and sustainable future.

Beyond the direct physical dangers, heat waves exert a profound emotional and mental toll. Factors such as poor sleep quality and the financial stress from prohibitive cooling costs can contribute to heightened anxiety, and stress.  The stark disparities experienced during heat waves reflect deep-seated social inequalities. While those with means find refuge in air-conditioned environments, poor women may lack access to even the most basic cooling comforts, such as the shade of trees, well-ventilated living and work spaces, or the simple luxury of a small fan. During a recent visit to Cambodia, while the country was experiencing a heat wave, we heard personal stories of people crying in the middle of the night in frustration as they found no respite from the extreme heat.

Indeed, the debate around air-conditioning highlights an ethical dilemma. Once a luxury, it has become a necessity in many homes, sharply dividing society into what climate writer Jeff Goodell aptly calls "the cool and the damned." 

Goodell points out that while air conditioners provide essential relief, they also contribute significantly to greenhouse gas emissions, exacerbating the climate change that drives the increasing need for cooling— a classic example of the tragedy of the commons. This scenario, where few benefit while many suffer, underscores a public health emergency fueled by extreme heat. 

Three strategic principles should be considered when addressing this crisis:

The coming health crisis due to extreme heat conditions needs to be understood as an issue closely related to socioeconomic vulnerabilities. Addressing the risk for women requires an understanding and integration of gender-related differences in data collection and analysis; consideration of women's specific needs in public health programs; provision of information campaigns targeted for women through communication channels that they use; home services for the elderly; and provision of cooling shelters that meet the needs of women for safety and privacy.

A concerted and intersectoral effort is needed in managing heat illness and health risks. This should happen through early warning systems, by providing specific support to women and vulnerable groups such as the elderly and disabled, and expanding urban infrastructure to include cooling shelters and green corridors. Enhanced urban planning is essential to mitigate the urban heat island effect, which impacts the urban poor and other vulnerable populations the most. 

Adaptation to heat requires interventions such as protective regulations for workers, but these regulations need to consider gender differences. For instance, shifting work schedules may have unintended negative consequences for women with care responsibilities. Laws to safeguard workers during heat waves should cater to the unique needs of female workers and include access to water, shade, protective clothing, regular breaks, and cooling measures.

The health sector plays a crucial role in preparing healthcare providers to effectively recognize and manage heat-related illnesses. This means providing specialized training and skills development to frontline staff, first responders, obstetricians, and gynecologists, with a focus on the impacts of heat on women and children.

Additionally, the sector should offer telephone check-ups for vulnerable groups and deploy mobile health services that address the access barriers faced by women, including those needing mental health or support services for gender-based violence.  Initiatives designed to provide relief during extreme heat conditions should also consider the specific nutritional needs of women, children, and other vulnerable populations.

The urgency for actionable gender-responsive adaptation measures to extreme heat is clear. We are only beginning to understand its vast impacts, underscoring the need to invest in knowledge and data to guide our responses to this emerging crisis. 

Prioritizing women's health and well-being is crucial to building a resilient and sustainable future. By focusing on these aspects, we can ensure that all individuals can navigate and thrive amid the mounting pressures of our changing climate.

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