According to the World Meteorological Organization, the year 2024 was the hottest year ever recorded, with global temperatures averaging approximately 1.55°C higher than pre-industrial levels. In India, December 2022 marked the warmest December since official temperature tracking began in 1901. Over the past two decades, the incidence of heatwaves in India has risen significantly compared to earlier periods.

The combination of high temperatures, humidity, and wind speed contributes to what is known as heat stress. When ambient temperatures approach or exceed the human body’s natural temperature of 37°C, the body's ability to dissipate internal heat becomes impaired, leading to feelings of exhaustion and physical strain. Prolonged exposure to such conditions can negatively affect vital organs like the brain, kidneys, and liver, and in severe cases, may even be fatal.

Socio-economic and Equity Concerns

• The repercussions of heatwaves extend beyond health, affecting socio-economic stability as well. Climate change-induced temperature increases are partly responsible for distress in India’s agricultural sector.
• Extreme heat hampers farm labour, reduces yields, and can even result in livestock fatalities, disproportionately affecting farmers and economically weaker communities.
• Agricultural productivity, livestock output, and outdoor labor capacity decline under heat stress, particularly in labour-intensive sectors like farming and construction.
• This results in reduced work hours and income losses for a significant portion of India’s workforce—estimated at around 380 million people or 75% of the labour force—who are directly exposed to extreme heat.
• Heat-induced economic losses may account for 3–5% of GDP in several countries, including India. In 2023 alone, around 6% of total working hours in India were lost due to heat stress.
• Furthermore, increased electricity demand during heatwaves often leads to power outages, which further disrupt industrial output. This cycle of reduced income and productivity may dampen overall economic growth.
• Heat stress tends to affect the most vulnerable groups in society—such as low-income individuals, migrant labourers, subsistence workers, elderly people, and women. Cultural and social norms often exacerbate women’s vulnerability, as many are expected to cook indoors or wear specific clothing, increasing their exposure. The disproportionate impact of heatwaves highlights broader issues of inequality and environmental justice.

The Rise of Heat Action Plans (HAPs)

• As early as the mid-19th century, researchers recognized that cities tend to be hotter than rural areas, largely due to human activities. Despite this, comprehensive strategies to combat heat took over a century to emerge.
• It wasn't until the early 2000s that countries—mostly from non-tropical regions—began developing formal Heat and Health Action Plans (HHAPs). India made significant strides when Ahmedabad in Gujarat became the first city in Asia to implement a heat action plan in 2013. Since then, more than 140 cities across 23 Indian states have adopted state- or city-level HAPs.
• The National Programme on Climate Change and Human Health (NPCCHH), under the NDMA, also disseminates heat-related advisories and public health information.

Improving HAP Effectiveness

• Typical heat action plans have four main elements: early warning systems to predict heatwaves, public education to promote heat safety, strengthening the health infrastructure, and long-term mitigation strategies like expanding urban green spaces and promoting reflective roofing.
• A crucial yet often underdeveloped fifth component is the collection and analysis of data on heat-related illnesses and deaths, essential for tailoring effective interventions.

Despite widespread adoption, many HAPs remain inconsistently implemented. Success is more likely when local authorities collaborate with state governments, public health institutions, NGOs, and community groups. As India potentially faces another year of extreme temperatures, several lessons can guide future planning:

• Update and customize HAPs: Each state should update its HAPs based on local vulnerability assessments and successful practices. Plans must account for humidity, not just temperature, and clearly assign roles to stakeholders. These plans should be operational by March each year.

• Enhance data accuracy: Indian cities often underreport deaths and illnesses due to heat. Detailed data collection, including geographic and demographic breakdowns, can help identify at-risk populations and tailor interventions.

• Use day and night temperature forecasts: Some countries, like the UK, now use both daytime and nighttime highs in their Heat Health Alert systems. India could benefit from similar systems to ensure safer working and schooling conditions by forecasting when temperatures are lower.

• Promote heat-resilient infrastructure: Improvements in urban design, construction materials, and cooling systems should be part of long-term strategies. Financial assistance for informal workers during heatwaves may also be necessary to mitigate wage losses.

• Reconsider 'stay indoors' advisories: Research from India, Pakistan, and Bangladesh shows that indoor temperatures can be even higher than outdoor ones in cramped, poorly ventilated neighborhoods. Tailored, context-sensitive advisories are essential.

• Build public cooling infrastructure: Cities should establish “summer shelters,” akin to winter shelters, and promote cool roof policies that reflect sunlight. Scientific and practical innovations are needed for long-term heatwave prevention.

• Ensure access to water and flexible work hours: Municipalities should install public drinking water stations and distribute oral rehydration solutions. Workplaces should allow flexible or staggered schedules, particularly for outdoor and informal sector workers, to prevent heat-related illnesses