Heat is both an environmental and occupational health hazard. The National Programme on Climate Change and Human Health (NPCC-HH) under the Ministry of Health and Family Welfare reported 46 heat-related deaths and over 19,000 cases of suspected heat stroke across the country in May 2024. The two key statistics that make heat-related news are maximum temperature and deaths.
This newspaper reported on June 18, “Noida: Amid heat wave, 7 people found dead with no injury marks”. According to the police spokesperson, the causes of death would be subject to the post-mortem reports but were tentatively presumed to be on account of the prevailing heat wave conditions. The National Heat-Related Illness (HRI) and Death Surveillance under the NPCC-HH defines “heat-related death” as a death in which exposure to high ambient temperature either caused the death or significantly contributed to it.
Two caveats are important: First, the diagnosis of heat-related death is based on a history of exposure to high ambient temperature and reasonable exclusion of other causes of hyperthermia. Second, the diagnosis may be established from the circumstances surrounding the death, investigative reports concerning environmental temperature, and/or measured antemortem body temperature at the time of the collapse. It unequivocally states that “autopsy findings are nonspecific, and autopsy is not mandatory in all cases of heat-related illnesses.” The over-emphasis on the autopsy runs the risk of a denial of diagnosis.
While the daily maximum temperature in Noida was about 44 degrees Celsius, the night temperature was about 33 degrees Celsius in the previous three days. The effect of heat on mortality — particularly in urban areas — from most diseases is understood to be higher during hot nights that were preceded by a hot day than in cool nights preceded by a hot day. Public Health England’s impact-based Heat Health Alert (HHA) systems are now based on both maximum daytime temperatures and overnight temperatures.
Who dies of heat-related causes?
As important as the “science” are the social and community dimensions of HRIs: Who are those who died? What were their social characteristics? What made these individuals succumb to these tragedies? In theory, heat-related deaths and illnesses are preventable, albeit with specific public health and multi-sectoral policies and interventions. The individuals who died and were identified in Noida included a ragpicker, a manual labourer and a security guard — and they were migrants. An analysis of five deaths in the last three days in different hospitals in Delhi also suggests a similar profile: A 40-year-old female manual labourer, a 39-year-old car male car mechanic and a 60-year-old male security guard.
It is critical to understand that all instances of heat-related morbidity and mortality are not merely cases of heat cramps, heat exhaustion, heat syncope, or heat stroke. As a medical emergency, heat stroke has a high case fatality rate (the proportion of people who die from a specified condition among all individuals diagnosed with the condition over a certain period, a marker of severity). Equally or more important in terms of numbers is the fact that heat conditions exacerbate underlying illnesses such as cardiovascular disease, diabetes, mental health, and asthma; transmission of some infectious diseases is facilitated too.
Heat conditions can also increase the risk of accidents. Commenting on the collision between the Kanchanjunga Express and a goods train in West Bengal on June 17, the general secretary of All India Railway Men’s Federation pointed to the prolonged exposure of locomotive drivers in non-air-conditioned engine cabs to temperatures upwards of 50 degrees Celsius.
Heat bureaucracies vs heat action
Increasing attention is being paid globally to unpacking the community and social determinants, both at the city and local area levels, that aggravate heat health-related risks. The range of factors includes ethnicity, cultural or linguistic isolation, income, food insecurity, and inability to afford energy bills. Add to that, socioeconomic status and the neighbourhood social environment, housing characteristics and neighbourhood characteristics such as crime and safety and urban heat islands.
Heat action plans (HAPs) in India — at national, state or city levels — cannot be faulted for not addressing vulnerability factors. The ‘local’ elements are limited to a few heat maps based on composite indices. Delhi’s HAP for example flags (i) vulnerable areas: Less urbanised minimal access to water and sanitation, minimal household amenities; and, (ii) vulnerable groups: Economically weaker sections; elderly, children, women, and work categories — construction workers, factory workers, transport, sweepers, labourers, and vendors/street hawkers. The action points or dos and don’ts are currently population-wide, with very few specificities according to the identified vulnerabilities. There is an urgent need for HAPs to graduate to the next level — conduct within-city analyses and use available methodologies to create local vulnerability maps that incorporate urban microclimate patterns.
Notwithstanding its multisectoral nature, the conceptual boundaries and interventions of the current HAPs are limited by what Critical Heat Study experts term the privileging by “hazard bureaucracies” of “objective” meteorological and thermometric measures over “subjective” sensory and lived experiences of heat events and obscuring political dimensions of heat inequity.
Addressing these inequities will entail engaging with more complex issues such as mitigating the processes through which heat-producing and heat-exacerbating outdoor built environments interact with socio-segregation patterns, putting those in weaker socio-economic positions at greater risks of heat illness and premature death.
The writer is professor (Community Health), Jawaharlal Nehru University, New Delhi and a collaborator in the Wellcome Trust Project: Economic and Health Impact Assessment of Heat Adaptation Action: Case studies from India
