On Independence day, 32 students and two police officers collapsed from heat during the morning parade celebrations in Assam. The air temperature was 37°C with humidity at 90% after early morning rain. This was gruelling enough but the real strain came from the compounding effect of standing in direct sunlight, crowded together, performing drills in uniform. The irony is stark: A day meant to celebrate freedom revealed we remain captive to colonial vestiges and outdated ways of measuring heat. Dry-bulb thermometers and the Factories Act of 1948 regulates only indoor thermal comfort, while erasing outdoor heat exposure and its negative impact on people’s lives. The failure to protect children and police officers on duty from extreme heat is not incidental but systemic. Unlike other climatic events like cyclones or floods, heat comes invisible, does not destroy property and lacks spectacularity. However, as a 2021 study in Lancet showed, heat is a leading weather-related cause of death and another study reported 191 billion potential labour hours were lost in 2022 due to heat exposure, globally. National-level extrapolations suggest that a single day of extreme heat could cause 3,400 excess deaths in India. Yet, official reporting captures only a fraction of this number. Because heat aggravates existing health conditions, doctors often record only the immediate cause of death on certificates, leaving heat’s role invisible in public statistics.Besides the seeming invisibility of heat – which legitimises inaction – a crucial question arises: for whom is exposure to extreme heat not regulated? While many of us have the option of working indoors in air-conditioned, ventilated, or shaded spaces, those who grow food, deliver goods, construct houses, play sports, direct traffic, or perform heat-intensive tasks such as cooking, perfume making, or brick firing must endure exhausting physical labor in the heat with little respite. The right to cool – including basic labour protections such as shade at work, water breaks, shift changes and even fundamental infrastructure like access to electricity and cooling technologies such as air-conditioners and air coolers remains inaccessible to many.Who bears the greatest burden of outdoor heat may itself explain why outdated science and governance persist. Indoor heat and ventilation was first regulated in India by the Factories Act of 1934, enacted to maintain productivity and protect British industries from cheap labour in India. It was formalised after Independence under the Factories Act of 1948.Also read: Thermal Injustice: 20,000 Indians Died in Heatwaves In 20 Years – Caste a Key FactorThe act required registered factories to ensure adequate ventilation by the circulation of fresh air and maintain such a temperature as will secure to workers therein reasonable conditions of comfort and prevent injury to health. Since labour laws are a concurrent subject, the legislation engendered model rules to guide states in enacting their own heat regulations like setting temperature standards and maintaining temperature and humidity registers in indoor settings. Remarkably, many states set a ceiling of 30°C wet-bulb temperature measured at 1.5 m above the floor, together with mandatory ventilation to ensure constant airflow. A rise in the dry bulb reading would lower the wet bulb reading, thus recognising humidity as a key factor in indoor setting.However, when it comes to outdoor exposure, the law is silent. The only legislative measure for outdoor exposure is the Building and Other Construction Workers Act, which only regulates construction in tunnels. A recent 2020 model creates some protection for dock workers, again of an advisory nature. Local level heat action plans, operational in 23 states, lack teeth as they too are advisory in nature. Given that about 50% of the labor force works outdoors, and the number is even higher if we include undercounted women in the informal workforce; this gap is egregious. Even a parliamentary question – on the disproportionate impact of extreme heat on the poor, marginalised migrant and subsistence workers, the elderly, and women – was deflected for lack of heat-related data or research, further obscuring both the consequences of exposure to extreme heat and the lived experiences of disadvantaged populations.Furthermore, outdoor heat is measured through dry bulb temperature readings – which is only a measure of air temperature through a regular thermometer reading. Like the abstraction that water boils at 100°C regardless of altitude or vessel, dry bulb readings ignore real-world conditions. For instance boiling temperature may vary depending on the material in which water is boiled and the properties of conducting heat. So, in Assam where the children and cops collapsed on Independence Day, heat experienced after the rainfall was not equivalent to the dry bulb temperature reading. Just like cricket, where runs scored in Mumbai and Ahmedabad can’t be compared without accounting for humidity, wind, and direct sun on the pitch, temperature readings that fail to factor in variables such as humidity, radiation, wind, physical activity, clothing and protective gear are misleading. The British knew this well; as Ramachandra Guha notes in A Corner of a Foreign Field, they frequently lamented the “un-English” conditions of playing cricket in India, likely factoring temperature with humidity. For the human body, perspiration is an important step through which the body cools and makes sure the internal body temperature does not rise above 37°C. So, when high humidity blocks sweat from evaporating, the body cannot cool and heat stress sets in. This is the reason why scientists developed the wet-bulb thermometer – which is temperature measured by tying a wet cloth to the bulb simulating perspiration. Historically, this has also been a factor in British designing the tropical wear for Europeans travelling to the tropics – textile that would breathe like native skin. Interestingly, initially the preferred material for tropical wear, including underwear, was wool, the pores meant to mimic perspiration. Dated measuresEven the wet bulb reading is dated. A more comprehensive measure, now adopted by the International Labour Organisation and used by FIFA, Olympic committee, US military and athletic brands is the Wet Bulb Globe Temperature (WBGT), which considers humidity, wind and radiation. WBGT is popular with sports federations and athletic wear designers, to determine physical exhaustion in sports and prevent athletes from heat stress. Even WBGT, while more comprehensive, remains limited – especially once heat is compounded by urban contexts. It creates what we call the urban heat island effect. For instance, asphalt surfaces can reach temperatures of over 60°C when ambient temperatures are only 30-35°C. Further, maximum day temperature readings, without factoring in the diurnal range, narrows our scope to grasp the experience of heat as it obliterates how or if, our bodies have a chance to cool at night.Heat metrics flatten lived experience, but heat is unequal – borne disproportionately by those forced to live and work outdoors. While temperature readings universalise heat, they capture only one dimension of it, flattening the unequal ways heat is actually embodied – shaped not only by our physical and mental abilities to endure, but more importantly by our everyday routines and livelihood practices. It is critical that laws confront the unequal experience of heat by addressing outdoor heat exposure and adopting comprehensive temperature measures that move beyond crude dry-bulb metrics to reflect the lived, sensory experience of heat. Even though WBGT cannot capture all the variables that shape embodied heat – such as the strain of continuous physical activity, protective gear, or the exhaustion of women balancing agricultural and domestic work and spending hours cooking in likely unventilated kitchens – it can be a beginning to recognising heat.Sanghamitra Padhy is an Associate Professor of Law and Society at Ramapo College of New Jersey.