New research conducted in Delhi has unveiled a stark discrepancy between official air temperature readings and the actual heat experienced by residents, with surface temperatures recorded at up to 64C in some parts of the city. This investigation, carried out by Greenpeace India using thermal cameras, highlights why the Indian capital feels considerably hotter than what conventional weather reports indicate, particularly during the ongoing severe heatwave.
While the India Meteorological Department (IMD) records air temperatures under standard conditions, thermal cameras measure the temperature of surfaces. The study found that urban elements such as roads, concrete structures, and stationary vehicles become superheated, radiating intense warmth that significantly increases the heat absorbed by the human body. For instance, at a busy traffic junction in south Delhi, the thermal camera registered 64C on bikers idling in direct sunlight, in contrast to 42C in shaded areas just metres away.
Nibedita Saha, a Greenpeace researcher involved in the study, emphasised the immediate relief gained from moving into shade, noting that 'moving just a few feet can help. We got instant relief. That's the difference just one tree can make.' This crucial observation underscores the role of urban planning and green spaces in mitigating extreme heat within cities. The findings are not peer-reviewed but provide direct observational data on urban heat island effects.
Dr A Fathahudeen, a pulmonologist, warned of the severe health implications of prolonged exposure to these elevated 'real feel' temperatures. He explained that when the core human body temperature exceeds 40C, normal bodily functions cease, leading to symptoms like excessive sweating, headaches, and fatigue. More severe cases can result in confusion, seizures, and even multiple organ failure, which can be fatal if not treated promptly. Dr Fathahudeen advises individuals to drink water regularly, wear loose, light-coloured clothing, and use umbrellas for protection.
The study also highlighted the disproportionate impact on Delhi's poorer populations, many of whom cannot afford the luxury of avoiding outdoor work during peak heat hours. Street vendors, for example, continue to operate in scorching conditions, with thermal cameras recording surface temperatures of 51.4C near the ground where they sit. These individuals face relentless heat from both the sun and the superheated ground, leading to severe discomfort and health risks, contrasting with existing research on urban heat stress in other global cities.