With north & west India’s night temperature 3-6°C above normal, the poor are exposed to grave health threats

It’s 10 pm and Champa Dawar, after a 12-hour day shift at a textile factory in Ahmedabad, is sitting inside her cramped room without switching on the fan. 

“It captures and blows only hot air. The room feels like a furnace,” she complains. There is no ventilation inside the room and the fan is the only device to help cope with the scorching heat. But the nighttime temperatures are such that the fan only worsens the existing warm conditions. 

Many parts of the country are going through unprecedented heatwave conditions. The most worrying part is the unusual increase in nighttime temperatures. 

In many northern and western cities, nighttime temperatures have been alarmingly high, hovering above 30 degrees Celsius. On June 18, 2024, Delhi recorded a minimum temperature of 33.8°C, Ahmedabad 30.7°C, Ambala 31.1°C, Amritsar 31.1°C, Alwar 37°C, Jaipur 33.6°C and Lucknow 32.6°C. 

These temperatures are at least three to five degrees above normal for this time of the year and this affects the vulnerable population the most.

For example, Champa and her husband both work through the day in scorching heat but the extended heat beyond the work hours doesn’t give their bodies a chance to cool down even during the night. 

Daily wage workers at construction sites, brick kilns, factories, gig workers, auto rickshaw drivers and street vendors are most at risk when minimum temperatures are high and the surface does not cool down even at night. 

Usually workers live at the premises of the construction or brick kiln sites in makeshift rooms in the ‘labour colony’. These rooms are made of tin and asbestos sheets, which absorb the heat from the sun and turn their living space into a furnace. 

“For people who are exposed to heat all day, it’s really important to be able to cool down, give their body a break and have a chance to recover. So, if they are going somewhere where they don’t have access to, say a fan, and a way to cool themselves at night and it stays hot, then that can have compounding health consequences over time. If a body can’t cool itself, a person can experience heat exhaustion and heat stroke,” said Luke Parsons, climate scientist, Global Science Division, The Nature Conservancy.  

A new study by Delhi-based think tank Centre for Science and Environment (CSE) uncovered a worrying phenomenon: Cities are not cooling down at night as much as they did during 2001-2010.

The study, Decoding the Urban Heat Stress among Indian cities, analysed data from six major cities – Delhi, Mumbai, Kolkata, Hyderabad, Chennai and Bengaluru — over a period of 23 years (January 2001-April 2024) and found that while cities used to cool down considerably at night, this night-time cooling has significantly reduced in recent years.