Why Chennai needs to put its ‘heat action plan’ to practice right away

Chennai Heat Action Plan

Coastal humidity should also be a factor in formulating a heat wave plan according to experts. Pic:WPFlare (CC BY:SA 2.0)

Chennai saw an unseasonal, early heat wave earlier this month, with the temperature soaring above normal for five consecutive days. The city also recorded its highest temperature of the year till date during this period, at 41.6 degree celsius.

Brutal summers in Chennai are not uncommon and people tailor their lives around these, but extreme or prolonged heat waves require a certain level of preparedness and planning to protect the most vulnerable persons in the city.

While cities work on climate action plans to mitigate the impact of climate change, parallel efforts must be made to create contingency plans for tackling the increasingly hot summers. To this end, many cities across India have evolved Heat Action Plans that lay down a set of protocols to manage heat wave conditions and excessively hot summer temperatures. 


Read more: Why some parts of Chennai felt hotter than others this summer


A Heat Action Plan is an early warning system that requires coordination between various government agencies, consultation with a wide range of stakeholders and timely and actionable community outreach. Such a plan will help those who are most vulnerable to protect themselves from the threat posed by heat waves. 

What qualifies as a heat wave

According to the Indian Meteorological Department (IMD), a heat wave is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal temperature. For coastal regions such as Chennai, a heat wave is declared when maximum temperature departure is 4.5 °C or more from normal, provided the actual maximum temperature is 37°C or more for two consecutive days.

While this definition acts as the trigger for various heat action plans across cities, experts stress on the need for more fine-tuning based on local microclimate. 

“In the case of coastal cities, when you think about the impact of heat on the human body, it is not only about temperature, but also about humidity. Both of these cause adverse reactions. When the temperature is 35 degrees but the humidity is 100% it is the same as having a high temperature of 45 degrees but a humidity of 50%,” says Dr Hem Dholakia, Environment and Health expert. 

Poster from Ahmedabad Heat Action plan.

Dr Hem calls for extensive studies to be conducted in Chennai over a period of time to ascertain those temperature and humidity thresholds where there is a significant adverse impact on human physiology. Based on the findings, triggers for various interventions in the heat action plan can be put in place. “Ahmedabad studied daily data on temperature, humidity and pollution for close to ten years to understand what the threshold for the city was and that served as the basis for the heat action plan. This is how it is done for cities the world over. For every city, this exercise needs to be carried out.”

Scenario in Chennai

In recent times, Chennai has seen an increase in phenomena such as urban heat islands. An urban heat island is identified as an urban area that faces significantly higher temperatures than the surrounding rural or semi-rural areas, caused primarily by human activity. The effect could be due to increased construction, vehicular and greenhouse emissions, and felling of trees to facilitate development work.

The temperature in these heat islands too have been increasing by 1-2 degrees celsius, according to a study by Anna University Centre for Climate Change and adaptation. Another study has shown a decline in thermal comfort levels especially in the summer months in Chennai owing to rising temperatures. Thermal comfort is defined as “that condition of mind which expresses satisfaction with the thermal environment”. Based on these findings, the study called for better cooling requirements and city planning to adapt to the future trends of the external environment.

Heat action plan

The National Disaster Management Authority conducted a workshop for all state representatives on how to evolve a comprehensive heat action plan in the backdrop of the National Platform for Disaster Risk Reduction 2017. Guidelines were provided to the states, on the basis of which heat action plans could be formulated at the state level, with nodal agencies to monitor and update the plan in subsequent years.


Read more: A garden on every roof: Help the Patchai Madi project turn Chennai into India’s urban farming capital


The Tamil Nadu State Disaster Management Authority is the nodal agency for the state’s heat action plan. On the basis of the recommendations by the NDMA, the state shared a heat action plan for the year 2019 and 2021. 

Some of the key elements of the Heat Action Plan are as follows:

Classification of High Risk Groups

  • Children, Pregnant women, Senior citizens
  • Labourers including those at construction sites/Outdoor workers/Farmers/MNREGS workers  Police personnel/security staff  
  • Industrial workers working at High Temperatures
  • Street hawkers/Salesmen  
  • Riksha pullers/auto drivers/Travellers/bus drivers  
  • Coolies/Slum residents/Beggars/Homeless  
  • Chronic sick/indoor cases 
  •  Patients on drug treatment  
  • Addicts (Alcohol, drugs etc)

Initial warning measures to be put in place

The heat wave action roadmap for 2019 broke the district level plan down into parts:

  • District Emergency Operation Center (DEOC) to be activated by the District Disaster Management Authority (DDMA). Toll free number of respective authorities to be published along with information on heatwave. For Chennai, the Commissioner of the Chennai Corporation heads the DDMA and the toll free number is 1913 
  • All key departments to be made aware of the heat wave alert for the city 
  • Advisories on heat wave to be disseminated widely though print and electronic media

Other preparedness measures

  • Ensuring availability of drinking water for all 
  • Unrestricted power supply especially for critical spots such as hospitals and primary health centers
  • Arranging for shelter and drinking water in public places such as bus depots/stops, markets, railway stations, pilgrimage, tourist, industrial areas 
  • Ensuring availability of necessary health supplies such as IV fluids, cooling packs, ORS water
  • Management of heat stroke patients
  • Enforcing better working conditions for workers, such as provision of sheds, safe drinking water, bathing facilities etc as per the Labour Act
  • Ensuring readiness of fire department to meet any emergencies
  • Making provisions for shelter for MNREGS workers and traffic police

Long term mitigation

  • Afforestation in Urban and Rural areas 
  • Encouraging terrace gardens and avenue plantations in residential areas 
  • Rain water harvesting in a mission mode 
  • Recycling of waste/kitchen water, which can be used for flushing and watering plants 
  • Cool roofs concept: Cool roofs function primarily by reflecting heat incident on a building back to the atmosphere. Develop a programme for cool roof (lime based white wash, white ceramic tiles covering), which can reduce temperature by 3-7 degrees for indoors
  • Development and Maintenance of Open Space Reservation (OSR) lands as parks by the urban local bodies

“While the plan that has been evolved is about immediately addressing the needs of the vulnerable groups, there must also be long term vision to reduce urban heat island effect. For this we must invest in urban greening, develop OSR land, focus on reducing emissions. These will help bring the temperature over a period of time,” says a former official with the TNSDMA.

On the ground

While the plan has been formulated on paper, there is little evidence of its execution, even as recently as the heat wave that gripped the city in April. An official from the Chennai Corporation said that they had not received any notifications from the TNSDMA on the triggering of the heat wave action plan at any point this year, despite the heat wave declaration in April. However, the official added that the  Corporation is mulling setting up a separate disaster management department to handle such issues in the future.

While authorities chalk out the way to implement such a plan, those from the population most vulnerable in the city find their own ways to manage the heat. Lawrence V, Convenor, Real Trust, that works with the homeless, says, “We see a slight increase in the number of homeless people who seek shelter during these months, especially during the day. During winter months, the shelter requests are for overnight stays as the chill is felt more at night. But during summer those, without a roof or home want some place to go to when the heat becomes unbearable.”

Charities that run shelters either accommodate more people during the day or direct individuals to the Corporation’s homeless shelter to secure respite from the heat.

For those such as Karikalan R, a daily wage labourer residing on Lang’s Garden Road, the fact that the city could conceive of a heat action plan seemed inconceivable. “I didn’t know the government could do anything about it. During the summer we have just resigned to having a tough time. My house has tin sheets, so it gets even hotter. We have not thought about going to a shelter. The only help we get is sometimes we get neer mor (buttermilk) from some NGOs, which set up stalls during May.”

Impact on health

A workable heat action plan also becomes paramount in view of the impact of rising heat on the human body. “Heat and humidity is a potent combination that can have huge implications for health, especially those who work outside such as construction workers, labourers and traffic police,” says Dr Muthu Chitra, ENT specialist and HOD at Kilpauk Medical College. 

Dr Chitra recommends those who work outdoors to be provided adequate shelter from the what, better access to water and reduction or modification of working hours to avoid peak heat. Keeping oneself hydrated is one of the key ways to tackle such heat waves.

The duration of exposure is also a concern, though how long that threshold is, depends on the physiology and health conditions of individuals. Despite this, Dr Chitra places a ceiling of a maximum of two hours on exposure for a healthy individual, before the likely onset of the effects of heat waves, such as dehydration and in worst cases, heat stroke and death.

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About Aruna Natarajan 152 Articles
Aruna is a staff reporter at Citizen Matters Chennai. Apart from writing, she enjoys watching football. She tweets at Aruna_n29.

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