In Karur, 41 people have lost their lives at a political rally organized by the Tamilaga Vettri Kazhagam. There are many lessons for us from this extremely unfortunate but avoidable incident that we must sincerely consider. We express our heartfelt condolences to the families of the victims and hope that the injured and hospitalized have a speedy recovery.
In recent years, India has seen a sharp rise in crowd-related accidents resulting in countless deaths and injuries. Be it politics, entertainment, cinema or sports, pathological overcrowding has become commonplace. The Puri Jagannath Yatra in June, the stampede at Tirupati temple in January, the Lairai Devi temple tragedy in Goa in May, the Manasa Devi temple incident in Uttarakhand in July, the Kumbh Mela stampede, the recent stampede in the Delhi Metro, the chaos at the RCB victory celebration after the IPL, and the Pushpa movie release tragedy are among the many unfortunate examples.
As of late, we observed a more worrying trend in crowd-related accidents. Extreme heat stress is becoming a serious issue in combination with crowded events. Factors such as global warming, land use change and urbanisation are contributing to the frequent occurrence of uncompensable stress conditions across Tamilnadu. At the Chennai Air show (6/10/2024), more than 15 lakh people had gathered, among which thousands of people fainted and at least five people died due to extreme heat stress. At an earlier mega-political rally of the TVK party held at Vikravandi, Tamilnadu on 27/10/2024, lakhs of people had gathered, and many fainted and suffered fatigue due to the extreme heat stress. The pattern repeated at the Madurai rally of TVK on 21/08/2025, where news reports confirmed that many fainted at that rally and that two people died, with the reason being extreme heat stress.
At the Karur stampede, news reports suggest that heat-related faintings started occurring even before Mr.Vijay entered the venue. One news suggested that a woman and her child had died before the larger stampede event happened, with the probable cause being heat. Before Mr.Vijay visited Karur, he was addressing a crowd at the nearby district of Namakkal. Multiple heat-related faintings were reported at Namakkal as well. We hence believe that extreme heat stress played a significant role in the events of the 27th of September – both at the Karur stampede, and the earlier Namakkal road show. To investigate the impact of heat stress during the Karur and Namakkal rallies, we utilised the Punal framework.
Methodology – Punal Framework
The human body must maintain an average temperature between 36.4–37.2°C, a balanced condition that is termed as ‘homeostasis’. Any significant increase or decrease in body temperature can lead to fainting, heat stroke or even death. Through millions of years of evolution, mankind gained the ability to adapt its body to the changing external temperature. Organs such as the skin, brain, and nervous system play a crucial role in maintaining the homeostasis of our body. When external temperature increases, blood flow rises to release excess heat through the skin. If this doesn’t cool enough, sweat glands produce sweat to cool the body. However, this mechanism functions only within certain limits.
Increasing temperatures and humidity as a result of global warming have maimed this cooling process. The human body cannot withstand extreme heat stress beyond a certain exposure time. At higher humidity levels, the cooling effect of sweat is also severely hampered, which could lead to increased core body temperatures. If left unchecked, the internal body temperature can rise uncontrollably, causing severe illnesses like heat stroke and even death. Hence, it is necessary to quantify the amount of heat stress that is prevalent at the venue.
To identify if dangerous heat stress conditions were prevalent, we utilised the Punal (Tamil : ‘Flux’) framework. This framework utilises on-ground reports to characterise the thermal environment and activity of the people on the location during the event timeline. Then, we used that information to calculate the Universal Thermal Climate Index (UTCI) which is an indicator of extreme heat stress for a scenario with crowds and one without. After this, we compared the timing of the faintings at the venue with the duration of extreme heat stress. To verify if extreme heat stress caused the faintings, we used thermophysiological models such as JOS3 to calculate the core body temperature. The framework diagram can be accessed in the annex, at the end of this document.
UTCI is a bioclimatic index which has been adopted by many European countries to accurately quantify extreme heat stress. It is calculated using a combination of temperature, humidity, mean radiant temperature, wind speed, and some other environmental variables. It accurately identifies the extreme heat conditions which can potentially lead to heat stroke and fatalities. UTCI > 38oC is considered extreme heat stress, as such exposure can cause exhaustion or fainting within 1-2 hours. Sustained exposure can result in breathlessness and heat syncope. UTCI > 46oC is potentially fatal.
After finding the UTCI, thermophysiological models such as JOS3 help validate the UTCI values by quantifying the change to internal body parameters such as core body temperature, heart rate, sweat rate etc in the presence of heat. In this specific study, we input the meteorological parameters to simulate the changes to the core body, pelvic and head temperatures. This can be handy in confirming if the above mentioned UTCI values did indeed cause faintings or deaths.
In real life, if a person’s core body temperature reaches 38.5 – 39.5o C , fainting, syncope and dizziness are highly likely. If the core body temperature reaches 40 – 41.1oC, heat stroke becomes imminent. Other extreme effects of hyperthermia such as heart attack, organ failure etc become highly likely as well. If the person experiencing extreme heat stress is unable to drink enough water or urinate for long durations, ill-effects such as extreme dehydration and kidney stress become highly likely. In such cases, blood toxicity can spike, potentially breaking the BBB (Blood-Brain barrier) and releasing toxins into the brain. In case of this unfortunate event, the thresholds are much lower as even 39oC core body temperature can be fatal. Multi-organ failure becomes imminent beyond this point. The JOS3 simulations can hence be used to simulate a person’s potential core body temperature change in response to heat stress.
Overview
On September 27th, 2025, the Tamilaga Vetri Kazhagam (TVK) organized its campaign rallies in the Namakkal and Karur districts. The party president Vijay, was scheduled to address the public on the road from his campaign vehicle. A large-scale publicity campaign had previously advertised that Vijay would appear in Namakkal by 8:45 a.m. and later proceed to Karur for another campaign rally at noon. However, Vijay departed from Chennai only at 8:45 a.m, reaching Tiruchirappalli International Airport around 9:30 a.m. From there, he travelled by car to Namakkal and later switched to his campaign vehicle.
The location allocated for the Namakkal event was a major road junction. It had four major entry roads converging and no proper exit routes, creating multiple bottlenecks for such a large gathering. A combination of crowd push-and-pull, lack of sufficient shade, food, and drinking water facilities created dangerous conditions. Vijay arrived at the Namakkal venue at around 2:30 p.m. By that time, a huge crowd of more than 20,000 people had gathered, and many of them had been waiting for hours. Hence, faintings had already started before his speech. Even during the course of his short speech, several cases of fainting were reported. Still, he managed to complete his party speech and the convoy headed towards Karur.
Meanwhile, at Karur, thousands of people, including children and women, had already gathered at the venue. The 27th of September was the salary day for workers and a school holiday, because of which large crowds showed up from Karur and the surrounding districts. Many of them were waiting from 9 a.m, eagerly waiting for TVK leader arrival which was scheduled for 12 pm.
The delay in the Namakkal rally meant that TVK leader entered Karur district only around 4:45 p.m. From there, it took nearly two more hours for his convoy to reach the final venue at Velusamypuram. In addition, nearly 5,000 supporters from neighbouring districts reportedly followed his vehicle throughout the route, further increasing congestion on the narrow roads.
The choice of the venue at Karur was a grave mistake. Although the venue has hosted several political events in the past, the Velusamypuram Road—a narrow stretch within a dense urban area—was wholly unsuitable for a massive, high-energy road show like Vijay’s. Both the party organisers and the local administration failed to anticipate the potential risks. By the time Vijay’s vehicle reached the spot, the crowd had swelled to more than 30,000 people, tightly packed with little ventilation or movement space. Reports of fainting and heatstroke began to emerge even before the leader’s arrival, and tragically, a few victims died en route to the hospital. Moments later, as the crowd surged forward in excitement, a stampede broke out, turning the gathering into one of the worst civilian disasters in Tamil Nadu’s history.
Why crowds + heat is so dangerous
As per government sources, the attendance at the Karur rally was around 27,000. But based on media reports and our geospatial analysis, we believe that the rally area must have had at least 50,000 people in attendance. At the Namakkal speech by Mr.Vijay, the attendance must have exceeded 20,000 people. Both events were held in tight urban spaces. The presence of such high numbers of people in such small areas resulted in crowd densities exceeding 4 people/m2. This is a critical crowd condition because the people collectively release massive amounts of metabolic heat and also act as obstructions to the windflow.
At this point, everyone in the crowd would be releasing metabolic heat depending on their activity. If the crowds are static and calm, the metabolic heat released would be lesser, in the order of 50 W/person. This means that the heat released would be around 200 W/m2. This is quite manageable. But if the crowds are unruly, and the crowds start pushing and pulling (which was the case in Karur), the heat released can exceed 250 W/person, or 1000 W/m2. Without proper wind flow, this heat would get trapped and raise local temperatures, while also impairing cooling of the human body. For 50,000 people in the event area at Karur, that is equivalent to 12 MW of heat within the 19,000 m2 area. For perspective, that is very close to the heat from the sun’s midday irradiation on that day (800 W/m2 ) in the same area, but diffused radially. This is why the crowd area heats up over time and eventually becomes unbearable.
Normally, a significant part of the metabolic heat would be lost to the surroundings through radiative, conductive, and convective cooling. Heat loss through radiation occurs to colder mediums around the body, while flowing winds or water enact convective cooling, and colder surfaces in touch provide conductive cooling. Sweating is the primary mechanism to relieve metabolic heat buildup.
But when many people are present together, these cooling mechanisms are severely impaired. When people pile up against each other, the sky view factor is reduced, due to which radiative cooling is massively reduced. Conductive cooling is minimal due to the contact with other human body surfaces in the crowd. Hence, the only two other ways of cooling are convective cooling (winds) and sweating.
The event day recorded considerable winds at both Karur and Namakkal (> 5 m/s), which means that the heat stress should have been significantly reduced. However, in the presence of large crowds, the wind-flow will be largely obstructed. Also, urban structures act as barriers to the wind flow, a characteristic observed in both event locations at Karur and Namakkal. This means that convective cooling from the wind was quite low in those locations. For most people, the effective wind would have been less than 1 m/s at the ground level.
The heat build-up and reduced wind must have resulted in profuse sweating, as it is the only remaining cooling mechanism. The large amount of evaporated sweat from the crowds could have increased humidity levels by 5-10% or higher in the absence of winds. The increased humidity would further reduce the cooling effect of sweat, creating a negative feedback loop.
When all cooling mechanisms fail, extreme heat stress reaches dangerous levels. Heat builds up inside the bodies at a dangerous rate. As mentioned before, when core body temperatures reach 38-39oC, fainting, dizziness etc. are observed. On further escalation, inner body temperatures can reach 40-41oC at which point extreme effects such as heat stroke, heart attack, organ failure becomes imminent. Also, if dehydration impairs kidney function, toxins can enter the brain at 39oC and break the blood-brain barrier, which can also result in serious illnesses. Extreme heat stress also impairs decision making and has been known to fuel mob behaviour, as observed at both the rallies.
Heat stress modelling – Results
- Namakkal rally
At Namakkal, the solar irradiation at noon reached 816 W/m2 . The mean radiant temperature crossed 55oC as a result. After 11 am, the crowd effect was reached, which means that the wind flow was heavily obstructed. This resulted in extreme heat stress conditions (UTCI > 38oC) between 10 am – 4 pm. Peak UTCI reached 42.6oC, which could have potentially caused faintings within 1-2 hours of sustained exposure depending on the person’s metabolic activity. Since people were waiting since morning in the hot sun, such a thermal dose would have had ill-effects persisting for the entire day.
Based on this result, we believe that the first faintings at Namakkal should have happened around 1:30 pm, 2.5 hours after 11 pm. Faintings must have continued to happen during Mr.Vijay’s speech at 2:35 pm as the extreme heat condition existed till 4:30 pm. This result matched press reports of faintings reported at the Namakkal venue coinciding with Mr.Vijay’s speech. To validate this, we simulated the case of an average male attendee on JOS3 starting from 11 am, around when crowd effects started to manifest.
Based on the environmental conditions at the Namakkal venue, the core body temperatures must have reached 38.5 around 12:30 pm. Mass faintings must have happened when the core body temperatures exceeded 39oC, which happened 2.5 hours after the crowd condition was satisfied, which is around 1:30 pm . This corresponds to the time horizon of reported faintings between 1:30 – 3:00 pm. This means that the fainting conditions existed before and during Vijay’s speech, which happened around 2:35 pm. The situation could have been worse if the event extended a bit more, which could’ve resulted in core body temperatures reaching 40oC or higher, potentially causing more heat stroke occurrences.
- Karur stampede
Similarly, Mr.Vijay was seven hours late for the Karur rally. This exposed the people to 5 hours of very high heat stress (UTCI > 38oC) from 12:30 pm – 5:30 pm. The solar radiation peaked at 794 W/m2 at midday, which resulted in the MRT values reaching 59oC. The crowds exceeded 20,000 as early as 3:30 pm, resulting in average crowd densities reaching 4 people/m2 . This is when the crowd effect must have significantly reduced the winds, trapping humidity and spiking the heat stress (UTCI > 38oC).
Without the crowds, the UTCI is around 38o C during the event. It drops well below the 38 mark after 4:30 pm. On applying the critical crowd condition, the UTCI crossed 40oC as early as 12:30 pm. This condition persisted till 5:30 pm, peaking to 42.6oC around 3:30 pm. This means that the crowded areas of the venue at Karur potentially experienced extreme heat stress from as early as 12:30 pm. Considering 3:30 pm as the starting point of crowd conditions based on media reports, the resultant heat stress must have caused fainting from 5:30 pm onwards. The faintings must have continued till 6:30 pm, right before Mr.Vijay entered the venue.
Reports suggest that a man reported that his wife and daughter died before Vijay arrived at the scene, around 6:00 pm. Though we cannot ascertain the exact conditions on ground, we can make some informed assumptions. For JOS3, the following parameters were applied for the mother and her daughter assuming that they struggled around in the crowds after 3:30 pm. They were also most likely waiting in the sun from much earlier, hence the body must already be in a state of mild heat stress. Considering the height of the mother, more wind possibly cooled her body compared to the child.
Here are the JOS3 simulations for this tragic case.
The simulations confirm that the conditions among the crowd potentially caused dangerous core body temperatures (>40oC) within 2:00 hours of the crowd condition being satisfied. By 6:00 pm, it is highly likely that the victims were already in a state of severe hyperthermia and potentially suffered a heat stroke. However, we need the exact post mortem analysis to verify this. Unfortunately, at this point in time the post mortem reports are not available for public view.
Other reports also suggest that breathlessness, fatigue, and fainting were prevalent among the attendees even before Mr. Vijay appeared at the venue. These are definite symptoms of extreme heat stress when the core body temperature exceeds 39.5oC , potentially on the verge of getting a heat stroke or other severe heat illnesses. Here is a JOS3 simulation for a young man who probably fainted at the Karur venue.
The JOS3 results suggest that the fainting must have ensued 2.5 hours after 3:30 pm, which is around 6:00 pm. This matches ground reports on the timing of the faintings and the reports of ambulances arriving even before Mr.Vijay entered the venue.
Reflections / Limits of the study
The models used in our study are based on a representative thermal environment which was designed based on meteorological data and crowd effect assumptions. Also, the microclimatic effects would vary based on factors such as the geometry of the surrounding structures, movement of the crowd, wind flow at different points of the event space etc. Hence the heat stress might not be sustained and uniform as modelled, but more erratic and ununiform. At the same time, since the model matched on-site reports on the timing and location of the faintings, it means that the fainting and heat stroke condition we modelled is consistent.
It is also important to note that acclimitized individuals will have slightly higher thermal thresholds, like athletes. This means that they can withstand extreme heat stress slightly more, with an increased threshold of 1-2oC in inner core body temperatures and higher sweat rates. However, there are limits to this thermostatic resistance. With longer exposure, they will also succumb to the effects of extreme heat stress.
Fossil fuel driven global warming is increasing the average temperatures day by day. The effect of extreme heat stress is only going to get worse in the future, and it is important to take such tragedies as a warning. For a culture that is rooted in social gatherings, we are seemingly at a point of no return. Our social thresholds for crowd-related gatherings has been broken.
Recommendations to the Government
Our study found that the Universal Thermal Climate Index (UTCI) exceeded 38°C at the Karur and Namakkal political rallies due to the combined effects of crowds, urbanisation, and global warming. Dangerously high extreme heat stress was prevalent in both the event areas. Such heat can cause fainting, heat stroke and even death within just a few hours in the absence of shade and cooling. Drinking water is essential but it will not be an antidote to the extreme heat stress on the location.
Considering this, we believe that every political party must place people’s safety and well-being above everything else. Whenever large gatherings are planned; the health and comfort of the public must be treated as the top priority.
Considering the findings from the Karur stampede during the TVK rally, we urge the Government to act immediately on the following points:
- Create clear rules and systems to plan large gatherings based on current temperature and weather conditions. Expert advice and heat safety research must guide permissions for such events.
- Ban roadshows that make people stand for several hours on narrow roads without shade, water, or shelter, only to wait long for leaders to arrive.
- Between February and October, when Tamil Nadu faces extreme heat, open-air events should not be allowed during the daytime.
- Allow only evening (after 6 PM) or indoor programs, where people are protected from direct heat.
- If a daytime event is necessary, organizers must:
- Provide enough shaded areas or tents for everyone, and
- Ensure each person has access to at least 2 litres of safe drinking water every hour.
- The Union Government should officially declare extreme heat as a disaster under the Disaster Management Act, so that emergency measures and relief can be provided quickly.
- Research institutions, including the India Meteorological Department (IMD), must study extreme heat regularly and publish their findings for public awareness.
- The IMD should issue early warnings whenever high heat or dangerous weather conditions are expected, just like cyclone or flood alerts.
- The IMD should start using the Universal Thermal Climate Index (UTCI) — a modern system that combines temperature, humidity, wind, and sunlight — to better measure and communicate heat risk to the public.
- Create first aid mechanisms involving instant cold relief and cooling centers as part of events involving large crowds
We earlier performed a study on the Madurai incident using the PUNAL framework, which you can access here :
Contact
Anu Mani
Priya Suresh
Nigazh
9445236388
Annex
- UTCI – Explanation
