Meenu Tewari was visiting a weaving company in Surat, western India, on a hot summer afternoon about a decade ago. Tewari, an urban planner, makes such visits frequently to gain a better understanding of how industrial organizations function. However, her tour of the manufacturing floor that day left her perplexed.
According to Tewari of the University of North Carolina at Chapel Hill, “there were no workers there… only machines.”
The missing employees weren’t far away, sitting under a nearby awning in the shade. Workers have been making blunders or fainting near the risky machinery due to the extreme heat, Tewari’s advisor told her. As a result, the corporation required employees to come in earlier and depart later to allow them to relax during the noon heat.
Wet bulb temperatures — a combined measure of heat and humidity — of roughly 35° Celsius, or about 95° Fahrenheit (SN: 5/8/20) are too hot for people’s bodies to bear. Evidence is mounting that when people’s bodies are stressed by heat, their performance on numerous tasks, as well as their overall coping strategies, diminish. Extreme heat has been associated to increased hostility, decreased cognitive function, and, as Tewari and colleagues demonstrated, lost productivity.
The consequences of high heat on human behavior could become a major problem as global temperatures rise and record-breaking heat waves bake sections of the globe (SN: 6/29/21).
Mumbai tailors working at their desks
In India, factory workers, such as these tailors in Mumbai, are frequently required to work in buildings without air conditioning. According to study, as the weather gets hot, production at these factories drops.
GETTY IMAGES/DANIEL BEREHULAK
Lower-income people and countries, which have fewer resources to keep cool as the world warms, are expected to suffer the most, according to academics. According to UCLA economist R. Jisung Park, “the physiological impacts of heat are universal, but the way they emerge… is highly unequal.”
Heat and acrimony
For over a century, scientists have documented humans’ struggles to cope with high heat. However, much of that work has been done in laboratories to ensure a high level of control.
Craig Anderson and colleagues, for example, gave undergraduates four video clips of couples engaged in dialogue a few decades ago. One tape was neutral in tone, but the other three depicted the duo’s growing enmity. The undergraduate students who were watching the clips were each seated in a room with a thermostat set to one of five temperatures ranging from a cool 14° C to a scorching 36° C. The students were then asked to rate the couples’ level of antagonism. Students in uncomfortably warm rooms rated all of the pairings, including the neutral one, as more unfriendly than students in rooms with comfortable temperatures, according to Anderson, who is now at Iowa State University in Ames. (Students in extremely cold rooms rated the couples as more aggressive as well.)
According to Anderson, whose findings were published in the Advances in Experimental Social Psychology in 2000, heat makes people irritated. As a result, “people basically interpret things as being more terrible when it’s hot than when it’s comfortable.”
When people don’t have an escape hatch, research suggests that such views can lead to actual violence. However, outside of the lab, proving the “heat-aggression hypothesis” has been difficult since separating the effect of heat from other environmental or biological variables connected to aggression is difficult in the messy real world. However, studies in the last few years have begun to support the theory.
Researchers have long known that when people are hot, they become more violent. A recent research of crime statistics in Los Angeles from 2010 to 2017 found that when temperatures climb above a pleasant 65° to 70° Fahrenheit, violent crime surges.
Changes in violent crime in Los Angeles as a function of temperature relative to 65°–70° Fahrenheit figure plotting violent crime and temperature, demonstrating that violent crime increases as temperatures rise over 65°–70° Fahrenheit.
For example, by focusing on convicts in Mississippi prisons and jails without air conditioning, a July working paper from the National Bureau of Economic Research came close to re-creating the level of control observed in a lab. From January 1, 2004, to December 31, 2010, economists Anita Mukherjee of the University of Wisconsin–Madison and Nicholas Sanders of Cornell University examined rates of violence in 36 correctional facilities. Each facility saw roughly 65 violent events every year on average. However, the team discovered that on days with temperatures exceeding 27° C — which occur roughly 60 days per year — the likelihood of inmate violence increased by 18%.