A recent study addressing temperature-related fatalities in Mexico has challenged the longstanding belief regarding which age groups are most affected by heat. Contrary to previous assumptions that primarily older adults and very young children are at greater risk during heat waves, the study indicates that individuals under 35 are disproportionately affected by extreme temperatures and high humidity levels.
The comprehensive analysis, which reviewed mortality data from 1998 to 2019, revealed a staggering rate of nearly 32 deaths among those aged 35 and younger for each heat-related death occurring in individuals over the age of 50 when temperatures and humidity levels reached uncomfortable thresholds, such as temperatures in the mid to upper 80s Fahrenheit (approximately 30 degrees Celsius) combined with 50% relative humidity.
Published in the journal Science Advances, this research uncovered a particularly alarming increase in heat-related fatalities among young adults aged 18 to 35, with this group experiencing nine times the number of temperature-related deaths compared to those older than 50. The researchers and experts are questioning the reasons behind this unexpected trend, considering that demographics alone do not provide clarity. Two possible explanations include the risks faced by outdoor laborers who cannot seek relief from the heat and the reality that younger individuals may not adequately recognize their physical limitations.
As global temperatures continue to rise due to human-induced climate change, the frequency of these concerning trends is expected to increase, according to computer modeling predicted by the research team. Jeffrey Shrader, a co-author of the study and a climate economist at Columbia University, noted that younger individuals are becoming significantly more susceptible to heat-related mortality as climate conditions worsen, frequently shifting the mortality burden away from older populations who are generally more vulnerable to colder temperatures.
The study’s authors found that data on cold-related fatalities reveals over 300 deaths among those 50 and older for every young adult who perished due to cold. Marina Romanello, executive director of the Lancet Countdown, which monitors the health effects of climate change, remarked that the study highlights how all age groups are increasingly at risk from rising temperatures. She emphasized that those previously considered less vulnerable to heat-related health issues may in fact be at greater risk than anticipated.
The researchers chose Mexico for their investigation due to its detailed mortality data and diverse climate, making it an ideal setting for exhaustive study. They also want to determine whether similar trends regarding increased heat-related deaths among young adults can be observed in other regions that experience higher temperatures and humidity levels.
Initially focused on analyzing mortality rates and what scientists refer to as wet-bulb globe temperatures, the research team broadened their inquiry when they observed significant age-related differences. Wet-bulb temperature serves as an indicator of the human body’s cooling process and is derived from a complex measurement system that incorporates humidity and solar radiation. A wet-bulb globe temperature at or above 95 degrees Fahrenheit (35 degrees Celsius) is considered the threshold for human survivability, a level rarely reached in most areas.
Through complex statistical methods, the researchers assessed temperature-related mortality and evaluated various factors influencing death rates, isolating temperature fluctuations as a significant cause. Co-authors Shrader and Andrew Wilson, a climate economics researcher from Columbia, noted that younger adults thrive at approximately nine degrees Fahrenheit (five degrees Celsius) cooler temperatures than older individuals.
Some experts not involved with the study initially found the results regarding higher youth mortality perplexing. Patrick Kinney, a professor of urban health and sustainability at Boston University, speculated that this study likely included a larger demographic of outdoor workers exposed to extreme heat conditions compared to previous studies. Climate scientist Tereza Cavazos from the Ensenada Center for Scientific Research and Higher Education reflected on how cultural practices, such as taking midday naps during intense heat, have declined.
Cavazos remarked on the current vulnerability of the population, illustrating the danger presented by three recent heat waves in central Mexico that yielded extended periods of unrelenting heat. These enduring high temperatures, especially lacking relief during cooler nights, can severely impact individuals’ recovery from heat-related stress. Young people often believe themselves to be immune to extremes of weather, leading them to participate in high-risk activities like sports in sweltering conditions, she added.
Dr. Renee Salas, an emergency medicine physician at Massachusetts General Hospital and climate change expert, explained that high humidity places additional stress on the body’s natural cooling mechanism through sweating, raising the likelihood that young and healthy individuals could experience dangerous heat injuries, such as heat stroke, when working outdoors in extreme heat conditions.
