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 Harvard researchers found that during a summer heat wave, students
living in dorms without air conditioning consistently scored lower
on daily cognitive tests over the course of nearly a week than
students in buildings with AC.
"For the first time, we've been able to find a detrimental effect of
heat waves in young healthy adults," said lead author Jose Guillermo
Cedeno Laurent, a research fellow and associate director of the
Healthy Buildings Program at the Harvard T. H. Chan School of Public
Health in Boston.
"Among that group (who had no AC) there were longer reaction times
and lower accuracy compared to an identical group of students who
lived with air conditioning," he told Reuters Health in an email.
The researchers followed 44 undergraduate and graduate students in
their late teens and early 20s for 12 consecutive days during July
of 2016. Twenty-four of the students resided in buildings
constructed in the 1990s that were equipped with central air
conditioning, while 20 lived in Neo-Georgian-style low-rise brick
buildings built between 1930 and 1950 with no cooling system.
The researchers designed their experiment so that the 12 days
included a five-day heat wave, preceded by five days with more
moderate temperatures, and followed by two days of cooler weather.
Temperatures inside the building without air conditioning averaged
26.3 degrees Celsius (79.3 degrees Fahrenheit) and ranged as high as
30.4 degrees C (86.7 F).
Average temperatures in the air-conditioned buildings were 21.4
degrees C (70.5 F), ranging up to 25 degrees C (77 F).
Each morning the students took two tests of cognition on their
smartphones. One test, which required students to correctly identify
the color of displayed words, measured their reaction speed and
ability to concentrate and block out distractions. The other test,
which presented basic arithmetic problems, measured mental quickness
and working memory.
During the heat wave, students in buildings with no cooling had 13.4
percent slower reaction times on the color-word tests and 13.3
percent lower scores on the math tests, compared to those living in
dorms with air conditioning.
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Much previous research on the effects of extremely hot weather has
been in vulnerable populations that are at risk of dying: either the
very young or the very old, the study authors note in PLOS Medicine.
"This study looks at the effects of heat in a population we all
think of as generally being resilient," said study coauthor Joe
Allen, co-director of Center for Climate, Health and the Global
Environment at the Harvard T. H. Chan School of Public Health.
And while much media coverage has been on people dying prematurely,
"the fact is, millions are impacted by heat waves," Allen said. "And
with climate change, and the increased duration of heat waves, we're
going to see an increased impact on performance and learning."
The new study "is adding to a very quickly growing literature on the
effects of heat exposure on student outcomes," said Jisung Park, an
assistant professor of environmental health sciences at the Fielding
School of Public Health at the University of California, Los
Angeles. "It's very consistent with other studies showing that hot
temperatures, whether at home or in the classroom, can have a
detrimental effect on learning."
No one knows exactly why we don't seem to be as smart when we're
hot. But it may be that the body is pulling blood away from certain
parts of the brain as it tries to cool itself down, said Park, who
wasn't involved in the current study.
"Of course, the elephant in the room is that heat waves are going to
be much more frequent," Park said. "While a 2 degree increase in
average temperature may not sound like much, an additional 30 days
of temperatures above 95 degrees each year may sound more urgent."
SOURCE: https://bit.ly/2zBXOJY PLOS Medicine, online July 10, 2018.
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