How hot weather impacts health and wellbeing

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July 13, 2017
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As the heat wave continues in Southern California, USC public health experts explain how high temperatures impact health.

Rising heat threatens wellbeing

“Body dehydration that occurs with heat stress can produce significant deterioration in cognitive functioning. Heat waves have been associated with increases in hospital admissions for mental health disorders, including dementia; mood [affective] disorders; neurotic, stress-related and somatoform disorders; disorders of psychological development; and senility.

“Some patients with mental illness are especially susceptible to heat. Dementia is a risk factor for hospitalization and death during heat waves. Medications may interfere with temperature regulation or even directly cause hyperthermia.

“Heat suppresses the thyroid hormone, which causes energy drain, while also stimulating growth hormone and a closely related protein hormone called prolactin, which cause lethargy. This also inhibits the effects of dopamine, a chemical in the brain that is associated with positive feelings.

“Suicide rates vary with weather, rising with high temperatures, suggesting potential climate change also impacts depression and other mental illnesses.”

Lawrence Palinkas is a professor of social work, anthropology and preventive medicine at the USC Suzanne Dworak-Peck School of Social Work.

Pollution threat rises with the heat

“The stagnant weather conditions that often accompany high-heat events can also set into motion a meteorological condition known as a temperature inversion. Think of it as a pot cover on something heating on the stove.

“Even though hot air rises, regional vehicle and industry emissions are prevented from dispersing vertically up into the atmosphere by a thermal ‘pot cover’ over the area, so pollution builds and builds under the ‘pot cover’ until a breeze develops to blow it horizontally away or the ‘pot cover’ is eventually removed [by atmospheric cooling].

“Under these conditions, think about ways to reduce your thermal stress: Drink plenty of water, try to avoid heavy exercise during hotter times of the day, wear lighter-colored clothing to better reflect solar radiation, wear a cap, sunglasses and use sunscreen.”

Ed Avol is a professor in the Environmental Health Division of the Department of Population and Public Health Sciences at the Keck School of Medicine of USC and has served on several expert panels to review national air quality standards, ensuring that health is a chief consideration in urban planning issues such as freeway expansions and the increased cargo goods movement.

Heat cranks up climate injustice

“Some people are more vulnerable than others to heat waves and climate extremes. Low-income communities and communities of color, along with people who are old, young or already sick are at greatest risk. Heat waves are further expected to exacerbate the adverse impacts of air pollution, poverty and aging infrastructure in Southern California.”

Jill Johnston is an assistant professor of preventive medicine at the Keck School of Medicine.