Southern California is experiencing a bout of unusually high humidity this week, prompting public health officials to sound alarms about potential health impacts. Residents accustomed to dry heat are now facing conditions that climate scientists describe as some of the highest humidity levels ever recorded in the region.
According to climate scientist Daniel Swain, the current atmospheric moisture is "extremely humid by anyone’s definition," noting that the absolute humidity is very high and at the ceiling of what has been seen in this part of the world. This isn't just a matter of feeling sticky; experts indicate that high humidity significantly hinders the body's natural cooling process.
When the air is moist, sweat struggles to evaporate from the skin, which is how our bodies release heat. With less evaporation, the body continues to warm, making it harder to maintain a stable internal temperature. Dr. David Eisenman, a professor with the David Geffen School of Medicine and Fielding UCLA School of Public Health, explained that our bodies work best around 98.6 degrees Fahrenheit and are constantly trying to maintain that number. This continuous effort to regulate temperature in hot, humid conditions is what he calls "heat stress."
Whether the heat is generated internally through exercise or externally by the environment, increased humidity forces the body to work much harder to keep cool. This added strain can lead to serious health complications.
Heat-related illness is not a new challenge in California. A 2021 investigation found nearly 4,000 heat deaths across the state over a decade, highlighting ongoing difficulties public agencies face in providing adequate help to those affected. Locally, the Los Angeles County public health department has observed a rise in emergency visits for heat-related illnesses during recent summer heat waves, indicating that the public is still adjusting to the dangers.
To combat the effects of this oppressive humidity, Dr. Eisenman suggests techniques like keeping as much bare skin continuously damp as possible. This can be achieved by misting water directly onto the face, neck, and forearms with a spray bottle, repeating every five to ten minutes to keep the skin visibly wet. Soaking clothing in cold water or applying iced, damp towels to the body can also help. The Los Angeles Department of Public Health has also issued guidance on recognizing signs of heat-related illness, which include nausea, dizziness, and muscle cramps.
