During the sweltering summer, air conditioning offers the refreshing coolness and comfort of spring. However, improper use of air conditioning can also cause discomfort, leading to symptoms like fatigue, headaches, back pain, limb pain, joint pain, diarrhea, and menstrual irregularities—collectively known as "air conditioning sickness."Japanese scientists have discovered that air conditioner sickness stems from improper indoor temperature regulation. Experiments show the human body can self-regulate its temperature within a 5°C to 7°C range. Within this margin, the body quickly adapts by adjusting sweat gland activity, pore dilation, capillary flow, and muscle contraction. However, when temperature fluctuations exceed this range, the body's natural regulation becomes insufficient.For instance, entering and exiting a room with an indoor-outdoor temperature difference exceeding 10°C every 15 minutes can trigger symptoms like diarrhea. Elderly individuals, children, and women are particularly susceptible to air conditioning sickness due to factors like physical constitution and clothing.
What is the optimal indoor air conditioning temperature in summer?
⊙ Keep the temperature within 5°C of the outdoor temperature
According to a technician from a well-known air conditioning brand, for individuals sitting still or performing light activities, setting the air conditioner to 26°C with indoor humidity around 50% provides a comfortable environment.The optimal air conditioning temperature for the human body ranges from 24°C to 27°C. During summer nights, setting the temperature to 26-28°C is most suitable for energy efficiency. The indoor-outdoor temperature difference should not exceed 5°C, as excessive differences can easily trigger air conditioning sickness. When cooling, raising the set temperature by 2°C can save 20% on electricity.
⊙ What is the most suitable temperature for sleeping at night?
At a constant temperature, maintaining a room temperature of 28°C is most conducive to rest. During rest, the body's immunity decreases. If the room temperature is too low, you may wake up feeling fatigued, with headaches, backaches, limb pain, joint pain, and more severe symptoms like diarrhea, menstrual irregularities, or "air conditioner sickness."During sleep, metabolic rate decreases by 30-50%. Nighttime air conditioning should not be set below 24°C (75°F), or use the sleep mode setting. Younger individuals should avoid leaving the AC running all night for excessive coolness. Instead, set it to night mode—just enough to fall asleep comfortably. Otherwise, you risk catching a chill while asleep.
⊙What temperature should the AC be set to prevent air conditioner sickness?
Respiratory illnesses are less common in summer, yet outpatient cases have risen in recent years. This correlates with prolonged indoor air-conditioned environments—both excessively low temperatures and uncleaned units that harbor bacteria like Legionella, weakening immunity.Nasal congestion, runny nose, headaches, insomnia, and endocrine disorders are typical symptoms of so-called "air conditioner sickness." One primary cause is excessive indoor-outdoor temperature differences. While the human body possesses thermoregulatory capabilities, these have limits. Ambient temperatures affect the skin by influencing the nervous system, triggering thermoregulatory responses that constrict or dilate blood vessels to maintain stable body temperature.The human body maintains a constant temperature of around 37°C primarily through the skin's thermoregulatory function, which accounts for approximately 90% of total body heat dissipation.Suddenly moving from a scorching outdoor environment into a cool indoor space makes it difficult for the body to adjust quickly, leading to a series of discomfort reactions. This occurs because air processed by air conditioners lacks negative ions. Additionally, excessively low indoor temperatures cause the skin's blood vessels, sweat glands, and sebaceous glands to constrict, disrupting neural regulation. Symptoms include dizziness, fatigue, general malaise, lethargy, and weakened immune function.This makes individuals particularly susceptible to colds, gastroenteritis, frozen shoulder, facial nerve paralysis, and poses significant risks for those with cardiovascular or cerebrovascular conditions. Physicians recommend keeping indoor-outdoor temperature differences moderate, ideally around 8°C to 10°C (14°F to 15°F). While summer temperatures may occasionally exceed 38°C (100°F), most daytime hours remain below 35°C (95°F), making an indoor temperature of approximately 26°C (79°F) optimal.
Four Major Symptoms of Summer Air Conditioning Illness
Symptom 1: Headache
Beyond causing colds, air conditioning can severely impact brain health, most commonly manifesting as headaches. After working outdoors in summer heat, people often rush into air-conditioned rooms. The sudden shift from hot to cold temperatures causes blood vessels to rapidly constrict from their dilated state, leading to headaches—especially when the indoor-outdoor temperature difference exceeds 5°C.
Symptom 2: Colds
During summer heat, many people set air conditioners to extremely low temperatures for cooling. When moving from hot outdoor environments into air-conditioned rooms, the respiratory tract becomes easily irritated. Additionally, when sweat-covered pores and capillaries suddenly encounter cold air, they constrict rapidly, making individuals prone to colds and heatstroke.Prolonged exposure to air-conditioned environments keeps pores constricted. Suddenly moving to a stuffy room or outdoors prevents pores from reopening promptly. If the body's regulatory center malfunctions, this can trigger heatstroke or wind-heat cold symptoms like sore throat and nasal congestion.Take atopic dermatitis, a common chronic skin condition, as an example. In hot weather, sweating can cause significant irritation and unbearable itching. Conversely, prolonged exposure to air-conditioned environments can lead to dry skin and itching due to excessive dryness.Individuals who wear contact lenses long-term, suffer from chronic conjunctivitis, or have dry eye syndrome are prone to dry eyes, with a higher risk of recurrence. The situation worsens if the air conditioning vents aren't properly cleaned. In enclosed office buildings, the air conditioning system continuously recirculates air, causing high concentrations of carbon dioxide to accumulate. Eyes exposed to oxygen deprivation while staring at computer screens for extended periods become prone to redness, itching, and pain.