The old wives’ tale of sickness from exposure to air conditioning has largely been debunked (they can even help with allergies!), but if you’ve ever gotten a nosebleed or a headache after entering or exiting a building with air conditioning, you may have been affected by thermoregulation problems that are associated with going in and out of air conditioning.
Thermoregulation is a normal physiological process designed to protect the body, but there are factors and circumstances that can cause your own thermoregulatory response to cause adverse health effects when moving to and from environments with diverse temperatures.
Going in and out of air conditioning may cause sickness by lowering the immune response. There are also immediate effects like dizziness and nose bleeds. How and when you are affected depends on personal health, temperature range, physiological response rate, behavioral responses, and frequency of change.
Physiological thermoregulation is a biological process by which a mammal’s body strictly controls an internal temperature independent of the temperatures of its surroundings. This is a process of homeostasis and is integral for survival.
How the Body Loses Heat
Sweat, while not the most pleasant thing in the world, is an essential process to maintain homeostasis in the body. When your core temperature is above a certain threshold, the hypothalamus triggers your sweat glands to secrete sweat. The sweat evaporates off of your skin, removing heat from your body, a process known as evaporative cooling.
Another process that helps remove heat is the vasodilation (widening) of peripheral blood vessels. This moves blood from your core to your skin and extremities to cool down your core as heat is lost from your blood. Vasodilation is what causes you to get red when your body temperature is high.
Increased respiration is mostly attributed to the more rapid delivery of oxygen to your cells when needed, but it also cools down the body. Hot air is expelled from your lungs, which lowers your body temperature and helps achieve homeostasis.
The Body Can Also Increase Heat Production
The body also maintains homeostasis by increasing heat production through processes like shivering, goosebumps, and increased metabolic activity.
Shivering is a rapid movement of skeletal muscles triggered by your hypothalamus. This movement generates heat and helps to restore homeostasis.
Goosebumps often go along with shivering and the process involves your hair erector muscles contracting. This rising of the skin at the hair follicles creates insulation to prevent more heat from escaping.
A more internal process of creating heat is increased metabolic activity. This is a process mostly performed by the liver’s chemical procedures.
Thermoregulation Is Designed to Protect the Body
Our bodies are complex machines with highly effective temperature homeostasis methods that are not harmful to our bodies. We can easily deal with far greater problems than minor fluctuations in body temperature.
Nevertheless, being exposed to extreme heat and then much cooler temperatures through air conditioning can have some minor effects on your health.
Potential Health Effects From Temperature Changes
The negative effects on your health from drastic temperature changes go both ways; going from hot to cold and vice versa can both be detrimental.
Hot to Cold
When the body senses an extreme temperature change, the first instinct is to alter blood flow. In the case of hot to cold, blood vessels would constrict to avoid heat loss due to a large amount of blood being concentrated right below the skin.
A diminishing in blood flow means that white blood cells also diminish in number. If the body has harmful bacteria or viruses present, this would make becoming sick much easier.
Another HVAC-Buzz article, Is It OK to Use Air Conditioning When You Have a Cold?, investigates further into the likelihood of an illness being caused solely by air conditioning.
Cold to Hot
The opposite also has some negative effects. A sudden change in temperatures can dry out various membranes of your body, including the skin, eyes, and inside the nose. This situation is what causes nose bleeds in situations of drastic temperature changes.
Acclimating to cold temperatures and then being exposed to heat can also cause headaches, dizziness, and even heatstroke due to heat intolerance from being in the cold for so long.
Factors Affecting the Likelihood of Health Effects
The adverse effects listed above are worst-case scenarios, and the likelihood of them happening depends on the conditions.
The frequency at which you are going in and out of air conditioning, the disparity in the temperatures of each environment, and your personal response to temperature changes all factor into how you will be affected by going in and out of air conditioning.
How Frequently Are You Coming and Going?
As mentioned above, heat intolerance can cause dizziness, headaches, and, at its worst, heatstroke. This is because your body is acclimated fully to the cool indoors and when it is thrust into muggy heat, it must work its hardest to acclimate you to a wholly new environment.
The same process applies to being adjusted to heat and then entering a cold building.
On the other hand, if you are dashing in between air conditioning and heat, your body is not fully acclimating to either environment, so the corrections to interior body temperature are less needed and thus much easier on the body.
Whether you are entering the cold after fully adjusting to the heat or vice versa, you are more likely to suffer adverse health effects than if you were to jump between the environments quickly.
Temperatures Extreme Enough to Make a Difference?
As with the frequency of going in and out of air conditioning, temperature ranges do make a difference.
A temperature change of 10°F is tangible, but a temperature change of 5°F is barely noticeable to most. These small changes are like stepping in and out of air conditioning on a hot day. The body doesn’t have to work hard to thermoregulate.
The magnitude of temperature change that could be dangerous is more of a 20°F difference and higher.
Signs of your body being exposed to a drastic change in temperature would be the physical changes noted above. For hot going to cold, it would be goosebumps, shivering, and pale skin from blood vessel constriction. For cold going to hot, it would be sweating, the opposite effect on your skin (redness), and dryness of the skin as well.
How Quickly Do You Naturally Adapt?
There are many processes in thermoregulation and if any of these were impaired, the risk of health effects from going in and out of air conditioning is increased.
The hypothalamus plays a large role in thermoregulation. If this part was to be damaged, your chances of successful thermoregulation decrease. Tumors in the central nervous system, hemorrhages in the brain, and spinal cord injuries can all impair thermoregulation.
I am certainly not adept at thermoregulation, my hands turn a bit blue in the winter, but some are perfectly fine at it!
The likelihood of adverse health effects from going in and out of air conditioning may be greatly affected by your body’s natural adaptability to temperature changes.
If you work in an office that runs its air conditioning on high, it’s wise to dress warmly. When you exit out into 90-degree heat, though, a sweater can cause heatstroke easily.
The same goes for dressing for warm weather but entering a freezing building.
Either way, the natural desire to not want to lug around a change of clothes and adjust to what may seem like minor discomfort can cause overheating as well as dangers on the other side of the spectrum.
Babies Are More at Risk
Babies are especially sensitive to both the cold and heat. They are not as adept at adjusting to temperature change as adults and, according to Stanford Children’s Health, “Babies can lose heat rapidly, nearly 4 times faster than an adult.”
Babies with little body fat, such as premature and very light babies, struggle even more with retaining heat.
On the other end things, infants and younger toddlers also easily overheat when overbundled/overdressed.
That being said, babies depend solely on their caretakers dressing and undressing them to help regulate their heat. This fact as well as the known dangers of entering and exiting air-conditioned buildings is why infants’ health must be prioritized when thermoregulation is a potential problem.