The common belief that air conditioning directly causes colds is a misconception. While many associate symptoms like a sore throat or runny nose with air-conditioned environments, scientific evidence shows air conditioning itself does not cause illness. The actual cause of the common cold lies elsewhere.
What Causes the Common Cold
The common cold is caused by viruses. Over 200 virus strains can cause a cold, with rhinoviruses being the most frequent. These viruses are highly contagious and primarily spread through respiratory droplets released into the air when an infected person coughs, sneezes, or talks.
Transmission also occurs through direct contact or by touching contaminated surfaces and then one’s eyes, nose, or mouth. Once a cold virus enters the body, it begins to replicate. The body’s immune system then mounts a response. This immune reaction, rather than direct viral damage, produces familiar cold symptoms like a runny nose, sneezing, sore throat, and cough.
How Air Conditioning Affects Your Body
While air conditioning does not directly cause viral infections, it can indirectly contribute to symptoms that resemble a cold or increase susceptibility to irritation. Air conditioners remove humidity, leading to dry indoor environments. This dryness can irritate mucous membranes in the nasal passages and throat, making them less effective at filtering airborne particles.
Rapid temperature changes, such as moving quickly from a hot outdoor environment into a cold, air-conditioned space, can also stress the body. This temperature shock can cause temporary discomfort, including throat irritation and sneezing, which might be mistaken for a cold. If AC systems are not properly maintained, they can circulate dust, allergens, and mold spores. Inhaling these airborne particles can trigger allergic reactions or respiratory irritation, mimicking cold symptoms such as a stuffy nose, coughing, and headaches.
Keeping Your Indoor Air Healthy
To mitigate potential negative health impacts associated with air conditioning, maintaining optimal indoor humidity levels is important. An ideal indoor humidity range for human health and comfort is generally between 40% and 60% relative humidity. Using a humidifier in conjunction with air conditioning can help achieve this balance, preventing excessive dryness of nasal passages and airways.
Regular cleaning or replacement of AC filters is also a simple yet effective preventative measure. Filters should typically be cleaned or replaced every one to three months, or more frequently in dusty environments or homes with pets. This practice helps prevent the accumulation and circulation of dust, allergens, and mold spores.
Ensuring proper ventilation by occasionally opening windows or using exhaust fans can further improve indoor air quality. Setting comfortable, non-extreme temperatures, ideally between 18°C and 21°C, helps prevent bodily stress from drastic temperature changes. Staying well-hydrated by drinking plenty of fluids keeps the body’s mucous membranes moist and supports overall respiratory health.