Why a draft feels like it makes you sick

The folk belief

In Italy, a colpo d'aria—literally a “blow of air”—is blamed for stiff necks, sore throats, earaches and colds. Sitting between two open windows, stepping from a hot street into a chilled shop, or sleeping under an air conditioner are all classic culprits. Many Italians will close a car window on a July afternoon rather than risk it.

Outside Italy, the idea is often treated as superstition. The truth is more interesting: the belief is wrong about the cause, and surprisingly close about the conditions.

What the research supports

• Cold air weakens nasal defenses. A 2022 study from Mass Eye and Ear found that a drop in nasal temperature of about 5°C reduced the nose's release of virus-fighting extracellular vesicles by nearly half.
• Some cold viruses replicate better when cool. Rhinovirus, the most common cause of colds, reproduces more readily at the cooler temperatures found inside the nose, partly because the immune response there is weaker.
• Dry air helps viruses travel. Influenza survives and transmits more efficiently at low humidity; very dry indoor air, common with heating and aggressive air conditioning, also dries the airway lining.
• Sudden temperature changes can irritate sensitive airways, especially for people with asthma or rhinitis.

What it does not support

You still need a virus. A draft on its own cannot give you a cold, and a stiff neck after sleeping under an air conditioner is more likely muscular—cold, tensed muscles held in one position—than infectious. Crowding indoors during cold months also matters as much as the air itself.

What a well-balanced room does instead

• Keep supply air from blowing directly on beds, desks and sofas. Redirect vanes or move the furniture.
• Avoid large, abrupt temperature swings between outdoors and indoors in summer; a moderate setpoint is gentler on the body.
• Hold relative humidity roughly between 30% and 50%, and ventilate so fresh air arrives without a stream across the body.
• Maintain air-conditioning filters and drain pans so the system does not circulate dust or microbial growth.

Why this matters to us

Colpo d'Aria takes its name from this idea because it describes the goal precisely: air that reaches you without being noticed. Not stillness from sealed windows, but movement, temperature and moisture balanced so that nothing in the room asks for your attention.