Health experts said leaving a fan on throughout the night during extreme heat can cause respiratory discomfort and dryness.
This warning comes as thousands of people [1] have turned to fans to cope with soaring temperatures during the 2026 [3] heat wave. While fans provide immediate relief, medical professionals said that the continuous flow of air can lead to adverse health effects.
In some regions, nighttime temperatures have climbed over 30 °C [2]. This extreme heat has pushed residents in Mexico and El Salvador to keep cooling devices running constantly to maintain a bearable sleeping environment.
Experts said that the practice can lead to the drying of nasal membranes and throat irritation. This dryness may increase susceptibility to respiratory issues or cause general discomfort upon waking. The constant air movement can also circulate dust and allergens throughout the bedroom, potentially triggering asthma or allergic reactions in sensitive individuals.
There is some disagreement among reports regarding the severity of these risks. One report said the practice can pose significant health risks, while another said it is not inherently dangerous but produces effects that are often overlooked.
Medical professionals said that while fans are necessary for survival in extreme heat, users should be mindful of air direction. Avoiding direct airflow onto the face and ensuring the room is well-ventilated may mitigate some of the dryness and irritation associated with overnight use.
“Leaving a fan on throughout the night during extreme heat can have health effects, ranging from dryness to respiratory discomfort.”
The tension between immediate thermal relief and long-term respiratory health highlights the challenges of urban living during extreme climate events. As nighttime temperatures rise, the reliance on basic cooling technology like fans becomes a public health concern, particularly for those with pre-existing respiratory conditions who may experience exacerbated symptoms due to dry air and airborne particulates.
