Do not let your hair air dry; instead, use a hair dryer set to a low temperature, held at a distance of 15 cm.

noli's read

This recommendation is based on a rigorous experimental study published in 2011 in the scientific journal Annals of Dermatology by Yoon-Hee Lee’s team. The researchers compared different drying methods and demonstrated that natural air drying keeps the hair fiber saturated with water for too long, causing prolonged swelling that weakens its internal structure. Conversely, using a hair dryer at a moderate temperature (approximately 47 °C) at a distance of 15 cm with continuous movement prevents this swelling without damaging the hair's outer cuticle. However, the absolute claim that one should 'never' air dry hair is slightly exaggerated, as the actual impact varies depending on hair type, thickness, and porosity. Cosmetic science instead suggests a hybrid method: remove excess water by gently pressing the hair with a microfiber towel, then finish with warm, mobile drying.

the sources

No named source held this one up — that absence is part of the verdict.