Driving Time and Facial Skin Hydration Asymmetry in Florida Drivers

his observational study examines whether time spent driving is associated with differences in skin hydration between the left and right cheeks in female drivers residing in Florida. In left-hand-drive vehicles, the driver's left cheek is chronically exposed to ultraviolet A (UVA) radiation through the unshaded side window during every daytime driving episode. A prior study by IAS Skin Care (NCT07564869, n=30) found that the left cheek was less hydrated than the right cheek in 60% of participants, suggesting a possible effect of driving-related UVA exposure on facial skin hydration asymmetry. Eighty female drivers aged 25-65 years residing in Florida will be enrolled. At a single visit, skin hydration will be measured at three facial zones (left cheek, right cheek, and forehead as a symmetrical control zone) using the BT-Analyze bioimpedance device. Participants will complete a structured questionnaire on driving habits, sun protection practices, and skin history. The primary outcome is the Hydration Asymmetry Index (HAI = right cheek minus left cheek BT-Analyze score). Associations between driving time, cumulative driving exposure, window tinting, sunscreen use, and HAI will be examined using Spearman correlation, Mann-Whitney U tests, and multiple linear regression.

Inclusion Criteria: * Female sex, aged 25 to 65 years (inclusive) * Valid driver's license and active driving for a minimum of 3 years * Driving frequency of at least 3 days per week on average * Florida residency for a minimum of 2 years prior to enrollment * Ability to provide written informed consent in English or Russian Exclusion Criteria: * Window tinting on the driver-side window of the participant's primary vehicle * Regular sunscreen application specifically to the left side of the face before driving (more than half of driving occasions in the past month) * Active skin disease on the face at time of assessment * Injectable cosmetic procedures (Botox or fillers) in the past 6 months * Laser resurfacing or chemical peel in the past 3 months * Inability to refrain from facial cosmetics for at least 2 hours prior to the visit