Young participants (13-17y) participating in baseline assessment 1A filled in a digital questionnaire at the location of 1A Visit 1. The 1A Youth Questionnaire is procedurally equivalent to the 2A Youth Questionnaire.

The 1A Youth Questionnaire contained the following sections and subsections:

• Education
• Family composition
• Household composition
• Personal data
• Employment status

• Acne
• Allergies
• Cold/Flu
• Digestive symptoms
• Ear conditions
• Eye conditions
• Fatigue (general)
• Insomnia
• Kidney & bladder diseases
• Musculoskeletal symptoms
• Neurological disorders
• Respiratory problems (ELON)
• Respiratory problems (general)
• Skin conditions
• Symptoms (general)

• Alcohol use
• Drug use
• Electronic device use
• Hobbies & activities
• Home environment (general)
• Physical activity (sports)
• Smoking & tobacco use

• Medication

• Familial bonds
• Youth Self Report (YSR)

• Diet (general)

• Subjective health (general)

• Contraception
• Menstruation
• Physical development