Professional Adult Medium Skin CPR-AED Training Manikin with CPR Monitor (Prestan) medical students trained as BLS trainers and medical students trained in BLS will provide 2 minutes cycle of BLS according to ERC guidelines 2021 wearing the breathable self-sterilizing nanofiber respirators with accelerated copper Procedure: Mout-to-mouth ventilation Chest rising during basic life support will be recorded as No breath (no visible chest rising) and Breath (chest rising) by the observer. Other Name: Basic life support ventilation Resusci Anne QCPR AED (Laerdal) medical students trained as BLS trainers and medical students trained in BLS will provide 2 minutes cycle of BLS according to ERC guidelines 2021 wearing the breathable self-sterilizing nanofiber respirators with accelerated copper