What’s the most healthy liquid I can use to vape on a vaporizer? I just want to generate smoke, but not harm my lungs.

Just buy any liquid without nicotine. By the way, what vaping device do you use? Personally, I buy 1 ml vape cartridge for my vape pen to utilize essential oil with a thick viscosity. As for juice, I like Caramel Nutz by Five Star E-Juice. Also, Humble juice is also good.