Are Air Fryers safe to use?

Air Fryers are really just small sized convection ovens (or OTGs) with a fan to circulate hot air more efficiently than in a large oven. This allows you to dehydrate the surface of foods really quickly and with very little oil.
As long as you don't char your food till it's visibly dark brown or black all over, air fried food is perfectly safe!
Convection baking has been used by human beings since the dawn of cooking, and air fryers (despite their name) use the exact same physics of hot air transferring heat to food.
And if you are someone looking to cut down calories from fat and also like crispy textures, this appliance is perfect for you. As always, focus on what you are ultimately eating rather than the appliance.