The problem there, though, is the lack of parental supervision, not the armbands themselves. The bands do keep the child's head above water. But no matter what, parents need to understand that you don't leave a small child alone near water.
Unfortunately those are profoundly unsafe. They only keep the child's head above water while they are slid all the way up to the shoulders. If they start to slip down the arms, which they are apt to do when swimming, they'll tend to slip all the way down to the hands and if the child isn't strong enough to pull themselves up out of the water it can keep them from being able to swim at all as it holds their hands up.
Try to imagine if you were less buoyant like if you had ankle weights on and someone tied two empty milk jugs to your hands. Your hands are suddenly not useful at all for swimming and you can't pull them underwater so now you're forced to hold yourself up by pushing your arms out.
Here's how it can look, and this makes it a bit clearer why it can be a hazard. https://i0.wp.com/renomomsblog.com/wp-content/uploads/2015/0... If it slips down to the wrists like this it's arguably worse than having nothing at all.
Re:Spot the Drowning Child (2015)
by OkayPhysicist on Wednesday March 04, 2020 @12:29PM
(#22485696)
Arm bands should never be used. Unless they're the kind that has a chest piece, there is a significant risk of them pinning a child's face in the water.
Those are widely considered NOT safe, a non-swimmer child is probably much safer without them than with them, as using them lulls the caregiver into a false sense of security and they pay much less attention to them. They also teach children the wrong posture for swimming/floating, which can be difficult to unlearn. In the US the common wisdom says that if you use them you must be in arms reach of the child at all times - but that's what you'd do without them anyway, so what's the point?
The idea that you'd leave a non-swimmer child unattended with them is, frankly, horrifying.
https://en.wikipedia.org/wiki/Inflatable_armbands