Safety officials say they aren't certain about the cause of the increase.

Yet consumer advocates point out that large and relatively cheap inflatable pools that are now widely available at supermarkets and big-box stores are a growing concern.

These pools, unlike in-ground models -- which usually require a construction permit -- are less likely to be subject to local safety codes that call for measures such as fencing, covers or alarms, advocates say.

Inflatable pools can be quite large, accommodating several adults and, in many cases, accessible by a ladder.Web Link