I thought they were using "eco balloons" made from biodegradable latex? But in this photo it looks like HD is holding a mylar (foil plastic) balloon, which is not biodegradable at all.
Fun fact - "biodegradable latex" that is used to make "eco balloons" (supposedly used by HDs event organisers) can take over 5 years to breakdown and even then it may not be fully biodegraded. In which time it poses a significant risk to wildlife, therefore can not be considered "eco friendly".
Are biodegradable balloons really eco-friendly? See test results, environmental impacts, and sustainable décor ideas for greener celebrations.
greencitizen.com