Actually - and I say this as a Certified Balloon Artist who does these all the time, a properly orchestrated balloon release poses NO threat to anything. A latex balloon decomposes at the same rate as a regular oak tree leaf. A lot less than your regular plastic carrier bag! The problems occur when people release balloons with ribbons or plastic valves attached. A responsible balloon professional would never release a balloon like that. I understand that
some states in the US do have banning orders on releases, but this is due to California Balloon Law, which mainly focuses on metallic (mylar) balloons which can cause power outage if they touch power lines upon release. Check out
www.nabas.co.uk for information on how to conduct a safe balloon release.
Sorry to get on my soap box, but this is my lively hood and it's ill informed people who are sharing incorrect information that are encouraging councils and environmental groups to jump on the band wagon and try and wipe out a fun industry.