The balloon industry claims that releasing purportedly “biodegradable” latex balloons (without attachments like string or ribbon) is environmentally friendly.
What is known about the fate of balloons in the environment?
Latex balloons are made of natural latex collected from the Hevea tree, which is mixed with additives and antidegradants (=chemicals) to achieve the properties necessary to craft a balloon and pigments (metal oxide powders or organic dyes) for color.
In a 1989 study¹ backed by the balloon industry looking into the effect of balloon releases on the environment, it was determined that the majority of helium-filled latex balloons released into the atmosphere shatter into tiny fragments approximately 28,000 ft (5 miles) above the ground. At this altitude, where the temperature is 40 °F below zero, the volume of the helium expands to a point that exceeds the elastic limits of the latex. Under these conditions, the material shatters in a ‘brittle fracture’ and the latex fragments float back to earth.
However, a subsequent 2012 study² that investigated this topic further found that approximately 12% of latex balloons shattered into small pieces at altitude, while approximately 81% survived with at least half of their material intact.
Foil (Mylar) Balloons
Foil balloons are made out of nylon sheet, which is coated with polyethylene on one side of the sheet and metallized with aluminum (aluminized) on the other.
When mylar balloons are released outdoors and come in contact with overhead power lines or electrical substation equipment, the conductive metallic finish can cause an arc-flash – a surge of electricity – that can lead to power outages and fires. For this reason, many states have laws that require vendors to attach a weight to the string of every mylar balloon sold to prevent their inadvertent release.
But mylar balloons can and do escape, and the attached strings and ribbons can also lead to entanglement and mortality in not only birds, sea turtles, and marine mammals, but also terrestrial mammals like bighorn sheep and desert tortoises.
¹ Burchette, D.K. 1989. A study of the effect of balloon releases on the environment. Unpublished report to the Environmental Committee National Association of Balloon Artists. 26 pp.