INFOGRAPHIC: How Wide Does the Sky Lantern Clean-Up Need to Be?

Thousands of sky lanterns light up the night sky in New Taipei City’s Pingxi District (平溪) once a year during the Lantern Festival, which falls on the 15th day of the first lunar month. The annual event was named by the Discovery Channel as “the world's second-largest carnival” in 2008, and one of the “10 best winter trips worldwide” by National Geographic in 2016.

But in the last few years, as sky lanterns have become a main tourist attraction in Pingxi, lanterns are cast into the sky nearly every night, instead of once a year. Local environmental groups have been calling for restrictions to the number of lanterns burnt each year, arguing that the lanterns harm nearby forests and wildlife, and potentially endanger public safety.

The groups say traditional sky lanterns are made from cotton paper with a bamboo frame, and usually burn out during flight. Any remaining parts decompose after time since they are natural materials. But modern sky lanterns are made from chemical-coated, water-resistant paper with a wire frame, which pollute the environment when they land.

The New Taipei City Tourism Bureau said last year that locals in the area make daily rounds to collect the remains of fallen sky lanterns which can be resold to lantern manufacturers.

In an article on local science news website PanSci, a professor calculates that given Pingxi’s average wind speed of 4 meters a second, a standard sky lantern (see below) can land anywhere within a 2-kilometer radius from where it was released into the sky.