INDIANAPOLIS (AP) — A billboard urging the Indianapolis Motor Speedway to end its tradition of releasing thousands of balloons before the Indianapolis 500 has been removed.

The sign unveiled this week in Indianapolis depicted someone holding a shredded balloon and read, “Balloons pollute and kill,” followed by the hashtag “StopLitteringIMS.” The sign was removed Monday.

Florida resident Danielle Vosburgh, who arranged for the sign, tells The Indianapolis Star that billboard owner Outlook Media told her it took down the billboard after it was deemed to be an attack ad.

She says the sign was funded by donations and a Fund for Wild Nature grant.

Speedway spokesman Alex Damron says track officials are consulting with stakeholders and experts “to fully understand the impact of this practice and determine its status in the years ahead.”