Mark Bollinger, Minneapolis Public Schools' executive director of facilities management and capital construction, said the district relies on widely accepted playground design guidelines, including those found in the "Public Playground Safety Handbook" published by the U.S. Consumer Product Safety Commission.
The district's aim is to cushion falls of up to 10 feet, which Bollinger
said leaves them just two options for ground cover: rubber or wood.
said a deep layer of wood infill was common on district playgrounds up until eight or nine years ago.
That also generated complaints from parents because a 9-inch layer of wood chips would retain moisture even on hot days.
"That moisture then would turn into mold, and children were getting sick and (having) allergic reactions and things like that because of the mold," Bollinger
"So, we had a definite, defined problem there."
Materials like sand and pea rock, once common in play areas, aren't rated for 10-foot falls, he
not out to argue with parents, but the district had to make the best choice for students and settled on rubber.
estimated it would cost the district $2.5 million to convert playgrounds back to woodchips.
"Although we are aware that the rubber may be made of different substances that are considered hazardous, they are only considered hazardous when released," he
said, adding that his
understanding was a release would require oven-like temperatures - close to 250 degrees Fahrenheit - or a chemical reaction.
"We have on occasion gone out with air tests - because the rubber will smell, there's no doubt about it," he