Clean air advocates tied their sneakers for a good cause this weekend along the Schuylkill River in Philadelphia.
On Sunday, thousands of concerned citizens attended the 36th Annual Run for Clean Air. The long-running event, organized by the Clean Air Council, is one of the largest Earth Day Celebration in the region.
Nearly 2,500 people participated in this year's event, which featured a 10K run, a 5K run, a 3K walk and fun runs for children.
Joseph Minott, the council's executive director, said organizers focused the event on spreading awareness about "reducing methane and natural gas emissions in Pennsylvania and nationwide."
The routes began and ended at Paine's Park on Martin Luther King Jr. Drive near the Philadelphia Museum of Art and sent participants along the river.
Organizers also take steps to ensure the event is certified green. Efforts include utilizing solar energy, running shirts made with recycled materials, racing bibs printed with soy-based inks and paper registration.
This year's celebration occurred a week after a PennEnvironment Research & Policy Center study named Philly the second smoggiest city in the northeast region of the U.S.
The Run for Clean Air celebration was established in 1981 and has featured more than 50,000 runners.