By Anita Oh

PHILADELPHIA (CBS) — More than 2,500 runners laced up their sneakers Sunday for the 36th annual Run for Clean Air in Philadelphia.

“I want to be part of the community,” said runner Nizom Djuraev. “It’s a great day to run outside, too.”

Organized by the city’s Clean Air Council, it’s the region’s largest Earth Day Celebration – which has grown to what it is from just over 100 participants in 1981.

Executive Director Joseph Minott says he’s encouraged by the turnout.

“Given what’s happening in Washington and what have you, I’m taking solace in the fact that people are here,” he said, “and hopefully become more politically engaged with protecting the environment.”

Both the 10K and the 5K races featured a scenic route on Martin Luther King Jr. Boulevard along the Schuylkill River.

Race organizers say they aim to keep this run as environmentally-friendly as possible by offering paperless registration and t-shirts printed using sustainable ink.

They even offered picture frame medals, something first-time racer, Christiania French-Franco, appreciated.

“I’m running with Team Humane League,” she said. “We’re running partly for the animals, partly for the environment, and partly for our health.”

Something these runners remembered with every step towards the finish line – and with every breath of clean air inhaled.