Rush-hour passengers in the busy subway of Iran's capital have brushed shoulders with a surprising commuter — President Hassan Rouhani.

Rouhani, along Foreign Minister Mohammad Javad Zarif and others in his government, took the subway and other mass transit in Tehran to work Monday. It was part of their effort to mark "National Clean Air Day."

Rouhani spoke to male and female passengers on the subway, as well as waved to surprised commuters. He also had time to hug and talk to a young boy on his trip to work.

Greater Tehran has a population of 12 million people and suffers from a score of urban problems, such as heavy pollution.