The tens of thousands of people who participated in Sunday's half marathon in India's capital had more than just running 21 kilometers (13 miles) through New Delhi's streets on a misty, chilly morning to deal with. They also had to overcome the city's unparalleled air pollution.

Last year, the World Health Organization named New Delhi the world's most polluted city. Twelve other Indian cities ranked among the world's most polluted 20.

On Sunday, most of the city's government-run air monitors were showing "very poor" readings, providing an extra challenge for the more than 30,000 people taking part in the annual half marathon.

Still, the event proceeded in a carnival atmosphere, with Ethiopia's Birhanu Legese and Kenya's Cynthia Limo winning the men's and women's elite categories, respectively.