Runners wore masks and were given sponges to wipe away the grime when an international marathon got underway in heavy smog in Beijing yesterday.

The 34th Beijing International Marathon began at Tian'anmen Square with many of the tens of thousands of participants wearing protective face masks.

The 42-kilometer course ended at the Chinese capital's Olympic Park, on a day when buildings across Beijing disappeared into the gray-tinged mist.

"Actually, on a normal day, nobody would run in such conditions," said Chinese participant Liu Zhenyu, a computer engineer. "But the event is happening today, so what can we do?"

About 30,000 people registered to take part in the marathon and an accompanying half-marathon.

The organizing committee made 140,000 sponges available at supply stations along the marathon route so runners could "clean their skin that is exposed to the air," the Beijing News reported.

The level of small pollutant particles known as PM2.5, which can embed themselves deep in the lungs, reached more than 400 micrograms per cubic meter in parts of the city as the runners lined up. The World Health Organization's recommended daily maximum average exposure is 25.

"When I looked at the state of the mask after 10 kilometers, I decided enough was enough," said British runner Chas Pope, 39, after dropping out of the race.

"It felt pretty ridiculous given we're meant to be running for health and fitness."

Top runners stay away

Many top long-distance athletes stayed away from the race, which was won by Ethiopia's Girmay Birhanu Gebru in two hours, 10 minutes and 42 seconds. His compatriot Fatuma Sado Dergo was the fastest woman with a time of 2:30:03.

"Today the smog did have a little impact on my performance, but not a major one," said China's Gong Lihua, who came third in the women's race.

An update on Saturday night on the marathon's official microblog, which was hosted by the Chinese Athletic Association and the Beijing Municipal Bureau of Sports, said "there might be slight or moderate smog." It asked competitors to take measures according to their own health, and advised the elderly and people with respiratory diseases to carefully consider whether to take part.

But the air yesterday was deemed severely polluted, according to Beijing's environmental center, the most serious level on China's air quality index, and came with a warning for children, the elderly and the sick to stay indoors, and for everyone else to avoid outdoor activities.

At the finish line, athletes tried not to let worries about air quality take the shine off pride in their performance.

"I'm used to the pollution," said local runner Liu Fan, who dropped out after 32 kilometers. His wife handed him a bunch of flowers, describing conditions as "terrible."

The marathon's organizing committee said late on Saturday that postponing the event would be difficult because of all the planning that had gone into it, and asked competitors to understand. It said that 46 percent of the competitors had traveled from abroad and other parts of China to take part.