Britain's Mara Yamauchi finished fifth on the Olympic marathon course in Beijing yesterday, starting in Tiananmen Square and ending in the city's National Stadium. When she returns for the Games in the summer Yamauchi might be wearing a mask although the city's pollution did not trouble the runners in this test event so much as the rain and cold.

"I'll consider it," said the 34-year-old Yamauchi, referring to the mask. "Anything that can help me perform my best on the day is worth trying."

Britain's No2 finished in 2hr 46min 16sec, more than 20 minutes outside her personal best. It was a morning more about absorbing the route rather than times, and China's Chen Rong won in a slow 2:30:42, more than 15 minutes outside Paula Radcliffe's world record.

Temperatures were between 12C and 15C but they are expected to be closer to 32C in August. Yamauchi knows little can be done to clear the smog totally.

The Japan-based runner suffered a dry throat and itchiness to her eye. She said of the conditions to be expected at the Olympics: "It'll be really hot, really humid. I think it'll be really tough. I am not going to acclimatise to pollution, I don't think you can do that. Heat you can acclimatise to. I don't think they can sort out the pollution and just magic it away. They can do things to reduce it and they're going to do it."

Zhou Chunxiu, who won the London Marathon last year in 2:20:38, was second in 2:37:49, the same time as her Chinese team-mate Zhu Xiaolin.