VALENCIA, Spain — World record holder Haile Gebrselassie is almost certain to miss the marathon at the Beijing Olympics because of the city's poor air quality.

The Ethiopian, who has asthma, fears damage to his health by running through the streets of the Chinese capital. The 34-year-old Gebrselassie would be a gold medal favorite if he did take part.

"That is not yet decided," Gebrselassie said.

Gebrselassie will make a final decision after the Hengelo meet on May 24 in the Netherlands, when he finds out if he has qualified for the 10,000-meter race in Beijing, his agent Jos Hermens said in a telephone interview Monday.

Gebrselassie already has two Olympic titles in the 10,000.

High temperatures could also be a problem in the marathon for Gebrselassie, Hermens said.

"Haile wants to do everything possible for his country," Hermens said. "With three Ethiopians, they could get gold, silver and bronze."

Concerns about Beijing's pollution have dominated preparations for the games.

Gebrselassie has had problems with his lungs in the past and is known to have a pollen allergy. Hermens said many racers who have performed in damaging conditions have never returned to their best.

"It may be 1 or 2 percent (damage), but that means a lot for such an athlete," Hermens said. "And if you look deep into his heart, he wants another marathon record."

Gebrselassie's record is 2 hours, 4 minutes, 26 seconds.

He also wants to keep running until the 2012 London Games, where the climate would better suit him.

After winning the 10,000 at the 1996 Atlanta Olympics and 2000 Sydney Games, Gebrselassie finished fifth in Athens in 2004 in a race won by teammate Kenenisa Bekele.

The marathon has a special reputation in Ethiopia since barefoot runner Abebe Bikila won the 1960 Rome marathon and repeated the feat, with shoes, in Tokyo four years later.

Gebrselassie also has four 10,000 world championship titles and has broken two dozen world records.

Because of pollution problems, many countries have based their training camps outside of China before the Olympics begin on Aug. 8.