The games, which open on August 8, are being touted as a landmark event by China's leaders, eager to show off the modern face of the country after 30 years of economic reforms.
Organisers have even promoted the games as the "green Olympics", although the use of that slogan has noticeably faded in recent months.
China has invested billions of dollars in new venues, transport links and other facilities for the games, and while these have been praised as world-class the issue of pollution stands out as the number one worry.
|Pollution in the capital remains the top worry |
for athletes and games organisers [Reuters]
In January, the mayor of Beijing, Guo Jinlong, warned that the task of bringing the city's pollution under control "remains arduous".
Already several Olympic squads have announced plans to base their training camps elsewhere in Asia, specifically because of the high levels of pollution in China.
The teams would then fly into Beijing only at the last minute to take part in specific events.
Other individual athletes have also expressed concerns, saying they may resort to wearing facemasks while in Beijing to block out harmful particulates.
"We have drawn up a contingency plan to ensure air quality at the Olympics"
Beijing organising committee
Last year, an inspection tour from the International Olympic Committee (IOC) warned that they could take the extreme steps of postponing, cancelling or even relocating some endurance events if pollution levels are too high.
Warnings over pollution have led to repeated assurances from games organisers and China's leaders that the air will be clear once the Olympics begin.
Al Jazeera's Beijing correspondent, Melissa Chan, says measures under way include a ban on most cars from the roads around the city and an initiative to introduce cleaner fuel.
She says the government has also ordered four provinces around Beijing to shut down their factories – not just during the games, but for two months ahead of the opening ceremony.
|Beijing has invested billions in new |
venues and facilities for the games
Sun Weide, spokesman for the Beijing games organising committee told Reuters "great progress" had been made in reducing air pollution, "air quality improving in each of the last nine years".
"In addition, we have drawn up a contingency plan to ensure air quality at the Olympics which involves Beijing and the surrounding five provinces joining hands.
"We are very confident, therefore, that we will deliver good air quality at games time."
Gebresalassie, who withdrew from the London marathon in 2007 because of his asthma, has said that he will not be pulling out of the Beijing games altogether.
Although he will not run in the Olympic marathon, he says he still hopes to qualify for Ethiopia in the Olympic 10,000 metre event.