KEY POINTS:
Colourless, odourless and tasteless, it can sneak up on an athlete without warning, more stealth-like than an unknown opponent.
And it could be the factor which ruins years of training and shatters dreams of gold.
Carbon monoxide (CO) is one of the biggest dangers facing athletes heading to Beijing, says Dr Richard Young, the man who has led New Zealand's efforts to confront the environmental challenges during the Olympic Games.
Known as a silent killer if inhaled in large quantities, even smaller levels of exposure to CO can significantly inhibit performance, invading the blood and squeezing out oxygen.
"Your blood likes it more than oxygen and that is the problem," says Young. "It competes oxygen right out of the way." Crucially too, it sticks around. It takes five hours for CO levels to reduce by half, and another five hours to halve again.
Getting stuck in a cloud of the stuff in the hours before competition, then, could be devastating.
Testing done on behalf of the New Zealand team has shown that levels of the pollutant could be about five to 10 times worse in heavy traffic in Beijing than what we experience in New Zealand's worst traffic congestion.
Travelling to venues, waiting for transport, and standing near generators will be when athletes need to take most care.
"There will be higher carbon monoxide and higher carbon dioxide," says Young. Other pollutants include sulphur dioxide, nitrogen dioxide, particulate matter and volatile organic compounds (chemical vapours).
Young, a former Canadian cyclist with a PhD in neuro-motor control, came to New Zealand four years ago and heads research, technology and innovation for Sport and Recreation NZ (Sparc).
Based at the Academy of Sport in Dunedin, he has worked with a variety of sports scientists and doctors to understand what the athletes will face. The information has been fed to the Beijing Acclimatisation Group, an 11-sport committee designed to make sure the Olympic team does not face any surprises.
Alongside human rights, pollution has been the grittiest issue for Chinese organisers to confront during the Games build-up.
Last week, the world's best marathon runner, Haile Gebrselassie, pulled out of the Olympic race, saying the pollution was a threat to his health.
The Ethiopian, who suffers from exercise-related asthma, will still run in the 10,000 metres, though his announcement irked organisers who have spent millions cleaning up Beijing's air. Factories have been moved, coal-burning generators shut and during the Games cars will be off the road and construction halted.
The International Olympic Committee this week announced that its studies suggested there would be no immediate threat to athletes' health, but conceded the pollution could affect world-class performances.
"I believe the conditions will be good for athletes although they will not necessarily be ideal," said the IOC's top medical official, Arne Ljungqvist. "There may be some risks. They would be associated with prolonged high risk respiratory functions. [Athletes] may breathe a lot of air that may be polluted."
The IOC would monitor conditions and, if necessary, take steps such as postponing events until air quality improved.
Road cycling, mountain bike, marathon, triathlon and road walking are among the events which will be monitored most closely.
Young says that while moves such as taking cars off the road will help, the fact that Beijing is a dense city with plenty of traffic means it will inevitably have a higher level of pollution than most cities.
To combat the issues, all team members will have masks and anti-oxidants to use in a bid to reduce their exposure to problems. The masks will mainly be for travelling, however, and are not suitable for training or competition. Young suspects the British team have come up with such a mask.
Young and his team have been sweating to find breakthroughs to give the New Zealand team any edge they can when it comes to beating the conditions.
Otago University researchers and the Horleys company have developed a sports drink especially for the heat and humidity, and Young says there are two other pieces of unpublished research which the team hopes will be significant aids. One enables competitors to retain more fluid in their bodies, and help them sweat for longer, and another will help cope with the pollution.
"They're some of the new things that we'll be keeping under our hat."
Within sports most likely to be effected, there is a serious effort being made to reduce the impact on athletes.
Triathlon NZ high performance manager Stephen Farrell said one strategy his athletes were using was avoiding Beijing as much as possible. "We're going to Jeju in Korea before the Olympics for our last training camp and then only going to Beijing on the 14th [of August] for the girls and the 15th for the guys," says Farrell.
The women's race is on August 18 and the men's August 19. Pollution was the main consideration behind taking this approach, he said.
Marathon runner Nina Rillstone has a similar strategy.
"My plan is to enter Beijing as close to my race as possible to limit time spent training there and hope for minimal discomfort during my race. I have never suffered from any respiratory problems and the screening tests I have undertaken as part of the pre-Beijing campaign have not suggested vulnerability for me in this area."
The difficulty, Rillstone points out, is that while it is possible to acclimatise to heat and humidity, it is impossible to do that for pollution.
New Zealand's chef de mission, Dave Currie, is confident the Chinese will do what they say they will to improve air quality during the Games.
But it is the team's responsibility to reduce any risks and make sure athletes are prepared for the conditions as best they can be.
"One of the mantras for us is, `It is what it is'. What you have got to do is be ready.
"Yes, it's hot and humid and air quality is a challenge. It's about taking good advice."
