Top marathon runner Paula Radcliffe says it's not the air pollution that worries her about competing in China's Beijing Olympics - it's the heat!
Some people are worried that poor air quality in Beijing may cause breathing problems for athletes in endurance events like the 26-mile marathon.
But Paula, who has asthma, says she's more worried about how her body will cope with the heat in China.
And she's concentrating on how to deal with the sticky climate in training.
"I need the right dosages of my asthma medication, but after that I don't think it's [the pollution] something you can worry about too much," she said.
"But heat and humidity are a different kettle of fish because they are things you can prepare for. I'm concentrating more on those factors than the pollution."