Beijing smog concerns Williamson

Alison Williamson is competing in her fifth Olympics

Alison Williamson is worried that the smog in Beijing may hinder her chances of winning another Olympic medal.

"I suffer from asthma, and I'm having to take supplements to protect my lung lining," she told BBC Radio Shropshire.

"Our competition lasts 6-8 hours a day for a whole week, so the build-up could have a bearing.

"There's pollution in any huge city, but I think we're more sceptical about Beijing as we're not perhaps getting the full picture from the authorities."

The Shropshire archer, who took individual bronze at the 2004 Games, says the pollution in the Chinese capital could affect many of the competitiors.

"I'm thankful I'm not doing something like the marathon," she added.