With Chile through to the knockout stage of the World Cup and soon to face hosts Brazil, things are certainly heating up in the capital Santiago. But it's the smoke that's causing the problems.

Bloomberg reports that Chile's government has asked football fans to refrain from burning charcoal on their barbecues due to their damaging effect on air quality.

A game against Australia caused a mini-emergency on June 13, with heavy smog leading to transport restrictions, and authorities are keen to prevent it from happening again.

Claudio Orrega, Santiago region intendant, said:

"It all adds up. One barbecue isn’t a problem. But when you have a pre-emergency and there are 20,000, 30,000 or 40,000 barbecues with charcoal or wood it is undoubtedly a contributor."

"I’ve been the butt of a lot of jokes for this and I take it with humour, but I also urge people to take it seriously."

In winter, the city is particularly prone to smog, as cold air traps it in the Santiago basin, which lies between two mountain ranges.