San Francisco to Charge Polluting Firms

The rules, due to come into effect on 1 July, could cost big emitters more than $50,000 (£25,000) a year, but most firms will pay less than $1 (50p).

Backers say the move sets an important precedent for the rest of the US.

But opponents say it may interfere with plans to introduce much tougher emissions targets across California.

The state's governor, Arnold Schwarzenegger, signed a landmark law designed to reduce greenhouse gas emissions and combat climate change in 2006.

The California Air Resources Board is due to release its preliminary proposals to implement the law next month, with a final plan to be approved later this year.

From the BBC.