polluting

The vehicles tend to be heavier, larger and more polluting than other cars, and researchers say they are more dangerous to pedestrians and cyclists.

"It is much more difficult than it is in the US. It's more expensive. It's more polluting. It's more disruptive."

Among critics’ biggest concerns are that the cap is too weak and there are too many credits for polluting companies.

Environmental Protection Agency has proposed looser regulations for polluting sectors such as power plants and vehicles.

The company was ordered to pay more than £900,000 last month after polluting a watercourse with millions of litres of chlorinated water, causing the death of hundreds of fish.