According to the Norwich Evening News, Norfolk (UK) County Council, in its Proposed Transport for Norwich Strategy has suggested congestion charging as part of its strategy to improve air quality. I used to live in Norwich, so I have a particular interest in this, so reviewing the Proposed Transport for Norwich Strategy does reveal that congestion charging is mentioned four times. Three times in the context of improving air quality and once to
The second part of its "vision" is "improving the quality of our air" and this includes "road charging/congestion charge" presumably as a tool to achieve this. This is far from helpful, because a congestion charge by definition is established to ease congestion. Yes it should also reduce emissions, but because it should only operate at the times and locations of congestion it isn't a scheme to comprehensively address emissions, like the London Ultra Low Emission Zone.
This is where confusion appears, because if you sell a congestion charge as a public policy measure based on it actually being a low emission zone, then it isn't a congestion charge.
A low emission zone operates much longer hours (indeed up to 24/7) because its purpose is to exclude higher polluting vehicles from the zone. It isn't to collect revenue (the only revenue are effectively fines or permits to drive in the zone for such vehicles). A congestion charge shouldn't operate at times of low or zero congestion, because then it would be overpricing the road.
There is some hope that the Norfolk County Council does actually mean congestion charging for the sake of improving trip reliability, for under the statement of policy "Journey times and reliability", the strategy states: