Powers to fine drivers who leave their engines idling could be expanded as part of a push to clean up the city's air.
Norwich City Council was last year granted enforcement powers as part of its efforts to reduce air pollution, an ongoing issue in the city.
In 2012, a Norwich Air Quality Management Area (AQMA) was created, centring on air pollution hotspots, to monitor progress.
In its latest update, which covers 2018 and was published in December, air pollution levels have dropped at the majority of measuring points.
But certain areas remain stubborn challenges - particularly those used regularly by buses and taxis.
Kevin Maguire, the city council's cabinet member for safe and sustainable city environment, welcomed the progress.
"But this is not something we can do alone - everyone has a part to play in tackling this issue," he said.
"Obviously air pollution isn't restricted to a boundary which means that our city centre is prone to pollutants from rural locations including the agricultural industry and neighbouring counties.
"We know there's more we can do for Norwich - particularly if we work with bus companies, surrounding local authorities and other organisations. But there are also things residents can do to help. This can be anything from walking rather than taking the car, being part of a car share or reducing your household air pollution however you can."
MORE: 'The city can't carry on' - air pollution strategy to focus on clean transport
To reflect major shake-ups to the city's road network, in January 2018 13 monitors were removed and nine new locations introduced - bringing the total number of nitrogen dioxide (NO2) monitors to 25.
Fine sooty particles, known as PM2.5, which have been linked to heart and lung disease and cancer, are also monitored at Castle Meadow and Lakenfields.
As part of several changes the council hopes will help - including completion of the NDR and eco-friendly upgrades to bus engines - the enforcement powers were granted to crack down on idling engines, with the potential of £20 fines for those who refuse to turn them off.
A spokesperson said no fines had been issued, because drivers had so far complied.
And the report said the powers were currently used in bus and taxi only roads, but that they were "expected to be extended to include other congested roads".
Waiting time signs could also be introduced at busy junctions, and the county council is exploring whether pollution monitor displays could be installed at existing electronic noticeboards at bus stops, the report said.
Annual mean levels of NO2 dropped year-on-year at most stations, and fell below the government target of 40ug/m3, and measures of PM2.5 had reduced at both sites.
But problem areas include Castle Meadow (which measured 54 for NO2), St Augustine's Street (44.4) and Chapelfield north (41.25).
Chris Speed, head of operations at First Eastern Counties, said congestion, particularly around the Castle Meadow and Prince of Wales Road junction, also created problems for buses, impacting reliability.
He said: "Air quality is high on everyone's agenda as we all want to improve the local environment we live in and we are certainly doing our bit in contribution to achieving that."
MORE: Norwich has some of the worst air pollution levels in the country, report shows
But he said it was a balancing act for drivers - while buses have an automatic system which cuts off their engines after three minutes of idling, when cold weather hits they had to run the engines to keep buses warm.
He said they had a 'drive green' system which gave rewards for driving standards, measuring steering, braking, acceleration and idling.
Meanwhile, a spokesperson for Konectbus said each double decker had the potential to take 75 cars off the road, and that they worked with drivers to reduce emissions through their style of driving.
"The biggest cause of carbon and NO2 emissions is congestion, and we are working with the local authority to encourage as many people as possible to use buses in order to reduce congestion in the area," they said.
"Our parent company Go-Ahead takes its impact on the environment very seriously, and is the UK's largest operator of electric buses with more coming this year. We also run the world's first air filtering bus which removes PM10 particulates out of the air."
Calls for vehicles to be banned from city
Calls have been made for vehicles to one day be banned from Norwich city centre.
In York, councillor hopes to end all "nonessential" vehicle journeys into its centre within three years, while Bristol has proposed banning diesel cars from a cental zone during weekdays.
Matt White launched the Car Free Norwich campaign in September 2018 in a bid to put Norwich on the same path, motivated initially by his own health battle with a lung condition, which he has lived with for more than a decade.
His efforts contributed to Norwich's involvement in Car Free Day in September last year. He said while it was a positive step, he was disappointed no roads were closed, with drivers instead encouraged to leave their cars at home.
Mr White said there needed to be a hard-hitting national campaign on air pollution.
"I have researched it and I have found out how damaging it is, particularly for children," he said.
He said he believed that air pollution monitors should be in place outside every school, to crack down on idling cars in particular.
MORE: 'I find it hard to breathe': The problem of air pollution in Norwich lingers on
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