Buses in Copeland produced far fewer emissions in 2021 than a decade before, with passenger journeys tumbling, new figures show.
The Local Government Association said buses can play a "huge role in reducing carbon and other harmful emissions".
Bus emissions data is measured by the equivalent amount of oil the journeys would have produced.
And Department for Energy Security and Net Zero figures show buses in Copeland produced 0.5 thousand tonnes of oil equivalent (ktoe) in 2021.
In 2011, a decade earlier, buses in the area emitted 1.2 ktoe.
The fall in emissions follows a significant reduction in people using buses.
Passengers in Cumbria completed 9.4 million journeys in the year to March 2022, the latest Department for Transport figures show. But in 2011-12, 17.7 million journeys were made – a decrease of 47%.
A spokesperson for the Local Government Association said: "Buses can play a huge role in reducing carbon and other harmful emissions as well as congestion, with a fully loaded double-decker bus being able to take 75 cars off the road.
"We need to reverse the decline in bus services and passenger numbers to help meet the country’s net-zero targets and keep our roads flowing and people and business connected. To help achieve this, the Government should fully commit to delivering its National Bus Strategy."
In Copeland, all vehicles emitted 22 ktoe in 2021. Personal transport, which includes all cars, buses and motorcycles, accounted for 70% of this, while freight transport accounted for 30%.
Petrol cars produced 7.7 ktoe, and diesel cars 6.7 ktoe.
The Department for Transport said directly linking reduced emissions with passenger numbers is "incorrect".
A spokesperson added: "Since February 2020, we have awarded over £300 million of dedicated funding for UK-built zero-emission buses, and are on track to reach our commitment of supporting the introduction of 4,000 new zero-emission buses by the end of this parliament."
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