The odour was first reported in September 2021 when residents noticed a 'chemical' whiff around the bridge at the bottom of Parson's Close Recreation Ground and its surrounding area, including town centre.
However, eight months on and different smells have also been described around Leighton-Linslade and CBC is appealing for specific details of the times and exact locations of both the 'chemical' and other smells.
One reader in a tweet to the LBO, claimed: "Think that smell is back again. Smells like diesel fumes around Brooklands Drive / South Street."
Another wrote to the LBO to say: "I was just wondering if there has been any update on the investigation into the chemical smell first reported in the LBO in October. The smell is still very much there."
Fingers were initially pointed at a local factory, but this has since been dismissed.
A CBC spokeswoman said: "Our pollution team has visited Leighton Buzzard regularly, following reports from residents, to try and figure out where the smell is coming from.
"We have received reports from residents across different parts of Leighton Buzzard, each saying it smells differently e.g. diesel, burning plastic, or something chemical.
"Due to each report coming from a different location and each person having witnessed a different smell and at different times of the day or night, our officers are still trying to track down the source.
"If residents or businesses can provide further details to assist us in our investigation please email [email protected].”