Three furnaces at a crematorium in Sheffield are to be replaced as they are repeatedly failing emission tests.
The machines at City Road crematorium are more than 25 years old and are difficult and expensive to maintain, according to a council report.
It said two of the cremators had been formally suspended within the past few years due to breaches in regulations, and needed to be replaced.
The work will be completed by October 2020 at a cost of £2.4m.
The Local Democracy Reporting Service reported that there would also be a small extension to house new office space, minor changes to the layout of the crematorium building and refurbishment.
In a report, Sheffield City Council officers said: "The threat of permanent suspension of use due to non-compliance with emissions regulations is becoming increasingly likely and requires urgent remedial works in order to avoid this."
The substances monitored by the government include hydrogen chloride, carbon monoxide, mercury and particulate matter.