Research into funeral costs for ITV News shows bereaved families are being charged extra for "environmental fees".
The surcharges are being added because the deceased can become a pollutant when they are cremated. We've found they can add over £100 to the costs of a final farewell.
Now there are calls for legal changes to how the charges are being applied.
It's the least welcome expenditure of all and funeral costs have been escalating for years. From behind the scenes of Britain's increasingly hi-tech cremation sector, we've got new details on how costs have grown because of a system which regards the deceased as a potential pollutant.
ITV News found that of 289 UK cremation facilities almost a quarter (24%) now specify environmental fees. We found these charges can range from £35 (Barnsley Council Crematorium) to £129 (Kettering Council Crematorium). With examples across the UK spanning private and local authority operators.
We asked Julie Dunk of the Institute of Cemetery and Crematorium Management how these fees can be justified on top of funerals, which are already so costly. She told us: "Crematoria have had to install equipment to help protect the environment, that's things like fitting abatement plants to filter mercury out of peoples teeth when mercury filings are cremated."
But we found that paying the environmental fee doesn't guarantee a clean cremation. About 70% have installed the anti-pollution measures and some who have not are still allowed to charge the fee. That's because they have to pay into a fund to "off-set" any environmental damage.
James Dunn of funeral comparison website Beyond, told us "Yet again bereaved people are facing a postcode lottery when it comes to funeral costs. These environmental surcharges vary dramatically across the country and we really can't see a good reason why.
"With officials now investigating the industry, it's time for councils and private operators to be clear on how they come up with these fees."
The cremations sector says it is being open about its environmental prices and has already succeeded in reducing pollution by around 70% since 2005. It says the cost of making an individual cremation more environmentally friendly is £50 - £60.
The Institute of Cemetery and Cremation Management has told ITV News it wants new laws to compel all crematoria to install environmental clean-up measures.