The landfill has been burning several times since the beginning of November, but on 23 December the fire increased in strength so much that the rescue service could not put it out.

And it's been burning ever since.

Residents in the area have complained about the smoke that when the wind is blowing in over their plots.

They want the fire extinguished.

Now they get support from the other side of the Atlantic.

Tony Sperling is a geotechnical engineer and worked from the beginning with the design of landfills.

But when one of his customers' tips started to burn, it fell to him to deal with the fire.

He then reacted to the fact that there seemed to be a lack of global expertise in the field.

He re-saddled and specialized in just dumping fires.

He has worked with this for more than 20 years now and has extinguished about 40 since then.

"The fire is manageable"

When he saw the pictures from Botkyrka, he reacted directly to the development of smoke and thought of the residents in the area.

- When this type of material burns, it leads to very harmful emissions.

It is not good that those who live nearby have been exposed to that smoke for such a long time, he says.

According to the Rescue Service, it is currently not possible to extinguish the fire, for two reasons.

On the one hand, there is a risk of landslides and on the other hand, there is a fear that the extinguishing work could lead to pollution of nature conservation values.

- I can not speak with certainty without having been in place, but these are valid question marks.

But if you have the right equipment and staff with the right knowledge, it is manageable.

I have worked in similar circumstances before.

Are these types of fires always possible to extinguish or are there circumstances that can make it better to let them burn out on their own?

- This type of fire must be extinguished, especially if people live nearby.

The ongoing emissions are so harmful to the environment that it is not an option to let it continue to burn indefinitely.

In the clip above, Tony Sperling gives examples of three methods that can be used for extinguishing.