Climate science, innovation and the role of industry are topics for discussion on the third day of the COP25 event in Madrid.

But an anticipated event at the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change could be the arrival of young Swedish activist Greta Thunberg.

Meanwhile, delegations from the 197 countries will continue talks in this first technical phase of the COP, which will conclude on the 13th. However, many events are still scheduled in parallel.

One is titled "Innovative technologies and key sectors for decarbonisation" with the participation of the Spanish Minister of Industry Reyes Maroto.

The association "Scientists for Future" will also talk about its objectives and activities, as well as the twenty-four scientific facts related to climate change that form the basis of the declaration on the climate crisis signed by more than 26,000 experts in Europe.

Activists want to '#Makethempay'

A small group of demonstrators today displayed banners asking "big polluters" to pay society for the damage they are doing to the planet. The protest took place on Wednesday morning.

Activists protest as part of the Make Big Polluters Pay campaign inside the venue of the U.N. climate change conference (COP25) in Madrid, Spain, December 4, 2019. REUTERS/Susana Vera

The main slogan of the protest is #makethenpay, although the demonstrators also alluded in their banners to the protection of indigenous communities and to "climate justice" so that the most vulnerable groups are not especially harmed by the climate emergency.

An unbreathable world

Some of the most polluted areas of the planet had their space in the climate conference.

Data from the World Health Organization (WHO) show that poor air quality causes seven million premature deaths in the world each year and a multimillion-euro health cost.

People visit a pollution pod by British artist Michael Pinsky outside the venue of the U.N. climate change conference (COP25), in Madrid, Spain, December 2, 2019 REUTERS/Susana Vera

Pollution of cities worsens many chronic respiratory diseases, increases the number of heart attacks, strokes, and causes more strokes, but also affects the brain, cognitive development and IQ of people, according to WHO.

The artist Michael Pinsky has installed his work "Pollution Pods" at the Madrid convention centre construction that simulates in five gigantic igloos connected the levels of some of the most polluted cities on Earth.

People visit a pollution pod by British artist Michael Pinsky outside the venue of the U.N. climate change conference (COP25), in Madrid, Spain, December 2, 2019. REUTERS/Susana Vera

The work recreates the environment of New Delhi, Beijing, Sao Paulo and London, and in contrast to all of them also the Norwegian city of Trondheim.

Spanish Minister for the Ecological Transition Teresa Ribera and the Director of Public Health and Environment of the World Health Organization (WHO) María Neira visited the installation.

Michael Pinsky's construction recreates the air that is breathed in some of the most polluted cities in the world.