The opening of Lascaux Cave after World War II changed the cave environment.
The exhalations of 1,200 visitors per day, presence of light, and changes in air circulation have created a number of problems.
Lichens and crystals began to appear on the walls in the late 1950s, leading to closure of the caves in 1963.
This led to restriction of access to the real caves to a few visitors every week, and the creation of a replica cave for visitors to Lascaux.
In 2001, the authorities in charge of Lascaux changed the air conditioning system which resulted in regulation of the temperature and humidity.
When the system had been established, an infestation of Fusarium solani, a white mold, began spreading rapidly across the cave ceiling and walls.
The mold is considered to have been present in the cave soil and exposed by the work of tradesmen, leading to the spread of the fungus which was treated with quicklime.
In 2007, a new fungus, which has created grey and black blemishes, began spreading in the real cave.

As of 2008, the cave contained black mold.
In January 2008, authorities closed the cave for three months, even to scientists and preservationists.
A single individual was allowed to enter the cave for twenty minutes once a week to monitor climatic conditions.
Now only a few scientific experts are allowed to work inside the cave and just for a few days a month, but the efforts to remove the mold have taken a toll, leaving dark patches and damaging the pigments on the walls.
In 2009 the mold problem was pronounced stable.
In 2011 the fungus seemed to be in retreat after the introduction of an additional, even stricter conservation program.
Two research programs have been instigated at the CIAP concerning how to best treat the problem, and the cave also now possesses a powerful climatisation system designed to reduce the introduction of bacteria.

Organized through the initiative of the French Ministry of Culture, an international symposium titled "Lascaux and Preservation Issues in Subterranean Environments" was held in Paris on 26 and 27 February 2009, under the chairmanship of Jean Clottes.
It brought together nearly three hundred participants from seventeen countries with the goal of confronting research and interventions conducted in Lascaux Cave since 2001 with the experiences gained in other countries in the domain of preservation in subterranean environments.
The proceedings of this symposium were published in 2011.
Seventy-four specialists in fields as varied as biology, biochemistry, botany, hydrology, climatology, geology, fluid mechanics, archaeology, anthropology, restoration and conservation, from numerous countries (France, United States, Portugal, Spain, Japan, and others) contributed to this publication.

In May 2018 Ochroconis lascauxensis, a species of fungus of the Ascomycota phylum, was officially described and named after the place of its first emergence and isolation, the Lascaux cave.
This followed on from the discovery of another closely related species Ochroconis anomala, first observed inside the cave in 2000.
The following year black spots began to appear among the cave paintings.
No official announcement on the effect or progress of attempted treatments has ever been made.

The problem is ongoing, as are efforts to control the microbial and fungal growths in the cave.
The fungal infection crises have led to the establishment of an International Scientific Committee for Lascaux and to rethinking how, and how much, human access should be permitted in caves containing prehistoric art.
The opening of Lascaux Cave after World War II changed the cave environment. The exhalations of 1,200 visitors per day, presence of light, and changes in air circulation have created a number of problems. Lichens and crystals began to appear on the walls in the late 1950s, leading to closure of the caves in 1963. This led to restriction of access to the real caves to a few visitors every week, and the creation of a replica cave for visitors to Lascaux. In 2001, the authorities in charge of Lascaux changed the air conditioning system which resulted in regulation of the temperature and humidity. When the system had been established, an infestation of Fusarium solani, a white mold, began spreading rapidly across the cave ceiling and walls. The mold is considered to have been present in the cave soil and exposed by the work of tradesmen, leading to the spread of the fungus which was treated with quicklime. In 2007, a new fungus, which has created grey and black blemishes, began spreading in the real cave.
As of 2008, the cave contained black mold. In January 2008, authorities closed the cave for three months, even to scientists and preservationists. A single individual was allowed to enter the cave for twenty minutes once a week to monitor climatic conditions. Now only a few scientific experts are allowed to work inside the cave and just for a few days a month, but the efforts to remove the mold have taken a toll, leaving dark patches and damaging the pigments on the walls. In 2009 the mold problem was pronounced stable. In 2011 the fungus seemed to be in retreat after the introduction of an additional, even stricter conservation program. Two research programs have been instigated at the CIAP concerning how to best treat the problem, and the cave also now possesses a powerful climatisation system designed to reduce the introduction of bacteria.
Organized through the initiative of the French Ministry of Culture, an international symposium titled "Lascaux and Preservation Issues in Subterranean Environments" was held in Paris on 26 and 27 February 2009, under the chairmanship of Jean Clottes. It brought together nearly three hundred participants from seventeen countries with the goal of confronting research and interventions conducted in Lascaux Cave since 2001 with the experiences gained in other countries in the domain of preservation in subterranean environments. The proceedings of this symposium were published in 2011. Seventy-four specialists in fields as varied as biology, biochemistry, botany, hydrology, climatology, geology, fluid mechanics, archaeology, anthropology, restoration and conservation, from numerous countries (France, United States, Portugal, Spain, Japan, and others) contributed to this publication.
In May 2018 Ochroconis lascauxensis, a species of fungus of the Ascomycota phylum, was officially described and named after the place of its first emergence and isolation, the Lascaux cave. This followed on from the discovery of another closely related species Ochroconis anomala, first observed inside the cave in 2000. The following year black spots began to appear among the cave paintings. No official announcement on the effect or progress of attempted treatments has ever been made.
The problem is ongoing, as are efforts to control the microbial and fungal growths in the cave. The fungal infection crises have led to the establishment of an International Scientific Committee for Lascaux and to rethinking how, and how much, human access should be permitted in caves containing prehistoric art.
Lascaux