Historical Pollution, Not Current Industrial Emissions, Damaged the World's Largest and Oldest Collection of Ancient Rock Art, Study Suggests

Industrial pollution has taken a greater toll on ancient rock art in the state of Western Australia than previously thought, but researchers say the damage likely occurred in the past. Current activity does not appear to be accelerating its deterioration. Those are the conclusions of a new report released by the Western Australia government, based on three years of research conducted by Curtin University scientists and Aboriginal community members that together make up the Murujuga Rock Art Monitoring Program.

The program focuses on the estimated one million to two million petroglyphs spread across the Burrup Peninsula and the Dampier Archipelago, in the Pilbara region of northwestern Western Australia. The land is the traditional home of the Ngarda-Ngarli people, a collective of five Aboriginal language groups: the Yaburara, Ngarluma, Yindjibarndi, Mardudhunera and Wong-Goo-Tt-Oo. The rock engravings, which depict animals, plants, rituals and cultural practices, were created by the Ngarda-Ngarli over tens of thousands of years.

In 2025, the rock art was added to the UNESCO World Heritage List in recognition of its “profound cultural and spiritual significance, reflecting over 50,000 years of continuous care and management.” Since the 1960s, the region has been a hub for industrial activity, home to fertilizer and liquefied natural gas plants. Scientists and locals have long questioned whether air pollution from these industrial facilities might be affecting the ancient rock art. The Murujuga Rock Art Monitoring Program was created, in part, to help answer that question.

Murujuga’s engravings were made by people pecking, pounding, scratching and rubbing the rock surface to reveal lighter rock beneath. The group’s research draws on measurements of rock conditions, laboratory experiments, air quality monitoring and rainfall chemistry to inform the long-term management and protection of the rock art. The work will help guide air quality and emissions standards in Western Australia.

For the newly released report, they revisited the issue using an expanded dataset. The new work confirmed the earlier findings, indicating that porosity tends to be higher at sites that are closer to industrial sites and lower at sites that are farther away from them. Atmospheric chemistry, rainfall pH and laboratory testing suggest that historic levels of sulfur dioxide are likely to blame for this deterioration.

Sulfur dioxide is a common industrial airborne pollutant. Once released into the atmosphere, sulfur dioxide can react with oxygen, water and other chemicals to form sulfuric acid, which contributes to acid rain. When it comes into contact with rocks, sulfuric acid can dissolve manganese and iron oxide, creating small holes in the surface.