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

Researchers say that past exposure to sulfur dioxide is likely to blame for the increased porosity of the Murujuga rock art created by the Ngarda-Ngarli people tens of thousands of years ago

Sarah Kuta | Daily Correspondent

August 28, 2026 2:04 p.m.

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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.

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.

“As traditional owners and custodians, we know that protecting Murujuga requires both cultural knowledge and robust science,” says Belinda Churnside, who represents the Ngarluma people on the Murujuga Aboriginal Corporation’s board of directors, in a statement. “These findings are an important step forward in helping us better understand the landscape and ensure it is protected for future generations.”

Last year, researchers reported that rock art in some areas of Murujuga showed signs of elevated porosity (tiny voids within the weathered outer layer of the rock), with higher levels observed near industrial areas. 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. “Transport fuels, shipping fuels industry all have some level of sulfur in their fuel,” Ben Mullins, who serves as the program’s lead scientist, tells Alistair Bates and Kimberley Putland of the Australian Broadcasting Corporation (ABC).

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.

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Based on the findings, the researchers think that most of the damage they observed on the Murujuga rocks occurred in the past and is not the direct result of current air pollution. They note that sulfur dioxide emissions have declined sharply since the 1970s and ’80s, as “shipping fuels have massively reduced sulfur levels and sulfur dioxide emissions,” Mullins tells the ABC. The researchers did not detect any acid rain during their observation period, and air quality remained within the limits set by the program’s interim environmental quality criteria.

Taken together, the findings suggest that industry and the Murujuga rock art can co-exist, provided air quality is carefully monitored and emissions remain within established limits.

“There are groups who will accept nothing other than complete removal of all industry from the Murujuga region,” Mullins and Katy Evans, the program’s lead inorganic geochemist, wrote for the West Australian last year. “However, with respect to impact from emissions, that view is not supported by the current scientific evidence.”

The researchers believe that sulfur dioxide likely worked in combination with microorganisms living on the rock’s surface to cause the damage seen on the Murujuga rock art. Moving forward, the group plans to investigate how these and other factors might be affecting the rock art.

“Damage to landscapes such as Murujuga rarely have a single cause,” Mullins, Evans, Churnside and statistician Nicola Armstrong write for the Conversation. “We’re tracking how many factors interact, sometimes over decades.”

The rock art program’s four-year research phase is nearing completion, with the final year intended to establish the basis for longer-term monitoring and management. In an essay for the West Australian, Matthew Swinbourn, Western Australia’s environment minister, indicated that the government would continue to support such efforts to “ensure that we have outcomes that are based on the strongest evidence, that are transparent and that ensure the voice of the traditional owners is at the heart of protecting the rock art.”

He adds, “This is not the end of the journey. We know that this report only informs a point in time, and it is necessary for this work to continue.”

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.