CARTAGENA, Colombia — “When I met with taxi drivers in Abu Dhabi about the pollution from their cars, they told me to talk to the desert,” recalled Dr George Thurston, director of New York University’s research program on the health impacts of ambient and occupational air pollution.

The taxi drivers’ retort points to a global challenge in the fight for clean air: while human-caused pollution can be regulated, natural sources — like sand storms, wildfires and dust — cannot be legislated away.

In cities across the Middle East, North Africa and Central Asia, sand and desert dust storms regularly buffet buildings, cars and neighbourhoods. These natural phenomena generate millions of tons of particulate matter annually that can travel thousands of miles, with well-documented health consequences for millions.

Yet dust from desert sandstorms is only part of the picture, according to experts convened at the second World Health Organization Air Pollution and Health conference in Cartagena, Colombia, last week. 

Rapid urbanisation in regions like the Middle East is adding new pollutants to the mix — sulfur dioxide, black carbon and nitrogen dioxide from factories, vehicles and shipping — all with well-established links to health conditions. This toxic blend makes the region an emerging pollution hotspot, affecting millions in Cairo, Tripoli, and Abu Dhabi daily.

But how to protect human health, and where more research is needed on long-term exposure impacts in arid countries, remains up for debate. Progress has been complicated by the misconception — shared by Abu Dhabi’s taxi drivers — that poor air quality in desert regions is an unavoidable “natural” fact of desert life.

Protecting health from ‘natural’ emissions

Sand and dust storms force road and airport closures, dramatically reduce visibility, deteriorate buildings and halt solar energy production, leading concerns to typically center around visibility, said Dr Kenza Khomsi, Morocco’s coordinator at the UN Industrial Development Organization.

Yet sand and dust storms hurl tonnes of loose sediment into the air, creating a whirlwind of health effects for livestock, agriculture and people alike. These microscopic particles pick up toxic, man-made chemicals and allergens, worsen coughs, trigger wheezing, exacerbate respiratory infections, and contribute to serious lung and cardiovascular diseases.

“We know particulate matter is harmful,” Khomsi said. “Dust is never just dust.” 

Morocco sits at the nexus of atmospheric currents — the Sahara, Atlantic Ocean and Mediterranean Sea all converge around the country, making it especially vulnerable to sandstorms. Khomsi, who previously served as head of the climate and climate change department for Morocco’s meteorological administration, said the country has increased its number of air monitoring stations, but “the health part is not aligned.”

Though severe sandstorms occur only about 10% of the year in the Middle East, dust is continuously re-suspended and natural desert particles mix with human-made pollutants year-round, creating air quality challenges that persist even when sandstorms aren’t occurring.

Region-specific research

Dust from sandstorms can travel thousands of miles. In 2020, an abnormally strong Saharan dust storm crossed the Atlantic Ocean to deposit 182 million tons of dust across the US and the Caribbean. The resulting air quality was hazardous in Puerto Rico and other Caribbean islands.

Just last year, plumes of Saharan dust sailed over the Atlantic from Africa’s coast over Europe, turning the skies of cities like London orange in a weather phenomenon observed by millions.

Though experts convened in Colombia emphasized that air pollution from sand and dust storms, especially fine particulate matter, has been extensively researched, the Middle East and North Africa lacked region-specific studies.

Most of the research on sand and dust health impacts comes from “receptor” regions in Southern Europe, North America, and other places where Sahara and desert sand settles. Sand traveling thousands of miles is diluted, and the chemical composition can change as well, said Rami Alfarra, principal scientist at the Qatar Environment and Energy Research Institute.

But in “source” regions — where the sand and dust originate — “we’re just starting this research,” said Alfarra, whose home country of Qatar, alongside the rest of the Middle East and North Africa, has emerged as an air pollution “hotspot,” according to University of Chicago research.

No representatives from the Middle East or North Africa were present at the WHO conference. 

“Particulate matter in the Middle East is different from the Amazon which is different from Europe.” This distinction means that for regions with huge exceedances from dust storms, perhaps the WHO guidelines are not specific enough, according to Alfarra. “Those [guidelines] are based on particulate mass, instead of region, decomposition, and source. There’s no definitive answer yet if [particle] toxicity is from the mass or chemical composition.”

Alfarra proposed region-specific air quality guidelines “where we have weighted factors for source-specific emissions”- differentiating between dust and combustion, for example – to account for natural sources.

But the composition of the particles shouldn’t matter, argued Dr Jonathan Samet, an American pulmonary physician and epidemiologist who served as dean of the Colorado School of Public Health. For Samet, whose career has spanned decades of air pollution research, the threat of air pollution requires action.

“In this case, the precautionary principle can be applied,” Samet said, noting the scientific literature is robust enough on the harms of particles that can travel deep into the lungs, implicated in cardiovascular and respiratory diseases, along with lung cancer, asthma, and allergies. He argues that the lack of full scientific certainty about the specifics of air pollutants should not be used as a justification to postpone action. 

“There’s been discussion for decades about what aspects of particles make them toxic,” Samet said. “There are many things that make particles toxic – the size, shape, charge, nature of their surface – but in the end they’re all going to go down the airway.”

“To try to pin down exactly what makes it toxic is a spurious question now.” 

Sufficient evidence to decarbonize 

Air quality in arid regions like the Middle East has continued to deteriorate in the past two decades, fueled by population growth and energy usage. Particulate matter pollution jumped 13% from 2021 to 2022, making the region’s air nearly four times more polluted than WHO guidelines recommend. 

Much of this increase comes from fossil fuel burning, not sand and dust storms. Nitrogen dioxide emissions – from transportation and industry in Egypt, Lebanon, Iraq, and Qatar have all increased since 2005, according to NASA satellite analysis.

If pollution levels were reduced to meet the WHO guideline, the 466.5 million residents of this region stand to gain 1.3 years in life expectancy, according to a report from the Air Quality Life Index from the University of Chicago.

And for a region producing 31% of global oil production, there is a clear leadership opportunity for energy-rich countries to drive decarbonization, asserts the Clean Air Task Force, a climate technology organization.

In Qatar, whose air ranks as one of the worst polluted in the world, “we don’t need any more research to regulate anthropogenic sources,” said Alfarra.

When nature fights back

Like desert regions contending with sandstorms, forest ecosystems face their own form of uncontrollable natural air pollution — wildfires.

Canada exemplifies this struggle against nature’s fury as the escalating impacts of the climate crisis raze forests around the world. While wildfires are a natural part of forest regeneration, their frequency and intensity have increased due to climate change.

Globally, wildfires have progressively burned larger portions of the world’s forests. These fires account for 33% of tree loss cover, compared to 20% in 2001, according to a World Resources Institute analysis.

Canada now battles approximately 8,000 wildfires annually, which consume more than 2.5 million hectares of forest. In 2023 alone, fires scorched an area equivalent to the size of England — representing 65% of global tree loss due to fires and releasing carbon dioxide equivalent to India’s annual fossil fuel emissions. The resulting smoke plumes, like desert dust, can travel thousands of miles to contaminate air in distant population centers.

“Seventeen percent of fine particulate matter in Canada — which can penetrate deep into the lungs and cause a host of health issues — is from wildfires,” said Dr Kathleen Buset, director of water and air quality at Health Canada. “That’s on par with emissions from cars, buses and trucks [combined].”

Unlike urban pollution sources that can be regulated, these forest fires often rage beyond human control. With finite sources to fight fires, many are left to burn in remote areas, she said. Canada cannot feasibly mobilize resources to extinguish all fires in its forests 15 times the size of the Great Lakes. Instead, the country has resorted to initiatives like satellite systems to monitor burns. 

“It’s an adaptation issue,” Buset added, highlighting a parallel to desert regions’ approach. When nature itself is the polluter, traditional regulatory tools become ineffective — cars, buses and factories can all be regulated, but the desert or a remote wildfire cannot.

For communities in both fire-prone and arid regions, adaptation takes similar forms: implementing better early warning systems to alert residents of poor air quality, mitigating re-suspension of dust after storms, and most critically, protecting indoor air quality.

“Eighty to 90 percent of our time is spent indoors,” noted Alfarra, adding that in the Middle East, that percentage can be even higher during the brutally hot summers.

This reality makes improved filtration systems, indoor air quality monitoring and public awareness campaigns essential components of any realistic solution. Buset emphasized the importance of “layered communication” — ensuring people check outdoor air quality conditions, limit time outdoors during hazardous periods and actively protect their indoor air environments.

Regulators can differentiate between car emissions and wildfire smoke, but really, “we breathe in everything,” said Alfarra.

Image Credits: WMO, Marc Szeglat/ Unsplash.