Breathing easier in the cities of tomorrow
From investigating the sources and chemistry of airborne particles and their effects on human health, to exploring how urban design can improve air quality, KAUST researchers are tackling urban air pollution and its associated risks by examining solutions from multiple perspectives.
Unraveling the chemistry of polluted air
Declining air quality is a major issue in many countries, including Saudi Arabia. Pollutants can be directly emitted from both natural sources —such as wind-blown mineral dust, transported soil particles, volcanic ash, wildfires, and pollen — and anthropogenic activities, including industrial and agricultural emissions, ship and automobile exhaust, cooking, and biomass burning.
“However, many pollutants, termed secondary air pollutants, are formed in the atmosphere. For example, plants emit volatile organic compounds (VOCs), which can form significant amounts of secondary organic aerosols upon solar irradiation,” says Chak Chan, an expert in pollution chemistry whose research focuses on aerosol science and air quality. The group’s research integrates laboratory simulations of atmospheric reactions with field measurements to improve understanding of the sources and formation mechanisms of particulate matter (PM), a major component of air pollution.
Although the health risks of this complex mixture of tiny solid particles and liquid droplets are receiving increasing attention, its formation pathways remain only partly understood. Atmospheric reactions can generate sulfate, nitrate, and organic compounds, which together account for the most significant fractions of PM.
The finest particles are especially harmful, as they can penetrate deep into the respiratory system and are linked to respiratory and cardiovascular diseases, cancer, and neurological disorders.
“With a better understanding of their formation mechanisms, policymakers can formulate targeted control strategies to effectively manage emissions of precursor pollutants, such as nitrogen dioxide, sulfur dioxide, and VOCs for controlling secondary pollutants such as PM and ozone,” says Chan. “Source-based emission control can subsequently reduce PM and ozone formation, lower atmospheric concentrations, improve air quality, and better safeguard public health,” he adds.
Linking pollution exposure to human health
Chan and his team, in collaboration with researchers at the Center of Excellence for Smart Health, are developing cellular and animal models to test how different air pollutants affect human health.
“The usual research model is to expose cell lines in the lab to purified aerosol particles, which is not how it works in real life,” says chair of the center, Imed Gallouzi. “Normally, these pollutants are inhaled together with many other substances, with their effects moderated by filtration in the nose and lungs.”
In the lab and beyond, KAUST researchers are uncovering the causes of urban air pollution and developing innovative strategies to make city air safer to breathe.
“We want to understand how pollutants trigger biological responses in people as a step towards developing personalized treatments,” says Gallouzi. “We have a lot of statistics to help identify the prevalence of given diseases, specifically respiratory diseases, and their association with proximity to polluted areas. But we don’t really understand how pollutants trigger these conditions and why some people are more susceptible than others,” he explains.
In a proof-of-concept study with smoke, the researchers will expose lung cells directly to cigarette smoke to examine the effect on genes and other aspects of cell metabolism.
This research will also explore the effects of pollution on specific conditions, including muscle injuries and brain aging, and the potential for AI and machine learning to predict and mitigate health risks associated with pollution exposure.
Gallouzi hopes the work will provide useful information for policymakers to help mitigate the negative health impacts associated with pollution.
Designing cleaner, healthier cities
Sami Al-Ghamdi, and his team at the Urban Lab are also providing information to policymakers, in their case with a goal of adapting the environment to reduce urban air pollution.
“Our work involves a combination of environmental monitoring, life cycle assessment, and urban-scale modeling to evaluate strategies for pollution mitigation,” says Al-Ghamdi.
In a project with the Makkah Region Development Authority in Saudi Arabia, Al-Ghamdi’s team has assessed air quality, using satellite images validated with ground station measurements. They developed a multi-year air quality index to track pollutants, identify their sources, and monitor changes over time. Their report is now guiding new provincial regulations aimed at improving air quality.
The Urban Lab has built advanced computational models, which enable them to predict the impact of various mitigation strategies, such as planting trees, under a range of scenarios.
“We have fairly sophisticated models that can predict, for example, how much different tree species help reduce temperature,” says Al-Ghamdi. “We are still in the early stages of doing the same for air quality, but we are working to integrate it.”
The team is also studying how low-carbon mobility systems — such as pedestrian-friendly infrastructure, electric public transit, and integrated cycling networks — affect air quality. Their models, for example, assess how reducing personal vehicle use could lower emissions in a city.
Al-Ghamdi is interested in how the way a city is designed, its urban form, can be optimized to improve air quality.
“The city’s shape, its flat areas, high-rises, and the placement of industry and green spaces, greatly affects air quality by influencing air circulation,” he says.
“If a power plant or cement factory is located in the north of the city, and the wind flows from north to south, it will clearly affect air quality,” he explains. “So, when designing cities, we ensure that industries, wastewater plants, and similar facilities are placed where they won’t harm urban air quality.”
Al-Ghamdi believes that cities of the future can be healthier, more resilient, and more liveable — with cleaner air, clean energy, smarter infrastructure, and fair access to green spaces for all residents.
“We envision compact, mixed-use neighborhoods where mobility, housing, and public services are designed to minimize emissions and maximize wellbeing,” he concludes.