1.9 million Cape Town residents face high to very high air pollution risk, new UCT research reveals

A new study at the University of Cape Town (UCT) has produced the first high-resolution map of air pollution across the Cape Town metropolitan area.

Its findings reveal a troubling reality: more than 40% of Cape Town’s population — roughly 1.9 million people — are exposed to high or very high levels of air pollution risk.

The research, published in the journal GeoHealth, goes beyond measuring pollution levels alone. Instead, it maps how environmental exposure intersects with poverty, housing and access to services, highlighting a pattern in which the city’s most vulnerable communities face the greatest risks.

Led by Dr Meryl Jagarnath from UCT’s Division of Environmental Health, the study, funded by the National Research Foundation, combines satellite-derived air quality data with a detailed social vulnerability index. The result is a high-resolution map that identifies “hotspots” where poor air quality and social disadvantage overlap.

Cape Town, she said, provided a critical case study for understanding the intersection of environmental and social risk. As one of the most unequal cities in South Africa, its spatial patterns of segregation and deprivation continued to shape both exposure to environmental hazards and the capacity of communities to respond to them.

“The study highlights how these structural inequalities are reflected in the geography of air pollution risk, underscoring the need for approaches that explicitly incorporate environmental justice into air quality management,” Jagarnath said.

The study addressed a critical gap in air pollution science, she said. “Conventional approaches to air quality assessment focus primarily on pollutant concentrations, often overlooking the social and structural conditions that shape exposure and health outcomes.”

To do this, researchers used data from the European Space Agency’s Sentinel-5P satellite, which measures atmospheric pollutants across large areas. They constructed an air quality index that includes nitrogen dioxide, sulphur dioxide, ozone and particulate matter — pollutants linked to respiratory and cardiovascular disease.

This environmental data was then layered with a social vulnerability index built from indicators such as income levels, housing conditions, infrastructure access and land use. 

By combining the two within a geographic information system, the researchers were able to pinpoint where high pollution exposure coincides with limited capacity to cope with its effects.

What emerges is a deeply unequal urban landscape. High-risk areas are concentrated in townships and informal settlements, including Khayelitsha, Crossroads, Philippi and Gugulethu.

In the communities, residents face a “double burden”: they are more exposed to harmful pollutants and also more socially vulnerable, with higher levels of poverty, overcrowding and limited access to healthcare.

By contrast, the city centre and northern coastal areas near Table Bay consistently show much lower risk levels, reflecting both better air quality and lower social vulnerability.

The study shows that air pollution in Cape Town is not evenly distributed. Instead, it follows the fault lines of the city’s history, shaped by apartheid-era spatial planning, persistent inequality and uneven development.

Communities that were historically marginalised remain more likely to live near pollution sources such as industrial zones, busy transport corridors and areas with poor infrastructure.

“This study highlights the intersection of social vulnerability and pollution exposure, emphasising how socioeconomic and demographic factors increase susceptibility in certain communities,” the authors said. 

“The results underscore the spatial distribution of high vulnerability zones, particularly in densely populated informal settlements and townships, where residents face compounded risks from both environmental and infrastructural deficiencies.”

Housing emerges as a critical factor. The research finds that people living in informal dwellings or unstable rental arrangements are more exposed to both outdoor and indoor air pollution.

Limited access to clean energy, combined with overcrowded conditions, increases reliance on polluting fuels and heightens exposure levels inside homes.

In some wards, up to 68% of residents rent and about 12% of households live in informal settlements. The conditions, the authors argue, are not just social issues but key drivers of environmental health risk.

The research also marks a significant methodological advance. By using satellite data, the team was able to map pollution across the entire metropolitan area, including places where ground-based monitoring stations are sparse or absent.

This is particularly important in lower-income areas, where monitoring infrastructure is often limited. Satellite observations provide continuous, large-scale coverage, offering a more complete picture of air quality and helping to “democratise” access to environmental information.

The study was conducted in collaboration with Dr Lerato Shikwambana from the Earth Observation Directorate at the South African National Space Agency. 

“The application of Earth observation represents an important advancement in public and environmental health research,” said Jagarnath, adding that satellite platforms provide continuous, large-scale and high-resolution data on atmospheric pollutants, overcoming the limitations of sparse and unevenly distributed ground-based monitoring networks. 

The findings had important implications for policy and practice, said Jagarnath, noting that air quality management strategies often adopted uniform approaches that did not account for localised differences in exposure and vulnerability. 

“The spatially resolved risk maps produced in this study provide a basis for targeted, location-specific interventions, enabling policymakers, urban planners and public health practitioners to prioritise communities at greatest risk.”

Such interventions might include reducing emissions in high-risk areas, improving housing and infrastructure, increasing access to healthcare and enhancing urban green spaces. 

“By addressing both environmental exposures and underlying social conditions, these strategies have the potential to reduce health inequalities and improve overall population health.”

The study also highlighted the value of integrating environmental data into health systems. Jagarnath said spatial information on air pollution and vulnerability could support more informed clinical and public health decision-making, particularly for conditions associated with air pollution exposure, including respiratory and cardiovascular diseases.

More broadly, the study demonstrated the potential of interdisciplinary approaches that combined environmental science, geospatial analysis and public health, she added.

“As cities across Africa continue to grow, the integration of Earth observation into environmental health research offers a scalable and transferable model for assessing and managing urban environmental risks.

“By making visible the spatial distribution of air pollution risk and its intersection with social vulnerability, this study provides a critical evidence base for advancing environmental justice in South Africa.”