Swiss air quality technology company IQAir has released its 2024 Annual World Air Quality Report, published in March 2025. This comprehensive report provides detailed insights into global air pollution trends, including rankings of the world’s most and least polluted countries, territories, and cities.
For the 2024 edition, PM2.5 air quality data was compiled from 8,954 cities across 138 countries, regions, and territories, using information from over 40,000 regulatory-grade and low-cost monitoring stations. PM2.5 (particulate matter with a diameter of 2.5 micrometers or less) is widely recognized as one of the most harmful air pollutants due to its ability to penetrate deep into the lungs and bloodstream.
According to IQAir, 12 of the 15 least polluted cities in Africa are located in South Africa. Topping the list is Nieuwoudtville in the Northern Cape, which recorded a PM2.5 concentration of just 1.2 µg/m³ - the lowest on the African continent and well below the World Health Organization (WHO) guideline of 5.0 µg/m³. Remarkably, Nieuwoudtville has maintained this standard for four consecutive years.
Other South African cities in the top rankings for clean air include:
- Worcester – 6.5 µg/m³ (2nd in Africa)
- Cape Town – 7.2 µg/m³ (3rd in Africa)
- Mossel Bay – 8.3 µg/m³ (5th in Africa)
- eSikhaleni – 8.4 µg/m³ (6th in Africa)
- George – 8.6 µg/m³ (7th in Africa)
- Port Shepstone – 8.8 µg/m³ (8th in Africa)
- Sunset Beach – 9.4 µg/m³ (9th in Africa)
- Gqeberha – 10.4 µg/m³ (10th in Africa)
- Empangeni – 10.6 µg/m³ (11th in Africa)
- Richards Bay – 11.4 µg/m³ (13th in Africa)
- Mokopane – 12.3 µg/m³ (15th in Africa)
Despite this positive trend, the report also highlights regions of concern. Centurion and Vereeniging, both located in Gauteng, rank among Africa's most polluted cities:
- Centurion – 37.0 µg/m³ (11th most polluted in Africa)
- Vereeniging – 34.0 µg/m³ (14th most polluted in Africa)
Overall, South Africa recorded a decrease in its national average PM2.5 concentration, dropping from 19.9 µg/m³ in 2023 to 18.8 µg/m³ in 2024, a reduction of 1.1 µg/m³. This positions South Africa as 47th worst out of the 131 countries ranked.
Pretoria, the administrative capital, showed notable improvement, falling below the 20 µg/m³ threshold for the first time since 2019. However, not all cities followed this positive trajectory. Johannesburg and eMbalenhle saw increases in PM2.5 levels, with eMbalenhle experiencing a sharp rise from 16.5 µg/m³ to 26.7 µg/m³, more than five times the WHO’s recommended limit.
Out of the South African cities with year-on-year data, 20 recorded an increase, 18 saw a decrease, and only Nieuwoudtville remained below the WHO guideline.
The number of African cities meeting data inclusion standards in the report increased from 79 in 2023 to 106 in 2024, yet only 24 out of 54 African countries had qualifying city-level air quality data.
Understanding PM2.5 and Health Risks
PM2.5 refers to airborne particulate matter with a diameter of 2.5 micrometers or smaller. Due to their small size, these particles can penetrate the respiratory system and have been linked to cardiovascular disease, lung cancer, and respiratory infections.
PM2.5 particles originate from both human activities and natural sources, including:
- Vehicle emissions and combustion engines
- Power plants and industrial activities
- Biomass burning (wood, coal, crop residue)
- Agricultural practices
- Dust storms and wildfires
Given the serious health implications, World Health Organization (WHO) recommends an annual PM2.5 concentration of no more than 5 µg/m³.
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