Johannesburg's Air Quality Exceeds WHO Limits, Study Reveals Health Risk Data Gap
A year-long air quality study in South Africa's largest city found PM2.5 pollution 62% above WHO annual standards, yet Africa remains critically under-monitored for particulate pollution. The findings could reshape corporate health liability assessments and influence investment decisions in cities across the continent where similar data is absent.
Originaltitel: Ambient PM2.5 chemical composition in a residential area in Johannesburg, South Africa
Johannesburgs luftkvalitet överskrider WHO-riktlinjer betydligt — en fund som underlättar utvärdering av exponeringsrisker för investerare i afrikansk hälsotech och miljöövervakning. Forskare från University of Pretoria och University of Gothenburg analyserade partiklar under ett år och fann att årsmedelhalten PM2,5 uppgick till 8,1 µg/m³, vilket överstiger WHO:s årliga gränsvärde på 5 µg/m³. Sju av 55 mätdagar överkom även dagsgränsen på 15 µg/m³. Kemisk analys identifierade svart och organiskt kol samt tolv spårelement, med järn, kalium, svavel och kisel som dominerande. Forskningen visar att föroreningarna kommer från återuppsvirvlat damm, trafikemissioner, bränning i bostäder och regionala gruv- och kolverksamheter. Vintermånaderna visade högre nivåer på grund av ökad förbränning och ogunstiga väderförhållanden. Resultaten motiverar investeringar i IoT-baserade luftövervakning och regulatorisk efterlevnad för hälso- och miljörelaterade produkter på den afrikanska marknaden.
Abstract PM 2.5 is associated with multiple adverse health outcomes, yet data on its concentration, composition and sources in African cities remain limited. This study presents the first detailed characterisation of outdoor PM 2.5 in Johannesburg, South Africa. Twenty-four-hour filter samples were collected every sixth day from 3 October 2020 to 12 October 2021 at a residential site in the suburb of Buccleuch. Samples were analysed using gravimetric methods, smoke-stain reflectometry, optical transmissometry and X-ray fluorescence. Source contributions were assessed using principal component analysis (PCA), enrichment factor (EF) analysis and Hybrid Single Particle Lagrangian Integrated Trajectory model for backward trajectories. The mean PM 2.5 concentration was 8.1 µg.m −3 (range: 0.04–30 µg.m −3 ), exceeding the World Health Organization (WHO) annual guideline (5 µg.m −3 ). Daily concentrations surpassed the WHO daily guideline (15 µg.m −3 ) on seven of the 55 sampling days. Mean black carbon (BC) and organic carbon (OC) concentrations were 0.51 and 0.46 µg.m −3 , respectively. Twelve trace elements were detected, with Fe, K, S and Si most abundant. PM 2.5 , BC, OC and several elements were significantly higher in winter and autumn, reflecting increased combustion activities and unfavourable meteorological conditions. Trajectory analysis indicated contributions from regional mining and coal-related activities. Integrated PCA and EF results showed that PM 2.5 comprised resuspended dust, traffic-related non-exhaust emissions, local residential combustion and regionally transported pollution. These findings highlight multi-source exposure and the need for coordinated air quality management at municipal and regional scales.