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Air in West Rand
Air in 2025 (modelled): nitrogen dioxide near the ground averaged 36 µg/m³, 3.6 times WHO’s guideline of 10; winters 45 µg/m³, summers 27 µg/m³.
Nitrogen dioxide (NO2) comes mostly from burning: power stations, vehicles, industry. Near the ground is what people breathe. The column is all of it in the air above, from the ground to the top of the sky, which is what a satellite sees. Sulphur dioxide (SO2) comes mostly from burning coal. Ozone forms in sunlight from other pollutants.
Modelled, not measured: these figures come from the Copernicus Atmosphere Monitoring Service’s reanalysis, a weather and chemistry model that takes in satellite readings. Its cells are about 80 km across, so a busy road or a smoky winter evening in one suburb is smoothed into the region around it. It is not a reading at any address.
2025
- 36 µg/m³Nitrogen dioxide near the groundThe year’s mean; 3.6 × WHO’s guideline
- 45 µg/m³In winterJune to August, against 27 µg/m³ in summer (last five years)
- 158 µmol/m²NO2 in the column aboveWhat a satellite sees, not what you breathe
- 178 µmol/m²SO2 in the column aboveMostly from burning coal
- 39 µg/m³Ozone near the groundThe year’s mean
WHO’s 2021 guideline for nitrogen dioxide is 10 µg/m³ as a yearly mean. It is a long-term health guideline, not a legal limit (South Africa’s national standard for the yearly mean is set separately), and these are modelled regional means, not readings where you live.
Month by month
| Month | NO2 near the ground | Ozone near the ground | NO2 column | SO2 column |
|---|---|---|---|---|
| December 2025 | 29 µg/m³ | 45 µg/m³ | 123 µmol/m² | 140 µmol/m² |
| November 2025 | 29 µg/m³ | 42 µg/m³ | 135 µmol/m² | 130 µmol/m² |
| October 2025 | 33 µg/m³ | 51 µg/m³ | 148 µmol/m² | 157 µmol/m² |
| September 2025 | 35 µg/m³ | 48 µg/m³ | 146 µmol/m² | 174 µmol/m² |
| August 2025 | 46 µg/m³ | 40 µg/m³ | 159 µmol/m² | 180 µmol/m² |
| July 2025 | 47 µg/m³ | 31 µg/m³ | 181 µmol/m² | 216 µmol/m² |
| June 2025 | 46 µg/m³ | 29 µg/m³ | 194 µmol/m² | 209 µmol/m² |
| May 2025 | 47 µg/m³ | 33 µg/m³ | 215 µmol/m² | 252 µmol/m² |
| April 2025 | 33 µg/m³ | 29 µg/m³ | 156 µmol/m² | 164 µmol/m² |
| March 2025 | 36 µg/m³ | 42 µg/m³ | 152 µmol/m² | 178 µmol/m² |
| February 2025 | 28 µg/m³ | 40 µg/m³ | 156 µmol/m² | 184 µmol/m² |
| January 2025 | 29 µg/m³ | 43 µg/m³ | 128 µmol/m² | 157 µmol/m² |
| December 2024 | 24 µg/m³ | 48 µg/m³ | 116 µmol/m² | 132 µmol/m² |
| November 2024 | 29 µg/m³ | 54 µg/m³ | 131 µmol/m² | 150 µmol/m² |
| October 2024 | 32 µg/m³ | 59 µg/m³ | 159 µmol/m² | 208 µmol/m² |
| September 2024 | 34 µg/m³ | 49 µg/m³ | 145 µmol/m² | 173 µmol/m² |
| August 2024 | 42 µg/m³ | 42 µg/m³ | 160 µmol/m² | 179 µmol/m² |
| July 2024 | 47 µg/m³ | 31 µg/m³ | 161 µmol/m² | 151 µmol/m² |
| June 2024 | 48 µg/m³ | 29 µg/m³ | 219 µmol/m² | 238 µmol/m² |
| May 2024 | 53 µg/m³ | 33 µg/m³ | 195 µmol/m² | 249 µmol/m² |
| April 2024 | 33 µg/m³ | 33 µg/m³ | 148 µmol/m² | 174 µmol/m² |
| March 2024 | 32 µg/m³ | 40 µg/m³ | 159 µmol/m² | 194 µmol/m² |
| February 2024 | 28 µg/m³ | 42 µg/m³ | 125 µmol/m² | 158 µmol/m² |
| January 2024 | 29 µg/m³ | 49 µg/m³ | 122 µmol/m² | 167 µmol/m² |
Over the last five years the NO2 column averaged 183 µmol/m² in winter against 132 µmol/m² in summer, and the SO2 column 204 µmol/m² against 157 µmol/m²: still winter air holds what is burnt close to the ground, and more is burnt to keep warm.
Every year since 2003
Show the numbers
| When or what | Figure |
|---|---|
| 2003 | 26 µg/m³ |
| 2004 | 25 µg/m³ |
| 2005 | 26 µg/m³ |
| 2006 | 27 µg/m³ |
| 2007 | 27 µg/m³ |
| 2008 | 30 µg/m³ |
| 2009 | 29 µg/m³ |
| 2010 | 30 µg/m³ |
| 2011 | 30 µg/m³ |
| 2012 | 30 µg/m³ |
| 2013 | 30 µg/m³ |
| 2014 | 30 µg/m³ |
| 2015 | 32 µg/m³ |
| 2016 | 32 µg/m³ |
| 2017 | 32 µg/m³ |
| 2018 | 33 µg/m³ |
| 2019 | 35 µg/m³ |
| 2020 | 35 µg/m³ |
| 2021 | 33 µg/m³ |
| 2022 | 36 µg/m³ |
| 2023 | 35 µg/m³ |
| 2024 | 36 µg/m³ |
| 2025 | 36 µg/m³ |
See it in the Copernicus Browser, the European Space Agency’s free viewer, on the newest image: Sentinel-5P, nitrogen dioxide · Sentinel-5P, sulphur dioxide. These are Sentinel-5P’s observed columns for one day, not our modelled yearly figures; days with cloud have gaps.
Every municipality, ranked · Everything we hold for West Rand · On the explore map
Source
Modelled, not measured: these figures come from the Copernicus Atmosphere Monitoring Service’s reanalysis, a weather and chemistry model that takes in satellite readings. Its cells are about 80 km across, so a busy road or a smoky winter evening in one suburb is smoothed into the region around it. It is not a reading at any address.
How we worked this out
What we changed: we averaged the reanalysis’s monthly means over each place by its area in each 0.75 degree cell, turned NO2 and ozone on the model’s lowest level from mass mixing ratio into micrograms per m3 with the month’s air density (surface pressure and temperature), and the columns from kg per m2 into micromol per m2.
Particles (PM2.5, PM10) and sulphur dioxide near the ground are not shown yet: the model reads them far higher over Gauteng and the Highveld than is plausible for a regional mean, so they wait for a check against ground stations.
Contains modified Copernicus Atmosphere Monitoring Service information 2003 to 2025. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains. Copernicus Atmosphere Monitoring Service (2020): CAMS global reanalysis (EAC4) monthly averaged fields. Copernicus Atmosphere Monitoring Service (CAMS) Atmosphere Data Store, DOI 10.24381/fd75fff2. Inness, A. and others (2019): The CAMS reanalysis of atmospheric composition, Atmos. Chem. Phys., 19, 3515 to 3556. Under CC BY 4.0.
Dataset: air quality by municipality, release of 12 November 2026.