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Satellite observations of air pollution support Finnish cleantech and sustainable development

Satellite observations of air pollution support Finnish cleantech and sustainable development

Satellite-based observations showed a decrease up to 90% in sulphur dioxide emissions from copper smelters in Namibia and Serbia, thanks to Finnish cleantech solutions.

A recent study shows that reductions in sulphur dioxide emissions and the efficacy of cleantech solutions can be monitored using satellite-based observations.

Sulphur dioxide (SO2) is a polluting gas, which it is toxic when present in high concentrations and affects negatively air quality and human health. Sulphur dioxide is produced from both man-made and natural sources. Enhancements in SO2 concentrations can be found close to metal smelters, power plants, oil refineries as well as volcanoes.

Satellite observations are able to monitor year-to-year changes in the emissions from individual point sources

Satellite-based measurements showed a decrease in SO2 concentrations from 2014 to 2016 over the copper smelters in Tsumeb (Namibia) and Bor (Serbia) (Fig. 1).

Figure 1. Average annual SO2 map over Tsumeb copper smelter. Enhanced SO2 concentrations are shown in red. The amount of SO2 in the lower atmosphere decreased from 2014 to 2016, due to the implementation of the sulphuric acid plant at the smelter.


Satellite-based annual SO2 emission estimations show up to 90% reduction starting 2015 (even with a 15% increase in copper production), when sulphuric acid plants, developed by Finnish cleantech company Outotec, were implemented at the smelters. The sulphuric acid plant is designed to transform gaseous sulphur dioxide into sulphuric acid. Satellite-based SO2 emissions and their year-to-year variability are in agreement within the uncertainties with the smelters' facility-level emission inventories (Fig. 2).

"We showed that satellite-based observations can be used to monitor air polluting emissions in support of the Finnish cleantech sector and to foster sustainable development and informed decision-making, in general," says Iolanda Ialongo, senior researcher at the Finnish Meteorological Institute.

Figure 2. Annual SO2 emissions since 2005 over the Tsumeb copper smelter. SO2 emissions (blue lines) decrease sensibly after 2014, while the copper production (red line) increases. Space-based SO2 emissions (blue solid line) agree with those reported in the facility-level emission inventories (blue dashed line).


Atmospheric SO2 observations and emission estimations from point sources derived from the Ozone Monitoring Instrument (OMI) on-board NASA's EOS-Aura satellite have been used in the study led by researchers at the Finnish Meteorological Institute. OMI instrument measures the solar light backscattered by the Earth's atmosphere and surface. The SO2 amount in the lower layers of the atmosphere is derived indirectly from these solar light measurements at different wavelengths.

The research work was carried on in collaboration with an international team including Environment and Climate Change Canada, NASA and Outotec. The results were achieved within the ILMApilot project funded by the Academy of Finland Key funding programme, which aims at increasing the societal impact of satellite-based atmospheric observations in air pollution monitoring applications.

Further information

Senior scientist Iolanda Ialongo, Finnish Meteorological Insitute, tel. +358 440 112 140,, @iolandaialongo

Ialongo, I., Fioletov, V., McLinden, C., Jåfs, M., Krotkov, N., Li, C., and Tamminen, J.: Application of satellite-based sulfur dioxide observations to support the cleantech sector: Detecting emission reduction from copper smelters, Environmental Technology & Innovation, 12, 172-179, ISSN 2352-1864,, 2018.

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