Clean Air and Water

A environmental chemist at CERN testing samples containing water from neighbouring streams to ensure that the Host States quality objectives are met.


CERN is constantly checking that its activities have an impact as little as possible on the air quality of nearby areas. Filters on the ventilation systems reduce CERN’s atmospheric emissions and ventilation-monitoring stations allow to compare air-quality readings with those of neighbouring regions.

Monitoring devices continuously measure the quality of the water CERN releases into local streams. These devices measure the temperature, pH, conductivity and turbidity of the water. Hydrocarbon detectors were specifically set up to detect immediately any pollution incident in order to react rapidly and mitigate the consequences on the local rivers. In addition these rivers are regularly sampled to evaluate CERN’s environmental impact.

The Service industriels de Genève (SIG) provides the majority of CERN’s water. CERN’s annual water consumption is approximately 5 million m3 per year when the LHC is running (shown in the graphic below). To put this figure in context, 75 million m3 of water are consumed each year in the Geneva canton. Roughly 75% of this water is returned to neighbouring rivers and streams after careful checks.

CERN’s annual water consumption (the first LHC long shutdown began after 2012 and ended beginning of 2015)

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