More than 100 CERN monitoring stations are constantly checking the quality of CERN’s water effluents before release as well as emissions into the atmosphere including ionising radiation. The quality of neighbouring rivers, soil, and agricultural products is also examined and tested. Roughly 2000 samples are taken and 7000 laboratory analyses are conducted each year by the CERN environmental laboratory.

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 actively mitigates the noise impact of its activities and facilities already at the planning stage by choosing material or settings that minimises noise. In addition, CERN yearly monitors its noise levels and sets up noise barriers around the worksites and facilities that cause concern.

CERN collects approximately 5500 tonnes of waste per year of which roughly 1700 tonnes are conventional waste and 1100 tonnes are hazardous waste (e.g. impregnated cable drums, chemicals waste, etc.) processed by specialised certified companies. Some 1850 tonnes is scrap metal, electric and electronic material, which is either recycled or sold. CERN strives to continuously reduce its waste and improve its recycling. Specialised companies collect and transport hazardous waste and CERN follows Host States regulations on this matter.

To study the composition of matter, CERN uses particle collisions that generate ionising radiation. CERN continuously monitors its ionising radiation levels to ensure that its releases to the environment are negligible. The vast majority of CERN’s radioactive materials are not contaminating and all radioactive materials are stored and handled following standard regulations. CERN adheres to the internationally accepted radiation protection system. Facilities and practices are continuously optimised to minimise radiological impact. With this system, the real radiological impact remains well below regulatory limits. All radioactivity measurements are regularly reported to the Swiss and French authorities.

More information about radiation.

To reduce the visual impact of new buildings on the landscape, plans are discussed with local authorities to ensure that additions to CERN sites do not alter the overall appearance. Landscaping projects include trees, bushes and grassy areas planted to ensure that CERN sites remain natural and indigenous to the local area.

CERN sites stretch over a total surface of 211 hectares shared between France and Switzerland. Of this, 109 hectares are green spaces such as lawn, meadows or woods. These green spaces are carefully maintained in order to respect their biodiversity. For example, CERN hosts the greatest variety of wild orchids in the Lake Geneva area boasting at least 16 known species. CERN prefers the natural maintenance of these areas, for example sheep are used to mow the lawn. CERN sites also hosts deer and many species of birds.

Outside of these enclosed areas, a further 415 hectares have been made available to the Organization's by the Host States. This land is preserved for future projects; in the meantime, they remain either farmland or woodland. The forests are maintained by the French national office of forests and the fields are cultivated by local farmers. The money earned from renting the land to farmers is used to finance projects benefiting the public, such as cycle paths and fitness trails.

With a growing number of users and various sites, relatively distant from each other, transport is a major concern at CERN. Several initiatives have been launched over the past years to facilitate mobility on site, to reduce CERN’s fleet of vehicles and to limit the impact from transport.

A car-sharing service, with 35 vehicles at 16 pick-up places, limits the size of CERN’s vehicle fleet. This service has recorded almost 16’000 bookings in 2014. With some 600 bikes freely available for its users, CERN has one of the largest bike fleets among Swiss companies and organisations. The shuttle service transported 107’000 passengers in 2014. CERN also promotes “Bike2Work”.

CERN has also launched a refurbishment programme for its buildings, most of which were built between the 50s and 70s. Civil engineering teams ensure that this refurbishment takes environmental constraints into account. All new buildings are conceived to minimise their energy consumption, by systematically including solar panels, high-performance insulation materials, and more.

CERN consumes the most electricity when its most powerful accelerator, the Large Hadron Collider (LHC), is running, which consumes roughly half of CERN’s electricity. CERN has a typical yearly consumption of about 1.2 terawatt-hours (based on the consumption of the year 2012 when the LHC was running). This figure represents approximately a third of the consumption of the Canton of Geneva.

A large proportion of the LHC’s electrical consumption keeps the superconducting magnet system at its operating temperatures (-271°C for most of the magnets). This superconducting property means that the energy consumption of the LHC is similar to that of its predecessor, the Large Electron-Positon collider (LEP), which has operated since the 80s, despite the LHC being a much more powerful machine.

Roughly 135 tonnes of liquid helium are necessary to maintain the LHC at very low temperatures. The helium is stored in a closed circuit and when the machine is stopped, the gas is partially stored in special tanks and partially sent back to the supplying companies.