The early detection by the Forsmark plant, one hour north of Stockholm, played a crucial role in forcing Soviet authorities to open up about the disaster that happened in Chernobyl in April 1986.

When the alarm sounded at Forsmark early in the morning of 28 April 1986, it was not immediately clear where the radioactive materials had been released despite staff scanning all the radiation detection instruments.

“We found nothing,” said Claes-Göran Runermark, who was the operation manager in charge at the time. “We went over all the radiation detection systems over and over again, and there was nothing from Forsmark.”

Despite the alarm, Forsmark employees did not panic. “I would say that we were quite calm during the day,” said Mr Runermark. After an analysis, they could identify the radioactive particles that they found in the grass as specific to the Soviet nuclear power plants. Also, during the weekend the wind had blown from the south-east and it had rained in the north-eastern parts of Sweden, depositing radioactive fall-out on the ground in that area. All the evidence was pointing towards one of the nuclear power plants in the Soviet Union. And late that evening, two days after the disaster, the Soviet Union declared that there had been an accident at Chernobyl in Ukraine, a republic of the Soviet Union at that time.

“Thanks to our early detection we could inform the Swedish authorities at an early stage, who then told the world about the radioactive pollution coming from the disaster in the Soviet Union,” said Mr Runermark.

Today, most harmful materials have decayed. But some harmful materials, such as Caesium and Plutonium, will remain in the environment over a longer period of hundreds, even thousands, of years, though at lower levels.

The Chernobyl disaster showed that pollution has no borders. In order to better protect human health and the environment, the EU takes a leading role to develop policies and international agreements to mitigate the threat of environmental catastrophes spreading, such as the one in Chernobyl.

The EU is, for example, working on creating a better environment through the European Centre for Pollution Research and on setting and enforcing environmental standards. Also the Institute for European Environmental Policy is working to produce better regulation on environmental issues.

In March 2014, the European Parliament backed a proposed update of EU law to make environmental impact assessments clearer and ensure they take account of biodiversity and climate change and involve the public. The Environmental Impact Assessment Directive sets out criteria for the information that must be submitted to national authorities for a project to be assessed for approval. In 2005-2008, the average number of environmental impact assessments carried out in the EU ranged from 15,000 to 26,000 per year.