A contact of Alexander Litvinenko who tested positive for the same substance found in the Russian's body has shown no evidence of "radiation toxicity".
Mario Scaramella met Mr Litvinenko the day he fell ill
Mario Scaramella, an Italian, is "well" and preliminary tests have not found any signs of illness, University College Hospital said.
Officials had previously said he tested positive for traces of polonium-210.
However, his friend Paolo Guzzanti told the BBC that doctors had told Mr Scaramella he was going to die.
Mr Scaramella was one of the last people to meet Mr Litvinenko, a Russian former spy, before his death last month, which is being linked to the discovery of polonium-210.
Mr Litvinenko's wife Marina is also said to have been "very slightly contaminated" but is not ill.
Easyjet said Mr Scaramella had flown on flight 3506 from Naples to Stansted on 31 October and also on flight 3505 from Stansted to Naples on 3 November.
But the Health Protection Agency (HPA) said it had no "public health concerns" about those flights.
It also said all three British Airways planes at the centre of the polonium-210 scare had been given the all-clear and were able to return to service.
Mr Litvinenko's wife, Marina, was slightly contaminated
On Saturday the Russian transport ministry's press service said traces of radioactive material had been found on a Finnish plane in Moscow that had flown from Berlin via Helsinki.
Experts from the Sellafield nuclear plant in Cumbria are now involved in the investigation into the Litvinenko poisoning.
Mr Scaramella met Mr Litvinenko, a former KGB agent who had been a critic of the Russian government since defecting to the UK, at a sushi restaurant in central London on 1 November.
It was later that day Mr Litvinenko fell ill.
Friends believe he was poisoned because of his criticisms of the Putin government.
Russian Defence Minister Sergey Ivanov said Moscow was ready to help investigate his death and he did not see "any grounds for speculation" implicating the Russian secret service, the FSB (formerly the KGB).
Contact with carrier's sweat or urine could lead to exposure
But polonium-210 must be ingested to cause damage
Radiation has very short range and cannot pass through skin
Washing eliminates traces
Meanwhile, the Ashdown Park Hotel, near East Grinstead, Sussex, has been given the all-clear after it was closed by officers probing the ex-spy's death.
And the HPA said a section of Arsenal Football Club's Emirates Stadium in north London had been checked as part of the polonium investigation but was also given the all clear.
HPA chief executive Pat Troop said: "People should be reassured that we're not allowing anything to be open if we are not content about it."
The agency added that just under 3,000 people had now called the NHS Direct line in the wake of the radiation scare, with 170 being followed up for further investigation.
A total of 60 samples have been tested, mainly from medical staff and ambulance workers, and all have proved negative.
The number of people referred as a precaution to a specialist outpatient clinic for radiological exposure assessment remains at 24.
Meanwhile health authorities in Ireland said on Saturday the ex-acting prime minister of Russia, Yegor Gaidar, had not been the victim of radiation poisoning.
After he fell ill in Dublin his daughter, Maria, said he had been the target of a political poisoning linked to the Litvinenko case but the British Embassy in Moscow dismissed this suggestion.
Mr Gaidar's spokesman said they were still waiting for the results of tests carried out by doctors in Moscow.