What is happening at the home of Alexander Litvinenko? It seems his house has been marked off limits until the radioactive Po-210 decays to harmless lead (Po-210 has a half life of around 130 days, so two years and most of the risk should be gone).

The Muswell Hill home of poisoned ex-spy Alexander Litvinenko has been declared a no-go zone, five months after the Russian was killed.

The house, in Osier Crescent, poses a hazard to anyone living in or entering the premises according to the Health Protection Agency. But in a letter to the street’s residents, Haringey Council stressed that the contamination does not affect neighbouring properties.

Being an alpha emitter of radiation, Po-210 is only lethal when ingested or inhaled because the radiation dissipates after a few centimeters. So there is no health risk across a wall. Apparently clean up has not been successful or deemed possible, so the only other option is to shutter the place as the Po-210 transforms to lead in the nuclear decay process.

But what struck me is the fact the house could even get that contaminated. Litvinenko could only trail Po-210 on his clothes or skin, the amount inside his body was 10 millionths of a gram and could not be the source of rampant contamination that would shutter a home. Some common sense from a neighbor:

Resident Hamish Stewart said: “I think it is a bit of an over-reaction to the situation. There may be traces of the substance but you have to ingest it to really be affected.

Unless there is more Po-210 than just particles that were trailed on clothes or flushed through bodily fluids. The only other place that remains sealed off like this is the Hotel Room at the Millenium Hotel where I claim the killer exposure took place with Litvinenko, Kovtun and Lugovoi present. [Note: The Pine Bar is also closed off, but it seems clear the dishwasher cleaning a contaminated teapot and cup may be the source for that location – the contaminated steam seems to have gone everywhere]. The hotel room site is reported to be very hot from a spill showing the source material. The key here is it was a site of the source material.

If Litvinenko was involved in smuggling, then he might use his home as a storage site for the material. And that may be why his house is so hot it must be sealed off. Po-210 is notoriusly hard to contain. The energy from its radioactive decay shoots dust-sized particles into the air which tend to get into everything. This has been reported about Po-210 many times over. So a large concentration can end up permeating walls and furniture with the dangerous material. But to do this requires a lot more material than what killed Litvinenko.

Another factor which is a clear indication is that Marina Litvinenko – his wife – and their son are not showing dangerous levels of contamination. Again, Po-210 cannot harm people at a distance or through walls so this might indicate material was found in a room that had access limited to Alexander Litvinenko only. It would make sense that if he had hidden in the material in the house he would make the hiding place off limits to his family.

It is one of the few scenarios that make sense. The rest of the trail surrounding Litvinenko’s movements is basically back open to the public – minus the hotel room, Pine Bar and some offices near Berezovsky offices (supposedly owned by people out of country). The remaining sites of contamination, by definition, are locations of large amounts of material and indicators of where major events with Po-210 took place. I cannot see how Litvinenko could have trailed that much Po-210 home without a hotter trail. The one exception is Akhmed Zakayev’s car – which is also a site of contamination. Other than that it is hard to see how it happened.