I would point out that inhalation of the particles would also be dangerous. The isotope emits alpha radiation, which is blocked by something as thin as paper or skin, so just sitting next to it wouldn't hurt you.
I think the insinuation by some authorities is that the polonium was carried into, or out of, the country was via someone who had boarded these planes, and subsequently contaminated these locations. Of course, it is not known whoever contaminated these planes had anything to do directly with Litvinenko's death.
Right now I am more concerned about the "worried well" and how they may flood the healthcare system with unjustifed worries thus placing a burden on hospitals. We have seen this in the aftermath of the anthrax attacks in the US, the Tokyo subway sarin nerve agent release, among others.