• A front page article, reporting on the nuclear crisis in Japan, said readings at the plant had reached "8,217 microsieverts per hour – described by broadcaster NHK as equivalent to eight times the radiation a person would usually experience in a year" and in a second story in the same issue – 15 March – we said that monitoring posts near the power station had "recorded radiation levels at 680 microsieverts per hour yesterday, a dose roughly equivalent to four months of natural background radiation". In both cases we compared a rate of dose with an amount of dose, which one reader suggested is not a like-for-like comparison and therefore meaningless. To clarify (we hope): NHK meant that a person who spends one hour in an area where the radiation level is 8,217 microsieverts per hour receives eight times the dose they would usually experience in a year. Our figure of 680 microsieverts over an hour is the dose a person might roughly be expected to receive at the end of four months due to natural background radiation (Race to save the reactors as Japan fears nuclear meltdown, page 1; An orange flash, a violent blast – and nuclear scare grows, page 2).
• A picture of Anish Kapoor's sculpture Her Blood misleadingly accompanied a report of a decision by the parliamentary select committee on culture that Arts Council England should sell works by leading artists in its collection. Tate Modern has asked us to make clear that this particular work belongs to the Tate Collection and is not for sale (Culture clash: MPs condemn Arts Council for spending too much money on itself, 28 March, page 3).